List of gravitational wave observations

This page contains a list of observed and candidate gravitational wave events.

The first measurement of a gravitational wave event

Origin and nomenclature

Direct observation of gravitational waves, which commenced with the detection of an event by LIGO in 2015,^[1] plays a key role in gravitational wave astronomy. LIGO has been involved in all subsequent detections to date, with Virgo joining in August 2017.^[2]

Joint observation runs of LIGO and Virgo, designated "O1, O2, etc." span many months, with months of maintenance and upgrades in-between designed to increase the instruments sensitivity and range. Within these run periods, the instruments are capable of detecting gravitational waves.

The first run, O1, ran from September 12, 2015, to January 19, 2016, and succeeded in its first gravitational wave detection. O2 ran for a greater duration, from November 30, 2016, to August 25, 2017.^[3] O3 began on April 1, 2019. The observing run was split in two, designated "O3a" and "O3b" with the first part suspended on September 30, 2019, for maintenance and upgrades. O3b began on November 1, 2019. Due to the COVID-19 pandemic^[4] O3 was forced to end prematurely.^[5] The early end meant that KAGRA did not have chance to participate in joint observations with LIGO and Virgo, so a short joint run was done in partnership with GEO. This run was designated "O3GK", and did not result in any additional detections.^[6]

O4 began on May 24, 2023; initially planned for March, the project needed more time to stabilize the instruments. The fourth observing run has been divided into three parts so far, designated "O4a", "O4b", and "O4c". The run, initially planned to end after one year, has been extended, following plans to make further upgrades for the O5 run.^[2][7] O4a started May 24, 2023 and ended January 16, 2024. O4b started April 10, 2024 and ended January 28, 2025 at 17:00 UTC. Unusually, O4c, followed directly from O4b, starting on January 28, 2025 at 17:00 UTC and is planned to continue to November 18, 2025. Updated observing plans are published on the official website, containing the latest information on these runs.^[7] There was a two month commissioning break from January to March 2024, and another from 1 April to a planned 11 June 2025, after which observations resumed.^[8] As of May 2025, O5 is planned to begin in late 2027.

Gravitational wave events are named starting with the prefix GW, while observations that trigger an event alert but have not (yet) been confirmed are named starting with the prefix S.^[9] Six digits then indicate the date of the event, with the two first digits representing the year, the two middle digits the month and two final digits the day of observation. This is similar to the systematic naming for other kinds of astronomical event observations, such as those of gamma-ray bursts.

Probable detections that are not confidently identified as gravitational wave events are designated LVT ("LIGO-Virgo trigger"). Known gravitational wave events come from the merger of two black holes (BH), two neutron stars (NS), or a black hole and a neutron star (BHNS).^[10][11] Some objects are in the mass gap (MG) between the largest predicted neutron star masses (Tolman–Oppenheimer–Volkoff limit) and the smallest known black holes.

List of gravitational wave events

• Events from LIGO & Virgo
• 
  O1 & O2/2015-2017 events
• 
  Distance and mass for events up to O4 in 2023

Confirmed events by distance 8 16 24 32 40 48 56 64 72 80 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

Initial objects by mass 9 18 27 36 45 54 63 72 81 90 1-2 M☉ 2-3 M☉ 3-5 M☉ 5-10 M☉ 10-20 M☉ 20-30 M☉ 30-40 M☉ 40-50 M☉ 50-60 M☉ 60-70 M☉ 70-80 M☉ 80-90 M☉ 90-100 M☉ 100-110 M☉ 110-120 M☉ 120-130 M☉ 130-140 M☉   neutron star   mass gap   black hole

List of binary merger events^[12][13]

GW event and time (UTC)[n 1]	Date published	Location area[n 2] (deg2)	Signal to Noise Ratio (SNR)	Luminosity distance (Mpc)[n 3]	Energy radiated/c2 (M☉) [n 4]	Chirp mass (M☉) [n 5]	Effective spin[n 6]	Primary		Secondary		Remnant			Notes	Ref.
								Type	Mass (M☉)	Type	Mass (M☉)	Type	Mass (M☉)	Spin[n 7]
GW150914 09:50:45	2016-02-11	179; mostly to the south	24.4+0.8 −0.8	430+150 −170	3.1+0.4 −0.4	28.6+1.6 −1.5	−0.01+0.12 −0.13	BH [n 8]	35.6+4.8 −3.0	BH [n 9]	30.6+3.0 −4.4	BH	63.1+3.3 −3.0	0.69+0.05 −0.04	First GW detection; first BH merger observed	[19][20][18]
GW151012 [fr] 09:54:43	2016-06-15	1555	10.0+0.5 −0.5	1060+540 −480	1.5+0.5 −0.5	15.2+2.0 −1.1	0.04+0.28 −0.19	BH	23.3+14.0 −5.5	BH	13.6+4.1 −4.8	BH	35.7+9.9 −3.8	0.67+0.13 −0.11	Formerly candidate LVT151012; accepted as astrophysical since February 2019	[21][13][12]
GW151226 03:38:53	2016-06-15	1033	13.1+0.0 −1.2	440+180 −190	1.0+0.1 −0.2	8.9+0.3 −0.3	0.18+0.20 −0.12	BH	13.7+8.8 −3.2	BH	7.7+2.2 −2.6	BH	20.5+6.4 −1.5	0.74+0.07 −0.05		[22][23]
GW170104 10:11:58	2017-06-01	924	13.0+0.0 −0.0	960+430 −410	2.2+0.5 −0.5	21.5+2.1 −1.7	−0.04+0.17 −0.20	BH	31.0+7.2 −5.6	BH	20.1+4.9 −4.5	BH	49.1+5.2 −3.5	0.66+0.08 −0.10		[14][24]
GW170608 02:01:16	2017-11-16	396; to the north	14.9+0.5 −0.8	320+120 −110	0.9+0.0 −0.1	7.9+0.2 −0.2	0.03+0.19 −0.07	BH	10.9+5.3 −1.7	BH	7.6+1.3 −2.1	BH	17.8+3.2 −0.7	0.69+0.04 −0.04	Smallest BH progenitor masses to date	[25]
GW170729 18:56:29	2018-11-30	1033	10.2+0.6 −0.4	2750+1350 −1320	4.8+1.7 −1.7	35.7+6.5 −4.7	0.36+0.21 −0.25	BH	50.6+16.6 −10.2	BH	34.3+9.1 −10.1	BH	80.3+14.6 −10.2	0.81+0.07 −0.13	Largest progenitor masses until GW190521	[13]
GW170809 08:28:21	2018-11-30	340; towards Cetus	12.4+0.0 −0.2	990+320 −380	2.7+0.6 −0.6	25.0+2.1 −1.6	0.07+0.16 −0.16	BH	35.2+8.3 −6.0	BH	23.8+5.2 −5.1	BH	56.4+5.2 −3.7	0.70+0.08 −0.09		[13]
GW170814 10:30:43	2017-09-27	87; towards Eridanus	16.3+0.9 −0.4	580+160 −210	2.7+0.4 −0.3	24.2+1.4 −1.1	0.07+0.12 −0.11	BH	30.7+5.7 −3.0	BH	25.3+2.9 −4.1	BH	53.4+3.2 −2.4	0.72+0.07 −0.05	First announced detection by three observatories; first polarization measurement	[26][27]
GW170817 12:41:04	2017-10-16	16; NGC 4993	33.0+0.0 −2.1	40±10	≥ 0.04	1.186+0.001 −0.001	0.00+0.02 −0.01	NS	1.46+0.12 −0.10	NS	1.27+0.09 −0.09	HMNS-BH [n 10]	≤ 2.8[n 11]	≤ 0.89	First NS merger observed in GW; first detection of EM counterpart (GRB 170817A; AT 2017gfo); nearest event to date	[17][31][32]
GW170818 02:25:09	2018-11-30	39; towards Pegasus	11.3+0.0 −0.0	1020+430 −360	2.7+0.5 −0.5	26.7+2.1 −1.7	−0.09+0.18 −0.21	BH	35.5+7.5 −4.7	BH	26.8+4.3 −5.2	BH	59.8+4.8 −3.8	0.67+0.07 −0.08		[13]
GW170823 13:13:58	2018-11-30	1651	11.1+0.4 −0.3	1850±840	3.3+0.9 −0.8	29.3+4.2 −3.2	0.08+0.20 −0.22	BH	39.6+10.0 −6.6	BH	29.4+6.3 −7.1	BH	65.6+9.4 −6.6	0.71+0.08 −0.10		[13]
GW190403_051519 2019-04-03 05:15:19	2022-05-11	3900	7.6+0.6 −1.1	8300+6700 −4300		34.0+15.1 −8.4	0.68+0.16 −0.43	BH	85.0+6.7 −4.3	BH	20.0+26.3 −8.4	BH	102+26 −24	0.91+0.05 −0.17		[33]
GW190408_181802 2019-04-08 18:18:02	2020-10-27	140	15.3+0.2 −0.3	1580+400 −590		18.3+1.4 −1.2	−0.03+0.13 −0.19	BH	24.5+5.1 −3.4	BH	18.3+3.2 −3.5	BH	41.0+3.8 −2.7	0.67+0.06 −0.07	Originally designated S190408an.	[34]
GW190412 2019-04-12 05:30:44	2020-04-17	156; towards Virgo or Boötes	18.9+0.2 −0.3	730+140 −170		13.3+0.4 −0.3	0.25+0.08 −0.11	BH	29.7+5.0 −5.3	BH	8.4+1.8 −1.0	BH	37.0+4.1 −3.9	0.67+0.05 −0.07	First possible observation of a merger of two black holes of very different masses. Originally designated S190412m.	[35][36]
GW190413_052954 2019-04-13	2020-10-27	1400	8.9+0.4 −0.7	4100+2410 −1890		24.0+5.4 −3.7	0.01+0.29 −0.33	BH	33.4+12.4 −7.4	BH	23.4+6.7 −6.3	BH	54.3+12.4 −8.4	0.69+0.12 −0.13		[34]
GW190413_134308 2019-04-13	2020-10-27	520	10.0+0.4 −0.5	5150+2440 −2340		31.9+7.3 −4.6	−0.01+0.24 −0.28	BH	45.4+13.6 −9.6	BH	30.9+10.2 −9.6	BH	72.8+15.2 −10.3	0.69+0.10 −0.12		[34]
GW190421_213856 2019-04-21	2020-10-27	1000	10.7+0.2 −0.4	3150+1370 −1420		30.7+5.5 −6.6	−0.05+0.23 −0.26	BH	40.6+10.4 −6.6	BH	31.4+7.5 −8.2	BH	68.6+11.7 −8.1	0.68+0.10 −0.11	Originally designated S190421ar.	[34]
GW190424_180648 2019-04-24 18:06:48	2020-10-27	26000	10.4+0.2 −0.4	2550+1560 −1330		30.3+5.7 −4.2	0.15+0.22 −0.22	BH	39.5+10.9 −6.9	BH	31.0+7.4 −7.3	BH	67.1+12.5 −9.2	0.75+0.08 −0.09		[34]
GW190425 2019-04-25 08:18:05	2020-01-06	430; towards Hercules[37]	12.4+0.3 −0.4	159+69 −72		1.44+0.02 −0.02	0.012+0.01 −0.01	NS	1.60 - 1.87	NS	1.46 - 1.69	?			Originally designated S190425z (z:26th trigger|UTC day), this trigger was detected by a single LIGO instrument (of three LVC stations), and is considered by some scientists to have been confirmed as a binary neutron star merger.[38] It was published in 2020 that a gamma-ray burst was detected (GRB 190425) ~0.5 seconds after the LIGO trigger, lasting 6 seconds and bearing similarities to GRB170817 (such as weakness [most power in sub-100 keV, or soft X-rays) bands], elevated energetic photon background levels [signal exceeding background by less than a factor of 2], and similar differences from other transients classified as short GRBs. Confidence was established for interpretation of a set of peaks through a control interval of only 2 days prior to the LIGO-Livingston trigger in INTEGRAL Electronic anticoincidence, could not be corroborated by other instruments and wasn't initially noted as a significant event. Non-detection in other instruments may be a consequence of an Earth-occulted source as the Fermi telescope attempted follow-up.[37]	[39][40]
GW190426_152155 2019-04-26 15:21:55	2020-10-27	1300	8.7+0.5 −0.6	370+180 −160		2.41+0.08 −0.08	−0.03+0.32 −0.30	BH?	5.7+3.9 −2.3	NS	1.5+0.8 −0.5	BH?			The primary object, being between 3.4 and 9.6 solar masses, is either a black hole or an object in the mass gap. Originally designated S230426c.	[34]
GW190426_190642 2019-04-26 19:06:42	2022-05-11	4600	8.7+0.4 −0.6	4600+3400 −2300		76.0+19.1 −17.4	0.23+0.42 −0.41	BH	106+45 −24	BH	76+26 −36	BH	173+38 −34	0.77+0.14 −0.16		[33]
GW190503_185404 2019-05-03 18:54:04	2020-10-27	94; towards Columba, Pictor, or Puppis	12.4+0.2 −0.3	1450+690 −630		30.2+4.2 −4.2	−0.03+0.20 −0.26	BH	43.3+9.1 −8.2	BH	28.4+7.7 −8.0	BH	68.6+8.8 −7.7	0.66+0.09 −0.12	Originally designated S230503bf.	[34]
GW190512_180714 2019-05-12 18:07:14	2020-10-27	220; towards Scorpius or Ophiuchus	12.2+0.2 −0.4	1430+550 −550		14.6+1.3 −1.0	0.03+0.12 −0.13	BH	23.3+5.3 −3.8	BH	12.6+3.6 −2.5	BH	34.5+3.8 −3.5	0.65+0.07 −0.07	Originally designated S230512at.	[34]
GW190513_205428 2019-05-13 20:54:28	2020-10-27	520; towards Sagittarius, Capricornus, Perseus, or Camelopardalis	12.9+0.3 −0.4	2060+880 −800		21.6+3.8 −1.9	0.11+0.28 −0.17	BH	35.7+9.5 −9.2	BH	18.0+7.7 −4.2	BH	51.6+8.2 −5.8	0.68+0.14 −0.12	Originally designated S230513bm.	[34]
GW190514_065416 2019-05-14 06:54:16	2020-10-27	3000	8.2+0.3 −0.6	4100+2700 −2200		28.5+7.9 −4.8	−0.19+0.29 −0.32	BH	39.0+14.7 −8.2	BH	28.4+9.3 −8.8	BH	65+18 −10	0.63+0.11 −0.15		[34]
GW190517_055101 2019-05-17 06:54:16	2020-10-27	470	10.7+0.4 −0.6	1860+1620 −840		26.6+4.0 −4.0	0.52+0.19 −0.19	BH	37.4+11.7 −7.6	BH	25.3+7.0 −7.3	BH	59.3+9.1 −8.9	0.87+0.05 −0.07	Originally designated S190517h.	[34]
GW190519_153544 2019-05-19 15:35:44	2020-10-27	860	15.6+0.2 −0.3	2530+1830 −920		44.5+6.4 −7.1	0.31+0.20 −0.22	BH	66+11 −12	BH	41+11 −11	BH	101+12 −14	0.79+0.07 −0.13	Originally designated S190519bj.	[34]
GW190521 2019-05-21 03:02:29	2020-09-02	765; towards Coma Berenices, Canes Venatici, or Phoenix	14.2+0.3 −0.3	5300+2400 −2600	7.6+2.2 −1.9	64+13 −8	0.08+0.27 −0.36	BH	85+21 −14	BH	66+17 −18	BH	142+28 −16	0.72+0.09 −0.12	Originally designated S190521g. Largest progenitor masses to date.	[41][42]
GW190521_074359 2019-05-21 07:43:59	2020-10-27	550	25.8+0.1 −0.2	1240+400 −570		32.1+3.2 −2.5	0.09+0.10 −0.13	BH	42.2+5.9 −4.8	BH	32.8+5.4 −6.4	BH	71.0+6.5 −4.4	0.72+0.05 −0.07	Originally designated S190521r.	[34]
GW190527_092055 2019-05-27 09:20:55	2020-10-27	3700	8.1+0.3 −0.9	2500+2500 −1200		24.3+9.2 −4.1	0.11+0.28 −0.28	BH	36.5+16.4 −9.0	BH	22.6+10.5 −8.1	BH	56.4+20.2 −9.3	0.71+0.12 −0.16		[34]
GW190602_175927 2019-06-02 17:59:27	2020-10-27	690	12.8+0.2 −0.3	2700+1800 −1100		49.1+9.1 −8.5	0.07+0.25 −0.24	BH	69+16 −13	BH	48+14 −17	BH	111+18 −15	0.70+0.10 −0.14	Originally designated S190602aq.	[34]
GW190620_030421 2019-06-20 03:04:21	2020-10-27	7200	12.1+0.3 −0.4	2800+1700 −1300		38.3+8.3 −6.5	0.33+0.22 −0.25	BH	57+16 −13	BH	36+12 −12	BH	87+17 −12	0.79+0.08 −0.15		[34]
GW190630_185205 2019-06-30 18:52:05	2020-10-27	1200	15.6+0.2 −0.3	890+560 −370		24.9+2.1 −2.1	0.10+0.12 −0.13	BH	35.1+6.9 −5.6	BH	23.7+5.2 −5.1	BH	56.4+4.4 −4.6	0.70+0.05 −0.07	Originally designated S190630ag.	[34]
GW190701_203306 2019-07-01 20:33:06	2020-10-27	46; towards Eridanus or Cetus	11.3+0.2 −0.3	2060+760 −730		40.3+5.4 −4.9	−0.07+0.23 −0.29	BH	53.9+11.8 −8.0	BH	40.8+8.7 −12.0	BH	90.2+11.3 −8.9	0.66+0.09 −0.13	Originally designated S190701ah.	[34]
GW190706_222641 2019-07-06 22:26:41	2020-10-27	650	12.6+0.2 −0.4	4400+2600 −1900		42.7+10.0 −7.0	0.28+0.26 −0.29	BH	67+15 −16	BH	38+15 −13	BH	99+18 −14	0.78+0.09 −0.18	Originally designated S190706ai.	[34]
GW190707_093326 2019-07-07 09:33:26	2020-10-27	1300	13.3+0.2 −0.4	770+380 −270		8.5+0.7 −0.6	−0.05+0.10 −0.08	BH	11.6+3.3 −1.7	BH	8.4+1.4 −1.7	BH	19.2+1.9 −1.3	0.66+0.03 −0.04	Originally designated S190707q.	[34]
GW190708_232457 2019-07-08 23:24:57	2020-10-27	14000	13.1+0.2 −0.3	880+330 −390		13.2+0.9 −0.6	0.02+0.08 −0.10	BH	17.6+4.7 −2.3	BH	13.2+2.0 −2.7	BH	29.5+2.5 −1.8	0.69+0.04 −0.04		[34]
GW190719_215514 2019-07-09 21:55:14	2020-10-27	2900	8.3+0.3 −0.8	3900+2600 −2000		23.5+6.5 −4.0	0.32+0.29 −0.31	BH	37+18 −10	BH	20.8+9.0 −7.2	BH	55+17 −10	0.78+0.11 −0.17		[34]
GW190720_000836 2019-07-20 00:08:36	2020-10-27	460; mostly towards Cygnus	11.0+0.3 −0.7	790+690 −320		8.9+0.5 −0.8	0.18+0.14 −0.12	BH	13.4+6.7 −3.0	BH	7.8+2.3 −2.2	BH	20.4+4.5 −2.2	0.72+0.06 −0.05	Originally designated S190720a.	[34]
GW190725_174728 2019-07-25 17:47:28	2022-05-11	2200	9.1+0.4 −0.7	1030+520 −430		7.4±0.5	−0.04+0.36 −0.16	BH	11.8+10.1 −3.0	BH?	6.3+2.1 −2.5	BH	17.6+7.7 −1.8	0.65+0.09 −0.07		[33]
GW190727_060333 2019-07-27 06:03:33	2020-10-27	830	11.9+0.3 −0.5	790+690 −320		28.6+5.3 −3.7	0.11+0.26 −0.25	BH	38.0+9.5 −6.2	BH	29.4+7.1 −8.4	BH	63.8+10.9 −7.5	0.73+0.10 −0.10	Originally designated S190727h.	[34]
GW190728_064510 2019-07-28 06:45:10	2020-10-27	400	13.0+0.2 −0.4	870+260 −370		8.6+0.5 −0.3	0.12+0.20 −0.07	BH	12.3+7.2 −2.2	BH	8.1+1.7 −2.6	BH	19.6+4.7 −1.3	0.71+0.04 −0.04	Originally designated S190728q.	[34]
GW190731_140936 2019-07-31 14:09:36	2020-10-27	3400	8.7+0.2 −0.5	3300+2400 −1700		29.5+7.1 −5.2	0.06+0.24 −0.24	BH	41.5+12.2 −9.0	BH	28.8+9.7 −9.5	BH	67+15 −11	0.70+0.10 −0.13		[34]
GW190803_022701 2019-08-03 02:27:01	2020-10-27	1500	8.6+0.3 −0.5	3300+2000 −1600		27.3+5.7 −4.1	−0.03+0.24 −0.27	BH	37.3+10.6 −7.0	BH	27.3+7.8 −8.2	BH	61.7+11.8 −8.5	0.68+0.10 −0.11		[34]
GW190805_211137 2019-08-05 21:11:37	2022-05-11	1600	8.1+0.5 −0.7	6100+3700 −3100		31.9+8.8 −6.3	0.37+0.29 −0.39	BH	46+15 −11	BH	31+12 −11	BH	72+18 −13	0.82+0.09 −0.16		[33]
GW190814 2019-08-14 21:11:18	2020-06-23	18.5; towards Cetus or Sculptor[citation needed]	24.9+0.1 −0.2	241+41 −45		6.09+0.06 −0.06	−0.002+0.06 −0.061	BH	23.2+1.1 −1.0	MG	2.59+0.08 −0.09	BH	25.6+1.1 −0.9	0.28+0.02 −0.02	No optical counterpart was discovered despite an extensive search of the probability region. The mass of the lighter component is estimated to be 2.6 times the mass of the Sun, placing it in the mass gap between neutron stars and black holes.[43]	[44][45][46][47][48] [49][50][51][52]
GW190828_063405 2019-08-28 06:34:05	2020-10-27	520	16.2+0.2 −0.3	2130+660 −930		25.0+3.4 −2.1	0.19+0.15 −0.16	BH	32.1+5.8 −4.0	BH	26.2+4.6 −4.8	BH	54.9+7.2 −4.3	0.75+0.06 −0.07	Originally designated S190828j.	[34]
GW190828_065509 2019-08-28 06:55:09	2020-10-27	660	10.0+0.3 −0.5	1600+620 −600		13.3+1.2 −1.0	0.08+0.16 −0.16	BH	24.1+7.0 −7.2	BH	10.2+3.6 −2.1	BH	33.1+5.5 −4.5	0.65+0.08 −0.08	Originally designated S190828l.	[34]
GW190909_114149 2019-09-09 11:41:49	2020-10-27	4700	8.1+0.4 −0.6	3800+3300 −2200		30.9+17.2 −7.5	−0.06+0.37 −0.37	BH	46+53 −13	BH	28+13 −13	BH	72+55 −17	0.66+0.15 −0.20		[34]
GW190910_112807 2019-09-10 11:28:07	2020-10-27	11000	14.1+0.2 −0.3	1460+1030 −580		34.3+4.1 −4.1	0.02+0.18 −0.18	BH	43.9+7.6 −6.1	BH	35.6+6.3 −7.2	BH	75.8+8.5 −8.6	0.70+0.08 −0.07		[34]
GW190915_235702 2019-09-15 23:57:02	2020-10-27	400; towards Coma Berenices, Canes Venatici, or Ursa Major	13.6+0.2 −0.3	1620+710 −610		25.3+3.2 −2.7	0.02+0.20 −0.25	BH	35.3+9.5 −6.4	BH	24.4+5.6 −6.1	BH	57.2+7.1 −6.0	0.70+0.09 −0.11	Originally designated S230915ak.	[34]
GW190916_200658 2019-09-16 20:06:58	2022-05-11	2400	8.1+0.3 −0.5	4900+3700 −2400		26.9+8.2 −5.4	0.20+0.33 −0.31	BH	44+20 −13	BH	23+13 −11	BH	65+17 −13	0.74+0.13 −0.24		[33]
GW190917_114630 2019-09-17 11:46:30	2022-05-11	1700	8.3+0.5 −0.8	720+300 −310		3.7±0.2	−0.08+0.21 −0.43	BH	9.7+3.4 −3.9	MG?	2.1+1.1 −0.4	BH	11.6+3.1 −2.9	0.42+0.14 −0.05		[33]
GW190924_021846 2019-09-24 02:18:46	2020-10-27	360; towards Hydra or Cancer	11.5+0.3 −0.4	570+220 −220		5.8+0.2 −0.2	0.03+0.30 −0.09	BH	8.9+7.0 −2.0	BH?	5.0+1.4 −1.9	BH	13.3+5.2 −1.0	0.67+0.05 −0.05	The secondary component, being between 3.1 and 6.4 solar masses, is either a black hole or an object in the mass gap. Originally designated S230924h.	[34]
GW190925_232845 2019-09-25 23:28:45	2022-05-11	2900	9.7+0.3 −0.6	930+460 −350		15.6±1.1	0.09+0.16 −0.15	BH	20.8+6.5 −2.9	BH	15.5+2.5 −3.6	BH	34.9+3.5 −2.6	0.71±0.06		[33]
GW190926_050336 2019-09-26 05:03:36	2022-05-11	2000	8.1+0.6 −0.8	3300+3400 −1700		24.4+9.0 −4.9	−0.02+0.25 −0.32	BH	41+21 −13	BH	20.4+11.4 −8.2	BH	60+22 −12	0.64+0.14 −0.20		[33]
GW190929_012149 2019-09-29 01:21:49	2020-10-27	2200	10.1+0.6 −0.8	2100+3700 −1100		35.8+14.9 −8.2	0.01+0.34 −0.33	BH	81+33 −33	BH	24+19 −11	BH	102+34 −25	0.66+0.20 −0.31		[34]
GW190930_133541 2019-09-30 13:35:41	2020-10-27	1700	9.5+0.3 −0.5	760+360 −320		8.5+0.5 −0.5	0.14+0.31 −0.15	BH	12.3+12.4 −2.3	BH?	7.8+1.7 −3.3	BH	19.4+9.2 −1.5	0.72+0.07 −0.06	The secondary component, being between 4.5 and 9.5 solar masses, is either a black hole or an object in the mass gap. Originally designated S190930s.	[34]
GW191103 2019-11-03 01:25:49	2021-11-17	2500	8.9+0.3 −0.5	990+500 −470		8.34+0.66 −0.57	0.21+0.16 −0.10	BH	11.8+6.2 −2.2	BH	7.9+1.7 −2.4	BH	19.0+3.8 −1.7	0.75+0.06 −0.05		[5]
GW191105 2019-11-05 14:35:21	2021-11-17	640	9.7+0.3 −0.5	1150+430 −480		7.82+0.61 −0.45	−0.02+0.13 −0.09	BH	10.7+3.7 −1.6	BH	7.7+1.4 −1.9	BH	17.6+2.1 −1.2	0.67+0.04 −0.05	Originally designated S191105e.	[5]
GW191109 2019-11-09 01:07:17	2021-11-17	1600	17.3+0.5 −0.5	1290+1130 −650		47.5+9.6 −7.5	−0.29+0.42 −0.31	BH	65+11 −11	BH	47+15 −13	BH	107+18 −15	0.61+0.18 −0.19	Originally designated S191109d.	[5]
GW191113 2019-11-13 07:17:53	2021-11-17	3600	7.9+0.5 −1.1	1290+1130 −650		10.7+1.1 −1.0	0.00+0.37 −0.29	BH	29+12 −14	BH	5.9+4.4 −1.3	BH	34+11 −10	0.45+0.33 −0.11		[5]
GW191126 2019-11-26 11:52:59	2021-11-17	1400	8.3+0.2 −0.5	1620+740 −740		8.65+0.95 −0.71	0.21+0.15 −0.11	BH	12.1+5.5 −2.2	BH	8.3+1.9 −2.4	BH	19.6+3.5 −2.0	0.75+0.06 −0.05		[5]
GW191127 2019-11-27 05:02:27	2021-11-17	980	9.2+0.7 −0.6	3400+3100 −1900		29.9+11.7 −9.1	0.18+0.34 −0.36	BH	53+47 −20	BH	24+17 −14	BH	76+31 −29	0.75+0.13 −0.29		[5]
GW191129 2019-11-29 13:40:29	2021-11-17	850	13.1+0.2 −0.3	790+260 −330		7.31+0.43 −0.28	0.06+0.18 −0.06	BH	10.7+4.1 −2.1	BH	6.7+1.5 −1.7	BH	16.8+2.5 −1.2	0.69+0.03 −0.05	Originally designated S191129u.	[5]
GW191204_110529 2019-12-04 11:05:29	2021-11-17	3700	8.8+0.4 −0.6	1800+1700 −1100		19.8+3.6 −3.3	0.05+0.26 −0.27	BH	27.3+11.0 −6.0	BH	19.3+5.6 −6.0	BH	45.0+8.6 −7.6	0.71+0.12 −0.11		[5]
GW191204_171526 2019-12-04 17:15:26	2021-11-17	350; towards Pictor, Caelum, or Eridanus	17.5+0.2 −0.2	650+190 −250		8.55+0.38 −0.27	0.16+0.08 −0.05	BH	11.9+3.3 −1.8	BH	8.2+1.4 −1.6	BH	19.21+1.79 −0.95	0.73+0.03 −0.03	Originally designated S191204r.	[5]
GW191215 2019-12-15 22:30:52	2021-11-17	530	11.2+0.3 −0.4	1930+890 −860		18.4+2.2 −1.7	−0.04+0.17 −0.21	BH	24.9+7.1 −4.1	BH	18.1+3.8 −4.1	BH	41.4+5.1 −4.1	0.68+0.07 −0.07	Originally designated S191215w.	[5]
GW191216 2019-12-16 21:33:38	2021-11-17	490	18.6+0.2 −0.2	340+120 −130		8.33+0.22 −0.19	0.11+0.13 −0.06	BH	12.1+4.6 −2.3	BH	7.7+1.6 −1.9	BH	18.87+2.80 −0.94	0.70+0.03 −0.04	Originally designated S191216ap.	[5]
GW191219 2019-12-19 16:31:20	2021-11-17	1500	9.1+0.5 −0.8	550+250 −160		4.32+0.12 −0.17	0.00+0.07 −0.09	BH	31.1+2.2 −2.8	NS	1.17+0.07 −0.06	BH	32.2+2.2 −2.7	0.14+0.06 −0.06	The event is unconfirmed due to difficulty accurately modelling the extreme mass ratio.	[5]
GW191222 2019-12-22 03:35:37	2021-11-17	2000	12.5+0.2 −0.3	3000+1700 −1700		33.8+7.1 −5.0	−0.04+0.20 −0.25	BH	45.1+10.9 −8.0	BH	34.7+9.3 −10.5	BH	75.5+15.3 −9.9	0.67+0.08 −0.11	Originally designated S191222n.	[5]
GW191230 2019-12-30 18:04:58	2021-11-17	1100	10.4+0.3 −0.4	4300+2100 −1900		36.5+8.2 −5.6	−0.05+0.26 −0.31	BH	49.4+14.0 −9.6	BH	37+11 −12	BH	82+17 −11	0.68+0.11 −0.13		[5]
GW200105 2020-01-05 16:24:26	2021-06-29	7200	13.7+0.2 −0.4	280±110		3.41+0.08 −0.07	−0.01+0.11 −0.15	BH	8.9+1.2 −1.5	NS	1.9+0.3 −0.2	BH	10.4+2.7 −2.0	0.43+0.04 −0.03	First event confirmed to be a black hole and neutron star merger. Originally designated S200105ae.	[53][54]
GW200112 2020-01-12 15:58:38	2021-11-17	4300	19.8+0.1 −0.2	1250+430 −460		27.4+2.6 −2.1	0.06+0.15 −0.15	BH	35.6+6.7 −4.5	BH	28.3+4.4 −5.9	BH	60.8+5.3 −4.3	0.71+0.06 −0.06	Originally designated S200112r.	[5]
GW200114 2020-01-14 02:08:08	2022-08-18	403; towards Gemini, Orion, or Eridanus		1250+1500 −400		68+6 −4	−0.75+0.50 −0.15	BH	78+10 −10	BH	70+10 −10	BH	140+15 −15		Originally designated S200114f. The event was initially published as an unmodeled gravitational wave burst, and different studies have offered conflicting interpretations. One study suggested it was a nearby high-mass black hole merger with component masses of 118+10 −12 and 89+18 −8 Msun which was poorly modeled because of its high mass.[55] Another study interpreted it as a somewhat smaller black hole merger taking place at the same time as a detector glitch.[56] Both studies conclude the signal is most likely a real event, and the latter model is included in the table.	[55][56]
GW200115 2020-01-15 04:23:09	2021-06-29	600	11.3+0.3 −0.5	300+150 −100		2.42+0.05 −0.07	−0.19+0.23 −0.35	BH	5.7+1.8 −2.1	NS	1.5+0.7 −0.3	BH	7.8+1.4 −1.6	0.38+0.04 −0.03	Second event confirmed to be a black hole and neutron star merger. Originally designated S200115j.	[53][57]
GW200128 2020-01-28 02:20:11	2021-11-17	2600	10.6+0.3 −0.4	3400+2100 −1800		32.0+7.5 −5.5	0.12+0.24 −0.25	BH	42.2+11.6 −8.1	BH	32.6+9.5 −9.2	BH	71+16 −11	0.74+0.10 −0.10	Originally designated S200128d.	[5]
GW200129 2020-01-29 06:54:58	2021-11-17	130; towards Equuleus, Delphinus, or Vulpecula	26.8+0.2 −0.2	900+290 −380		27.2+2.1 −2.3	0.11+0.11 −0.16	BH	34.5+9.9 −3.2	BH	28.9+3.4 −9.3	BH	60.3+4.0 −3.3	0.73+0.06 −0.05	Originally designated S200129m.	[5]
GW200202 2020-02-02 15:43:12	2021-11-17	170	10.8+0.2 −0.4	410+150 −160		7.49+0.24 −0.20	0.04+0.13 −0.06	BH	10.1+3.5 −1.4	BH	7.3+1.1 −1.7	BH	16.76+1.87 −0.66	0.69+0.03 −0.04		[5]
GW200208_130117 2020-02-08 13:01:17	2021-11-17	30; towards Pyxis or Antlia	10.8+0.3 −0.4	2230+1000 −850		27.7+3.6 −3.1	−0.07+0.22 −0.27	BH	37.8+9.2 −8.2	BH	27.5+6.1 −7.4	BH	62.5+7.3 −6.4	0.66+0.09 −0.13	Originally designated S200208q.	[5]
GW200208_222617 2020-02-08 22:26:17	2021-11-17	2000	7.4+1.4 −1.2	4100+4400 −1900		19.6+10.7 −5.1	0.45+0.43 −0.44	BH	51+104 −30	BH	12.3+9.0 −5.7	BH	61+100 −25	0.83+0.14 −0.27		[5]
GW200209 2020-02-09 08:54:52	2021-11-17	730	9.6+0.4 −0.5	3400+1900 −1800		26.7+6.0 −4.2	−0.12+0.24 −0.30	BH	35.6+10.5 −6.8	BH	27.1+7.8 −7.8	BH	59.9+13.1 −8.9	0.66+0.10 −0.12		[5]
GW200210 2020-02-10 09:22:54	2021-11-17	1800	8.4+0.5 −0.7	940+430 −340		6.56+0.38 −0.40	0.02+0.22 −0.21	BH	24.1+7.5 −4.6	MG	2.83+0.47 −0.42	BH	26.7+7.2 −4.3	0.34+0.13 −0.08	The secondary component, being between 2.41 and 3.30 solar masses, is an object in the mass gap.	[5]
GW200216 2020-02-16 22:08:04	2021-11-17	2900	8.1+0.4 −0.5	3800+3000 −2000		32.9+9.3 −8.5	0.10+0.34 −0.36	BH	51+22 −13	BH	30+14 −16	BH	78+19 −13	0.70+0.14 −0.24		[5]
GW200219 2020-02-19 09:44:15	2021-11-17	700	10.7+0.3 −0.5	3400+1700 −1500		27.6+5.6 −3.8	−0.08+0.23 −0.29	BH	37.5+10.1 −6.9	BH	27.9+7.4 −8.4	BH	62.2+11.7 −7.8	0.66+0.10 −0.13	Originally designated S200219ac.	[5]
GW200220_061928 2020-02-20 06:19:28	2021-11-17	3000	7.2+0.4 −0.7	6000+4800 −3100		62+23 −15	0.06+0.40 −0.38	BH	87+40 −23	BH	61+26 −25	BH	141+51 −31	0.71+0.15 −0.17		[5]
GW200220_124850 2020-02-20 12:48:50	2021-11-17	3200	8.5+0.3 −0.5	4000+2800 −2200		28.2+7.3 −5.1	−0.07+0.27 −0.33	BH	38.9+14.1 −8.6	BH	27.9+9.2 −9.0	BH	64+16 −11	0.67+0.11 −0.14		[5]
GW200224 2020-02-24 22:22:34	2021-11-17	50; towards Virgo or Crater	20.0+0.2 −0.2	1710+490 −640		31.1+3.2 −2.6	0.10+0.15 −0.15	BH	40.0+6.9 −4.5	BH	32.5+5.0 −7.2	BH	68.6+6.6 −4.7	0.73+0.07 −0.07	Originally designated S200224ca.	[5]
GW200225 2020-02-25 06:04:21	2021-11-17	370; towards Ursa Minor or Cepheus	12.5+0.3 −0.4	1150+510 −530		14.2+1.5 −1.4	−0.12+0.17 −0.28	BH	19.3+5.0 −3.0	BH	14.0+2.8 −3.5	BH	32.1+3.5 −2.8	0.66+0.07 −0.13	Originally designated S200225q.	[5]
GW200302 2020-03-02 01:58:11	2021-11-17	6000	10.8+0.3 −0.4	1480+1020 −700		23.4+4.7 −3.0	0.01+0.25 −0.26	BH	37.8+8.7 −8.5	BH	20.0+8.1 −5.7	BH	55.5+8.9 −8.6	0.66+0.13 −0.15	Originally designated S200302c.	[5]
GW200306 2020-03-06 09:37:14	2021-11-17	4600	7.8+0.4 −0.6	2100+1700 −1100		17.5+3.5 −3.0	0.32+0.28 −0.46	BH	28.3+17.1 −7.7	BH	14.8+6.5 −6.4	BH	41.7+12.3 −6.9	0.78+0.11 −0.26		[5]
GW200308 2020-03-08 17:36:09	2021-11-17	2000	7.1+0.5 −0.5	5400+2700 −2600		19.0+4.8 −2.8	0.65+0.21 −0.17	BH	36.4+11.2 −9.6	BH	13.8+7.2 −3.3	BH	47.4+11.1 −7.7	0.91+0.03 −0.08		[5]
GW200311 2020-03-11 11:58:53	2021-11-17	35; towards Cetus	17.8+0.2 −0.2	1170+280 −400		26.6+2.4 −2.0	−0.02+0.16 −0.20	BH	34.2+6.4 −3.8	BH	27.7+4.1 −5.9	BH	59.0+4.8 −3.9	0.69+0.07 −0.08	Originally designated S200311bg.	[5]
GW200316 2020-03-16 21:57:56	2021-11-17	190	10.3+0.4 −0.7	1120+470 −440		8.75+0.62 −0.55	0.13+0.27 −0.10	BH	13.1+10.2 −2.9	BH	7.8+1.9 −2.9	BH	20.2+7.4 −1.9	0.70+0.04 −0.04	Originally designated S200316bj.	[5]
GW200322 2020-03-22 09:11:33	2021-11-17	6500	6.0+1.7 −1.2	3600+7000 −2000		15.5+15.7 −3.7	0.24+0.45 −0.51	BH	34+48 −18	BH	14.0+16.8 −8.7	BH	53+38 −26	0.78+0.16 −0.17		[5]
GW230518 2023-05-18 12:59:08	2025-08-25	490	14.2+0.2 −0.4	237+108 −98		2.80±0.06	−0.01+0.09 −0.11	BH	8.17+0.84 −0.92	NS	1.45+0.13 −0.10	BH	9.46+0.76 −0.80	0.38±0.03	Originally designated S230518h.	[58]
GW230529 2023-05-29 18:15:00	2024-04-05	24000	11.6+0.3 −0.4	201+103 −96		1.94+0.04 −0.04	−0.1+0.12 −0.18	MG	3.66+0.82 −1.21	NS	1.42+0.60 −0.22	BH?	4.92+0.62 −0.63	0.58+0.08 −0.06	Originally designated S230529ay. Was detected using only the LIGO Livingston detector. It provides strong support for the primary object to be within the mass gap.	[59][58]
GW230601 2023-06-01 22:41:34	2025-08-25	3300	12.3+0.2 −0.3	600+280 −260		45.0+10.0 −7.3	−0.03+0.27 −0.32	BH	64+17 −13	BH	44+14 −15	BH	102+21 −14	0.67+0.12 −0.13	Originally designated S230601bf.	[58]
GW230605 2023-06-05 06:53:43	2025-08-25	1000	10.5+0.3 −0.4	1100+600 −500		11.9+1.0 −0.9	0.06+0.16 −0.10	BH	17.2+6.5 −3.5	BH	11.1+2.5 −2.7	BH	27.3+4.1 −2.7	0.69±0.05	Originally designated S230605o.	[58]
GW230606 2023-06-06 00:43:05	2025-08-25	1400	10.3+0.3 −0.4	2700+1500 −1400		26.5+5.7 −3.6	−0.10±0.30	BH	37.6+13.4 −7.6	BH	25.8+8.1 −8.3	BH	60.7+12.8 −7.9	0.64+0.11 −0.14	Originally designated S230606d.	[58]
GW230608 2023-06-08 20:50:47	2025-08-25	2200	9.8+0.3 −0.5	3500+2200 −1700		32.8+7.3 −5.4	−0.04+0.25 −0.26	BH	48+13 −11	BH	31+11 −10	BH	75+15 −11	0.69+0.11 −0.14	Originally designated S230608as.	[58]
GW230609 2023-06-09 06:49:58	2025-08-25	1700	9.8+0.3 −0.5	3400+1900 −1700		25.5+5.8 −3.6	−0.10+0.20 −0.30	BH	35.3+10.7 −6.9	BH	25.2±7.5	BH	57.8+12.2 −7.7	0.64+0.09 −0.13	Originally designated S230609u.	[58]
GW230624 2023-06-24 11:31:03	2025-08-25	1300	9.7+0.4 −0.5	1900+1300 −1000		18.0+3.2 −2.4	0.20±0.30	BH	27.2+13.4 −6.9	BH	16.1+4.8 −4.5	BH	41.8+10.7 −6.3	0.72+0.12 −0.11	Originally designated S230624av.	[58]
GW230627 2023-06-27 01:53:37	2025-08-25	110	28.5±0.1	310+60 −130		6.02+0.16 −0.07	0.02+0.08 −0.03	BH	8.37+1.67 −1.26	BH	5.79+0.95 −0.92	BH	13.5+0.8 −0.5	0.68+0.02 −0.03	Originally designated S230627c.	[58]
GW230628 2023-06-28 23:12:00	2025-08-25	660	15.5+0.2 −0.3	2300+800 −1100		25.5+3.8 −2.2	−0.01±0.16	BH	32.5+5.9 −3.9	BH	27.1+4.9 −5.2	BH	56.5+8.1 −4.6	0.69+0.08 −0.06	Originally designated S230628ax.	[58]
GW230630_125806 2023-06-30 12:58:06	2025-08-25	4300	8.1+0.4 −0.5	5400+5100 −3000		35.0+11.4 −8.5	0.20±0.30	BH	51+20 −14	BH	33+15 −13	BH	80+25 −18	0.75+0.11 −0.16	Originally designated S230630am.	[58]
GW230630_234532 2023-06-30 23:45:32	2025-08-25	1500	9.4+0.3 −0.5	1100±500		7.06+0.57 −0.48	−0.04+0.16 −0.08	BH	10.0+3.5 −1.8	BH	6.64+1.46 −1.59	BH	16.1+2.1 −1.4	0.66+0.04 −0.05	Originally designated S230630bq.	[58]
GW230702 2023-07-02 18:54:53	2025-08-25	2500	9.5+0.3 −0.5	2400+1900 −1100		22.9+4.0 −3.5	0.05+0.29 −0.26	BH	40+20 −13	BH	18.0+8.5 −6.5	BH	57+15 −11	0.64+0.13 −0.15	Originally designated S230702an.	[58]
GW230704_021211 2023-07-04 02:12:11	2025-08-25	1500	9.0+0.3 −0.5	2700+1800 −1500		21.8+4.4 −3.2	−0.01+0.21 −0.24	BH	32.4+11.9 −7.9	BH	19.9+6.5 −6.0	BH	50.5+10.6 −7.9	0.66+0.10 −0.13	Originally designated S230704f.	[58]
GW230704_212616 2023-07-04 21:26:16	2025-08-25	7400	8.0+1.0 −1.0	7200+6100 −4200		55+23 −14	0.30+0.30 −0.40	BH	89+42 −27	BH	49+30 −25	BH	132+47 −30	0.77+0.12 −0.19	Originally designated S230704bd.	[58]
GW230706 2023-07-06 10:43:33	2025-08-25	1500	9.0+0.3 −0.5	1900+900 −1000		11.8+1.7 −1.1	0.20±0.10	BH	16.3+5.4 −3.0	BH	11.5+2.6 −2.7	BH	26.5+4.3 −2.8	0.75+0.07 −0.06	Originally designated S230706ah.	[58]
GW230707 2023-07-07 12:40:47	2025-08-25	3200	10.6+0.2 −0.4	4500±2300		35.1+8.6 −5.3	−0.05+0.25 −0.29	BH	46.1+12.2 −8.2	BH	36.4+10.6 −9.8	BH	78+18 −11	0.68+0.09 −0.10	Originally designated S230707ai.	[58]
GW230708_053705 2023-07-08 05:37:05	2025-08-25	1900	8.3+0.4 −0.6	3300+2000 −1700		22.2+4.4 −3.3	0.07+0.23 −0.24	BH	29.1+8.2 −5.4	BH	22.8+5.5 −5.4	BH	49.4+9.7 −7.2	0.72±0.09	Originally designated S230708t.	[58]
GW230708_230935 2023-07-08 23:09:35	2025-08-25	2600	9.2+0.3 −0.5	3500+2300 −1600		42.5+9.7 −7.8	0.01+0.27 −0.30	BH	64+20 −15	BH	39+14 −15	BH	98+20 −15	0.67+0.12 −0.16	Originally designated S230708cf.	[58]
GW230709 2023-07-09 12:27:27	2025-08-25	3600	8.5+0.3 −0.5	4600+3500 −2400		31.0+9.4 −6.6	0.08+0.30 −0.31	BH	45+16 −11	BH	30±13	BH	71+19 −13	0.71+0.12 −0.15	Originally designated S230709bi.	[58]
GW230712 2023-07-12 09:04:05	2025-08-25	1400	8.0±1.0	2000+2600 −1000		16.5+11.1 −3.2	−0.03+0.35 −0.31	BH	32+17 −10	BH	13.1+14.6 −5.9	BH	45+20 −11	0.66+0.17 −0.22	Originally designated S230712aj.	[58]
GW230723 2023-07-23 10:18:34	2025-08-25	1100	9.7+0.3 −0.5	1600+700 −900		11.4+1.6 −0.9	−0.20±0.20	BH	16.7+5.9 −3.4	BH	10.6±2.8	BH	26.4+4.2 −2.6	0.61+0.09 −0.08	Originally designated S230723ac.	[58]
GW230726 2023-07-26 00:29:40	2025-08-25	28000	10.2+0.2 −0.4	2000+1200 −1000		27.3+4.4 −3.4	−0.02+0.21 −0.23	BH	35.6+9.0 −5.9	BH	27.9±6.0	BH	60.6+9.7 −7.4	0.69±0.08	Originally designated S230726a.	[58]
GW230729 2023-07-29 08:23:17	2025-08-25	2200	8.2+0.3 −0.6	1600±800		8.33+0.94 −0.75	0.10+0.20 −0.10	BH	12.3+7.6 −2.7	BH	7.62+2.12 −2.63	BH	19.4+5.1 −2.4	0.71±0.06	Originally designated S230729z.	[58]
GW230731 2023-07-31 21:53:07	2025-08-25	710	11.9+0.2 −0.3	1100+300 −500		7.77+0.58 −0.36	−0.05+0.11 −0.06	BH	10.4+2.9 −1.4	BH	7.80+1.24 −1.64	BH	17.4+1.6 −1.0	0.67+0.04 −0.03	Originally designated S230731an.	[58]
GW230803 2023-08-03 03:34:12	2025-08-25	4100	7.7+0.4 −0.6	4900+4000 −2600		30.5+9.3 −6.7	0.06+0.29 −0.31	BH	45+19 −12	BH	28+12 −10	BH	70+21 −15	0.71+0.12 −0.14	Originally designated S230803d.	[58]
GW230805 2023-08-05 03:42:49	2025-08-25	2400	9.0+0.3 −0.5	3500+2600 −1700		23.1+5.9 −4.2	0.06+0.27 −0.28	BH	32.1+12.5 −7.3	BH	22.6+7.8 −7.5	BH	52.4+13.0 −9.2	0.71+0.11 −0.12	Originally designated S230805x.	[58]
GW230806 2023-08-06 20:40:41	2025-08-25	4600	8.5+0.3 −0.5	5500+3700 −2900		35.8+10.7 −6.9	0.08+0.28 −0.27	BH	51+18 −12	BH	35+14 −13	BH	81+23 −15	0.71+0.11 −0.13	Originally designated S230806ak.	[58]
GW230811 2023-08-11 03:21:16	2025-08-25	940	12.8+0.3 −0.4	2100+1200 −1100		24.0+4.1 −2.4	0.02±0.18	BH	35.6+8.7 −7.5	BH	22.1+6.7 −5.1	BH	55.3+8.3 −6.4	0.69±0.09	Originally designated S230811n.	[58]
GW230814_061920 2023-08-14 06:19:20	2025-08-25	5200	9.4+0.3 −0.5	4000+3400 −2000		45.5+11.9 −9.9	0.05+0.29 −0.28	BH	69+19 −17	BH	42+17 −16	BH	105+24 −19	0.69+0.12 −0.14	Originally designated S230814r.	[58]
GW230814_230901 2023-08-14 23:09:01	2025-08-25	26000	42.1±0.1	280+170 −130		26.7+0.9 −1.0	−0.01+0.06 −0.08	BH	33.6+2.8 −2.2	BH	28.3+2.1 −3.0	BH	58.9±1.9	0.68+0.02 −0.03	Originally designated S230814ah.	[58]
GW230819 2023-08-19 17:19:10	2025-08-25	4800	8.9+0.4 −0.5	4000+3900 −2200		42+14 −11	−0.04+0.36 −0.43	BH	70+47 −21	BH	35+20 −19	BH	102+41 −22	0.64+0.19 −0.25	Originally designated S230819ax.	[58]
GW230820 2023-08-20 21:25:15	2025-08-25	2100	8.4+0.4 −0.5	4000+3000 −2100		38.6+11.2 −9.8	0.20±0.30	BH	62+23 −15	BH	34±18	BH	92+21 −16	0.74+0.12 −0.25	Originally designated S230820bq.	[58]
GW230824 2023-08-24 03:30:47	2025-08-25	3700	10.0+0.2 −0.4	4700+2900 −2300		37.0+9.1 −6.3	0.00+0.23 −0.27	BH	52+16 −12	BH	36+12 −13	BH	84+19 −13	0.68+0.10 −0.13	Originally designated S230824r.	[58]
GW230825 2023-08-25 04:13:34	2025-08-25	3400	8.1+0.5 −0.6	4900+4200 −2900		29.4+9.4 −6.3	0.30+0.20 −0.30	BH	43+17 −12	BH	27.3+11.9 −8.9	BH	67+20 −15	0.79+0.08 −0.15	Originally designated S230825k.	[58]
GW230831 2023-08-31 01:54:14	2025-08-25	4000	8.1+0.3 −0.7	4900+4200 −2900		30.7+10.6 −6.5	0.03±0.30	BH	42+18 −12	BH	30+12 −10	BH	69+24 −14	0.71±0.12	Originally designated S230831e.	[58]
GW230904 2023-09-04 05:10:13	2025-08-25	1800	10.2+0.3 −0.5	1000+600 −400		7.54+0.53 −0.60	0.05+0.17 −0.07	BH	10.6+4.1 −1.9	BH	7.12+1.52 −1.88	BH	17.1+2.5 −1.6	0.69±0.04	Originally designated S230904n.	[58]
GW230911 2023-09-11 19:53:24	2025-08-25	27000	10.6+0.3 −0.4	1400+1200 −700		23.1+3.4 −3.0	−0.03+0.19 −0.23	BH	33.6+8.1 −7.3	BH	21.7+5.6 −5.7	BH	53.0+7.4 −6.7	0.67+0.09 −0.11	Originally designated S230911ae.	[58]
GW230914 2023-09-14 11:14:01	2025-08-25	1900	16.2+0.2 −0.3	2700+1600 −1200		39.6+7.5 −6.2	0.10±0.20	BH	59+12 −11	BH	36+13 −12	BH	90.9+14.0 −9.7	0.71+0.09 −0.14	Originally designated S230914ak.	[58]
GW230919 2023-09-19 21:57:12	2025-08-25	730	15.7+0.2 −0.3	1300+800 −500		21.0+1.8 −1.9	0.20±0.10	BH	27.3+5.5 −3.7	BH	21.4+3.5 −4.3	BH	46.5+3.9 −4.3	0.75+0.06 −0.05	Originally designated S230919bj.	[58]
GW230920 2023-09-20 07:11:24	2025-08-25	2100	10.1+0.3 −0.4	2900+1800 −1400		23.9+4.6 −3.4	0.00+0.22 −0.23	BH	32.4+9.1 −6.2	BH	23.8+6.6 −6.9	BH	53.9+9.6 −7.6	0.69±0.10	Originally designated S230920al.	[58]
GW230922_020344 2023-09-22 02:03:44	2025-08-25	330; towards Piscis Austrinus or Aquarius	11.8+0.3 −0.4	1600±700		29.2+3.6 −2.6	0.03+0.20 −0.21	BH	39.3+10.0 −6.3	BH	29.2+5.6 −6.2	BH	65.4+8.4 −6.1	0.70±0.08	Originally designated S230922g.	[58]
GW230922_040658 2023-09-22 04:06:58	2025-08-25	5100	11.4+0.2 −0.4	6400+4100 −3500		52+17 −12	0.30±0.30	BH	76+28 −18	BH	51+23 −24	BH	119+34 −21	0.79+0.08 −0.14	Originally designated S230922q.	[58]
GW230924 2023-09-24 12:44:53	2025-08-25	1300	12.9+0.2 −0.3	2400±1000		22.3+3.1 −2.1	0.02±0.18	BH	28.8+5.9 −4.0	BH	23.1±4.4	BH	49.3+6.6 −4.6	0.70+0.07 −0.06	Originally designated S230924an.	[58]
GW230927_043729 2023-09-27 04:37:29	2025-08-25	1500	10.5+0.2 −0.4	3300±1700		26.5+5.5 −3.5	0.01+0.20 −0.22	BH	34.9+8.7 −6.1	BH	27.1+7.2 −6.5	BH	58.9+11.9 −7.6	0.69±0.08	Originally designated S230927l.	[58]
GW230927_153832 2023-09-27 15:38:32	2025-08-25	330	19.7±0.2	1200+400 −500		16.4+1.4 −0.8	0.03±0.08	BH	21.9+3.7 −2.9	BH	16.5+2.6 −2.5	BH	36.5+3.1 −2.1	0.69+0.04 −0.03	Originally designated S230927be.	[58]
GW230928 2023-09-28 21:58:27	2025-08-25	3700	8.9+0.4 −0.6	5000+3900 −2500		33.6+9.9 −7.5	0.40+0.20 −0.30	BH	54+19 −15	BH	29+14 −11	BH	79+21 −17	0.83+0.07 −0.15	Originally designated S230928cb.	[58]
GW230930 2023-09-30 11:07:30	2025-08-25	3300	8.0+0.3 −0.5	4900+3200 −2500		24.9+6.3 −4.2	0.03+0.26 −0.27	BH	34.4+12.9 −7.8	BH	24.4+8.3 −7.4	BH	56.3+14.2 −9.7	0.69+0.10 −0.12	Originally designated S230930al.	[58]
GW231001 2023-10-01 14:02:20	2025-08-25	4300	9.6+0.3 −0.5	4400+3800 −2400		46.4+14.3 −9.9	−0.04+0.32 −0.35	BH	75+26 −22	BH	40+18 −16	BH	111+31 −21	0.64+0.15 −0.20	Originally designated S231001aq.	[58]
GW231004 2023-10-04 23:23:46	2025-08-25	3500	8.2+0.3 −0.6	4300+3600 −2200		40.1+11.7 −8.5	−0.05+0.30 −0.37	BH	65+24 −19	BH	35+16 −14	BH	96+26 −19	0.64+0.14 −0.19	Originally designated S231004bq.	[58]
GW231005_021030 2023-10-05 02:10:30	2025-08-25	5600	9.4+0.3 −0.4	6400+4700 −3300		54+17 −12	0.10+0.35 −0.37	BH	83+31 −22	BH	49+22 −20	BH	126+35 −24	0.72+0.14 −0.17	Originally designated S231005j.	[58]
GW231005_091549 2023-10-05 09:15:49	2025-08-25	2900	8.0+0.3 −0.6	3800+2600 −1900		21.3+4.8 −3.5	−0.03+0.23 −0.26	BH	28.8+10.1 −6.1	BH	21.2+6.4 −6.1	BH	48.0+10.8 −7.9	0.68+0.10 −0.11	Originally designated S231005ah.	[58]
GW231008 2023-10-08 14:25:21	2025-08-25	3000	8.9+0.4 −0.5	3000+2500 −1300		28.9+6.8 −5.6	−0.01+0.26 −0.28	BH	45+17 −12	BH	25.5+10.7 −9.7	BH	68+15 −13	0.66+0.13 −0.19	Originally designated S231008ap.	[58]
GW231014 2023-10-14 04:05:32	2025-08-25	1800	8.7+0.4 −0.5	2300+1400 −1200		15.0+2.7 −1.9	0.20±0.30	BH	20.6+7.8 −4.0	BH	14.7+3.9 −4.3	BH	33.8+6.6 −4.3	0.75+0.10 −0.11	Originally designated S231014r.	[58]
GW231018 2023-10-18 23:30:37	2025-08-25	1600	8.2+0.3 −0.6	1500+800 −700		7.90+0.88 −0.68	0.01+0.17 −0.13	BH	11.6+4.9 −2.5	BH	7.23+1.87 −2.00	BH	18.2+3.3 −2.0	0.67+0.05 −0.07	Originally designated S231018by.	[58]
GW231020 2023-10-20 14:29:47	2025-08-25	1500	10.5+0.3 −0.4	1200+500 −600		8.06+0.81 −0.53	0.10+0.30 −0.10	BH	12.1+9.1 −2.7	BH	7.30+2.06 −2.85	BH	18.9+6.3 −2.0	0.72+0.06 −0.04	Originally designated S231020ba.	[58]
GW231028 2023-10-28 15:30:06	2025-08-25	1300	21.0±0.2	4100+1400 −1900		63+13 −10	0.40±0.20	BH	95+33 −20	BH	58+21 −25	BH	144+27 −14	0.84+0.05 −0.10	Originally designated S231028bg.	[58]
GW231029 2023-10-29 11:15:08	2025-08-25	29000	11.2+0.2 −0.3	3100+2400 −1700		44.2+10.5 −8.0	0.10±0.20	BH	65+17 −14	BH	42+15 −16	BH	101+21 −15	0.72+0.10 −0.15	Originally designated S231029y.	[58]
GW231102 2023-11-02 07:17:36	2025-08-25	3000	13.3+0.2 −0.3	3800+2100 −1800		43.4+9.3 −6.3	0.06+0.23 −0.22	BH	61+14 −12	BH	43±13	BH	98+19 −12	0.70+0.09 −0.10	Originally designated S231102w.	[58]
GW231104 2023-11-04 13:34:18	2025-08-25	1100	11.0+0.2 −0.4	1500+500 −700		8.84+0.87 −0.56	0.10±0.10	BH	12.3+4.5 −2.1	BH	8.56+1.79 −2.16	BH	20.0+2.8 −1.7	0.72+0.05 −0.04	Originally designated S231104ac.	[58]
GW231108 2023-11-08 12:51:42	2025-08-25	1000	12.4+0.2 −0.3	2100+700 −900		17.3+2.1 −1.3	−0.08+0.13 −0.15	BH	23.2+5.5 −3.6	BH	17.4+3.2 −3.1	BH	38.8+4.9 −3.2	0.66+0.06 −0.05	Originally designated S231108u.	[58]
GW231110 2023-11-10 04:03:20	2025-08-25	800	11.0+0.3 −0.4	1900±900		13.4+1.7 −1.2	0.20±0.10	BH	19.5+5.8 −4.1	BH	12.5+3.1 −2.9	BH	30.6+4.2 −3.3	0.74+0.06 −0.05	Originally designated S231110g.	[58]
GW231113_122623 2023-11-13 12:26:23	2025-08-25	2800	7.8+0.4 −0.7	3400+2400 −1700		27.9+6.3 −5.5	0.30+0.20 −0.30	BH	39.7+17.3 −9.6	BH	26.4+9.0 −9.4	BH	63+15 −12	0.81+0.08 −0.16	Originally designated S231113bb.	[58]
GW231113_200417 2023-11-13 20:04:17	2025-08-25	1600	10.1+0.3 −0.5	1200+600 −500		8.01+0.68 −0.64	0.10±0.10	BH	11.5+5.1 −2.3	BH	7.41+1.76 −2.00	BH	18.3+3.2 −1.9	0.72+0.06 −0.04	Originally designated S231113bw.	[58]
GW231114 2023-11-14 04:32:11	2025-08-25	1700	9.8+0.3 −0.5	1400+900 −600		11.6±1.1	0.08+0.22 −0.16	BH	22.7+9.6 −6.4	BH	8.20+2.56 −2.18	BH	30.0+7.8 −4.8	0.61±0.06	Originally designated S231114n.	[58]
GW231118_005626 2023-11-18 00:56:26	2025-08-25	1100	10.5+0.3 −0.5	2200+900 −1000		12.6+1.6 −1.1	0.40±0.10	BH	19.8+6.6 −4.9	BH	10.9+3.3 −2.4	BH	29.3+5.3 −3.6	0.80+0.06 −0.05	Originally designated S231118d.	[58]
GW231118_071402 2023-11-18 07:14:02	2025-08-25	3600	8.5+0.3 −0.5	4300+3500 −2200		30.4+7.9 −6.1	0.10±0.30	BH	43+15 −10	BH	30±10	BH	69+17 −13	0.72+0.11 −0.14	Originally designated S231118ab.	[58]
GW231118_090602 2023-11-18 09:06:02	2025-08-25	1100	10.9±0.4	1400+500 −600		8.37+0.76 −0.56	0.08+0.36 −0.09	BH	13.1+13.7 −3.3	BH	7.29+2.13 −3.27	BH	19.7+10.6 −2.3	0.70+0.08 −0.04	Originally designated S231118an.	[58]
GW231119 2023-11-19 07:52:48	2025-08-25	5900	7.7+0.3 −0.5	6700+5500 −3700		34.4+12.4 −7.8	0.00+0.28 −0.30	BH	49+23 −13	BH	34+15 −13	BH	79+27 −18	0.68+0.11 −0.16	Originally designated S231119u.	[58]
GW231123 2023-11-23 13:54:30	2025-07-10	1700	20.7+0.2 −0.3	2200+2000 −1500		137+23 −18	0.30+0.20 −0.40	BH	137+23 −18	BH	101+22 −51	BH	222+27 −42	0.84+0.07 −0.19	Originally designated S231123cg. The most massive black hole merger detected as of July 2025	[60][58]
GW231127 2023-11-27 16:53:00	2025-08-25	4400	8.3+0.3 −0.5	4500+3600 −2500		30.5+9.5 −6.7	0.05+0.30 −0.32	BH	45+18 −12	BH	29±12	BH	71+21 −14	0.69+0.12 −0.17	Originally designated S231127cg.	[58]
GW231129 2023-11-29 08:17:45	2025-08-25	3700	7.5+0.4 −0.7	3800+3600 −2100		27.7+7.7 −5.7	0.02+0.27 −0.26	BH	45+15 −12	BH	23.8+10.0 −8.2	BH	66+17 −14	0.67+0.13 −0.16	Originally designated S231129ac.	[58]
GW231206_233134 2023-12-06 23:31:34	2025-08-25	2400	11.0+0.3 −0.4	3200±1800		27.2+5.9 −3.9	−0.09+0.22 −0.24	BH	35.6+9.1 −6.3	BH	28.1+7.5 −7.1	BH	60.6+12.7 −8.4	0.67+0.09 −0.10	Originally designated S231206ca.	[58]
GW231206_233901 2023-12-06 23:39:01	2025-08-25	350	21.0+0.1 −0.2	1500+300 −500		28.1+2.7 −1.7	−0.05+0.14 −0.15	BH	37.6+6.6 −4.6	BH	28.4+5.4 −6.0	BH	63.1+5.0 −3.4	0.67+0.06 −0.07	Originally designated S231206cc.	[58]
GW231213 2023-12-13 11:14:17	2025-08-25	2600	9.7+0.2 −0.4	4000+2300 −2000		26.7+6.3 −4.2	0.06+0.24 −0.23	BH	35.5+10.3 −6.7	BH	27.2+8.1 −7.5	BH	59.5+13.4 −8.8	0.71±0.09	Originally designated S231213ap.	[58]
GW231221 2023-12-21 13:50:41	2025-08-25	3700	7.8+0.4 −0.6	4600+3700 −2500		30.7+9.5 −6.8	0.01+0.36 −0.38	BH	47+21 −13	BH	28±13	BH	72+20 −15	0.69+0.15 −0.17	Originally designated S231221ax.	[58]
GW231223_032836 2023-12-23 03:28:36	2025-08-25	4200	8.8+0.3 −0.5	4200+3100 −2100		31.8+8.6 −7.0	−0.20+0.30 −0.40	BH	46+16 −11	BH	31+12 −14	BH	73+17 −13	0.63+0.13 −0.17	Originally designated S231223j.	[58]
GW231223_075055 2023-12-23 07:50:55	2025-08-25	1500	8.8+0.4 −0.6	970+580 −430		7.79+0.58 −0.59	0.06+0.22 −0.12	BH	11.9+6.8 −2.8	BH	6.80+2.00 −2.13	BH	18.1+4.8 −1.9	0.69+0.06 −0.05	Originally designated S231223aa.	[58]
GW231223_202619 2023-12-23 20:26:19	2025-08-25	27000	9.8+0.2 −0.4	890+490 −440		8.36+0.66 −0.57	0.10+0.13 −0.11	BH	11.1+3.8 −1.6	BH	8.33+1.36 −1.93	BH	18.7+2.2 −1.5	0.71±0.05	Originally designated S231223bg.	[58]
GW231224 2023-12-24 02:43:21	2025-08-25	390	12.9+0.2 −0.3	950+290 −400		7.13+0.48 −0.29	−0.01+0.08 −0.06	BH	9.31+2.20 −1.09	BH	7.30+1.01 −1.33	BH	15.9+1.3 −0.8	0.68+0.04 −0.03	Originally designated S231224e.	[58]
GW231226 2023-12-26 10:15:20	2025-08-25	190	33.7±0.1	1200+200 −400		32.4+1.8 −1.4	−0.09+0.09 −0.10	BH	40.1+4.4 −2.9	BH	35.0+3.2 −4.9	BH	71.4+3.8 −2.8	0.67±0.04	Originally designated S231226av.	[58]
GW231230 2023-12-30 17:01:16	2025-08-25	6700	7.4+0.4 −0.7	5700+4800 −3200		36.9+14.3 −8.4	−0.20+0.30 −0.40	BH	54+50 −15	BH	35+15 −14	BH	86+47 −19	0.62+0.13 −0.20	Originally designated S231230ar.	[58]
GW231231 2023-12-31 15:40:16	2025-08-25	27000	13.1+0.2 −0.3	1100+600 −500		17.1+1.6 −1.4	−0.03±0.12	BH	22.5+5.7 −3.3	BH	17.2+2.9 −3.2	BH	38.1+4.0 −3.2	0.67+0.06 −0.05	Originally designated S231231ag.	[58]
GW240104 2024-01-04 16:49:32	2025-08-25	28000	14.1+0.2 −0.3	1900+1000 −1000		31.8+5.1 −3.9	0.09±0.19	BH	42.3+9.4 −6.7	BH	32.1+7.5 −8.0	BH	70.6+10.7 −7.9	0.73±0.08	Originally designated S240104bl.	[58]
GW240107 2024-01-07 01:32:15	2025-08-25	4800	8.5+0.4 −0.5	5800+4800 −3200		36.2+14.0 −9.5	0.30+0.30 −0.40	BH	59+27 −18	BH	32+20 −16	BH	87+28 −19	0.79+0.10 −0.19	Originally designated S240107b.	[58]
GW240109 2024-01-09 05:04:31	2025-08-25	27000	10.4+0.2 −0.4	1500+1000 −800		19.6+2.7 −2.2	−0.07+0.20 −0.23	BH	28.8+7.5 −6.2	BH	18.1+4.8 −4.1	BH	45.1+6.5 −5.5	0.64±0.09	Originally designated S240109a.	[58]
GW250114 2025-01-14 08:22:03	2025-09-10	145; towards Ursa Major, Leo Minor, Leo, or Cancer	80	403+74 −70		28.6±0.5	−0.03+0.03 −0.04	BH	33.6+1.2 −0.8	BH	32.2+0.8 −1.3	BH	62.7+1.0 −1.1	0.68±0.01	Originally designated S250114ax.	[61]

Gravitational Wave Transient Catalog 1. Credit:LIGO Scientific Collaboration and Virgo Collaboration/Georgia Tech/S. Ghonge & K. Jani

Candidate events and marginal detections

There is possible detection of nanohertz waves by observation of the timing of pulsars, but they have not been confirmed at the 5 sigma level of confidence, as of 2023^[update].^[62]

Marginal detections from O1 and O2

In addition to well-constrained detections listed above, a number of low-significance detections of possible signals were made by LIGO and Virgo. Their characteristics are listed below, only including detections with a <50% chance of being noise:

Marginal event detections

Candidate event	Detection time (UTC)	Date published	Luminosity distance (Mpc)[n 12]	Detector [n 13]	False alarm rate (year)	Effective spin	Primary		Secondary		Probability of terrestrial noise	Notes	Ref
							Type	Mass (M☉)	Type	Mass (M☉)
151205	2015-12-05 19:55:25	2019-10-11	3000+2400 −1600	H,L	0.61	0.14+0.40 −0.38	BH	67+28 −17	BH	42+16 −19	0.47		[63]
170121	2017-01-21 21:25:36	2019-04-15		H,L		−0.3±0.3	BH	29+4 −3	BH		<0.01		[64]
170304	2017-03-04 16:37:53	2019-10-11	2300+1600 −1200	H,L	2.5	0.11+0.29 −0.27	BH	44.9+17.6 −9.4	BH	31.8+9.5 −11.6	0.30		[63]
170402	2017-04-02 21:51:50	2019-10-21		H,L							0.32		[65]
170727	2017-07-27 01:04:30	2019-10-11	2200+1500 −1100	H,L	180	−0.05+0.25 −0.30	BH	41.6+12.8 −7.9	BH	30.4+7.9 −8.2	0.006		[63]
170817A	2017-08-17 03:02:46	2019-10-21		H,L,V	11.5	0.5±0.2	BH	56+16 −10	BH	40+10 −11	0.14		[65]

Observation candidates from O3/2019

From observation run O3/2019 on, observations are published as Open Public Alerts to facilitate multi-messenger observations of events.^[66][67][68] Candidate event records can be directly accessed at the Gravitational-Wave Candidate Event Database (GraceDB).^[69] On 1 April 2019, the start of the third observation run was announced with a circular published in the public alerts tracker.^[70] The first O3/2019 binary black hole detection alert was broadcast on 8 April 2019. A significant percentage of O3 candidate events detected by LIGO are accompanied by corresponding triggers at Virgo.

False alarm rates are mixed, with more than half of events assigned false alarm rates greater than 1 per 20 years, contingent on presence of glitches around signal, foreground electromagnetic instability, seismic activity, and operational status of any one of the three LIGO-Virgo instruments. For instance, events S190421ar and S190425z weren't detected by Virgo and LIGO's Hanford site, respectively.

The LIGO/Virgo collaboration took a short break from observing during the month of October 2019 to improve performance and prepare for future plans, with no signals detected in that month as a result.^[71]

The Kamioka Gravitational Wave Detector (KAGRA) in Japan became operational on 25 February 2020,^[72] likely improving the detection and localization of future gravitational wave signals.^[73] However, KAGRA does not report their signals in real-time on GraceDB as LIGO and Virgo do, so the results of their observation run will likely not be published until the end of O3.

The LIGO-Virgo collaboration ended the O3 run early on March 27, 2020, due to health concerns from the COVID-19 pandemic.^[74][75]

Candidate detections from O3 by month

1 2 3 4 5 6 7 8 9 10 19/04 19/05 19/06 19/07 19/08 19/09 19/10 19/11 19/12 20/01 20/02 20/03   BNS mergers   NS-BH mergers   mass gap   BBH mergers   terrestrial noise   false positives   unidentified

O3 detections by distance

2 4 6 8 10 12 14 16 18 20 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

List of unconfirmed O3 event alerts^[12][13]

GW event	Detection time (UTC)	Location area[n 14] (deg2)	Luminosity distance (Mpc)[n 15]	Detector [n 16]	False alarm Rate (Hz)	False alarm chance in O3[n 17]	Classification					Notes	Ref
							NS / NS [n 18]	NS / BH [n 19]	BH / BH [n 20]	Mass gap [n 21]	Terrestrial [n 22]
S190901ap	2019-09-01 23:31:01	14753	241±79	L,V	7.0 10−9	0.181	0.861	0.0	0.0	0.0	0.139		[76]
S190910d	2019-09-10 01:26:19	2482	632±186	H,L	3.7 10−9	0.100	0.0	0.976	0.0	0.0	0.024		[77]
S190910h	2019-09-10 08:29:58	24264	230±88	L	3.6 10−8	0.642	0.612	0.0	0.0	0.0	0.388	Detected by only the Livingston detector, resulting in a bad sky localization.	[78]
S190923y	2019-09-23 12:55:59	2107	438±133	H,L	4.8 10−8	0.746	0.0	0.677	0.0	0.0	0.322		[79]
S190930t	2019-09-30 14:34:07	24220	108±38	L	1.5 10−8	0.348	0.0	0.743	0.0	0.0	0.257	Detected by only the Livingston detector, resulting in a bad sky localization; last detection of the O3a run.	[80]
S191205ah	2019-12-05 21:52:08	6378	385±164	H,L,V	1.2 10−8	0.290	0.0	0.932	0.0	0.0	0.068		[81]
S191213g	2019-12-13 04:34:08	4480	201±81	H,L,V	3.5 10−8	0.631	0.768	0.0	0.0	0.0	0.232		[82]
S200213t	2020-02-13 04:10:40	2326	201±80	H,L,V	1.8 10−8	0.401	0.629	0.0	0.0	0.0	0.371		[83]

Observation candidates from O4/2023

On 15 June 2022, LIGO announced to start the O4 observing run in March 2023.^[84] As the date got closer, engineering challenges delayed the observing run to May 2023.^[85] An engineering run to assess the sensitivity of LIGO, Virgo, and KAGRA began in April, with the Hanford detector's first operations beginning on April 29,^[86] and the Livingston and Virgo detectors' first operations beginning on May 5.^[87]

On March 7, 2023, a gamma-ray burst compatible with a neutron star merger was detected by the Fermi telescope and named GRB 230307A. The burst, identified as being from a host galaxy approximately 296 Mpc away, would likely have only been marginally detected at best by LIGO if it had been operating at the time, as the detectors would only later achieve a sensitivity of 160 Mpc for neutron star mergers by O4's beginning, 3 months later.

Near the end of the engineering run on 15 May 2023, LIGO announced that O4 would be beginning on 24 May 2023, running for 20 months with up to 2 months of maintenance. The LIGO detectors initially failed to achieve the hoped for 160-190 Mpc sensitivity for neutron star mergers, but did achieve an improved 130-150 Mpc sensitivity over O3's 100-140 Mpc, later improving to nearly 160 Mpc for both detectors by late 2023. Virgo was found to have both a damaged mirror and other new, unknown noise sources, limiting its sensitivity to just 31-35 Mpc (similar to its performance during O2 in 2017, and lower than O3's 40-50 Mpc.) As a result, Virgo spent most of 2023 in commissioning, with a deadline of March 2024 to improve its sensitivity before joining O4. KAGRA achieved its planned 1 Mpc sensitivity before returning to commissioning in July, with plans to rejoin at an improved 10 Mpc sensitivity by early 2024. However, the M_w7.5 2024 Noto earthquake occurred on 1 January 2024 only 103 kilometres (64 mi) from KAGRA, damaging the detector's sensitive instruments and delaying its development by at least several months.

On 18 May 2023, near the end of the engineering run and shortly before O4 proper, the first candidate gravitational wave event was detected. Four more were detected before the official beginning of the run. In October, LIGO announced a planned pause between January and March 2024, for a mid-run commissioning break intended to reduce noise and improve the uptime of the detectors.

The O4b run began in April 2024 with the addition of the Virgo detector at a sensitivity of 55 Mpc. The Livingston detector achieved an increased sensitivity of 170-175 Mpc, while the Hanford detector maintained its pre-break sensitivity of 155-160 Mpc. Due to a variety of factors including delays in technologies required for O5, the decision was made in June 2024 to extend O4 by several months to June 2025, with O5 expected to begin in late 2027 or early 2028.

Candidate detections from O4 by month^{[n 23]}

5 10 15 20 25 30 2305 06 07 08 09 10 11 12 2401 02 03 04 05 06 07 08 09 10 11 12 2501 02 03 04 05 06 07 08 09 10   BNS mergers   NS-BH mergers   mass gap   BBH mergers   unidentified

O4 detections by distance^{[n 23]}

15 30 45 60 75 90 105 120 135 150 <100 Mpc 100-200 Mpc 200-500 Mpc 500-1000 Mpc 1-2 Gpc 2-5 Gpc 5-10 Gpc 10+ Gpc   BNS mergers   NS-BH mergers   mass gap   BBH mergers

List of O4 event alerts

GW event	Detection time (UTC)	Location area[n 24] (deg2)	Luminosity distance (Mpc)[n 25]	Detector [n 26]	False Alarm Rate (Hz)	False Alarm chance in O4[n 27] [n 23]	Classification					Notes	Ref
							NS / NS [n 28]	NS / BH [n 29]	BH / BH [n 30]	Mass gap [n 31]	Terrestrial [n 32]
S230520ae	2023-05-20 22:48:41	1702	2014±663	H,L	3.1 10−9	0.161	0.0	0.0	~1.0	0.0	1.4e−7	Detected during the engineering phase, before the official start of O4.	[88]
S230522a	2023-05-22 09:38:04	24219	3102±1032	L	1.0 10−8	0.448	0.0	0.0	0.99973	0.00071	0.00027		[89]
S230522n	2023-05-22 15:30:32	29021	2221±870	L	6.5 10−9	0.311	0.0	0.0	0.993	0.0041	0.0069		[90]
S230708z	2023-07-08 07:18:59	3373	4647±1696	H,L	7.0 10−8	0.982	0.0	0.0	0.954	0.0041	0.046		[91]
S230802aq	2023-08-02 11:33:59	25885	576±246	H	2.2 10−8	0.722	0.0	0.020	0.289	0.657	0.035	The other component is a black hole. Detected by only the Hanford detector, resulting in a bad sky localization.	[92]
S230807f	2023-08-07 20:50:45	5436	5272±1900	H,L	7.1 10−8	0.983	0.0	0.0	0.913	0.041	0.047		[93]
S230822bm	2023-08-22 23:03:37	3974	5154±1771	H,L	2.6 10−8	0.773	0.0	0.0	0.939	0.042	0.019		[94]
S231020bw	2023-10-20 18:05:09	386	2620±694	H,L	3.5 10−10	0.020	0.0	0.0	0.99965	0.0	0.00035		[95]
S240406aj	2024-04-06 06:28:47	1724	2449±692	H,L	1.6 10−15	8.9 10−8	0.0	0.0	~1.0	0.0	9.2e−9		[96]
S240413p	2024-04-13 02:20:19	34; towards Leo or Sextans	526±101	H,L,V	3.2 10−10	0.018	0.0	0.0	0.584	0.400	0.020		[97]
S240420ax	2024-04-20 04:21:16	6423	?	H,L	5.7 10−8	0.961	0.0	0.0	0.0	0.0	?	Unidentified gravitational wave "burst" lasting 33 milliseconds at a frequency of 219 Hertz.	[98]
S240422ed	2024-04-22 21:35:13	259; towards Puppis, Pyxis, or Hydra	188±43	H,L,V	3.1 10−13	1.8 10−5	0.0	0.541	0.0	0.459	1.3e−5		[99]
S240426s	2024-04-26 03:14:51	3050	3452±1295	H,L	7.6 10−9	0.354	0.0	0.0	0.968	0.030	0.00191		[100]
S240428dr	2024-04-28 22:54:40	286	765±177	H,V	2.1 10−14	1.2 10−6	0.0	0.0	~1.0	0.0	7.4e−8		[101]
S240430ca	2024-04-30 09:35:17	4061	6212±2593	H,L	7.5 10−8	0.986	0.0	0.0	0.920	0.041	0.039		[102]
S240501an	2024-05-01 03:35:34	1079	4022±1460	H,L,V	4.2 10−10	0.024	0.0	0.0	0.99999	0.0	1.3e−5		[103]
S240505av	2024-05-05 13:35:52	1469	4570±1415	H,L,V	2.3 10−8	0.731	0.0	0.0	0.985	0.0	0.015		[104]
S240507p	2024-05-07 04:16:32	279; mostly towards Canis Major or Cassiopeia	1328±370	H,L,V	6.3 10−10	0.036	0.0	0.0	0.963	0.036	0.00031		[105]
S240511i	2024-05-11 03:15:07	85; towards Crater or Hydra	1906±404	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99998	0.0	1.7e−5		[106]
S240512r	2024-05-12 02:41:39	216	1082±266	H,L,V	3.2 10−10	0.018	0.0	0.020	0.958	0.020	0.0017		[107]
S240513ei	2024-05-13 18:33:02	37; towards Auriga or Perseus	2254±458	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99973	0.0	0.00027		[108]
S240514c	2024-05-14 08:03:21	30758	4182±1833	L	9.6 10−9	0.425	0.0	0.0	0.9932	0.0	0.0064	Detected by only the Livingston detector, resulting in a bad sky localization.	[109]
S240514x	2024-05-14 12:17:13	142; mostly towards Reticulum	2594±587	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99998	0.0	1.8e−5		[110]
S240515m	2024-05-15 00:53:01	978	3559±976	H,L,V	5.3 10−21	0.0	0.0	0.0	~1.0	0.0	4.3e−14		[111]
S240520cv	2024-05-20 21:36:16	89; towards Ursa Major, Indus, or Tucana	1136±235	H,L,V	3.2 10−10	0.018	0.0	0.030	0.921	0.047	0.0018		[112]
S240525p	2024-05-25 03:12:10	1517	4337±1519	H,L,V	1.7 10−8	0.619	0.0	0.0	0.902	0.086	0.012		[113]
S240527en	2024-05-27 18:34:29	986	5850±1907	H,L,V	2.5 10−9	0.135	0.0	0.00090	0.99907	0.0	2.7e−5		[114]
S240527fv	2024-05-27 23:09:10	19; towards Horologium	1119±188	H,L,V	1.4 10−8	0.559	0.0	0.0	0.987	0.0036	0.0096		[115]
S240530a	2024-05-30 01:24:17	196	1066±226	H,L,V	9.5 10−10	0.053	0.0	0.0	0.910	0.085	0.0048		[116]
S240531bp	2024-05-31 07:52:48	1323	3766±1491	H,L,V	3.7 10−12	0.00022	0.0	0.0	0.99999	0.0	6.5e−6		[117]
S240601aj	2024-06-01 06:12:00	2009	5366±2095	H,L	3.1 10−8	0.829	0.0	0.0	0.507	0.0	0.493		[118]
S240601co	2024-06-01 23:10:04	1110	1421±390	H,L,V	6.0 10−11	0.0034	0.0	0.0	0.928	0.072	0.00023		[119]
S240615dg	2024-06-15 11:36:20	5; towards northern Andromeda	1420±236	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99998	0.0	1.7e−5		[120]
S240615ea	2024-06-15 16:07:35	653	3590±1058	H,L,V	1.5 10−8	0.582	0.0	0.0	0.99938	0.0	0.00062		[121]
S240618ah	2024-06-18 07:16:27	5116	5939±2437	H,L	6.5 10−8	0.976	0.0	0.0	0.921	0.041	0.038		[122]
S240621dy	2024-06-21 19:50:59	21; towards Perseus	1184±199	H,L,V	4.0 10−20	0.0	0.0	0.0	~1.0	0.0	0.0		[123]
S240621eb	2024-06-21 20:09:35	920	4492±1407	H,L,V	4.3 10−8	0.916	0.0	0.0	0.9987	0.0	0.0013		[124]
S240621em	2024-06-21 21:40:41	3069	7458±2672	H,L,V	6.8 10−8	0.979	0.0	0.0	0.920	0.041	0.039		[125]
S240622h	2024-06-22 00:40:48	199	1350±303	H,L,V	1.2 10−8	0.499	0.0	0.0	0.974	0.011	0.015		[126]
S240627by	2024-06-27 13:16:22	934	1479±420	H,L,V	1.2 10−8	0.500	0.0	0.0	0.911	0.080	0.0084		[127]
S240629by	2024-06-29 14:52:56	66	1173±245	H,L,V	3.2 10−10	0.018	0.0	0.073	0.798	0.127	0.0015		[128]
S240630t	2024-06-30 10:17:03	670	3161±841	H,L,V	1.9 10−12	0.00011	0.0	0.0	~1.0	0.0	3.3e−6		[129]
S240703ad	2024-07-03 19:13:55	3785	1894±679	H,V	1.2 10−13	6.8 10−6	0.0	0.0	~1.0	0.0	2.8e−7		[130]
S240705at	2024-07-05 05:32:15	172	3694±880	H,L,V	7.1 10−16	3.8 10−8	0.0	0.0	~1.0	0.0	0.0		[131]
S240716b	2024-07-16 03:49:00	10324	1821±686	L,V	7.9 10−16	4.5 10−8	0.0	0.0	~1.0	0.0	3.6e−9		[132]
S240807h	2024-08-07 21:45:59	12857	1018±295	L,V	2.0 10−11	0.0012	0.0	0.00010	0.956	0.044	3.2e−5		[133]
S240813c	2024-08-13 03:45:48	13782	1240±392	L,V	2.6 10−9	0.139	0.0	0.0	0.909	0.089	0.0022		[134]
S240813d	2024-08-13 04:39:13	1776	1065±259	L,V	1.8 10−18	0.0	0.0	0.0	~1.0	0.0	1.2e−11		[135]
S240825ar	2024-08-25 05:51:46	1203	1342±380	H,L,V	3.2 10−9	0.166	0.0	0.025	0.930	0.036	0.0091		[136]
S240830gn	2024-08-30 21:11:20	410	1118±297	H,L,V	6.3 10−10	0.036	0.0	0.105	0.891	0.084	0.0031		[137]
S240902bq	2024-09-02 14:33:06	584	2420±828	H,L,V	2.5 10−9	0.135	0.0	0.0	0.99990	0.0	9.94e−5		[138]
S240907cg	2024-09-07 15:38:33	1065	4333±1354	H,L,V	9.1 10−10	0.051	0.0	0.0	0.99914	0.0	0.00086		[139]
S240908bs	2024-09-08 08:26:28	74; towards northern Aries	3350±1130	H,L,V	3.2 10−10	0.018	0.0	0.0	0.997	0.0031	1.4e−5		[140]
S240908dg	2024-09-08 12:51:34	1021	5004±1764	H,L,V	7.2 10−8	0.984	0.0	0.0	0.910	0.041	0.050		[141]
S240910ci	2024-09-10 10:35:35	394	662±166	H,L	3.2 10−10	0.018	0.0	0.280	0.628	0.090	0.0015		[142]
S240915b	2024-09-15 00:13:57	18; towards Southern Puppis	872±149	H,L,V	3.2 10−10	0.018	0.0	0.121	0.745	0.132	0.0015		[143]
S240915bd	2024-09-15 10:51:51	4244	612±139	H,V	3.3 10−14	1.9 10−6	0.0	0.00037	0.899	0.101	1.2e−7		[144]
S240917cb	2024-09-17 13:02:37	8644	6657±3466	H,L	5.4 10−8	0.955	0.0	0.0	0.903	0.057	0.040		[145]
S240919bn	2024-09-19 06:15:59	16; towards Southern Perseus	1711±490	H,L,V	4.0 10−20	0.0	0.0	0.0	~1.0	0.0	0.0		[146]
S240920bz	2024-09-20 07:34:24	349	1372±305	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99972	0.0	0.00028		[147]
S240920dw	2024-09-20 12:40:24	135	977±160	H,L	9.7 10−52	0.0	0.0	0.0	~1.0	0.0	0.0		[148]
S240921cw	2024-09-21 20:18:35	471	866±204	L,V	3.2 10−10	0.045	0.0	0.0	0.997	0.0025	0.00078		[149]
S240922df	2024-09-22 14:21:06	97; towards Capricornus	1175±262	H,L,V	1.4 10−24	0.0	0.0	0.0	0.965	0.035	0.0		[150]
S240923ct	2024-09-23 20:40:06	216; towards Hercules, Corona Borealis, or Serpens Caput	4025±1076	H,L,V	7.6 10−16	4.5 10−8	0.0	0.0	~1.0	0.0	2.9e−9		[151]
S240924a	2024-09-24 00:03:16	660	3816±1285	H,L,V	2.5 10−9	0.132	0.0	0.0	0.99993	0.0	7.1e−5		[152]
S240925n	2024-09-25 00:58:59	40; towards central Aquila	329±76	H,L,V	4.0 10−20	0.0	0.0	0.0	0.742	0.258	0.0		[153]
S240930aa	2024-09-30 00:58:59	457	1400±323	H,L,V	3.1 10−19	0.0	0.0	0.0	0.99960	0.00040	1.7e−12		[154]
S240930du	2024-09-30 23:46:14	708	3874±1404	H,L	1.3 10−8	0.521	0.0	0.0	0.666	0.0	0.334		[155]
S241002e	2024-10-02 03:05:59	1237	1607±557	L,V	1.4 10−21	0.0	0.0	0.0	0.997	0.003	1.05e−14		[156]
S241006k	2024-10-06 01:53:33	263	1899±441	H,L,V	5.9 10−42	0.0	0.0	0.0	~1.0	0.0	0.0		[157]
S241007bw	2024-10-07 08:29:43	967	4355±1289	H,L,V	1.6 10−8	0.611	0.0	0.0	0.988	0.0	0.012		[158]
S241009l	2024-10-09 02:28:35	2544	6642±2029	H,L,V	3.3 10−8	0.851	0.0	0.0	0.971	0.004	0.025		[159]
S241009an	2024-10-09 08:48:16	542	1208±365	H,L,V	1.9 10−12	0.00011	0.0	0.0	0.982	0.017	2.9e−6		[160]
S241009em	2024-10-09 22:04:55	813	3831±1633	H,L,V	2.8 10−9	0.149	0.0	0.0	0.998	0.0	0.0025		[161]
S241011k	2024-10-11 23:38:34	76; towards Ophiuchus or Serpens Cauda	232±51	H,V	2.5 10−34	0.0	0.0	0.00022	0.967	0.033	1.1e−16		[162]
S241101ee	2024-11-01 22:05:23	7670	2160±685	L,V	1.4 10−11	0.00079	0.0	0.0	0.99998	0.0	2.0e−5		[163]
S241102br	2024-11-02 12:40:58	28; towards Andromeda or Lacerta	364±54	H,L,V	1.1 10−41	0.0	0.0	0.0067	0.850	0.144	1.1e−16		[164]
S241102cy	2024-11-02 14:47:29	834	3443±1068	H,L,V	1.5 10−8	0.582	0.0	0.0	0.999	0.0	0.0011		[165]
S241109p	2024-11-09 03:33:17	1761	2282±1082	L,V	6.0 10−11	0.0035	0.0	0.0	0.99992	0.0	8.3e−5		[166]
S241109bn	2024-11-09 11:59:24	10138	603±159	H,V	1.4 10−11	0.00082	0.0	0.121	0.047	0.830	0.0026	The other component is a black hole.	[167]
S241110br	2024-11-10 12:41:23	102; towards Northern Centaurus	749±173	H,L,V	4.7 10−9	0.236	0.0	0.0	0.942	0.054	0.0038		[168]
S241111bn	2024-11-11 11:15:52	424	1393±412	H,L	7.1 10−30	0.0	0.0	0.0	~1.0	0.0	0.0		[169]
S241113p	2024-11-13 16:35:07	11825	1321±400	L,V	1.5 10−14	8.4 10−7	0.0	0.0	~1.0	0.0	4.0e−8		[170]
S241114y	2024-11-14 02:47:11	152	2511±729	H,L,V	9.1 10−14	5.2 10−6	0.0	0.0	~1.0	0.0	2.4e−7		[171]
S241114bi	2024-11-14 23:52:58	10127	752±195	L,V	1.8 10−13	1.0 10−5	0.0	0.00049	0.943	0.056	4.2e−7		[172]
S241116cq	2024-11-16 15:17:53	2292	5600±2218	H,L,V	7.0 10−9	0.330	0.0	0.0	0.99992	0.0	8.3e−5		[173]
S241122a	2024-11-22 17:51:00	28549	2267±948	L	6.4 10−8	0.975	0.0	0.0	0.955	0.0	0.045	Detected by only the Livingston detector, resulting in a bad sky localization.	[174]
S241125n	2024-11-25 01:01:16	76	4174±1591	H,L,V	9.5 10−10	0.053	0.0	0.0	0.99999	0.0	1.1e−5		[175]
S241127aj	2024-11-27 06:10:08	53; mostly towards Musca or Southern Centaurus	1050±67	H,L,V	6.5 10−39	0.0	0.0	0.0	~1.0	0.0	0.0		[176]
S241129aa	2024-11-29 02:18:32	269	2499±437	H,L,V	4.0 10−20	0.0	0.0	0.0	0.993	0.006	0.0		[177]
S241130n	2024-11-30 03:49:08	302	1790±518	H,L,V	4.0 10−20	0.0	0.0	0.0	~1.0	0.0	0.0		[178]
S241130be	2024-11-30 11:04:22	1069	1226±321	H,L,V	1.9 10−10	0.011	0.0	0.0	0.963	0.037	0.00063		[179]
S241201ac	2024-12-01 05:57:58	2300	7122±2366	H,L,V	4.3 10−8	0.917	0.0	0.0	0.926	0.041	0.033		[180]
S241210d	2024-12-10 02:33:35	3777	5007±2073	H,L	4.4 10−8	0.920	0.0	0.0	0.926	0.041	0.033		[181]
S241210cw	2024-12-10 06:06:06	495	2199±597	H,L,V	6.3 10−10	0.036	0.0	0.0	0.99995	0.0	5.1e−5		[182]
S241210fu	2024-12-10 12:09:00	3326	3603±1378	H,L	2.7 10−8	0.791	0.0	0.0	0.978	0.0014	0.021		[183]
S241225c	2024-12-25 04:25:53	2264	666±137	L,V	2.0 10−15	1.1 10−7	0.0	0.0	0.964	0.036	8.0e−9		[184]
S241225v	2024-12-25 08:28:15	1192	2008±695	H,L	2.2 10−21	0.0	0.0	0.0	~1.0	0.0	1.5e−14		[185]
S241230bd	2024-12-30 08:45:04	11129	2811±842	L,V	6.2 10−14	3.6 10−6	0.0	0.0	~1.0	0.0	1.6e−7		[186]
S241230ev	2024-12-30 23:36:18	355	2940±1041	H,L,V	2.2 10−8	0.717	0.0	0.0	0.984	0.0	0.016		[187]
S241231bg	2024-12-31 05:41:33	125	830±159	H,L,V	3.2 10−8	0.018	0.0	0.0	0.931	0.067	0.0015		[188]
S250101k	2025-01-01 01:12:05	455	3231±945	H,L,V	5.6 10−8	0.959	0.0	0.079	0.882	0.0	0.039		[189]
S250104v	2025-01-04 01:51:22	1514	4932±1471	H,L,V	9.5 10−13	5.5 10−5	0.0	0.0	~1.0	0.0	1.7e−6		[190]
S250108eo	2025-01-08 15:22:21	796	4306±1349	H,L,V	1.8 10−11	0.0010	0.0	0.0	0.99997	0.0	2.6e−5		[191]
S250109f	2025-01-09 01:05:41	243	3200±948	H,L,V	2.9 10−12	0.00017	0.0	0.0	~1.0	0.0	4.4e−6		[192]
S250109bi	2025-01-09 07:45:52	2819	2255±734	H,V	2.1 10−8	0.692	0.0	0.0	0.985	0.0	0.015		[193]
S250118t	2025-01-18 02:32:25	2332	6631±2213	H,L,V	4.0 10−10	0.023	0.0	0.0	0.961	0.039	0.00039		[194]
S250118az	2025-01-18 05:58:02	1219	1336±410	H,L,V	9.8 10−9	0.430	0.0	0.00065	0.807	0.185	0.0073		[195]
S250118dp	2025-01-18 17:05:23	798	1916±465	H,L	5.6 10−25	0.0	0.0	0.0	0.994	0.0063	0.0		[196]
S250119ag	2025-01-19 02:51:38	538	3000±676	H,L,V	3.3 10−13	1.9 10−5	0.0	0.0	~1.0	0.0	1.5e−6		[197]
S250119cv	2025-01-19 19:02:38	9; towards 67 Piscium	472±112	H,L,V	4.0 10−20	0.0	0.0	0.0	~1.0	0.0	0.0		[198]
S250202cu	2025-02-02 18:49:02	4768	5196±2263	H,L	1.5 10−8	0.568	0.0	0.0	0.948	0.042	0.0099		[199]
S250204ax	2025-02-04 05:52:59	318	2056±690	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99974	0.0	0.00026		[200]
S250205bk	2025-02-05 10:35:41	64; towards western Hydra	748±160	H,L,V	9.5 10−10	0.053	0.0	0.014	0.970	0.00815	0.0072		[201]
S250205ee	2025-02-05 21:52:15	1574	2493±889	H,L	1.8 10−9	0.100	0.0	0.0	0.998	0.0	0.0017		[202]
S250206dm	2025-02-06 21:25:30	547	373±104	H,L	1.3 10−9	0.070	0.143	0.211	0.0	0.568	0.077	The other component is a neutron star.	[203]
S250207bg	2025-02-07 11:56:45	80	508±95	L,V	4.9 10−36	0.0	0.0	0.0	~1.0	0.0	0.0		[204]
S250208ad	2025-02-08 03:51:06	1128	4871±1417	H,L,V	3.8 10−10	0.021	0.0	0.0	0.99956	0.0	0.00044		[205]
S250211aa	2025-02-11 02:25:46	248	1121±258	H,L,V	4.7 10−18	0.0	0.0	0.0	0.990	0.010	3.2e-11		[206]
S250211be	2025-02-11 04:35:43	91; towards Leo or Ursa Major	3337±1194	H,L,V	1.8 10−8	0.641	0.0	0.0	0.987	0.0	0.013		[207]
S250226dl	2025-02-26 22:48:38	1218	3361±1041	H,L	1.2 10−12	6.7 10−5	0.0	0.0	~1.0	0.0	2.4e-5		[208]
S250227e	2025-02-27 00:13:02	210	2004±524	H,L,V	2.6 10−12	0.00015	0.0	0.0	~1.0	0.0	4.0e-6		[209]
S250304cb	2025-03-04 06:22:45	1569	1768±541	H,L,V	5.6 10−8	0.960	0.0	0.0	0.944	0.018	0.038		[210]
S250319bu	2025-03-19 06:25:36	989	4713±1546	H,L,V	4.7 10−10	0.027	0.0	0.0	0.99954	0.0	0.00046		[211]
S250326y	2025-03-26 01:54:06	1460	5412±1720	H,L,V	3.6 10−12	0.00020	0.0	0.0	~1.0	0.0	6.2e-6		[212]
S250328ae	2025-03-28 05:40:27	14; towards southwestern Leo	511±82	H,L,V	3.2 10−10	0.018	0.0	0.0	0.934	0.065	0.00151		[213]
S250331o	2025-03-31 01:34:48	18; towards Triangulum	657±91	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99972	0.0	0.00028		[214]
S250628am	2025-06-28 18:23:19	287	902±223	H,L,V	1.7 10−14	9.7 10−7	0.0	0.0	~1.0	0.0	4.6e-8		[215]
S250629ae	2025-06-29 05:50:36	2834	7075±2116	H,L,V	3.2 10−8	0.844	0.0	0.0	0.978	0.0	0.022		[216]
S250629bs	2025-06-29 12:13:04	3008	4847±1746	H,L	4.3 10−8	0.917	0.0	0.0	0.940	0.0	0.060		[217]
S250701bp	2025-07-01 20:34:40	26503	939±300	L	3.1 10−17	0.0	0.0	0.0	~1.0	0.0	1.8e-10	Detected by only the Livingston detector, resulting in a bad sky localization. Chirp mass 99.98% likely to be between 22 and 44 Solar masses.	[218]
S250701bq	2025-07-01 23:17:46	25010	480±118	L	4.3 10−17	0.0	0.0	0.0	~1.0	0.0	2.2e-10	Detected by only the Livingston detector, resulting in a bad sky localization. Chirp mass 93.7% likely to be between 11 and 22 Solar masses.	[219]
S250702n	2025-07-02 13:32:00	1758	2180±913	H,L	1.8 10−8	0.633	0.0	0.0	0.989	0.0	0.011	Chirp mass 89.3% likely to be between 22 and 44 Solar masses (11-22 10.7%)	[220]
S250704ab	2025-07-04 04:30:48	43.7; towards central Auriga	531±101	H,L,V	3.2 10−10	0.018	0.0	0.149	0.824	0.144	0.0020	Chirp mass 99.999% likely to be between 5.5 and 11 Solar masses	[221]
S250705cb	2025-07-05 16:29:56	333	1143±299	H,L,V	9.5 10−10	0.050	0.0	0.0	0.995	0.0	0.0054	Chirp mass 86.2% likely to be between 5.5 and 11 Solar masses (11-22 13.6%)	[222]
S250711q	2025-07-11 03:27:25	2016	4756±2023	H,L,V	1.6 10−9	0.086	0.0	0.0	0.9986	0.0	0.0014	Chirp mass 59.0% likely to be between 22 and 44 Solar masses (44-88 41.0%)	[223]
S250712cd	2025-07-12 14:25:32	155; towards border of Cygnus and Draco	2439±870	H,L,V	2.7 10−11	0.0015	0.0	0.0	0.99989	0.0	0.00011	Chirp mass 99.87% likely to be between 22 and 44 Solar masses	[224]
S250725j	2025-07-25 04:09:44	18.6; towards northern Lupus	380±93	H,L,V	4.3 10−11	0.0024	0.0	0.0	0.99995	0.0	5.3e-5	Chirp mass 99.98% likely to be between 11 and 22 Solar masses	[225]
S250725l	2025-07-25 04:20:50	1532	2567±766	H,L,V	3.0 10−8	0.819	0.0	0.0	0.985	0.00062	0.015	Chirp mass 98.9% likely to be between 11 and 22 Solar masses	[226]
S250726ak	2025-07-26 08:28:15	361	3333±1448	H,L,V	4.7 10−12	0.00027	0.0	0.0	0.99998	0.0	2.3e-5	Chirp mass 99.2% likely to be between 22 and 44 Solar masses	[227]
S250727cl	2025-07-27 18:03:29	205; mostly towards Eastern Cancer	2152±515	H,L,V	4.0 10−20	0.0	0.0	0.0	~1.0	0.0	0.0	Chirp mass 74.2% likely to be between 22 and 44 Solar masses (11-22 25.8%)	[228]
S250727dc	2025-07-27 20:01:48	15.4; towards eastern Columba	1389±318	H,L,V	1.1 10−18	0.0	0.0	0.0	~1.0	0.0	8.2e-12	Chirp mass 99.999% likely to be between 22 and 44 Solar masses	[229]
S250802dn	2025-08-02 20:25:12	3209	3070±1219	H,L	5.5 10−8	0.957	0.0	0.0	0.927	0.0	0.073	Chirp mass 91.1% likely to be between 22 and 44 Solar masses	[230]
S250810ck	2025-08-10 14:23:57	180	621±129	H,V	5.4 10−20	0.0	0.0	0.00053	0.905	0.094	4.4e-13	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[231]
S250813k	2025-08-13 02:12:00	12; towards border of Ursa Major, Camelopardalis, and Draco	932±209	H,L,V	1.3 10−10	0.0072	0.0	0.0	0.997	0.0	0.0029	Chirp mass 99.993% likely to be between 22 and 44 Solar masses	[232]
S250818t	2025-08-18 02:08:58	319	1209±290	H,L,V	1.7 10−11	0.00099	0.0	0.0	0.983	0.0174	7.4e-5	Chirp mass 54.0% likely to be between 5.5 and 11 Solar masses (11-22 46.0%)	[233]
S250827l	2025-08-27 01:27:57	615	2464±700	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99998	0.0	2.0e-5	Chirp mass 87.8% likely to be between 22 and 44 Solar masses (11-22 12.2%)	[234]
S250827fo	2025-08-27 22:29:40	470	1005±261	H,L,V	2.3 10−11	0.0013	0.0	0.0	0.943	0.057	9.2e-5	Chirp mass 92.5% likely to be between 5.5 and 11 Solar masses	[235]
S250830m	2025-08-30 03:27:09	3194	3731±1474	H,L	1.2 10−8	0.495	0.0	0.0	0.979	0.0	0.021	Chirp mass 99.7% likely to be between 22 and 44 Solar masses	[236]
S250830bp	2025-08-30 10:24:18	3.73; towards Nu Octantis	427±69	H,L,V	3.2 10−10	0.018	0.0	0.132	0.702	0.165	0.0017	Chirp mass 99.8% likely to be between 5.5 and 11 Solar masses	[237]
S250901cb	2025-09-01 18:59:41	581	2018±482	H,L,V	3.2 10−14	1.8 10−6	0.0	0.0	~1.0	0.0	9.5e-8	Chirp mass 100% likely to be between 11 and 22 Solar masses	[238]
S250904ae	2025-09-04 03:33:07	1021	3330±863	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99999	0.0	1.3e-5	Chirp mass 71.2% likely to be between 11 and 22 Solar masses (22-44 28.8%)	[239]
S250904br	2025-09-04 10:22:08	373	2748±681	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99998	0.0	2.0e-5	Chirp mass 100% likely to be between 22 and 44 Solar masses	[240]
S250904cv	2025-09-04 13:49:52	1237	2414±670	H,L	3.2 10−10	0.018	0.0	0.0	0.99968	0.0	0.00032	Chirp mass 99.6% likely to be between 11 and 22 Solar masses	[241]
S250906ca	2025-09-06 12:23:59	520	1195±307	H,L,V	1.1 10−13	6.3 10−6	0.0	0.00055	0.942	0.058	3.1e-7	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[242]
S250908y	2025-09-08 14:34:28	11002	1280±403	H,V	1.2 10−10	0.0077	0.0	0.0	0.998	0.0023	0.00015	Chirp mass 81.3% likely to be between 5.5 and 11 Solar masses (11-22 18.7%)	[243]
S250911ac	2025-09-11 07:46:39	1012	1102±300	H,L	6.0 10−9	0.292	0.0	0.118	0.779	0.067	0.036	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[244]
S250912f	2025-09-12 06:40:08	393	2870±784	L,V	2.9 10−13	1.7 10−5	0.0	0.0	~1.0	0.0	6.8e-7	Chirp mass 99.4% likely to be between 44 and 88 Solar masses	[245]
S250917aq	2025-09-17 13:21:54	5646	687±182	H,V	1.1 10−13	6.3 10−6	0.0	0.00045	0.972	0.027	3.1e-7	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[246]
S250927ck	2025-09-27 15:24:48	177	4333±1544	H,L,V	3.1 10−8	0.835	0.0	0.0	0.978	0.0	0.022	Chirp mass 88.5% likely to be between 44 and 88 Solar masses (22-44 11.1%)	[247]
S250927cy	2025-09-27 17:30:41	1551	4064±1180	H,L,V	5.3 10−8	0.953	0.0	0.0	0.962	0.0	0.038	Chirp mass 91.5% likely to be between 22 and 44 Solar masses (11-22 8.5%)	[247]
S250929c	2025-09-29 00:27:32	1828	3796±1511	H,L,V	2.5 10−8	0.766	0.0	0.0	0.983	0.0	0.017	Chirp mass 89.3% likely to be between 22 and 44 Solar masses (11-22 10.6%)	[248]
S251006dd	2025-10-06 23:37:17	109	706±151	H,L,V	5.4 10−16	3.2 10−8	0.0	0.0023	0.862	0.136	7.0e-7	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[249]
S251013x	2025-10-13 02:44:14	1589	1946±505	H,L,V	1.5 10−8	0.574	0.0	0.0	0.990	0.0	0.010	Chirp mass 100% likely to be between 22 and 44 Solar masses	[250]
S251014cn	2025-10-14 11:33:23	172	607±164	H,L	3.2 10−10	0.018	0.0	0.0	0.99820	0.0	0.0018	Chirp mass 93.8% likely to be between 11 and 22 Solar masses	[251]
S251018bi	2025-10-18 15:25:47	1463	5450±1489	H,L,V	3.2 10−10	0.018	0.0	0.0	0.99999	0.0	6.7e-6	Chirp mass 61.8% likely to be between 22 and 44 Solar masses (44-88 38.2%)	[252]
S251021u	2025-10-21 03:22:15	3859	5884±2089	H,L	2.2 10−9	0.120	0.0	0.0	0.99992	0.0	8.2e-5	Chirp mass 59.7% likely to be between 44 and 88 Solar masses (22-44 40.3%)	[253]
S251026bn	2025-10-26 21:16:05	744	1202±347	H,L	4.8 10−12	0.00028	0.0	0.0	0.924	0.076	8.2e-6	Chirp mass 100% likely to be between 5.5 and 11 Solar masses	[254]

See also

• GRB 150101B, a weak gamma-ray burst trigger observed prior to LIGO O1 (beginning September 12, 2015), with claimed similarities to neutron star merger GW170817/GRB 170817A/AT2017gfo.

Notes

1. The detection date of a GW event is indicated by its designation; i.e., event GW150914 was detected on 2015-09-14.
2. The relatively large and distant area of the sky within which it is claimed to be possible to localize the source.
3. 1 Mpc is approximately 3.26 Mly.
4. c²M_☉ is about 1.8×10³ foe; 1.8×10⁴⁷ J; 1.8×10⁵⁴ erg; 4.3×10⁴⁶ cal; 1.7×10⁴⁴ BTU; 5.0×10⁴⁰ kWh, or 4.3×10³⁷ tonnes of TNT.
5. The chirp mass is the binary parameter most relevant to the evolution of the inspiral gravitational waveform, and thus is the mass that can be measured most accurately. It is related to, but less than, the geometric mean ${\displaystyle (m_{geo})}$ of the binary masses, according to ${\displaystyle m_{geo}\left({\frac {m_{geo}}{m_{1}+m_{2}}}\right)^{1/5}}$, thus ranging from ~87% of ${\displaystyle m_{geo}}$ when the masses are the same to ~78% when they differ by an order of magnitude.
6. The dimensionless effective inspiral spin parameter is: ${\displaystyle {\frac {m_{1}a_{1}cos\theta _{LS_{1}}+m_{2}a_{2}cos\theta _{LS_{2}}}{m_{1}+m_{2}}},}$^[14] where ${\displaystyle m}$ is the mass of a black hole, ${\displaystyle a}$ is its spin, and ${\displaystyle \theta _{LS}}$ is the angle between the orbital angular momentum and a merging black hole's spin (ranging from ${\displaystyle 0}$ when aligned to ${\displaystyle \pi }$ when antialigned). It is the mass-weighted linear combination of the components of the black holes' spins aligned with the orbital axis^[14][13] and has values ranging from −1 to 1 (the extremes correspond to situations with both black hole spins exactly antialigned and aligned, respectively, with orbital angular momentum).^[15] This is the spin parameter most relevant to the evolution of the inspiral gravitational waveform, and it can be measured more accurately than those of the premerger BHs.^[16]
7. Values of the dimensionless spin parameter ${\displaystyle a=}$ cJ/GM² for a black hole range from zero to a maximum of one. The macroscopic properties of an isolated astrophysical (uncharged) black hole are fully determined by its mass and spin. Values for other objects can potentially exceed one. The largest value known for a neutron star is ≤ 0.4, and commonly used equations of state would limit that value to < 0.7.^[17]
8. Spin estimate is 0.26+0.52
   −0.24.^[18]
9. Spin estimate is 0.32+0.54
   −0.29.^[18]
10. Based on a descending spin-down GW-chirp lasting 3.7 seconds post-merger, a hyper-massive neutron star was produced in delayed gravitational collapse to a Kerr black hole after 0.92 seconds.^{[28] [29]}
11. Besides the loss of mass due to GW emission that occurred during the merger, the event is thought to have ejected 0.05±0.02 M_☉ of material.^[30]
12. 1 Mpc is approximately 3.26 Mly.
13. Which instruments observed the event. (H = LIGO Hanford, L=LIGO Livingston, V=Virgo)
14. The area of the sky within which it was possible to localize the source.
15. 1 Mpc is approximately 3.26 Mly.
16. Which instruments observed the event. (H = LIGO Hanford, L=LIGO Livingston, V=Virgo)
17. The chance a random signal of this significance would occur at any point in O3's 11-month run. Calculated by 1 - (1-false alarm rate in Hz)^28,512,000. This is not the chance of the given signal being 'real' or not: Background contamination (such as earthquakes) can cause statistically significant signals as well, and although four detections have a >50% chance to have occurred randomly in O3, there is only a 19.4% chance that none of these signals would be real.
18. Probability that both components have mass < 3 M_☉
19. Probability that one component has mass < 3 M_☉ and the other has mass > 5 M_☉
20. Probability that both components have mass > 5 M_☉
21. Probability that at least one component has a mass in the range 3-5 M_☉, between those of known neutron stars and black holes, a range sometimes identified as the "lower" mass gap
22. Probability that the source is terrestrial or non-cosmological (e.g. foreground noises and signals [e.g. "noise"] or a technical/systematic error ["glitch"])
23. The following events had a pAstro of over 50%, but were at a low significance and thus not validated by the LIGO-Virgo collaboration. Many of these events are likely real, but at least some are likely false positives:
    2023 May: S230524b (BBH, pAstro = 0.725), S230525a (BBH, pAstro = 0.724), S230527bv (BBH, pAstro = 0.882), S230528a (NSMG, pAstro = 0.643), S230528bt (BBH, pAstro = 0.880)
    June: S230604z (BBH, pAstro = 0.748), S230606z (BBH, pAstro = 0.835), S230609a (BBH, pAstro = 0.956), S230615av (BBH, pAstro = 0.912), S230615az (BNS, pAstro = 0.847), S230623at (BBH, pastro = 0.707), S230628aj (BBH, pAstro = 0.694)
    July: S230711b (BBH, pAstro = 0.792), S230716o (BBH, pAstro = 0.750), S230725am (BBH, pAstro = 0.502), S230728ap (BBH, pAstro = 0.940)
    August: S230822ac (BBH, pAstro = 0.813), S230830q (BBH, pAstro = 0.923)
    September: S230902af (BBH, pAstro = 0.798), S230904bg (BBH, pAstro = 0.688)
    October: S231007w (BBH, pAstro = 0.746), S231025a (BNS, pAstro = 0.588), S231025ap (BBH, pAstro = 0.830)
    November: S231124z (BBH, pAstro = 0.647)
    2024 January: S240116p (BBH, pAstro = 0.789)
    April: S240407v (BBH, pAstro = 0.882), S240420dc (BBH, pAstro = 0.887), S240427am (BBH, pAstro = 0.639)
    May: S240513cx (BBH, pAstro = 0.738), S240525dy (BBH, pAstro = 0.885), S240526ak (BBH, pAstro = 0.626), S240527dh (BBH, pAstro = 0.915), S240531aa (BBH, pAstro = 0.905)
    June: S240613z (BBH, pAstro = 0.923), S240619z (BBH, pAstro = 0.739), S240621ch (BBH, pAstro = 0.680), S240627co (BBH, pAstro = 0.713)
    July: S240701bn (BBH, pAstro = 0.824)
    September: S240901ew (BBH, pAstro = 0.881), S240907ah (BBH, pAstro = 0.910), S240913bs (BBH, pAstro = 0.875), S240914db (BBH, pAstro = 0.608), S240915aw (BBH, pAstro = 0.678), S240921s (BBH, pAstro = 0.736), S240921cs (BBH, pAstro = 0.702)
    October: S241031cn (BBH, pAstro = 0.583)
    November: S241101s (BBH, pAstro = 0.800), S241106ae (BBH, pAstro = 0.927), S241111u (BBH, pAstro = 0.703), S241115cn (BBH, pAstro = 0.626), S241124w (BBH, pAstro=0.913), S241128cf (BBH, pAstro=0.648)
    December: S241210ba (BBH, pAstro = 0.632)
    S241219gz (BBH, pAstro = 0.771)
    2025 January: S250103ei (BBH, pAstro = 0.697), S250105dn (BBH, pAstro = 0.753), S250120ah (BBH, pAstro = 0.901), S250123l (BBH, pAstro = 0.809), S250129p (BBH, pAstro = 0.798)
    February: S250204ar (BBH, pAstro = 0.779), S250207da (BBH, pAstro = 0.707), S250214bv (BBH, pAstro = 0.635), S250228p (BBH, pAstro = 0.798)
    March: S250304df (BBH, pAstro = 0.731), S250309co (BBH, pAstro = 0.665), S250313j (BBH, pAstro = 0.646), S250313aj (BBH, pAstro = 0.861), S250315ab (BBH, pAstro = 0.765), S250318bl (MGBH, pAstro = 0.584), S250321l (BBH, pAstro = 0.721), S250327u (BBH, pAstro = 0.635)
    June: S250614bb (BBH, pAstro = 0.648), S250619ca (BBH, pAstro = 0.787)
    July: S250717x (BBH, pAstro = 0.789)
    August: S250801h (BBH, pAstro = 0.665), S250805eg (BBH, pAstro = 0.833), S250813ak (BBH, pAstro = 0.660), S250817fb (BBH, pAstro = 0.703), S250822as (BBH, pAstro = 0.713), S250828ch (BBH, pAstro = 0.773)
    September: S250912x (BBH, pAstro = 0.944), S250926s (BBH, pAstro = 0.906)
    October: S251016be (BBH, pAstro = 0.861), S251020el (BBh, pAstro = 0.731)
24. The area of the sky within which it was possible to localize the source.
25. 1 Mpc is approximately 3.26 Mly.
26. Which instruments observed the event. (H = LIGO Hanford, L=LIGO Livingston, V=Virgo)
27. The chance a random signal of this significance would occur at any point in O4's 20-month run. Calculated by 1 - (1-false alarm rate in Hz)^57,456,000. This is not the chance of the given signal being 'real' or not: Even if there is a 90% chance of O4 having random noise eventually reach a certain level of significance, the chance of such noise occurring 100 separate times in the same period is still very low (in this example, around 0.0026%).
28. Probability that both components have mass < 3 M_☉
29. Probability that one component has mass < 3 M_☉ and the other has mass > 5 M_☉
30. Probability that both components have mass > 5 M_☉
31. Probability that at least one component has a mass in the range 3-5 M_☉, between those of known neutron stars and black holes, a range sometimes identified as the "lower" mass gap
32. Probability that the source is terrestrial or non-cosmological (e.g. foreground noises and signals [e.g. "noise"] or a technical/systematic error ["glitch"])