(9948) 1990 QB2

(9948) 1990 QB₂ (provisional designation 1990 QB₂) is a stony Nysian asteroid from the inner region of the asteroid belt, approximately 3.4 kilometers (2.1 miles) in diameter. It was discovered on 22 August 1990, by American astronomer Henry Holt at the Palomar Observatory in California.^[1] The likely elongated S-type asteroid has a rotation period of 3.53 hours.^[3] This asteroid has not been named.^[1]

(9948) 1990 QB₂

Orbit of 1990 QB2 (blue), the inner planets and Jupiter (outermost)
Discovery[1]
Discovered by	H. E. Holt
Discovery site	Palomar Obs.
Discovery date	22 August 1990
Designations
MPC designation	(9948) 1990 QB2
Alternative designations	1990 QB2 · 1979 SJ6 1990 SQ26
Minor planet category	main-belt[1][2] · (inner)[3] Nysa[4]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	38.43 yr (14,035 d)
Aphelion	2.9012 AU
Perihelion	1.8657 AU
Semi-major axis	2.3835 AU
Eccentricity	0.2172
Orbital period (sidereal)	3.68 yr (1,344 d)
Mean anomaly	187.50°
Mean motion	0° 16m 4.08s / day
Inclination	2.0964°
Longitude of ascending node	171.55°
Argument of perihelion	151.67°
Physical characteristics
Mean diameter	3.345±0.717 km[5][6] 3.351 km[7]
Synodic rotation period	3.523±0.0025 h (R)[8] 3.5257±0.0007 h[9] 3.53±0.010 h (R)[10]
Geometric albedo	0.2232[7] 0.250±0.093[5][6]
Spectral type	S (SDSS-MOC)[11] S (Pan-STARRS)[12]
Absolute magnitude (H)	13.79±0.54[12] 14.290±0.200 (R)[10] 14.3[2] 14.338±0.004 (R)[8] 14.5[6] 14.62[3][7]

Orbit and classification

1990 QB₂ is member of the Nysa family (405),^[4] located in the Nysa–Polana complex. It is named after 44 Nysa and one of the largest families in the main belt.^[13]: 23

The asteroid orbits the Sun in the inner asteroid belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,344 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.22 and an inclination of 2° with respect to the ecliptic.^[2] The asteroid was first observed as 1979 SJ₆ at Crimea–Nauchnij in September 1979. The body's observation arc begins at Palomar with its official discovery observation in 1990.^[1]

Physical characteristics

1990 QB₂ has been characterized as a common, stony S-type asteroid by Pan-STARRS' survey and in the SDSS-based taxonomy.^[3][11][12]

Rotation period

In November 2005, a first rotational lightcurve of 1990 QB₂ was obtained from photometric observations by Australian amateur astronomer David Higgins. Lightcurve analysis gave a well-defined rotation period of 3.5257 hours with a high brightness variation of 0.77 magnitude (U=3).^[9] In January 2014, observations in the R-band at the Palomar Transient Factory in California gave two concurring periods of 3.523 and 3.53 hours with an amplitude of 0.60 magnitude (U=2/2).^[8][10] A high brightness amplitude typically indicates that the body has a non-spherical shape

Diameter and albedo

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, 1990 QB₂ measures 3.345 kilometers in diameter and its surface has an albedo of 0.250.^[5][6] The Collaborative Asteroid Lightcurve Link adopts Petr Pravec's revised WISE-result, that is, an albedo of 0.2232 and a diameter of 3.351 kilometers based on an absolute magnitude of 14.62.^[3][7]

Naming

This minor planet was numbered on 2 February 1999 (M.P.C. 33659).^[14] As of 2018, it has not been named.^[1]