1244 Deira

1244 Deira (prov. designation: 1932 KE) is a dark background asteroid and slow rotator from the inner region of the asteroid belt. The X-type asteroid has an exceptionally long rotation period of 210.6 hours and measures approximately 31 kilometers (19 miles) in diameter. It was discovered on 25 May 1932, by English-born South African astronomer Cyril Jackson at the Union Observatory in Johannesburg,^[4] who named it after Deira, an old kingdom near his birthplace, the market town of Ossett, located in West Yorkshire, England.^[3]

1244 Deira

Modelled shape of Deira from its lightcurve
Discovery[1]
Discovered by	C. Jackson
Discovery site	Johannesburg Obs.
Discovery date	25 May 1932
Designations
MPC designation	(1244) Deira
Pronunciation	/ˈdaɪrə/ DY-rə or /ˈdɛərə/ DAIR-ə[2]
Named after	Deira, near the town of Ossett, England[3] (alt. Celtic Kingdom of Deira)
Alternative designations	1932 KE · 1930 YR 1984 YQ6 · A908 TD A921 GC · A924 BH
Minor planet category	main-belt[4][1] · (inner) background[5][6]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	109.13 yr (39,861 days)
Aphelion	2.5731 AU
Perihelion	2.1129 AU
Semi-major axis	2.3430 AU
Eccentricity	0.0982
Orbital period (sidereal)	3.59 yr (1,310 days)
Mean anomaly	335.23°
Mean motion	0° 16m 29.28s / day
Inclination	8.6950°
Longitude of ascending node	277.12°
Argument of perihelion	261.45°
Physical characteristics
Mean diameter	28.816±0.546 km[7] 30.432±9.136 km[8] 30.95±1.9 km[9] 31.799±0.487 km[10] 32.28±0.35 km[11] 33.15±7.01 km[12] 35.19±0.19 km[13]
Synodic rotation period	5 (poor) h[14] 210.6±0.1 h[a] 216.98±0.05 h[15] 217.1±0.1 h[b]
Pole ecliptic latitude	(314.0°, −46.0°) (λ1/β1)[6] (107.0°, −56.0°) (λ2/β2)[6]
Geometric albedo	0.03±0.00[13] 0.0357±0.0051[10] 0.037±0.011[12] 0.0416±0.0312[8] 0.052±0.001[11] 0.0557±0.007[9]
Spectral type	X (S3OS2)[16] P (WISE)[10]
Absolute magnitude (H)	11.30[9][10][11] 11.50[1][17][8]

Orbit and classification

Deira is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.^[5][6] It orbits the Sun in the inner asteroid belt at a distance of 2.1–2.6 AU once every 3 years and 7 months (1,310 days; semi-major axis 2.34 AU). Its orbit has an eccentricity of 0.10 and an inclination of 9° with respect to the ecliptic.^[1] The body's observation arc begins with its first observations as A908 TD at Heidelberg Observatory in October 1908, or more than 23 years prior to its official discovery observation at Johannesburg.^[4]

Naming

This minor planet was named by the discoverer Cyril Jackson after his birthplace, the market town of Ossett, located in West Yorkshire, England (also see 2193 Jackson).^[3] The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 115).^[3] While the naming citation reads that Deira is the ancient name for his birthplace, the Celtic Kingdom of Deira was actually much larger, encompassing at its height most of Yorkshire in Northern England.

Physical characteristics

Deira has been characterized as a primitive P-type asteroid by the space-based Wide-field Infrared Survey Explorer (WISE).^[10] While P-type bodies are common in the outermost asteroid belt and among the Jupiter trojans, they are rarely found in the inner main belt. In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Deira is an X-type asteroid.^[6][16]

Rotation period

In March 2011, a rotational lightcurve of Deira was obtained from photometric observations by Julian Oey at his Leura Observatory (E17) in Australia. Lightcurve analysis gave a rotation period of 210.6 hours with a brightness variation of 0.5 magnitude (U=2),^[a] while Oey previously published a slightly longer period of 217.1 hours and an amplitude of 0.6 magnitude (U=n.a.).^[b] This makes Deira one of the Top 300 slow rotators known to exist.

Spin axis

In 2016, an international study modeled a lightcurve with a concurring period of 216.98 hours and found two spin axis of (314.0°, −46.0°) and (107.0°, −56.0°) in ecliptic coordinates (λ, β).^[15]

Diameter and albedo

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's WISE telescope, Deira measures between 28.816 and 35.19 kilometers in diameter and its surface has an albedo between 0.03 and 0.0557.^{[7][8][9][10][11][12][13]}

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0465 and a diameter of 30.89 kilometers based on an absolute magnitude of 11.5.^[17]

Notes

1. Oey (2011) LCDB. (1244) Deira – rotation period 210.6±0.1 hours with a brightness amplitude of 0.50±0.03 mag. Quality code of 2. Summary figures at the LCDB.
2. Oey (2007) website. (1244) Deira – rotation period 217.1±0.1 hours with a brightness amplitude of 0.60±0.05 mag. No quality code. Lightcurve-plot and summary figures at the archived Leura Observatory website. Astronomers comment: "The data is re-reduced with Canopus 9.5 Comp Star Selector feature. Linkage over the 2.5 months period showing a main period of 217h. Slow rotator with deviation from the mean due to Psyn-sid and tumbling characteristics."