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(9948) 1990 QB₂
	Orbit of 1990 QB2 (blue), the inner planets; and Jupiter (outermost)
Discovery
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 · (inner); Nysa
Orbital characteristics
	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; 3.351 km
Synodic rotation period	3.523±0.0025 h (R); 3.5257±0.0007 h; 3.53±0.010 h (R)
Geometric albedo	0.2232; 0.250±0.093
Spectral type	S (SDSS-MOC); S (Pan-STARRS)
Absolute magnitude (H)	13.79±0.54; 14.290±0.200 (R); 14.3; 14.338±0.004 (R); 14.5; 14.62

(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]

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]

References

^ ^a ^b ^c ^d ^e ^f "9948 (1990 QB2)". Minor Planet Center. Retrieved 31 May 2018.
^ ^a ^b ^c ^d "JPL Small-Body Database Browser: 9948 (1990 QB2)" (2018-02-25 last obs.). Jet Propulsion Laboratory. Retrieved 31 May 2018.
^ ^a ^b ^c ^d ^e "LCDB Data for (9948)". Asteroid Lightcurve Database (LCDB). Retrieved 31 May 2018.
^ ^a ^b "Asteroid (9948) 1990 QB2". Small Bodies Data Ferret. Retrieved 31 May 2018.
^ ^a ^b ^c Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68. S2CID 118745497.
^ ^a ^b ^c ^d Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 118700974. (catalog)
^ ^a ^b ^c ^d Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026.
^ ^a ^b ^c Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. S2CID 8342929.
^ ^a ^b Higgins, David; Pravec, Petr; Kusnirak, Peter; Reddy, Vishnu; Dyvig, Ron (September 2006). "Asteroid lightcurve analysis at Hunters Hill Observatory and collaborating stations - summer 2005/6". The Minor Planet Bulletin. 33 (3): 64–66. Bibcode:2006MPBu...33...64H. ISSN 1052-8091.
^ ^a ^b ^c Chang, Chan-Kao; Ip, Wing-Huen; Lin, Hsing-Wen; Cheng, Yu-Chi; Ngeow, Chow-Choong; Yang, Ting-Chang; et al. (August 2015). "Asteroid Spin-rate Study Using the Intermediate Palomar Transient Factory". The Astrophysical Journal Supplement Series. 219 (2): 19. arXiv:1506.08493. Bibcode:2015ApJS..219...27C. doi:10.1088/0067-0049/219/2/27. S2CID 17093124.
^ ^a ^b Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 30 October 2019. (PDS data set)
^ ^a ^b ^c Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. S2CID 53493339.
^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). "Identification and Dynamical Properties of Asteroid Families". Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131. S2CID 119280014.
^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 31 May 2018.