9965 GNU

9965 GNU, provisional designation 1992 EF2, is a background asteroid from the inner regions of the asteroid belt, approximately 4 kilometers (2 miles) in diameter. It was discovered on 5 March 1992, by astronomer of the Spacewatch program at the Kitt Peak National Observatory in Arizona, United States.[1] The uncertain D-type asteroid has a long rotation period of 39.7 hours.[5] It was named for the free-software GNU Project.[1]

9965 GNU
Orbits of GNU (blue), the inner planets and Jupiter (outermost)
Discovery [1]
Discovered bySpacewatch
Discovery siteKitt Peak National Obs.
Discovery date5 March 1992
Designations
(9965) GNU
Named after
GNU Project [1]
(free software project)
1992 EF2 · 1988 BD4
1993 QR3
main-belt [1][2] · (inner)
background [3]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc30.17 yr (11,019 d)
Aphelion2.8283 AU
Perihelion2.0080 AU
2.4181 AU
Eccentricity0.1696
3.76 yr (1,373 d)
276.39°
0° 15m 43.56s / day
Inclination12.206°
156.48°
82.938°
Physical characteristics
Mean diameter
2.07±0.53 km[4]
4.10 km (calculated)[5]
6.22±2.14 km[6]
6.293±0.159 km[7][8]
39.720±0.1589 h (R)[9]
39.745±0.1589 h (S)[9]
0.102±0.014[7]
0.1022±0.0145[8]
0.105±0.125[6]
0.20 (assumed)[5]
0.53±0.12[4]
D (Pan-STARRS)[10]
S (SDSS-MOC)[11]
S (assumed)[5]
14.10[6][8]
14.3[2][5]
14.31±0.14[10]
14.398±0.005 (R)[9]
14.72[4]
14.966±0.011 (S)[9]

    Orbit and classification

    GNU is a non-family asteroid from the main belt's background population.[3]

    It orbits the Sun in the inner asteroid belt at a distance of 2.0–2.8 AU once every 3 years and 9 months (1,373 days; semi-major axis of 2.42 AU). Its orbit has an eccentricity of 0.17 and an inclination of 12° with respect to the ecliptic.[2] The body's observation arc begins with its first observation as 1988 BD4 at La Silla Observatory in January 1988, or 4 years prior to its official discovery observation at Kitt Peak.[1]

    Physical characteristics

    GNU has been characterized as a dark D-type asteroid by Pan-STARRS' survey and in the SDSS-based taxonomy.[10][11] It is also an assumed S-type asteroid, the most common type in the inner asteroid belt.[5]

    Rotation period

    In September and October 2012, two rotational lightcurves of GNU were obtained from photometric observations by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 39.720 and 39.745 hours, with a brightness amplitude of 0.36 and 0.42 magnitude in the R- and S-band, respectively (U=2/2).[9] While not being a slow rotator, GNU' period is significantly longer than the average spin rate of 2 to 20 hours, seen among the majority of asteroids.

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, GNU measures between 2.07 and 6.293 kilometers in diameter and its surface has an albedo between 0.102 and 0.53.[4][6][7][8] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 4.10 kilometers based on an absolute magnitude of 14.3.[5]

    Naming

    This minor planet was named for the free-software GNU Project, created by Richard Stallman 1984. GNU is the recursive acronym for "GNU is not Unix". The collaborative projects enables programmers to trade and improve upon free software.[1] The official naming citation was published by the Minor Planet Center on 11 November 2000 (M.P.C. 41571).[12]

    References
    1. "9965 GNU (1992 EF2)". Minor Planet Center. Retrieved 28 May 2018.
    2. "JPL Small-Body Database Browser: 9965 GNU (1992 EF2)" (2018-03-22 last obs.). Jet Propulsion Laboratory. Retrieved 28 May 2018.
    3. "Asteroid 9965 GNU". Small Bodies Data Ferret. Retrieved 28 May 2018.
    4. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
    5. "LCDB Data for (9965) GNU". Asteroid Lightcurve Database (LCDB). Retrieved 28 May 2018.
    6. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
    7. 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.
    8. 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. (catalog)
    9. 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.
    10. 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.
    11. 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)
    12. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 May 2018.

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