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 by	Spacewatch
Discovery site	Kitt Peak National Obs.
Discovery date	5 March 1992
Designations
MPC designation	(9965) GNU
Named after	GNU Project[1] (free software project)
Alternative designations	1992 EF2 · 1988 BD4 1993 QR3
Minor planet category	main-belt[1][2] · (inner) background[3]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	30.17 yr (11,019 d)
Aphelion	2.8283 AU
Perihelion	2.0080 AU
Semi-major axis	2.4181 AU
Eccentricity	0.1696
Orbital period (sidereal)	3.76 yr (1,373 d)
Mean anomaly	276.39°
Mean motion	0° 15m 43.56s / day
Inclination	12.206°
Longitude of ascending node	156.48°
Argument of perihelion	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]
Synodic rotation period	39.720±0.1589 h (R)[9] 39.745±0.1589 h (S)[9]
Geometric albedo	0.102±0.014[7] 0.1022±0.0145[8] 0.105±0.125[6] 0.20 (assumed)[5] 0.53±0.12[4]
Spectral type	D (Pan-STARRS)[10] S (SDSS-MOC)[11] S (assumed)[5]
Absolute magnitude (H)	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]