19741 Callahan

19741 Callahan (provisional designation 2000 AN₁₄₁) is a stony background asteroid from the inner regions of the asteroid belt, approximately 3.5 kilometers in diameter.

19741 Callahan

Discovery[1]
Discovered by	LINEAR
Discovery site	Lincoln Lab ETS
Discovery date	5 January 2000
Designations
MPC designation	(19741) Callahan
Named after	Diane Callahan (mentor at DCYSC)[2]
Alternative designations	2000 AN141 · 1978 RQ8
Minor planet category	main-belt[3] · (inner)[4] background
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	38.66 yr (14,121 days)
Aphelion	2.5407 AU
Perihelion	1.9559 AU
Semi-major axis	2.2483 AU
Eccentricity	0.1301
Orbital period (sidereal)	3.37 yr (1,231 days)
Mean anomaly	163.76°
Mean motion	0° 17m 32.64s / day
Inclination	8.0506°
Longitude of ascending node	167.39°
Argument of perihelion	227.28°
Physical characteristics
Dimensions	3.12 km (calculated)[4] 3.876±0.166 km[5][6]
Synodic rotation period	7.2684±0.0015 h[7]
Geometric albedo	0.20 (assumed)[4] 0.224±0.044[5][6]
Spectral type	S[4]
Absolute magnitude (H)	14.3[5] · 14.4[1] · 14.444±0.004[7] · 14.89[4]

It was discovered on 5 January 2000, by the Lincoln Near-Earth Asteroid Research, LINEAR, at the Lincoln Laboratory's Experimental Test Site, Socorro, New Mexico, and named after a mentor of the 2003 Discovery Channel Young Scientist Challenge.^[2][3]

Orbit and classification

The S-type asteroid orbits the Sun in the inner main-belt at a distance of 2.0–2.5 AU once every 3 years and 4 months (1,231 days). Its orbit has an eccentricity of 0.13 and an inclination of 8° with respect to the ecliptic.^[1] Callahan was first identified as 1978 RQ8 at ESO's La Silla Observatory in 1978, which extends the asteroid's observation arc by 22 years prior to its official discovery observation.^[3]

Physical characteristics

In December 2009, a rotational lightcurve for this asteroid was obtained from photometric observations at the U.S. Palomar Transient Factory, California. It gave a rotation period of 7.2684±0.0015 hours with a relatively high brightness variation of 0.81 in magnitude (U=2), indicative of a non-spherical shape.^[7]

According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Callahan measures 3.9 kilometers in diameter and its surface has an albedo of 0.22.^[5] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.1 kilometers, with an absolute magnitude of 14.89.^[4]

Naming

This minor planet was named after Diane Callahan, teacher at U.S. Fairfield Middle School, Ohio, who mentored a finalist in the 2003 Discovery Channel Youth Science Challenge (DCYSC), a middle school science competition.^[2] The approved naming citation was published by the Minor Planet Center on 10 October 2003 (M.P.C. 49772).^[8]