19741 Callahan

19741 CallahanDiscovery[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]

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.

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[edit]

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[edit]

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[edit]

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]

## References[edit]

1. ^ a b c d "JPL Small-Body Database Browser: 19741 Callahan (2000 AN141)" (2017-05-01 last obs.). Jet Propulsion Laboratory. Retrieved 5 July 2017.
2. ^ a b c Schmadel, Lutz D. (2006). "(19741) Callahan [2.25, 0.13, 8.0]". Dictionary of Minor Planet Names – (19741) Callahan, Addendum to Fifth Edition: 2003–2005. Springer Berlin Heidelberg. p. 142\. doi:10.1007/978-3-540-34361-5_1597. ISBN 978-3-540-34360-8.
3. ^ a b c "19741 Callahan (2000 AN141)". Minor Planet Center. Retrieved 22 March 2016.
4. ^ a b c d e f "LCDB Data for (19741) Callahan". Asteroid Lightcurve Database (LCDB). Retrieved 17 May 2016.
5. ^ 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. Retrieved 17 May 2016.
6. ^ a b 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. Retrieved 3 December 2016.
7. ^ 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. Retrieved 17 May 2016.
8. ^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 17 May 2016.

## External links[edit]

* Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
* Dictionary of Minor Planet Names, Google books
* Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
* Discovery Circumstances: Numbered Minor Planets (15001)-(20000) – Minor Planet Center
* 19741 Callahan at AstDyS-2, Asteroids—Dynamic Site
* Ephemeris * Observation prediction * Orbital info * Proper elements * Observational info
* 19741 Callahan at the JPL Small-Body Database
* Close approach * Discovery * Ephemeris * Orbit diagram * Orbital elements * Physical parameters

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