4175 Billbaum

4175 Billbaum, provisional designation 1985 GX, is a background asteroid from the central regions of the asteroid belt, approximately 9 kilometers (6 miles) in diameter. It was discovered on 15 April 1985, by American astronomer Edward Bowell at the Anderson Mesa Station of the Lowell Observatory near Flagstaff, Arizona. The uncommon L-type asteroid has a short rotation period of 2.73 hours and was named for American astronomer William A. Baum.[1][4]

4175 Billbaum
Discovery [1]
Discovered byE. Bowell
Discovery siteAnderson Mesa Stn.
Discovery date15 April 1985
Designations
(4175) Billbaum
Named after
William A. Baum [1]
(American astronomer)
1985 GX · 1974 UE
1978 QF2 · 1978 RL4
main-belt [1][2] · (middle)
background [3] · Eunomia [4]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc66.14 yr (24,159 d)
Aphelion3.1831 AU
Perihelion2.1842 AU
2.6836 AU
Eccentricity0.1861
4.40 yr (1,606 d)
239.61°
0° 13m 27.12s / day
Inclination13.612°
163.41°
316.77°
Physical characteristics
Mean diameter
8.873±0.278 km[5]
9.60 km (calculated)[4]
2.730±0.005 h[lower-alpha 1]
2.7425±0.0009 h[6]
2.908±0.001 h[7]
0.21 (assumed)[4]
0.270±0.038[5]
L [8] · S (assumed)[4]
11.96±0.72[8]
12.30[5]
12.4[2][4]

    Orbit and classification

    Billbaum is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[3] Based on osculating Keplerian orbital elements, the asteroid has also been classified as a member of the Eunomia family (502), a prominent family of stony S-type asteroid and the largest one in the intermediate main belt with more than 5,000 members.[4]

    It orbits the Sun in the central main-belt at a distance of 2.2–3.2 AU once every 4 years and 5 months (1,606 days; semi-major axis of 2.68 AU). Its orbit has an eccentricity of 0.19 and an inclination of 14° with respect to the ecliptic.[2] The body's observation arc begins with a precovery taken at Palomar Observatory in August 1951, almost 34 years prior to its official discovery observation at Anderson Mesa.[1]

    Physical characteristics

    Billbaum has been characterized as an uncommon L-type asteroid by Pan-STARRS survey.[8][4]

    Rotation period

    In January and February 2011, three rotational lightcurves of Billbaum were obtained from photometric observations by Ralph Megna, Josep Aymami and astronomers at the Oakley Southern Sky Observatory.[6][7][lower-alpha 1] Analysis of the best-rated lightcurve gave a short rotation period of 2.73 hours and a consolidated brightness amplitude between 0.08 and 0.15 magnitude (U=3-).[4]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Billbaum measures 8.87 kilometers in diameter and its surface has an albedo of 0.27,[5] while the Collaborative Asteroid Lightcurve Link assumes a stony standard albedo of 0.21, derived from 15 Eunomia, the Eunomia family's parent body – and calculates a diameter of 9.60 kilometers based on an absolute magnitude of 12.4.[4]

    Naming

    This minor planet was named after American astronomer William A. Baum (1924–2012) who was on the directorship of the Lowell Observatory's Planetary Research Center. He also worked on the Hubble Space Telescope.[1] The official naming citation was published by the Minor Planet Center on 28 April 1991 (M.P.C. 18139).[9]

    Notes
    1. Ralph Megna (2011) web: rotation period 2.730±0.005 hours with a brightness amplitude of 0.15±0.03 mag. Quality code of 3-. Summary figures for (4175) Billbaum at the LCDB

    References
    1. "4175 Billbaum (1985 GX)". Minor Planet Center. Retrieved 25 April 2018.
    2. "JPL Small-Body Database Browser: 4175 Billbaum (1985 GX)" (2017-09-28 last obs.). Jet Propulsion Laboratory. Retrieved 25 April 2018.
    3. "Asteroid 4175 Billbaum – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 29 October 2019.
    4. "LCDB Data for (4175) Billbaum". Asteroid Lightcurve Database (LCDB). Retrieved 25 April 2018.
    5. 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.
    6. Ditteon, Richard; West, Josh (October 2011). "Asteroid Lightcurve Analysis at the Oakley Southern Observatory: 2011 January thru April". The Minor Planet Bulletin. 38 (4): 214–217. Bibcode:2011MPBu...38..214D. ISSN 1052-8091.
    7. Aymami, Josep Maria (July 2011). "CCD Photometry and Lightcurve Analysis of 1318 Nerina, 4175 Billbaum and 5168 Jenner from Observatori Carmelita (MPC B20) in Tiana". The Minor Planet Bulletin. 38 (3): 158–159. Bibcode:2011MPBu...38..158A. ISSN 1052-8091.
    8. 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.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 25 April 2018.

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