161989 Cacus

161989 Cacus
	Shape model of Cacus from its lightcurve
Discovery
Discovered by	H.-E. Schuster
Discovery site	La Silla Obs.
Discovery date	8 February 1978
Designations
MPC designation	(161989) Cacus
Named after	Cacus (Roman mythology)
Alternative designations	1978 CA
Minor planet category	Apollo · NEO · PHA
Orbital characteristics
	Epoch 4 September 2017 (JD 2458000.5)
	Uncertainty parameter 0
Observation arc	38.59 yr (14,096 days)
Aphelion	1.3634 AU
Perihelion	0.8828 AU
Semi-major axis	1.1231 AU
Eccentricity	0.2140
Orbital period (sidereal)	1.19 yr (435 days)
Mean anomaly	345.40°
Mean motion	0° 49m 41.16s / day
Inclination	26.060°
Longitude of ascending node	161.24°
Argument of perihelion	102.16°
Earth MOID	0.0152 AU · 5.9 LD
Physical characteristics
Mean diameter	0.64±0.02 km; 1.126±0.073 km; 1.86 km; 1.9 km
Synodic rotation period	3.7538±0.0019 h; 3.756 h; 3.761 h; 3.77±0.11 h
Geometric albedo	0.09; 0.119 (derived); 0.199±0.052; 0.46±0.09
Spectral type	Tholen = S · Q; B–V = 0.910; U–B = 0.484
Absolute magnitude (H)	16.58 · 17.1 · 17.2 · 17.32 · 17.43

161989 Cacus (prov. designation: 1978 CA) is a stony asteroid, classified as near-Earth object and a potentially hazardous asteroid of the Apollo group, approximately 1 kilometer in diameter. It was discovered on 8 February 1978, by German astronomer Hans-Emil Schuster at ESO's La Silla Observatory in northern Chile.^[2] Its orbit is confined between Venus and Mars.

This minor planet was named from Roman mythology, after Cacus, a fire-breathing monster, which was killed by Hercules.^[2] The official naming citation was published by the Minor Planet Center on 24 November 2007 (M.P.C. 61270).^[10]

Close approaches^[1]
Date	JPL SBDB nominal geocentric distance	uncertainty region (3-sigma)
1941-09-02	2418754 km	± 6 km
2022-09-01	8607710 km	± 21 km^[11]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h "JPL Small-Body Database Browser: 161989 Cacus (1978 CA)" (2016-09-12 last obs.). Jet Propulsion Laboratory. Archived from the original on 22 November 2020. Retrieved 13 January 2018.
^ ^a ^b ^c ^d "161989 Cacus (1978 CA)". Minor Planet Center. Retrieved 13 January 2018.
^ ^a ^b ^c 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.
^ ^a ^b ^c 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. S2CID 35447010.
^ ^a ^b ^c Degewij, J.; Lebofsky, L.; Lebofsky, M. (March 1978). "1978 CA and 1978 DA". IAU Circ. 3193 (3193): 1. Bibcode:1978IAUC.3193....1D. Retrieved 13 January 2018.
^ ^a ^b ^c ^d ^e ^f "LCDB Data for (161989) Cacus". Asteroid Lightcurve Database (LCDB). Retrieved 13 January 2018.
^ ^a ^b Schuster, H. E.; Surdej, A.; Surdej, J. (September 1979). "Photoelectric observations of two unusual asteroids - 1978 CA and 1978 DA". Astronomy and Astrophysics Supplement Series. 37: 483–486. Bibcode:1979A&AS...37..483S.
^ Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; et al. (October 2014). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June". The Minor Planet Bulletin. 41 (4): 286–300. Bibcode:2014MPBu...41..286K. ISSN 1052-8091.
^ Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004.
^ "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 13 January 2018.
^ "Horizons Batch for 2022-Sep-01 06:54 UT". JPL Horizons. Archived from the original on 17 January 2022. Retrieved 17 January 2022.

External links

Lightcurve Database Query (LCDB), at www.minorplanet.info
Dictionary of Minor Planet Names, Google books
Asteroids and comets rotation curves, CdR – Geneva Observatory, Raoul Behrend
161989 Cacus at NeoDyS-2, Near Earth Objects—Dynamic Site
- Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
161989 Cacus at ESA–space situational awareness
- Ephemerides · Observations · Orbit · Physical properties · Summary
161989 Cacus at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

[jpldata-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h "JPL Small-Body Database Browser: 161989 Cacus (1978 CA)" (2016-09-12 last obs.). Jet Propulsion Laboratory. Archived from the original on 22 November 2020. Retrieved 13 January 2018.

[MPC-object-2] "161989 Cacus (1978 CA)". Minor Planet Center. Retrieved 13 January 2018.

[Nugent-2016-3] 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.

[WISE-4] 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. S2CID 35447010.

[Degewij-1978b-5] Degewij, J.; Lebofsky, L.; Lebofsky, M. (March 1978). "1978 CA and 1978 DA". IAU Circ. 3193 (3193): 1. Bibcode:1978IAUC.3193....1D. Retrieved 13 January 2018.

[lcdb-6] ^ ^a ^b ^c ^d ^e ^f "LCDB Data for (161989) Cacus". Asteroid Lightcurve Database (LCDB). Retrieved 13 January 2018.

[Schuster-1979-7] Schuster, H. E.; Surdej, A.; Surdej, J. (September 1979). "Photoelectric observations of two unusual asteroids - 1978 CA and 1978 DA". Astronomy and Astrophysics Supplement Series. 37: 483–486. Bibcode:1979A&AS...37..483S.

[Koehn-2014-8] Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; et al. (October 2014). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June". The Minor Planet Bulletin. 41 (4): 286–300. Bibcode:2014MPBu...41..286K. ISSN 1052-8091.

[Thomas-2014-9] Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004.

[MPC-Circulars-Archive-10] "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 13 January 2018.

[Horizons2022-11] "Horizons Batch for 2022-Sep-01 06:54 UT". JPL Horizons. Archived from the original on 17 January 2022. Retrieved 17 January 2022.

[1]

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

[11]