1798 Watts

1798 Watts

Discovery[1]
Discovered by	Indiana University (Indiana Asteroid Program)
Discovery site	Goethe Link Obs.
Discovery date	4 April 1949
Designations
MPC designation	(1798) Watts
Named after	Chester Watts (American astronomer)[2]
Alternative designations	1949 GC · 1934 VS 1937 RL · 1970 YB 1973 UD6
Minor planet category	main-belt · Flora[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	82.46 yr (30,117 days)
Aphelion	2.4676 AU
Perihelion	1.9315 AU
Semi-major axis	2.1996 AU
Eccentricity	0.1219
Orbital period (sidereal)	3.26 yr (1,192 days)
Mean anomaly	136.39°
Mean motion	0° 18^m 7.56^s / day
Inclination	6.1941°
Longitude of ascending node	44.269°
Argument of perihelion	4.0161°
Known satellites	1[4][a]
Physical characteristics
Dimensions	6.45±0.28 km[5] 6.631±0.186 km[6] 6.986±0.060 km[7] 7.14 km (calculated)[3]
Synodic rotation period	3.5060±0.0004
Geometric albedo	0.24 (assumed)[3] 0.2765±0.0258[7] 0.294±0.053[5]
Spectral type	SMASS = S[1] · LS[8] · S[3]
Absolute magnitude (H)	12.8[7] · 12.9[1][3][5] · 13.05±0.17[8]

1798 Watts, provisional designation 1949 GC, is a stony asteroid and binary system from the inner regions of the asteroid belt, approximately 7 kilometers in diameter.

It was discovered on 4 April 1949, by IU's Indiana Asteroid Program at Goethe Link Observatory near Brooklyn, Indiana, United States.^[9] The asteroid was named for American astronomer Chester Burleigh Watts.^[2] Its small minor-planet moon has a period of 26.96 hours.

Orbit and classification

Watts is a member of the Flora family, a large group of stony S-type asteroids in the inner main-belt. It orbits the Sun at a distance of 1.9–2.5 AU once every 3 years and 3 months (1,192 days). Its orbit has an eccentricity of 0.12 and an inclination of 6° with respect to the ecliptic.^[1] Watts was first observed and identified as 1934 VS at Yerkes Observatory in 1934, extending the body's observation arc by 15 years prior to its official discovery observation.^[9]

Physical characteristics

Spectral type

In the SMASS classification, Watts is characterized as a common stony S-type asteroid.^[1] It is also classified as a LS-type by PanSTARRS's photometric survey.^[8]

Diameter and albedo

According to the survey carried out by NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Watts measures 6.63 kilometers in diameter and its surface has an albedo between 0.276 and 0.294.^[5][6][7] The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.24 – derived from 8 Flora, the largest member and namesake of this asteroid family – and calculates a diameter of 7.14 kilometers with an absolute magnitude of 12.9.^[3]

Moon and lightcurve

In February 2017, a rotational lightcurve of Watts was obtained from photometric observations by . Lightcurve analysis gave a rotation period of 3.5060 hours with a low brightness amplitude of 0.06 magnitude, indicating that the body has a spheroidal shape (U=n.a.). ^[a]

During the photometric observations, a minor-planet moon was discovered, making Watts a binary asteroid. The satellite of the synchronous binary has an orbital period of 26.96 hours.^[4][a]

Naming

This minor planet was named in honour of American astronomer Chester Burleigh Watts (1889–1971), a graduate of Indiana University. He worked at the United States Naval Observatory for 44 years, making distinguished contributions in the field of positional astronomy and pioneered in the field of automation of transit circle observations, which led to results of the highest systematic accuracy. From the late 1940 until 1963 he meticulously mapped every feature on the marginal zone of the Moon.^[2] The official naming citation was published by the Minor Planet Center on 15 June 1973 (M.P.C. 3508).^[10]

Notes

1. D. Pray (2017), photometry for (1798) Watts at Collaborative Asteroid Lightcurve Link (CALL). Currently 2017CBET.4374....1P is missing on the SAO/NASA Astrophysics Data System (ADS)

References

1. "JPL Small-Body Database Browser: 1798 Watts (1949 GC)" (2017-04-30 last obs.). Jet Propulsion Laboratory. Retrieved 8 June 2017.
2. Schmadel, Lutz D. (2007). "(1798) Watts". Dictionary of Minor Planet Names – (1798) Watts. Springer Berlin Heidelberg. p. 144. doi:10.1007/978-3-540-29925-7_1799. ISBN 978-3-540-00238-3.
3. "LCDB Data for (1798) Watts". Asteroid Lightcurve Database (LCDB). Retrieved 19 December 2016.
4. Johnston, Robert (19 March 2017). "(1798) Watts". johnstonsarchive.net. Retrieved 8 June 2017.
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. Retrieved 19 December 2016.
6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121. Retrieved 19 December 2016.
7. 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.
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. Retrieved 19 December 2016.
9. "1798 Watts (1949 GC)". Minor Planet Center. Retrieved 19 December 2016.
10. Schmadel, Lutz D. (2009). "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. Bibcode:2009dmpn.book.....S. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

External links

• Asteroids with Satellites, Robert Johnston, johnstonsarchive.net
• 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 (1)-(5000) – Minor Planet Center
• 1798 Watts at AstDyS-2, Asteroids—Dynamic Site
  • Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
• 1798 Watts at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters