444 Gyptis

444 Gyptis
Discovery
Discovered by	J. Coggia
Discovery date	31 March 1899
Designations
MPC designation	(444) Gyptis
Pronunciation	/ˈdʒɪptɪs/
Named after	Gyptis
Alternative designations	1899 EL
Minor planet category	Main belt
Adjectives	Gyptidian
Orbital characteristics
	Epoch 31 July 2016 (JD 2457600.5)
	Uncertainty parameter 0
Observation arc	116.54 yr (42568 d)
Aphelion	3.25674 AU (487.201 Gm)
Perihelion	2.28337 AU (341.587 Gm)
Semi-major axis	2.77005 AU (414.394 Gm)
Eccentricity	0.17569
Orbital period (sidereal)	4.61 yr (1684.0 d)
Mean anomaly	11.8852°
Mean motion	0° 12m 49.615s / day
Inclination	10.2775°
Longitude of ascending node	195.716°
Argument of perihelion	154.984°
Physical characteristics
Dimensions	179×150 km
Mean diameter	159.331±0.490 km; 164.63±2.60 km
Mass	1.25×1019 kg; (1.06±0.28)×1019 kg
Mean density	5.53±1.46 g/cm3; 4.55±1.23 g/cm3
Synodic rotation period	6.214 h (0.2589 d)
Geometric albedo	0.051±0.008
Spectral type	C
Absolute magnitude (H)	8.07

444 Gyptis is a main-belt asteroid that was discovered by J. Coggia on March 31, 1899, in Marseilles. It is classified as a C-type asteroid and is probably composed of carbonaceous material. The spectra of the asteroid displays evidence of aqueous alteration.^[5]

In 2004, Kochetova estimated Gyptis to have a mass of 1.25×10¹⁹ kg with a high density of 5.53 g/cm³.^[4] In 2012 Carry estimated the mass as (1.06±0.28)×10¹⁹ kg with a high density of 4.55±1.23 g/cm³.^[3] The adaptive optics instrument at the W. M. Keck Observatory showed an object with a diameter of 129 km, which is much smaller than the estimate of 160 km from the IRAS observatory measurements, indicating an irregular shape. The size ratio between the major and minor axes is estimated at 1.40.^[6] Observations of an occultation on October 14, 2007, produced six chords indicating a cross-section ellipsoid of 179×150 km.^[2]

Between 1990 and 2021, 444 Gyptis has been observed to occult 17 stars.

References

^ ^a ^b ^c ^d ^e ^f "JPL Small-Body Database Browser: 444 Gyptis (1899 EL)" (2024-09-25 last obs). Retrieved 19 December 2024.
^ ^a ^b "2007 European Asteroidal Occultation Results". euraster.net (a website for Asteroidal Occultation Observers in Europe). 14 October 2007. Retrieved 1 December 2008. (Chords)
^ ^a ^b ^c ^d Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
^ ^a ^b ^c Jim Baer (2008). "Recent Asteroid Mass Determinations". Personal Website. Archived from the original on 2 July 2013. Retrieved 27 November 2008.
^ Fornasier, S.; et al. (February 1999), "Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites", Astronomy and Astrophysics Supplement, 135: 65−73, Bibcode:1999A&AS..135...65F, doi:10.1051/aas:1999161.
^ Marchis, F.; et al. (November 2006), "Shape, size and multiplicity of main-belt asteroids. I. Keck Adaptive Optics survey", Icarus, 185 (1): 39–63, Bibcode:2006Icar..185...39M, doi:10.1016/j.icarus.2006.06.001, PMC 2600456, PMID 19081813.