Physical model of asteroid 1620 Geographos from radar and optical data

Citation
Rs. Hudson et Sj. Ostro, Physical model of asteroid 1620 Geographos from radar and optical data, ICARUS, 140(2), 1999, pp. 369-378
Citations number
19
Categorie Soggetti
Space Sciences
Journal title
ICARUS
ISSN journal
00191035 → ACNP
Volume
140
Issue
2
Year of publication
1999
Pages
369 - 378
Database
ISI
SICI code
0019-1035(199908)140:2<369:PMOA1G>2.0.ZU;2-0
Abstract
We develop a physical model of asteroid 1620 Geographos using Goldstone del ay-Doppler radar images obtained August 1994 (Ostro et al. 1996, Icarus 121 ., 46-66) with resolution as fine as 75 m, and optical lightcurves obtained in 1969, 1983, and 1993-1994 (Magnusson et al. 1996, Icarus 123, 227-244). The data set admits a geometric ambiguity that precludes a unique model. W ithin this constraint, our model has maximum dimensions of (5.0, 2.0, 2.1) +/- 0.15 km and a volume of less than or equal to 8.8 km(3), equivalent to a sphere of less than or equal to 2.56 km diameter. The radar equivalent sp herical albedo is greater than or equal to 0.12. The photometric solution p rovides Hapke parameters w greater than or equal to 0.22, g = -0.34 +/- 0.1 0, and <(theta)over bar> = 25 +/- 10 degrees with assumed values h = 0.02 a nd B-0 = 1.32. The spin state solution does not differ significantly from t hat of Magnusson et al, having lambda = 55 +/- 6 degrees, beta = -46 +/- 4 degrees, and P = 5.2233270 +/- 0.00000072 h. We identify seven main feature s in the delay-Doppler images and their corresponding locations on the mode l. (C) 1999 Academic Press.