From: Dark Matter, Missing Planets & New Comets…, T. Van Flandern
BACKGROUND FIRST ASTEROID SATELLITE REPORT OCCURRED MARCH 5, 1977 AROUND 2H35M UT HST OBSERVATIONS OF HEBE HAVE NOT SHOWN EVIDENCE OF A SATELLITE DUNHAM ESTIMATES DISTANCE 900KM FROM PRIMARY
HST SEARCH CONDUCTED BY ALEX STORRS TWICE IN MARCH 2001: Both times the asteroid was in one of the (lower resolution) wide field chips, but near to the planetary camera chip of WFPC2 from communication 7/14/11. RANGE OF DETECTION COVERED THE HILL SPHERE
HST WFPC2 RESOLUTION A conservative estimate for detection in the wide-field chips would be about 19.5 magnitude, or about 1 km diameter. Something this size or larger we should see fairly easily. If its too close to the main body (conservatively again, within an arcsec) we might miss it in the scattered light. Might also miss something faint thats right on the edge of the chipsour images were near the apex of the WFPC2 pyramid.
The observations of (6) Hebe in this program reveal no companions brighter than 7 mag fainter than the primary, or larger than 8km in diameter
MISSING DATA IF SECONDARY OCCULTATION WAS REAL, WAS IT CAUSED BY ANOTHER PASSING ASTEROID? 2 nd SEARCH CARRIED OUT JULY 2011 BY DR. FAITH VILAS (PLANETARY SCIENCE INSTITUTE) NEW SEARCH: UT 2:30 to 2:40, Hebe traveled 0.81 s in RA, and 5.5" in Dec. SEARCH BOX DEFINED: 5 s in RA and 30" in Dec.
RESULTS 3092 COMETS ANALYZED IN JPL DATABASE NO ASTEROIDS OTHER THAN HEBE IN SEARCH BOX 554,557 asteroids in the JPL database, both numbered and unnumbered, were searched. NO KNOWN OBJECTS FOUND
CONCLUSION IF A NATURAL SATELLITE EXISTS, IT DOES NOT CORRELATE WITH ANY KNOWN OBJECTS HST DETECTION CAPABILITY WITH WFPC2 OPTICS MAY NOT HAVE PICKED IT UP