Moving target visit planning impossible due to limitations in APT. Corrected cycle to Cycle 9. ----- Submission 7 (Fri Feb 20 16:28:34 GMT 2004) ----- ----- Submission 8 (Fri Feb 20 16:53:03 GMT 2004) ----- Moving target visit planning impossible due to limitations in APT. We recently made the first-ever discovery of a satellite of an asteroid from the Earth, using adaptive optics (Merline et al. 1999a, 1999b). We propose here to acquire the first separate, comparative, and simultaneous spectra of an asteroid and its satellite. We will employ the UV-capabilities and high-spatial-resolution properties of STIS to study (45)Eugenia, and its satellite, S/1998(45)1, by obtaining medium-resolution spectra over the range 2900-10300 Angstrom, using only two grating settings, on a single HST orbit. We will determine whether the spectra, and hence surface compositions, are similar or different in a parent-satellite pair, and to test hypotheses concerning satellite production mechanisms. From the orbital parameters, determined using our ground-based adaptive-optics images, we have already determined that (45)Eugenia has a surprisingly low density of 1.2 g cm^-3. We know the spectrum of Eugenia is a (Tholen) FC-type, which is similar to the common C-types, but differs by the lack of a UV-band or UV-dropoff and by subtle, but measurable differences in the spectral slope. Both the UV-region and the existence of subtle absorption features in the near-IR (~ 0.9 micron) are diagnostic of the specific differences between F-, C-, and (Bus') X-class. HST spectroscopy is the only way to separate the pair, because ground-based adaptive optics is not available in the UV and cannot yet provide adequate resolution in the visible.

Standard aquisition images of 1s prior to incorporating the 52x2 slit for spectroscopic observations. Gratings 430L and 750L at prime tilts each at two dither-along-slit exposure pairs. Binning by 4 in dispersion axis only. Fringe flat for 750L exposures. Orient angle of 100 degrees is selected as near nominal roll angle in March 2004. Timing, as expressed through phase, is such that target primary and satellite are both along slit at orient angle 100 degrees (sky position angle of 55 degrees) or 180 degree flip. Fringe flat for 750L. Spectral features of interest have comparable scale to fringes, so they must be measured per standard procedures for such data. Soonest opportunity preferred to maximize projected separation and brightness of this receeding target. SOLAR SYSTEM 12 false false false false false SUPPORTED SOLAR SYSTEM satellite is 6 mag fainter ASTEROID Eugenia TYPE=ASTEROID,A=2.7202531,E=0.0831485,I=6.61223,O=147.9608,W=85.67345,M=251.0385,EQUINOX=J2000,EPOCH=27-DEC-2003:00:00:00 STIS/CCD Imaging No F28X50LP STIS/CCD Spectroscopic No G430L 4300 false false STIS-ALONG-SLIT false 90.0 1 0.9385 DITHER 2 LINE POS-TARG /var/tmp/OPVisit11008.xml 1077739623576 Timing of this visit is such that satellite and primary separation axis is within 20 degrees of STIS slit. Real period of system is 4.708days, but 180 degree symmetry, so every 2.354days is a visit allowable time. Phased so that exposure level phase is 0.5 +- 0.106. (Tic-Visit :proposal-id 8578 :visit-id "01" :proposal-version -1 :trans-version "20031014" :date "25-Feb-2004 15:06:54.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 83952 :tdrss-contact-duration 0 ) (Tic-Obset :proposal-id 8578 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 8578 :visit-id "01" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2832 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3200 :pcs-gap 0 ) true 1077294445260