----- Submission 1 (Fri Oct 29 17:51:55 GMT 2004) ----- ----- Submission 2 (Mon Dec 20 01:40:11 GMT 2004) ----- UV/Visible Spectroscopy of Asteroid 762 Pulcova and its Newly-discovered Moon We propose to acquire separte, comparative, and simultaneous spectra of asteroid 762 Pulcova and its satellite. We will compare our results with those we obtain[ed] in a program approved in cycle 9 for 45 Eugenia and its moon. We discovered both of these moons using ground-based adaptive optics -- Eugenia in 1998, but Pulcova only in the last year. We can now compare two systems that both have primaries of the relatively uncommon F-like spectral class. We will use the high-spatial-resolution and UV-capabilities of STIS to obtain medium-resolution spectra over the range 2900-10300 Anstrom, using only two grating settings, on a single HST orbit. We will determine whether the surface compositions are similar or different in the parent-satellite pair and test hypotheses concerning satellite production mechanisms. Our fits to the orbits yield a surprisingly low density for Eugenia of 1.2 g/cm^3, but that of Pulcova is 50% higher. F-type spectra are similar to the common C-types, but differ 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 (approx 9000 Anstroms) are diagnostic of the specific differences between F-, C-, and (Bus') X-class. HST is required because the ground-based adaptive optics is not available in the UV and cannot yet provide adequate resolution in the visible.
This is a modification to the original proposal to use ACS/HRC instead of STIS. In this version, 4 exposures for dither and CR-split are taken in each of three modes: broadband imaging (3s per), prism spectroscopic (300s per), and grism spectroscopic (300s). The images substitute for the usual pre-spectroscopic image and are specified explicitly to optimize for CR/bad pixel rejection and appropriate dynamic range. The pair of spectroscopic modes are ideal for the critical distinguishing features in the near-UV and near-IR. 12 false 0.0 false false false false false AVAILABLE SOLAR SYSTEM satellite is 4 mag fainter ASTEROID Pulcova TYPE=ASTEROID,A=3.1591679,E=0.0965021,I=13.04942,O=306.03842,W=188.09717,M=332.08682,EQUINOX=J2000,EPOCH=30-JAN-2005:00:00:00 ACS/HRC Imaging No No F555W ACS/HRC Spectroscopic No No PR200L ACS/HRC Spectroscopic No No G800L /data/lorelei1/proposals/OP-cache/9059-v01.xml (Tic-Visit :proposal-id 9059 :visit-id "01" :proposal-version -1 :trans-version "20041107" :date "20-Dec-2004 17:00:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 423232 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 9059 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 9059 :visit-id "01" :orbit-number 1 :pcs-time 365 :si-vis-utilization 2657 :al-overhead-at-end 0 :internal-dur-at-end 199 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3060.0 :pcs-gap 0 ) false 1 0 /data/lorelei1/proposals/OP-cache/9059-v01.xml AUTOIMAGE=NO because explicitly taking an equivalent image with appropriate exposure time for both primary and secondary. Intentional short exposure to extract more information from red end of primary's spectrum which may be saturated in other spectra. Intentional saturation on primary at red end allows deeper on secondary toward blue end. Intentional saturation on primary allows deeper on secondary in lower efficiency region. 360s allows simultaneous buffer dump. Intentionally short in case primary red spectra are unexpectedly saturated.