0 Assigned ID: 873 ----- Attempting Submission 1 (Fri Apr 10 21:41:11 GMT 2015) ----- For the best data quality, it is strongly recommended that all four FP-POS positions be used when observing at a given COS CENWAVE setting. INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS INEFFICIENT ORDERING OF FP-POS POSITIONS 0 ----- Attempting Submission 1 (Fri Jul 17 22:30:18 GMT 2015) ----- HST Phase II Proposal 14130 (gd16_cycle23_phaseii.apt) successfully submitted. Receipt: # 14130-1 ----- Attempting Submission 2 (Wed Dec 09 19:48:04 GMT 2015) ----- HST Phase II Proposal 14130 (gd16_cycle23_phaseii.apt) successfully submitted. Receipt: # 14130-2 ----- Attempting Submission 3 (Fri Dec 11 22:37:58 GMT 2015) ----- FP-POS positions were discussed with the CS, but more discussion is welcome. FP-POS changes are always in the most efficient direction during actual orbital visibility. A rewind to the earlier FP-POS positions must be done at some point regardless of what strategy is pursued. How water is distributed in a planetary system critically affects the formation, evolution, and habitability of its constituent rocky bodies. White dwarf stars provide a unique method to probe the prevalence of water-rich rocky bodies outside of our Solar system and where they preferentially reside in a planetary system. However, as evidenced by the case of GD 362, some parent bodies that at first glance might appear to be water-rich can actually be quite water-scarce. At this time there are only a small number of plausibly water-rich rocky bodies that are being actively accreted by their host white dwarf star. Given such a sample size it is crucial to characterize each one in sufficient detail to remove interlopers like GD 362 that might otherwise affect future statistical analyses. In this proposal we seek to vet GD 16, a water-rich candidate yet to be observed with HST-COS that is the brightest remaining such target in the UV. Detecting or constraining the absorption lines which inform our science goals requires observations in the 1800-2040 Ang range. Medium spectral resolution ultraviolet spectroscopy with COS and the G185M grating and a central wavelength of 1921 Ang will satisfy the observational requirements. Two FP-POS positions will be used to mitigate bad pixels and address fixed pattern noise. For the GALEX measured NUV flux of GD 16 (NUV AB magnitude of 16.22+/-0.02) it should be possible to obtain average S/N~20 in the 1800-2040 Ang wavelength range with a total on-source exposure time of ~12,500 seconds. Signal-to-noise ratio of ~20 for the 1800-2040 Ang wavelength range will enable detection or tight limits on the abundances of silicon, carbon, and aluminum (the main science goals). Such a signal-to-noise ratio will also enable the detection or constraint of other elements (e.g., S, Ni, Co, Mn, and others). These estimates are made using the COS ETC assuming standard background parameters and with a GD 16 spectral energy distribution matched to precise optical photometry obtained by us for this proposal (note that this precise photometry limits any reddening to E(B-V)<~0.01). Our requested time estimate for COS is increased assuming 20 minutes of instrument overhead (including all acquisition and exposure overheads as suggested in the COS manual) per visit and 6 minutes of observatory overhead per orbit (spacecraft acquisition). In sum, we request 5 orbits for COS observations of GD 16. Observations will be done in the TIME-TAG mode using TAG-FLASH wavelength calibration. GD 16 is an ICRS object (SDSS position with less than 0.4" positional uncertainty), has a measured GALEX NUV flux, and is safe for the COS detectors in our desired setups. EXTRA-SOLAR PLANETS 12 false true false false SUPPORTED STAR DA DB DZ NO GD16 J2000 J2000 GALEX NUV ABmag = 16.22+/-0.02 COS/NUV Spectroscopic No No G185M 1921 1449873298171 /private/var/folders/0m/1rqjzh0n6nv2rddxlww1163m0000gn/T/OPVisit5090124048205034246.xml The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. 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