0 Assigned ID: 1753 ----- Attempting Submission 2 (Fri Mar 01 20:50:08 GMT 2013) ----- 0 changed to F28X50LP,the ETC run is already with that aperture. 1875541785 ----- Attempting Submission 1 (Mon Jun 24 21:08:11 GMT 2013) ----- HST Phase II Proposal 13432 (tychob-hst.apt) successfully submitted. ----- Attempting Submission 2 (Wed Jun 26 18:05:20 GMT 2013) ----- HST Phase II Proposal 13432 (tychob-hst.apt) successfully submitted. ----- Attempting Submission 3 (Thu Jun 27 13:55:15 GMT 2013) ----- Despite the importance of Type Ia SNe, we still do not know whether they result from mass transfer onto a WD from a non-degenerate companion, from the coalescence of two degenerate stars, or perhaps a from a combination of these two pathways. Here we seek to show, by identifying the donor star, that SN1572--the prototypical Galactic SN Ia reported by Tycho--resulted from the single-degenerate scenario. We know from ground-based high-resolution spectra that many stars near the projected center of SN1572 lack the characteristics expected for a donor companion. But one of them, the unusual A-star denoted Tycho-B, exhibits fast rotation and an unusual abundance pattern of low overall metallicity ([Fe/H]~-1) yet high abundances of C and O. Tycho-B is a few arcsec from the geometric center of SN1572, and our distance estimate is consistent with that for SN1572. If Tycho-B is in fact the surviving companion, it must be located within the SNR shell. In this case, we expect it will show broad, blue-shifted absorption in Fe II from undecelerated cold ejecta that have long-since swept past the companion star, but have not yet encountered a reverse shock. We propose to use HST/STIS to obtain UV spectra that will clearly reveal such absorption. While a positive result is not guaranteed, the potential payoff of establishing Tycho-B as the donor is large. If Tycho-B is instead a background object, these spectra will still provide an important probe for the cold ejecta in SN1572, as we have done for the older Ia remnant of SN1006. We are aiming to acquire a STIS NUV spectrum of the the star Tycho-B (U=16.78). Tycho-B is located roughly 3 arcseconds from Tycho-A (U=15.96), which we will use as a acquisition and "guide" star. We want to have the slit over both these stars so we know about the contamination of Tycho-B from Tycho-A. We plan to acquire once and then spent our two orbits observing. RESOLVED STELLAR POPULATIONS 12 false true 0.0 0.0 false false false SUPPORTED STAR A0-A3 V-IV This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 B=16.35, U=16.78 STAR F0-F2 This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 U=15.96 STIS/NUV-MAMA Spectroscopic No No G230L 2376 1372341307761 The scheduling data was generated by CASM 21.2. CASM was run in Phase II mode. /private/var/folders/v2/z0nm04hj495cj432_4xwvzmh0000gn/T/OPVisit317638308738666747.xml (Tic-Visit :proposal-id 13432 :visit-id "01" :proposal-version -1 :trans-version "20130502" :date "27-Jun-2013 09:55:07.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 191856 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13432 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13432 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3161 :al-overhead-at-end 217 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13432 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3289 :al-overhead-at-end 217 :internal-dur-at-end 319 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3511 :pcs-gap 0 ) true 2 0