0 Assigned ID: 359 ----- Attempting Submission 1 (Fri Mar 06 00:34:59 GMT 2020) ----- HST Phase I Proposal 359 successfully submitted. Receipt: # 359-1 ----- Attempting Submission 2 (Fri Mar 06 19:22:31 GMT 2020) ----- FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser FLASH level may be too high for this exposure or a long subexposure. See extended explanation in the diagnostic browser 0 ----- Attempting Submission 1 (Tue Jun 30 00:17:34 GMT 2020) ----- ----- Attempting Submission 2 (Mon Nov 09 19:59:17 GMT 2020) ----- FLASH has been set to achieve FLASH levels aropund 20 e/pix, instead of 12, which trigers this error. The metal-poor dwarf galaxy PHL293B (23 Mpc) contained a luminous blue variable (LBV) candidate that was identified based on its spectrum. This source was detected at roughly constant luminosity during 2001-2009, modeled as a massive LBV with log(L/Lsun)=6.4-6.7. This is similar to eta Carinae, and notably, similar to the progenitors of SN2009ip and SN2015bh. In more recent data, the source has faded beyond ground-based limits, and spectral signatures of the LBV are now gone. A massive LBV-like star at roughly 0.1 Z solar provides important clues for understanding the role of eruptive mass loss at low metallcity, and the star's recent disappearance may hold critical clues about the fate of such stars. The sudden fading in the last decade could be the result of either the end of a giant LBV eruption, or it could be the death of a very massive star when it collapsed to a black hole with no bright supernova. To rule out the second hypothesis, we would need to detect the surviving star, but ground-based data cannot do this because the source is too faint and lost in galaxy light. There are two plausible scenarios for a surviving star: (1) When the LBV eruption ended, the star faded in the optical because it got hotter, shifting its energy distribution into the UV, or (2) it faded at visual wavelengths because it formed dust, in which case the star should still be detectable in the near-IR. We propose deep imaging with WFC3 UVIS and IR to either detect the surviving star in the UV/optical/IR, or to confirm that it has vanished to deep limits. If it is gone, this would be the first secure case of a very massive star that vanished to a black hole. The goal of these observations is to obtain post-event optical and near-IR magnitudes or deep upper limits of the source at the position of an LBV star that has faded beyond detectability in ground-based data (perhaps largely due to spatial resolution, as it is now indistinguishable from surropunding galaxy light from the goround). We also aim to obtain photometry of all nearby bright sources to help constrain the host environments age and/or star formation history. The UVIS observations are all set up in one visit of two orbits, but these orbits can be separated if neeeded. There are no special orients needed, although we would prefer both orbits taken at the same orient if they need to separated into separate visits because we are combining two exposures of F438W including one from each oribit. We are using full frame instead of sub-array because we need the whole nearby stellar population. PI N. Smith and co-I J. Groh are both experts in studying LBVs and supernovae. Smith has broad experience in observational studies in both spectroscopy and multi-wavelength imaging, and Groh has expertise in modeling the spectra of LBVs and SNe IIn with CMFGEN and with stellar evolution models. CoIs A. Allan and E. Farrell are a graduate students working with Prof. Groh on this topic, and Allan was the first author of our paper on the fading seen in optical data. J. Andrews is a postoc working with Smith, and is an expert on observational studies of supernovae and massive star populations. A. Mehner is an expert on observational studies of LBVs. Stellar Physics and Stellar Types 6 false false true false false false false SUPPORTED EXT-STAR BLUE STRAGGLER ETA CARINAE STAR LUMINOUS BLUE VARIABLE J2000 J2000 WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F225W WFC3/IR Imaging No No F125W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false POS-TARG DITHER 0.636 LINE false false 2 41.788 WFC3-IR-DITHER-LINE 2 false 1604951857222 The scheduling data was generated by CASM 28.2. CASM was run in Phase II mode. /private/var/folders/t7/ycrqvyps6fl_49m45dblccm00000gn/T/OPVisit488751651452763410.xml (Tic-Visit :proposal-id 16172 :visit-id "01" :proposal-version -1 :trans-version "20200619" :date "09-Nov-2020 12:57:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2887456 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16172 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16172 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2755 :al-overhead-at-end 126 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16172 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2747 :al-overhead-at-end 126 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 2 0 1593476174523 The scheduling data was generated by CASM 28.2. 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