0 Assigned ID: 337 ----- Attempting Submission 1 (Thu Apr 06 23:14:15 GMT 2017) ----- HST Phase I Proposal 337 (PS1-12sk_2017.apt) successfully submitted. Receipt: # 337-1 ----- Attempting Submission 2 (Fri Apr 07 23:59:05 GMT 2017) ----- ----- Attempting Submission 3 (Sat Apr 08 00:49:30 GMT 2017) ----- We have updated visits 2-5 to have "same orient as visit 1" constraint so that all the visits will have the same orientation. 1201824228 ----- Attempting Submission 1 (Thu Jul 13 21:46:58 GMT 2017) ----- ----- Attempting Submission 2 (Fri Nov 10 20:01:16 GMT 2017) ----- The mystery of a supposed massive star exploding in a brightest cluster galaxy Most of the diversity of core-collapse supernovae results from late-stage mass loss by their progenitor stars. Supernovae that interact with circumstellar material (CSM) are a particularly good probe of these last stages of stellar evolution. Type Ibn supernovae are a rare and poorly understood class of hydrogen-poor explosions that show signs of interaction with helium-rich CSM. The leading hypothesis is that they are explosions of very massive Wolf-Rayet stars in which the supernova ejecta excites material previously lost by stellar winds. These massive stars have very short lifetimes, and therefore should only found in actively star-forming galaxies. However, PS1-12sk is a Type Ibn supernova found on the outskirts of a giant elliptical galaxy. As this is extraordinary unlikely, we propose to obtain deep UV images of the host environment of PS1-12sk in order to map nearby star formation and/or find a potential unseen star-forming host. If star formation is detected, its amount and location will provide deep insights into the progenitor picture for the poorly-understood Type Ibn class. If star formation is still not detected, these observations would challenge the well-accepted hypothesis that these are core-collapse supernovae at all. SUMMARY: We plan to map the star formation rate in the region surrounding the explosion location of PS1-12sk now that the supernova has faded. This will be accomplished with 4.5 orbits of UV imaging of the field with WFC3+F300X. We need very deep ultraviolet images with very low sky background to detect low-surface-brightness star-forming regions. In the event that we find an unseen host galaxy, we will also need an optical image that matches HST's resolution to aid in registration with the ground-based localization. We will therefore obtain an additional half orbit in SDSS r' (WFC3+F625W). In addition, HST will likely be able to resolve the nearby dwarf galaxy, which is a possible host, and any potential gas flows leading toward the supernova location from either the brightest cluster galaxy or the dwarf galaxy. DETAILS: We have separated each of our five orbits into a separate visit for flexibility. However, scheduling the orbits together would save some time reacquiring, which could be added to the UV exposure for deeper limits. Because we are searching for a low-surface-brightness source, CTE losses may be important. We have used the FLASH settings recommended by the APT to reach 12 electrons per pixel. However, because we are potentially interested in sources up to ~30" from the supernova location, we cannot move the target closer to the amplifiers (i.e., we choose the UVIS2 aperture). We choose a three-point dither for each of the first four orbits in order to (1) break up the exposures for cosmic ray rejection, (2) better sample the PSF, and (3) cover the chip gap. For the fifth orbit, we use the three-point dither for F625W but only a two-point dither for F300X to save time spent on overhead. Ultimately, we will stack all 14 exposures in F300X for analysis. Stellar Physics 6 false true false false false false SUPPORTED CLUSTER OF GALAXIES BCM COOLING FLOW STAR FORMING REGION This object was generated by the target selector and retrieved from the NED database. RXCJ0844.9+4258 CGCG208-042 J2000 J2000 WFC3/UVIS Imaging No No F300X WFC3/UVIS Imaging No No F625W POS-TARG DITHER 1.813 LINE false true 3 85.759 WFC3-UVIS-DITHER-LINE-3PT 1 false POS-TARG DITHER 1.82 LINE false true 2 85.759 WFC3-UVIS-DITHER-LINE 2 false /tmp/OPVisit240643432841115607.xml Hst Same orient constraint links visits (01 02 03 04 05) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15236 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "10-Nov-2017 19:58:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 866240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15236 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15236 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2964 :al-overhead-at-end 122 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3298 :pcs-gap 0 ) true 1 0 /tmp/OPVisit5126236503628617697.xml Hst Same orient constraint links visits (01 02 03 04 05) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15236 :visit-id "02" :proposal-version -1 :trans-version "20170613" :date "10-Nov-2017 19:58:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 866240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15236 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15236 :visit-id "02" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2964 :al-overhead-at-end 122 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3298 :pcs-gap 0 ) true 1 0 /tmp/OPVisit1124730546469579466.xml Hst Same orient constraint links visits (01 02 03 04 05) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15236 :visit-id "03" :proposal-version -1 :trans-version "20170613" :date "10-Nov-2017 19:58:58.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 866240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15236 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15236 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2964 :al-overhead-at-end 122 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3298 :pcs-gap 0 ) true 1 0 /tmp/OPVisit869412172484554447.xml Hst Same orient constraint links visits (01 02 03 04 05) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15236 :visit-id "04" :proposal-version -1 :trans-version "20170613" :date "10-Nov-2017 19:58:59.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 866240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15236 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15236 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2964 :al-overhead-at-end 122 :internal-dur-at-end 352 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3298 :pcs-gap 0 ) true 1 0 /tmp/OPVisit1992526913077659443.xml Hst Same orient constraint links visits (01 02 03 04 05) The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15236 :visit-id "05" :proposal-version -1 :trans-version "20170613" :date "10-Nov-2017 19:57:57.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1443744 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15236 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15236 :visit-id "05" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2964 :al-overhead-at-end 119 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3298 :pcs-gap 0 ) true 1 0