0 Assigned ID: 1051 ----- Attempting Submission 1 (Fri Apr 08 23:43:41 GMT 2016) ----- HST Phase I Proposal 1051 (phase1-GO.apt) successfully submitted. Receipt: # 1051-1 ----- Attempting Submission 2 (Fri Apr 08 23:45:45 GMT 2016) ----- HST Phase I Proposal 1051 (phase1-GO.apt) successfully submitted. Receipt: # 1051-2 0 ----- Attempting Submission 1 (Sat Jul 09 14:23:46 GMT 2016) ----- Exploring the source of the late-time brightness of SN 2011dh Late-time HST broad-band photometric observations of SN 2011dh in 2014 and 2016 have shown that, rather than continuing to decline in brightness, the light curve is flattening off. The reason for this is unknown, but could be due to "freeze-out" in the ejecta, the onset of interaction between the ejecta and a new dense circumstellar medium, the presence of a light echo or, even, the presence of a binary companion being slowly revealed. Scenarios involving the onset of interaction between the ejecta and a distant circumstellar medium and the presence of a light echo in a dust shell around the SN, all depend directly on the mass loss history of the Yellow Supergiant progenitor. We propose a series of broad and narrow band observations of SN 2011dh to test each of the possible scenarios, and place constraints on the current properties of the ejecta of this SN and the mass loss history of the star that exploded. Only HST is capable of providing the combination of spatial resolution and depth at UV and optical wavelengths that will be critical to making precise photometric measurements of SN 2011dh. The aim of this program is to acquire a series of broad and narrow band photometric observations of the fading Type IIb SN 2011dh. We aim to reach F336W~25.5, F555W~25.5 and F814W ~24.5 @ S/N=3 and 0.5 *10^(-18) ergs s^-1 cm^-2 A^-1 in the F631N and F657N bands, respectively. The observations in each filter will only require a single cr-split with a dither offset to enable rejection of hotpixels (and other detector artifacts) and cosmic rays, but resampling of the PSF is not required. Stellar Physics 12 false false false false false false SUPPORTED EXT-STAR SUPERNOVA TYPE II NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F631N WFC3/UVIS Imaging No No F657N POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false /private/var/folders/lq/q2m0s1952w7bw727v0rkfsl40000gn/T/OPVisit2919687122596436372.xml The scheduling data was generated by CASM 24.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14763 :visit-id "01" :proposal-version -1 :trans-version "20160601" :date "09-Jul-2016 15:21:35.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 45776 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14763 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14763 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3018 :al-overhead-at-end 41 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14763 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3130 :al-overhead-at-end 44 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14763 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3130 :al-overhead-at-end 44 :internal-dur-at-end 87 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3352 :pcs-gap 0 ) true 3 0