0 Assigned ID: 634 ----- Attempting Submission 1 (Wed Jan 23 19:31:18 GMT 2019) ----- ORBITAL VISIBILITY OVERRUN 0 ----- Attempting Submission 1 (Thu Feb 07 18:45:40 GMT 2019) ----- I currently have an 8s orbit over-run. It's fine to slice off the last 8 seconds from the last exposure in the sequence. A near-IR spectrum of the old Type Ia SN 2017erp We ask for 1 orbit of WFC3/IR+G141 to acquire a spectrum of a Type Ia supernova (SN Ia) >500 days after maximum light. The SN in question, SN 2017erp, is one that we have been following along with several other SNe Ia with HST in F160W and F350LP. These observations have revealed a plateau in the F160W (H) band, after which the light curve once again begins to decline. Several works have published near-IR spectra of SNe Ia taken during this plateau, but no near-IR spectrum of a SN Ia exists at >500 days, during the second decline phase. The spectrum we will acquire through this proposal will be the first such spectrum for a SN Ia; reveal why SNe Ia transition from the plateau to the decline phase; and complete our analysis. The goal of this program is to obtain a G141 spectrum of a faint supernova (F160W=22 mag, Vega). It is located in an outer spiral arm of a nearby, face-on galaxy, so there is fear of contamination. I ask that the observations be carried out as soon as possible, to maximize the signal-to-noise ratio of the resultant spectrum. The available visibility windows, coupled with the above constraint, afford only a limited range of orients. To minimize contamination, I ask that the orient be limited to +305 to +307 degrees. I couple the grism observation with a direct image in F160W. Although usually F140W would be used, I have been observing this supernova in F160W, so another photometry point in this filter would be valuable. Stellar Physics 0 false SUPPORTED EXT-STAR SUPERNOVA TYPE IA NO This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 J2000 F160W = 21.5 (Vega) WFC3/IR Spectroscopic No No G141 POS-TARG DITHER 0.636 LINE false false 2 41.788 WFC3-IR-DITHER-LINE 3 false /home/orgraur/projects/telescope_proposals/HST_DD/phaseII/OP-cache/GO15686-v01.xml The scheduling data was generated by CASM 26.2.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15686 :visit-id "01" :proposal-version -1 :trans-version "20181130" :date "07-Feb-2019 10:31:07.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 835616 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15686 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15686 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2824 :al-overhead-at-end 0 :internal-dur-at-end 462 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3149 :pcs-gap 0 ) true 1 1