0 Assigned ID: 1318 ----- Attempting Submission 1 (Tue Jan 24 20:55:07 GMT 2017) ----- 0 ----- Attempting Submission 1 (Fri Feb 03 22:37:59 GMT 2017) ----- 0 The latest generation of untargeted time domain surveys have discovered new rare types of transients such as superluminous supernovae and tidal disruption events. Recent discoveries have also included luminous transients coincident with the nuclei of their host galaxies, making classification into established categories difficult, especially when the galaxy also has an active galactic nucleus. We propose to obtain imaging and UV spectroscopy using STIS of PS16dtm, a recently discovered luminous nuclear transient with unusual properties. We will use the imaging to dramatically refine the location of PS16dtm to assess the nuclear nature of the event. The UV spectrum will allow us to understand the nature of absorption in the UV and extend our spectroscopic comparisons to bluer wavelengths. These HST observations are critical for understanding the origin of this rare transient as a superluminous supernova, tidal disruption event, or AGN variability. We request one orbit to obtain two observations of PS16dtm: a NUV spectrum with STIS/NUV-MAMA and an optical image with STIS/CCD. Stellar Physics Massive Black Holes and their Hosts 0 SUPPORTED UNIDENTIFIED NUCLEUS J2000 J2000 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Imaging No No 50CCD POS-TARG DITHER 0.2835 LINE 0.2835 false false 143.130102 4 26.6 STIS-CCD-BOX 1 false 1486573443741 /private/var/folders/46/4jpf0wpx40jbz16h87362w240001d2/T/OPVisit6163520593804132289.xml The scheduling data was generated by CASM 25.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 14902 :visit-id "01" :proposal-version -1 :trans-version "20170109" :date "08-Feb-2017 12:04:03.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 161040 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14902 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14902 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2757 :al-overhead-at-end 0 :internal-dur-at-end 340 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3210 :pcs-gap 0 ) true 1 0