0 Assigned ID: 4 ----- Attempting Submission 1 (Fri Jun 01 16:44:00 GMT 2018) ----- INEFFICIENT ORDERING OF FP-POS POSITIONS 0 ----- Attempting Submission 1 (Fri Jun 08 03:39:39 GMT 2018) ----- I'm not sure why this error is showing up. The latest generation of wide-field time-domain surveys has led to the discovery of rare, extreme transients such as superluminous supernovae (SLSNe). Recently, exotic power sources such as a magnetar central engine have gained traction as a plausible explanation for their enormous luminosities. However, due to their low volumetric rates, only a handful of SLSNe have been discovered at z < 0.1 where the effects of the power source can be probed in the greatest detail. A key region of the spectrum for testing the effects of various proposed power sources is the UV, where the spectral energy distributions peak. Fully understanding the UV characteristics and diversity revealed by ground-based observations of high-redshift events and HST observations of low-redshift events requires additional observations. Here we propose to obtain FUV and NUV observations with HST of SN2018bsz at a redshift of z = 0.026, the nearest SLSN discovered to date. In addition to one epoch of FUV+NUV observations, we request two additional epochs of NUV observations to monitor the UV evolution. SN2018bsz provides an exellent opporunity to obtain high signal-to-noise UV spectroscopy that can be compared with other events with UV spectra and with radiative transfer models. Characterizing the UV spectra of low-z SLSNe with HST is critical for understanding the rest-frame UV spectra of future events that will be discovered at z > 1 with upcoming surveys such as LSST. We request a single visit with 2 orbits of COS/FUV and 1 orbit of STIS/NUV. Stellar Physics 0 false SUPPORTED EXT-STAR SUPERNOVA NO J2000 J2000 U = 15.50, UVW1 = 15.51, UVM2 = 16.05, UVW2 = 16.42 STIS/NUV-MAMA Spectroscopic No No G230L 2376 COS/FUV Spectroscopic No No G140L 1105 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/NUV-MAMA Spectroscopic No No G230L 2376 1528463087070 /private/var/folders/8k/sxlgy5ts2xdbykzf_vw6jrfw0001c5/T/OPVisit868799084757696621.xml The scheduling data was generated by CASM 26.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 15488 :visit-id "01" :proposal-version -1 :trans-version "20180409" :date "08-Jun-2018 09:04:46.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 192208 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15488 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Obset :proposal-id 15488 :visit-id "01" :obset-id "P1" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15488 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2905 :al-overhead-at-end 0 :internal-dur-at-end 38 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15488 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3015 :al-overhead-at-end 0 :internal-dur-at-end 331 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15488 :visit-id "01" :orbit-number 3 :pcs-time 333 :si-vis-utilization 2907 :al-overhead-at-end 198 :internal-dur-at-end 319 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3240 :pcs-gap 0 ) true 3 0