Corrected slit on Visit 1 G750L exposure. Changed exposure time for target aquisition (25sec => 2sec). 1905254123 ----- Attempting Submission 3 (Thu Jun 13 21:24:42 GMT 2013) ----- Early Time UV Spectroscopy of a Stripped-Envelope Supernova: A New Window We propose to continue our Cycle 19 program and obtain 4 epochs of UV spectroscopy of a Target of Opportunity stripped-envelope core-collapse supernova during 2 weeks roughly centered on maximum brightness. The underlying nature of these objects, from the mass-loss process stripping the envelope to the details of the explosion mechanism, remain mysterious. Connections to gamma-ray bursts and X-ray flashes further motivate this study. Many supernovae (SNe) of all types will be found in future high-redshift transient surveys, but the ability to distinguish between thermonuclear Type Ia SNe and stripped-envelope core-collapse SNe will require thorough knowledge of the latter, especially at UV wavelengths. The spectra will lead to several new insights. By comparing the evolution of the spectra as the photosphere recedes to deeper layers of the ejecta with our time series of spectral models, we will gain a better understanding of the explosion, and possibly of the progenitor star. Specifically, we may be able to determine the metal content of the progenitor through comparisons with our spectral models, and we should be able to probe the degree of mixing during the explosion. With coordinated observations of the SN in the optical and near-IR using our ground-based programs, we will be able to comprehensively characterize the nature of the emission radiated by these SNe. The heterogeneity seen in stripped-envelope SNe will allow us to choose a transient with different characteristics than the one to be observed in Cycle 19, gaining further insights into this unique class of cosmic explosion. Obtain STIS UV spectra of one bright (Vmax < 15.5 mag), nearby, stripped-envelope SN as soon as possible after discovery (preferably at t < -6 d, relative to maximum brightness), with subsequent spectra taken at predetermined intervals as follows, for a total of 5 epochs (15 orbits): Epoch(days) -6 -2 2 6 V(mag) 15.56 15.23 15.12 15.16 Orbits 4 4 4 3 S/N(2376Ang) 9 9 8.5 5 S/N(4300Ang) 47 54 56 52 S/N(7751Ang) 50 62 68 69 The cadence of the spectral observations is determined from the timescale over which significant changes are observed in ground-based optical/near-UV spectra. This is a disruptive ToO observation of a single bright SN. However, it is not an ultra-rapid (< 2 day turnaround) ToO. We will work with STScI staff to expedite the observations, and we will try to choose an object that minimizes the time between ToO activation and observations. If our object is found 14 days before maximum brightness, and we have a turnaround time of 8 days (i.e., significantly longer than the 25 day minimum), the first observation will commence about 6 days before maximum light. Our observations use both the STIS CCD and MAMA detectors in order to provide full wavelength coverage. The CCD observations do not need an entire orbit, and can be done during the final MAMA orbit of each epoch. The requirement described in the STIS Instrument Handbook for Cycle 20 that such observations be split into separate visits presents a substantial problem for our program. The spectra of SNe change rapidly (on a time scale of 12 days) at these early phases; temporally separating pieces of the spectrum might seriously compromise our ability to model it. Our program would greatly benefit if the whole spectrum were obtained in a single visit. Therefore, we request an exception to the rule as outlined in Section 2.6 of the STIS Instrument Handbook (MAMA Scheduling Policies). However, if this request cannot be accommodated, we request visits not more than 1 day from each other. Our SN, which is optically bright, will have ground-based astrometry with respect to HST guide stars accurate to better than 0.2''. Using the STIS Acquisition ETC we find acquisition times of less than 1 min for all epochs, for the 0.2'' slit. Previously, we have successfully acquired SNe with STIS in this manner. This is a ToO proposal. We will update our phase 2 with the supernova coordinates as they become available. HOT STARS 12 false false 0.0 0.0 false false false SUPPORTED STAR SUPERNOVA TYPE IB Based on the UV magnitudes obtained with SWIFT on UT 20130613, the MAMA detectors can be safely used to observe this target. We ask the target to be observed as soon as possible, because of the rapid decline in UV flux in stripped envelope SNe. J2000 U=15.09 UW1=16.14 UM2=16.74 UW2=17.09 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 POS-TARG DITHER 1.1 LINE false false 10 90.0 STIS-ALONG-SLIT 1 false POS-TARG DITHER 1.14 LINE false false 7 90.0 STIS-ALONG-SLIT 2 false Timing link suitability includes constraints ([02 After 01 by 3.0 to 7.0 days]) The scheduling data was generated by CASM 21.0. CASM was run in Phase II mode. C:\Users\Physics-admin\Documents\OP-cache\SNNGC4414-v01.xml (Tic-Visit :proposal-id 13030 :visit-id "01" :proposal-version -1 :trans-version "20121031" :date "13-Jun-2013 14:18:25.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 4 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 913136 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13030 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13030 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2664 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13030 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2775 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13030 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2775 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13030 :visit-id "01" :orbit-number 4 :pcs-time 222 :si-vis-utilization 2772 :al-overhead-at-end 0 :internal-dur-at-end 620 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) true 4 0 Target of Opportunity Timing link suitability includes constraints ([02 After 01 by 3.0 to 7.0 days] [03 After 02 by 3.0 to 7.0 days]) The scheduling data was generated by CASM 21.0. CASM was run in Phase II mode. 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CASM was run in Phase II mode. 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CASM was run in Phase II mode. C:\Users\Physics-admin\Documents\OP-cache\SNNGC4414-v04.xml (Tic-Visit :proposal-id 13030 :visit-id "04" :proposal-version -1 :trans-version "20121031" :date "13-Jun-2013 14:18:40.0" :trans-errors '(:WARNINGS 0 :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 686976 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 13030 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 13030 :visit-id "04" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2664 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13030 :visit-id "04" :orbit-number 2 :pcs-time 222 :si-vis-utilization 2775 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) (Tic-Orbit :proposal-id 13030 :visit-id "04" :orbit-number 3 :pcs-time 222 :si-vis-utilization 2773 :al-overhead-at-end 0 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2997 :pcs-gap 0 ) true 3 0 Target of Opportunity