14899( 2) - 06-Dec-2016 13:48:33 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14899 Version: 2 Check-in Time: 06-Dec-2016 13:48:33 STScI Edit Number: 0 Title DES16C2nm: Is the Highest-Redshift Supernova to Date also the Most Luminous? ------------------------------------------------------------------------------------ Type Cycle GO/DD 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Chris D'Andrea University of Pennsylvania Y CoI: Dr. Mark Sullivan University of Southampton N CoI: Dr. Mathew Smith University of Southampton N CoI: Prof. Bob Nichol University of Portsmouth N CoI: Prof. Masao Sako University of Pennsylvania N ------------------------------------------------------------------------------------ Abstract The Dark Energy Survey (DES) has discovered DES16C2nm, a superluminous supernova (SLSN) at redshift of 1.998. DES16C2nm is the highest-redshift spectroscopically-classified supernova of any type ever discovered. The griz photometry from DES shows a flat, slightly rising light curve over the past 80 days (27 days rest-frame), and we estimate that DES16C2nm may be the most luminous SLSN ever discovered (Mu < -23). But our DES photometry only covers the rest-frame UV, making it impossible to accurately measure the bolometric luminosity of this event. Furthermore, the high redshift of this SN makes it possible to obtain photometry of the FUV region, essential for understanding how to find SLSNe at even higher redshifts. Finally, while we can confirm the classification and redshift of this object with our optical photometry, to fully compare with low-redshift SLSNe we need to obtain rest-frame optical spectra. We propose to use cadenced HST UV photometry along with NIR photometry and spectroscopy to obtain a complete picture of this unique, most distant ever supernova. ------------------------------------------------------------------------------------ Observations Description ------------------------ We observe the z=1.9985 Superluminous Supernova DES16C2nm (H~23.2) with the F160W filter and take a spectrum using the G141 grism in order to constrain the rest-frame optical properties of this highest-redshift-ever spectroscopically-classified supernova. We assume the spectral shape of a blackbody with T=10000 K to estimate observing times. The G141 filter is 46.5A per pixel, which is 15.5A per pixel in the rest-frame. For a 'classifiable' spectrum, we want to obtain a minimum SNR of 3 per 10A resolution element, thus a minimum SNR of 3.7 per resolution element across the spectrum. This is achievable across the entirety of the sensitive range of the G141 filter (1.1-1.65 um) with an exposure of 2369s, with the peak SNR 50% higher than this minimum value. We conservatively suppose the SN may fade by ~ 0.5 mag by the time of our requested observations. To obtain 20-sigma detections (mag uncertainty 0.05) in the F160W filter, we estimate a 285s integration time. We use a two-point WFC3-IR-DITHER-BLOB dither pattern with a set of F160W and 14899( 2) - 06-Dec-2016 13:48:33 - [ 2] G141 spectra taken in each dither. This allows the F160W exposure to serve as a pointing constraint for the spectrum. The total exposure time in F160W in this visit is 306s, and the G141 spectrum is 2406s, exceeding both of our exposure time requirements. ------------------------------------------------------------------------------------ 14899( 2) - 06-Dec-2016 13:48:33 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 DES16C2NM EXT-STAR, SUPERNOVA RA=03H40M14.8300S, J2000 H = 23.2 DEC=-29D05'53.50" Reference Frame: ICRS Comments: The H-band flux is rather uncertain, as it is derived by fitting a blackbody to the observed griz data and extrapolating a blackbody into the H-band (superluminous supernovae do not have very well-defined templates). The current magnitude could span from 22.9 - 23.6. The host galaxy is 1.5 magnitudes fainter in the both the DES i and z filters than the target. The galaxy's H-band magnitude is unknown. ------------------------------------------------------------------------------------------------------------------------------------ 14899( 2) - 06-Dec-2016 13:48:33 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BLOB Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 5.183 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.859 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 14899( 2) - 06-Dec-2016 13:48:33 - [ 5] Visit: 01 (01) Visit Requirements: On Hold Comments: Additional Comments: A dithered set of exposures using the F160W filter followed by G141 spectra. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 DES16C2NM WFC3/IR MULTIAC GRISM1024 F160W NSAMP=7, SAMP-SEQ=SPARS25 1 DEF PATTERN 2 1-2 CUM (305.871 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 DES16C2NM WFC3/IR MULTIAC GRISM1024 G141 NSAMP=13, SAMP-SEQ=SPARS100 1 DEF CUM (2405.872 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ DES16C2NM 1 WFC3/IR MULTIAC GRISM102 F160W 1 none none none 1 N/A CUM 4 DES16C2NM 1 WFC3/IR MULTIAC GRISM102 F160W 2 none none none 1 N/A CUM 4 DES16C2NM 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 DES16C2NM 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 14899( 2) - 06-Dec-2016 13:48:33 - [ 6] Summary Form for Proposal 14899 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM1024 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=7, SAMP-SEQ=SPARS100, SAMP-SEQ=SPARS25 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 2 1-2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, G141 ------------------------------------------------------------------------------------------------------------------------------------ Target Names DES16C2NM ------------------------------------------------------------------------------------------------------------------------------------