15958( 3) - 29-Aug-2019 21:15:00 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15958 Version: 3 Check-in Time: 29-Aug-2019 21:15:00 STScI Edit Number: 0 Title A global view of the UV rest-frame properties of a star-forming galaxy at z~6: the absorption lines, the lyman-alpha emission and the continuum. ------------------------------------------------------------------------------------ Type Cycle GO 27 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Susanna Vergani Observatoire de Paris - Section de Meudon Y CoI: Dr. Hakim Atek CNRS, Institut d'Astrophysique de Paris N CoI: Dr. Annalisa De Cia European Southern Observatory - Germany N CoI: Prof. Andrew James Levan Radboud Universiteit Nijmegen N CoI: Mr. Joseph McGuire University of Leicester N CoI: Dr. Ruben Salvaterra INAF, Instituto di Astrofisica Spaziale e N Fisica, Milano CoI: Ilane Schroetter Observatoire de Paris - Section de Meudon N CoI: Prof. Nial Rahil Tanvir University of Leicester N CoI: Jure Japelj Universiteit van Amsterdam N ------------------------------------------------------------------------------------ Abstract The characterization of star-forming galaxies impacting cosmic reionization is one of the primary scientific drivers of future space and ground missions. With the help of deep fields, currently we can study routinely their ultraviolet (UV) continuum and Lyman-alpha emission. However, to access the properties of their interstellar medium (ISM) absorbing gas is extremely difficult. The host galaxy of the long gamma-ray burst GRB130606A at z~6 is the only very high-redshift galaxy for which the Lyman-alpha emission, the continuum and the ISM gas absorption are detected. Thanks to the absorption lines present in the GRB afterglow spectrum, it was possible to determine the neutral hydrogen content, the metallicity and dust depletion of the host galaxy ISM along the GRB line of sight. At high redshift, long GRBs are thought to be associated with the bulk of star-forming galaxies. Therefore GRB130606A provides a unique global view on the UV properties of a typical faint high-redshift star forming galaxy. Indeed its Lyman-alpha luminosity is representative of Lyman-alpha emitters at these redshifts. Nonetheless we do not have enough information on its continuum properties to assess GRB130606A host place among the high-redshift galaxy population. We ask here for 4 orbits of HST time to obtain WFC3/F105W and F160W observations, so as to be able to determine the UV spectral slope of the galaxy and compare it to that of lyman-break galaxies at the same redshift and having similar absolute magnitudes. In addition to the characterization of the galaxy itself, these data will also be used to study for the first time of the counterparts of strong MgII absorbers at z>3. ------------------------------------------------------------------------------------ Observations Description ------------------------ The host galaxy of GRB 130606A has been detected in the F140W filter of WFC3 with a magnitude of 26.34 (AB), and is compact (only marginally resolved). The aim of these observations is to determine the colours (in particular the 15958( 3) - 29-Aug-2019 21:15:00 - [ 2] rest-frame UV spectral slope 'beta') through observations in F105W and F160W. We therefore do not know the precise expected magnitudes in these bands, but can estimate extrema by assuming that F_lambda is proportional to lambda^beta, and -1 < beta < -3. In 7200s exposure time in F105W we then obtain a signal to noise in the range S/N=13-23 and in F160W we find a S/N=6-8 (note that because this is for varying spectral slope a minimum in one band corresponds to a maximum in the other, which offsets error introduced because of the uncertainty in this slope). This will enable us to measure beta to an accuracy of +/-0.3. To dither we will use a 2-points line pattern with a 3-point line sub-pattern, optimizing the exposure time. ------------------------------------------------------------------------------------ 15958( 3) - 29-Aug-2019 21:15:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GRB-130606A GALAXY, HIGH REDSHIFT RA=16H37M35.1200S, J2000 WFC/F140W AB magnitude: 26.34 GALAXY DEC=+29D47'46.40" Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database.This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 15958( 3) - 29-Aug-2019 21:15:00 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type LINE WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER DITHER Number_Of_Points 2 3 Point_Spacing 5.183 0.605 Line_Spacing Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 41.859 41.788 Angle_Between_Sides Center_Pattern NO NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BLOB WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER DITHER Number_Of_Points 2 4 Point_Spacing 5.183 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG POS-TARG Pattern_Orient 41.859 18.528 Angle_Between_Sides 74.653 Center_Pattern YES NO ------------------------------------------------------------------------------------------------------------------------------------ 15958( 3) - 29-Aug-2019 21:15:00 - [ 5] Visit: 01 Visit Requirements: SCHED 100% On Hold Comments: Additional Comments: 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 GRB-130606A WFC3/IR MULTIAC IR F160W NSAMP=9, SAMP-SEQ=SPARS100 1 DEF PATTERN 1 1 CUM (4817.609 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 | ------------------------------------------------------------------------------------------------------------------------------------ GRB-130606A 1 WFC3/IR MULTIAC IR F160W 1 1 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F160W 1 2 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F160W 1 3 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F160W 2 1 none none 2 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F160W 2 2 none none 2 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F160W 2 3 none none 2 N/A CUM 15958( 3) - 29-Aug-2019 21:15:00 - [ 6] Visit: 02 Visit Requirements: SCHED 80% On Hold Comments: Additional Comments: 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 GRB-130606A WFC3/IR MULTIAC IR F105W NSAMP=13, SAMP-SEQ=SPARS50 1 DEF PATTERN 2 1 CUM (4823.502 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 | ------------------------------------------------------------------------------------------------------------------------------------ GRB-130606A 1 WFC3/IR MULTIAC IR F105W 1 1 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 1 2 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 1 3 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 1 4 none none 1 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 2 1 none none 2 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 2 2 none none 2 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 2 3 none none 2 N/A CUM GRB-130606A 1 WFC3/IR MULTIAC IR F105W 2 4 none none 2 N/A CUM 15958( 3) - 29-Aug-2019 21:15:00 - [ 7] Summary Form for Proposal 15958 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=9, SAMP-SEQ=SPARS100, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 2 1, SCHED 100%, SCHED 80% ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GRB-130606A ------------------------------------------------------------------------------------------------------------------------------------