16710( 2) - 29-Jul-2021 14:09:12 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16710 Version: 2 Check-in Time: 29-Jul-2021 14:09:12 STScI Edit Number: 0 Title Measuring ionizing photon escape from an exceptionally bright gravitationally lensed arc at z=1.43 ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ramesh Mainali NASA Goddard Space Flight Center Y CoI: Prof. Daniel P. Stark University of Arizona N CoI: Dr. Jane R. Rigby NASA Goddard Space Flight Center N CoI: Dr. John Chisholm University of Texas at Austin N CoI: Prof. Tucker Jones University of California - Davis N ------------------------------------------------------------------------------------ Abstract We propose WFC3 UVIS/G280 grism observations to measure escaping ionizing photons (LyC) from a galaxy at z=1.43 having nebular conditions similar to reionization era systems. The galaxy is a uniquely bright (r~20) gravitationally lensed system with an extended arc (9" long) allowing ionizing photon escape at a sub-kpc level. Based on a newly developed indirect measure of LyC escape fraction using Mg II emission lines, the galaxy is inferred to be a strong LyC leaker with ionizing photons escape fraction (dust corrected) of 27+/-4%. The proposed observations will (i) directly test the utility of Mg II based measure of LyC escape fraction for a high redshift galaxy, (ii) provide a sub-kpc map of ionizing photon escape allowing detailed probe of LyC escape. To date, only one source exists at any redshift where a spatially resolved study of LyC photons is possible. However, it is not clear whether the source is representative of reionization era galaxies. Our observations will exploit the ultraviolet capability of HST allowing the study of production and escape of ionizing photons from an exceptionally bright z=1.43 galaxy that is representative of reionization epoch. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will use WFC3 UVIS G280 grism to obtain Lyman continuum and Lyman-alpha in a bright gravitationally lensed arc (r=20.5) at z=1.425. We select the coordinates of the brightest star forming region as the RA/DEC and place it at the center of chip2 in order to boost the QE and flux calibration at shorter wavelengths. We split total 10 orbits into 3 visits (4 orbits, 3 orbits and 3 orbits) to improve schedulability. Prior to each visit, we will obtain two direct imaging using F300X with integration time of 200s each. For undispersed imaging, we will use G280-REF as an aperture. Following suggestion from the Instrument Scientist, we will use post-flash for the F300X images to achieve a background of ~20 electron/pix. In order to avoid contamination from a bright source, we request an ORIENT angle of 113 degree. This will ensure non contamination of spectra by nearby bright sources around the wavelength of interests. ------------------------------------------------------------------------------------ 16710( 2) - 29-Jul-2021 14:09:12 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CSWA-141 GALAXY, GRAVITATIONAL RA=08H46M47.5000S, J2000 V = 20.5 +/- 0.2 LENS, HIGH REDSHIFT DEC=+04D46'9.65" GALAXY, STARBURST Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 16710( 2) - 29-Jul-2021 14:09:12 - [ 3] Visit: 01 (CSWA-141-visit1) Visit Requirements: ORIENT 113D TO 113 D; ORIENT 293D TO 293 D 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 CSWA-141 WFC3/UVI ACCUM G280-REF F300X CR-SPLIT=2, FLASH=19 1 400 S (400 POS TARG null, -50 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2105 S POS TARG null, -50 S see below (2067 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG null, -50 S see below (2742 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG null, -50 S see below (2742 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG null, -50 S see below (2742 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 | ------------------------------------------------------------------------------------------------------------------------------------ CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 1 1 N/A S CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 2 1 N/A S CSWA-141 2 WFC3/UVI ACCUM UVIS G280 none none none none 1 2067.0 S S CSWA-141 3 WFC3/UVI ACCUM UVIS G280 none none none none 2 2742.0 S S CSWA-141 4 WFC3/UVI ACCUM UVIS G280 none none none none 3 2742.0 S S CSWA-141 5 WFC3/UVI ACCUM UVIS G280 none none none none 4 2742.0 S S 16710( 2) - 29-Jul-2021 14:09:12 - [ 4] Visit: 02 (CSWA-141-visit2) Visit Requirements: ORIENT 113D TO 113 D; ORIENT 293D TO 293 D 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 CSWA-141 WFC3/UVI ACCUM G280-REF F300X FLASH=19, CR-SPLIT=2 1 400 S (400 POS TARG -0.092, -50.098 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2105 S POS TARG -0.092, -50.098 S see below (2067 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG -0.092, -50.098 S see below (2742 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG -0.092, -50.098 S see below (2742 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 | ------------------------------------------------------------------------------------------------------------------------------------ CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 1 1 N/A S CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 2 1 N/A S CSWA-141 2 WFC3/UVI ACCUM UVIS G280 none none none none 1 2067.0 S S CSWA-141 3 WFC3/UVI ACCUM UVIS G280 none none none none 2 2742.0 S S CSWA-141 4 WFC3/UVI ACCUM UVIS G280 none none none none 3 2742.0 S S 16710( 2) - 29-Jul-2021 14:09:12 - [ 5] Visit: 03 (CSWA-141-visit3) Visit Requirements: ORIENT 113D TO 113 D; ORIENT 293D TO 293 D 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 CSWA-141 WFC3/UVI ACCUM G280-REF F300X FLASH=19, CR-SPLIT=2 1 400 S (400 POS TARG -0.185, -50.197 S S) ------------------------------------------------------------------------------------------------------------------------------------ 2 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2105 S POS TARG -0.185, -50.197 S see below (2067 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG -0.185, -50.197 S see below (2742 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 CSWA-141 WFC3/UVI ACCUM UVIS G280 1 2780 S POS TARG -0.185, -50.197 S see below (2742 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 | ------------------------------------------------------------------------------------------------------------------------------------ CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 1 1 N/A S CSWA-141 1 WFC3/UVI ACCUM G280-REF F300X none none none 2 1 N/A S CSWA-141 2 WFC3/UVI ACCUM UVIS G280 none none none none 1 2067.0 S S CSWA-141 3 WFC3/UVI ACCUM UVIS G280 none none none none 2 2742.0 S S CSWA-141 4 WFC3/UVI ACCUM UVIS G280 none none none none 3 2742.0 S S 16710( 2) - 29-Jul-2021 14:09:12 - [ 6] Summary Form for Proposal 16710 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures G280-REF, UVIS ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2, FLASH=19 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 113D TO 113 D, ORIENT 293D TO 293 D, POS TARG -0.092, -50.098, POS TARG -0.185, -50.197, POS TARG null, -50 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F300X, G280 ------------------------------------------------------------------------------------------------------------------------------------ Target Names CSWA-141 ------------------------------------------------------------------------------------------------------------------------------------