12266( 4) - 02-Aug-2011 18:13:10 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12266 Version: 4 Check-in Time: 02-Aug-2011 18:13:10 STScI Edit Number: 0 Title Lyman Continuum Escape Fractions with a Lensed LBG in the 'Sweet Spot' ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Ms. Anna M. Quider University of Cambridge CoI: Dr. Vasily Belokurov University of Cambridge N CoI: Dr. Brian Siana University of California - Riverside Y CoI: Prof. Alice E. Shapley University of California - Los Angeles N CoI: Prof. Charles C. Steidel California Institute of Technology N CoI: Prof. Max Pettini University of Cambridge N CoI: Dr. Brendon Brewer University of California - Santa Barbara N CoI: Prof. Geraint F. Lewis University of Sydney N CoI: Prof. Wyn Evans University of Cambridge N ------------------------------------------------------------------------------------ Abstract We propose to search for Lyman continuum (LyC) emission from the Cosmic Horseshoe. This star-forming galaxy at z = 2.38115 has been strongly lensed into a nearly complete Einstein ring of 10 arcsec diameter and magnified by a factor of 25 to g=20.1. The Cosmic Horseshoe is an ideal candidate for finding escaping LyC photons and studying in detail how LyC emission happens within a galaxy. In previous work we have shown that this galaxy has gaps in its interstellar medium, which are strongly correlated with a high escape fraction of LyC photons. We will improve the sensitivity of LyC escape fraction measurements by over an order of magnitude, thanks to the flux and resolution boost from gravitational lensing and the fortuitous location of the HST/UVIS F275W filter in the 'sweet spot' just redward of the Lyman limit. We will probe LyC escape fractions down to <3% at the 3-sigma level and constrain LyC emission across hundreds of resolution elements, corresponding to galactic structures as small as 100 pc. This galaxy has been well-characterized by studies in multiple wavebands, allowing us to place the LyC emission into the broader context of the Cosmic Horseshoe's properties. These HST observations will allow us to constrain how LyC emission happens within this galaxy and will guide our understanding of cosmic reionization. ------------------------------------------------------------------------------------ Observations Description ------------------------ We have received 10 orbits and will conduct our observations with HST/UVIS+F275W in a four point box dither pattern and a two point line dither pattern with sub-pixel dithering to better sample the point spread function (PSF). As our observations will be read noise limited, we will take long exposures of half of an orbit per exposure. We will execute two visits of five orbits each, with each visit completing two four-point box dither patterns and a two-point line dither pattern. Real Time Justification ----------------------- 12266( 4) - 02-Aug-2011 18:13:10 - [ 2] Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12266( 4) - 02-Aug-2011 18:13:10 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 J114833+1930 GALAXY, EINSTEIN RING, RA=11H48M33.1800S +/- 0.1", J2000 Z = V = 20.1 u=21.6, g=20.1, i=19.7, 03 GRAVITATIONAL LENS, DEC=+19D30'3.50" +/- 0.1" 2.38115 E(B-V)=0.15 HIGH REDSHIFT GALAXY Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 12266( 4) - 02-Aug-2011 18:13:10 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 12266( 4) - 02-Aug-2011 18:13:10 - [ 5] Visit: 01 Visit Requirements: 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG 0, -10; PATTERN 003 S see below 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG 5.00, -10.00; 003 S see below PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG -5, -10; 003 S see below PATTERN 2 3 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 1 1360.0 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 1360 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 3 none none none 2 1415.0 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 4 none none none 2 1415.0 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 3 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 3 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 3 none none none 4 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 4 none none none 4 1415 S S J114833+193003 3 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 5 1415 S S J114833+193003 3 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 5 1415 S S 12266( 4) - 02-Aug-2011 18:13:10 - [ 6] Visit: 02 Visit Requirements: SAME ORIENT AS 01 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG 0, -5; PATTERN 003 S see below 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG +5.00, -5.00; 003 S see below PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 J114833+193 WFC3/UVI ACCUM UVIS2 F275W 1 1250 S POS TARG -5, -5; PATTERN 003 S see below 2 3 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 1 1360.0 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 1 1360.0 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 3 none none none 2 1415.0 S S J114833+193003 1 WFC3/UVI ACCUM UVIS2 F275W 4 none none none 2 1415.0 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 3 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 3 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 3 none none none 4 1415 S S J114833+193003 2 WFC3/UVI ACCUM UVIS2 F275W 4 none none none 4 1415 S S J114833+193003 3 WFC3/UVI ACCUM UVIS2 F275W 1 none none none 5 1415 S S J114833+193003 3 WFC3/UVI ACCUM UVIS2 F275W 2 none none none 5 1415 S S 12266( 4) - 02-Aug-2011 18:13:10 - [ 7] Summary Form for Proposal 12266 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2, PATTERN 2 3, POS TARG +5.00, -5.00, POS TARG -5, -10, POS TARG -5, -5, POS TARG 0, -10, POS TARG 0, -5, POS TARG 5.00, -10.00, SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F275W ------------------------------------------------------------------------------------------------------------------------------------ Target Names J114833+193003 ------------------------------------------------------------------------------------------------------------------------------------