16888( 3) - 28-Feb-2022 17:57:47 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16888 Version: 3 Check-in Time: 28-Feb-2022 17:57:47 STScI Edit Number: 0 Title High-resolution imaging of the highest-redshift OH megamaser ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrew Baker Rutgers the State University of New Jersey Y CoI: Dr. Sarah Blyth University of Cape Town N CoI: Prof. Jeremy Darling University of Colorado at Boulder N CoI: Dr. Roger Deane University of Witwatersrand - Wits N University CoI: Dr. Marcin Glowacki University of the Western Cape N CoI: Dr. Benne Willem Holwerda University of Louisville Research N Foundation, Inc. CoI: Dr. Hengxing Pan University of the Western Cape N CoI: Hayley Roberts University of Colorado at Boulder N CoI: Dr. Swara Ravindranath Space Telescope Science Institute - CSA - N JWST ------------------------------------------------------------------------------------ Abstract We propose high-resolution imaging of the OH 1667 MHz main line and 1 GHz continuum of the highest redshift known OH megamaser, which was recently discovered in early observations for the LADUMA (Looking At the Distant Universe with the MeerKAT Array) survey. As is typical in the local universe, the host system is an ultraluminous infrared galaxy; the OH emission may be tracing an outflow, but the system's possible merger status and AGN strength are uncertain. In conjunction with two orbits of HST time, our VLA observations will allow us to localize the OH emission relative to the host galaxy's optical and radio structures, which may include multiple nuclei and/or radio jets; to determine the host galaxy's stellar morphology and its possible evolution into a post-merger elliptical; and to place stronger constraints on the OH brightness temperature, thereby informing models of physical conditions in the masing gas. The resulting analysis will place the use of spectral line surveys like LADUMA for studying the cosmic history of gas-rich mergers on a much firmer foundation. ------------------------------------------------------------------------------------ Observations Description ------------------------ This program is using WFC3/IR to image the host galaxy of a recently discovered OH megamaser at z = 0.52. One orbit will use the medium-bandwidth F098M filter, which includes the H alpha line at this redshift, and the other orbit will use the wide-bandwidth F125W (~ J) filter, which will be used to subtract stellar continuum from the F098M image and search for low surface brightness signatures of interaction and merging. (We have not attempted to match S/N in these two images, which would optimize S/N in the difference image, since we don't know how bright the H alpha line will be, and we don't want to sacrifice too much of our sensitivity to low surface brightness features in the F125W image.) We will use the standard WFC3-IR-DITHER-BOX-MIN pattern with four positions in order to 16888( 3) - 28-Feb-2022 17:57:47 - [ 2] optimally sample the PSF. The field of view of interest will be well contained within the optimally sampled region, based on ground-based imaging. We estimated the target's surface brightness of 20.18 mag/arcsec^2 (Vega-relative) from ground-based imaging, which reveals a ~2" diameter source and (from the VISTA Deep Extragalactic Observations = VIDEO survey) a total magnitude J = 19.94. Due to the presence of a nearby bright star that could fall in the WFC3/IR field of view for certain roll angles, we have chosen to prioritize dynamic range by using STEP50 sequences in conjunction with the same four-point dither pattern for each filter. The first STEP50 sequence for each filter has NSAMP = 11 and will deliver four 299.232s sub-exposures; the second STEP50 sequence has NSAMP = 10 and will deliver four 249.342s sub-exposures. (It was necessary to use different NSAMP values here to avoid orbit overruns; STEP25 sequences are not practical as an alternative because they cause inconveniently timed buffer dumps.) The total integration time per object (2193.858s) should yield detection signal-to-noise ratios (in a 5x5 pixel box) of 116 and 229 for the F098M and F125 filters, respectively, based on the output of the WFC3/IR imaging ETC for an extended source with a redshifted Arp 220 spectrum (our target is a ULIRG) and nominal background conditions. These depths will ensure high signal-to-noise over the target, as required by the proposal's scientific goals. (Note: ETC runs appropriate for the two STEP50 sequences separately, reflecting lower S/N, have been included with the Phase II submission.) ------------------------------------------------------------------------------------ 16888( 3) - 28-Feb-2022 17:57:47 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 WISEAJ0330 GALAXY, ULTRALUMINOUS RA=03H30M49.2600S, J2000 V = 21.1 IR GAL DEC=-27D55'18.30" Reference Frame: ICRS Comments: Quoted V-band magnitude is an average of g = 21.71 and r = 21.4. Near-IR magnitudesare J = 18.94, H = 18.84, K = 18.51 (Vega-relative). ------------------------------------------------------------------------------------------------------------------------------------ 16888( 3) - 28-Feb-2022 17:57:47 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 16888( 3) - 28-Feb-2022 17:57:47 - [ 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 WISEAJ0330 WFC3/IR MULTIAC IR F125W SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 1 CUM (1196.93 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 WISEAJ0330 WFC3/IR MULTIAC IR F125W SAMP-SEQ=STEP50, NSAMP=10 1 DEF PATTERN 1 2 CUM (996.928 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 WISEAJ0330 WFC3/IR MULTIAC IR F098M SAMP-SEQ=STEP50, NSAMP=11 1 DEF PATTERN 1 3 CUM (1196.93 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 WISEAJ0330 WFC3/IR MULTIAC IR F098M SAMP-SEQ=STEP50, NSAMP=10 1 DEF PATTERN 1 4 CUM (996.928 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISEAJ0330 1 WFC3/IR MULTIAC IR F125W 1 none none none 1 N/A CUM WISEAJ0330 1 WFC3/IR MULTIAC IR F125W 2 none none none 1 N/A CUM WISEAJ0330 1 WFC3/IR MULTIAC IR F125W 3 none none none 1 N/A CUM WISEAJ0330 1 WFC3/IR MULTIAC IR F125W 4 none none none 1 N/A CUM WISEAJ0330 2 WFC3/IR MULTIAC IR F125W 1 none none none 1 N/A CUM WISEAJ0330 2 WFC3/IR MULTIAC IR F125W 2 none none none 1 N/A CUM WISEAJ0330 2 WFC3/IR MULTIAC IR F125W 3 none none none 1 N/A CUM WISEAJ0330 2 WFC3/IR MULTIAC IR F125W 4 none none none 1 N/A CUM WISEAJ0330 3 WFC3/IR MULTIAC IR F098M 1 none none none 2 N/A CUM WISEAJ0330 3 WFC3/IR MULTIAC IR F098M 2 none none none 2 N/A CUM 16888( 3) - 28-Feb-2022 17:57:47 - [ 6] 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 | ------------------------------------------------------------------------------------------------------------------------------------ WISEAJ0330 3 WFC3/IR MULTIAC IR F098M 3 none none none 2 N/A CUM WISEAJ0330 3 WFC3/IR MULTIAC IR F098M 4 none none none 2 N/A CUM WISEAJ0330 4 WFC3/IR MULTIAC IR F098M 1 none none none 2 N/A CUM WISEAJ0330 4 WFC3/IR MULTIAC IR F098M 2 none none none 2 N/A CUM WISEAJ0330 4 WFC3/IR MULTIAC IR F098M 3 none none none 2 N/A CUM WISEAJ0330 4 WFC3/IR MULTIAC IR F098M 4 none none none 2 N/A CUM 16888( 3) - 28-Feb-2022 17:57:47 - [ 7] Summary Form for Proposal 16888 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=10, NSAMP=11, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2, PATTERN 1 3, PATTERN 1 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F098M, F125W ------------------------------------------------------------------------------------------------------------------------------------ Target Names WISEAJ0330 ------------------------------------------------------------------------------------------------------------------------------------