Science Keywords: Select from 2 to 5 items. Science Keywords is a required field. Only letters, numerals, '.', '+' and '-' are allowed in target names. Blank spaces are not allowed. Target names are limited to 2 to 31 characters. 0 Assigned ID: 2639 ----- Attempting Submission 1 (Thu Nov 11 15:08:30 GMT 2021) ----- Joint NRAO/HST Thanks for your patience in waiting for this submission. My one residual concern is the bright star that can be seen in the target confirmation chart; based on my read of the documentation, WFC3/IR does not require special measures here, so I have (tentatively) not imposed any roll angle constraints. -583574438 ----- Attempting Submission 1 (Thu Dec 16 20:32:50 GMT 2021) ----- ----- Attempting Submission 3 (Mon Feb 28 17:00:01 GMT 2022) ----- Change to the coordinates. 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. 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 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.) The team includes considerable expertise working with HST data (Holwerda, Ravindranath) and with the radio-wavelength data that will be also taken for this project (Baker, Blyth, Darling, Deane, Glowacki, Pan, Roberts + unlisted Rutgers collaborator Amir Kazemi-Moridani) as a conseuence the approved VLA proposal that spawned this HST proposal. Galaxies 6 false false false false false false false false SUPPORTED GALAXY ULTRALUMINOUS IR GAL 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). J2000 J2000 WFC3/IR Imaging No No F098M WFC3/IR Imaging No No F125W POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 1 false 1639676246377 The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16888 :visit-id "01" :proposal-version -1 :trans-version "20210514" :date "16-Dec-2021 12:37:26.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 3203296 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16888 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16888 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2668 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3165 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16888 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2668 :al-overhead-at-end 0 :internal-dur-at-end 671 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3165 :pcs-gap 0 ) false 2 0