7460( 3) - 05/20/97 15:35 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 7460 Version: 3 Check-in Date: 20-May-1997 15:35:13 1.Proposal Title: The Nature of Red Outlier Galaxies: Age vs Dust ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COSMOLOGY GO 7 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: LEONIDAS MOUSTAKAS UNIVERSITY OF CALIFORNIA CoI: Marc Davis University of California N CoI: Steve Zepf University of California N CoI: Andrew Bunker University of California N ------------------------------------------------------------------------------------ 6. Abstract We propose to use HST and F160W on NICMOS to target a class of faint (I~gt 25) field galaxies which have blue optical colors (V-I=0-2) but red infrared colors (I-K>4). If the red color of these ``red outlier galaxies'' (ROGs) is due to dusty, evolved nuclei, we expect that high-resolution imaging in the near-infrared will reveal the central region to be very concentrated compared to the optical. Observations of several preselected candidates with F160W on NICMOS will make this distinction directly, and will also provide enough data to constrain the location of the 4000Angstrom\ break for the ROGs. The surface density of the ROGs is several per square arcminute, and as such comprise an important fraction of galaxies in deep near-infrared surveys. The targets are in the deep portion of the Groth Survey Strip (dGSS), for which we already have WFPC2 archival data and very deep K band imaging from the Keck telescope, which allows us to pre-select all the targets. We will specifically target ROGs in the PC portion of the dGSS with Camera NIC2 and F160W. Cameras NIC1 and NIC3, both with F160W, will be used simultaneously, targeted on a second set of ROGs. ------------------------------------------------------------------------------------ 7460( 3) - 05/20/97 15:35 - [ 2] Observations Description ------------------------ While we will concentrate our efforts on F160W imaging of an area that includes three ROG candidates within the PC field of dGSS, we will use the two other cameras simultaneously to observe other parts of the area we have already surveyed. We shall observe the main targets with NIC2, which has a FOV of 19arcs2. All the ROGs we have identified in the PC portion of the WFPC2 dGSS images will fall nicely within the field of view of NIC2. NIC3 (FOV=51arcs2) with F160W will simultaneously target another set of pre-selected ROGs in the dGSS. Even if NIC3 is significantly out of focus with respect to NIC2, the F160W magnitudes will be valuable in combination with the ground-based K photometry we have. We are making the observations in F160W (roughly equivalent to the H band), primarily to take advantage of the low background. We do not know at what wavelength between the I and K bands the 4000Angstrom\\\\ break falls, and so in the signal-to-noise (SNR) calculations we carry out, we consider a best- and a worst-case scenario (see Table 2). The faintest ROGs have K~22 and I~27 (Figure 1). Presumably the 4000Angstrom\\\\ break falls between those two bands. If the break falls longward of F160W (1.59Mum), we interpolate the I flux level to F160W assuming a flat spectrum in F_Nu. The corresponding F160W magnitude is 26.1 which is 3.56times10^-8 Jy. This is the worst-case scenario. The best-case scenario assumes that the break is shortward of F160W, and that we can extrapolate the K flux to F160W assuming a flat spectrum again. The corresponding flux is then F160W=22.5 magnitudes, or 9.81times10^-7 Jy. An adequate SNR for determination of the SED is ~5, and higher SNR will enable morphological study. In 4 orbits we reach reasonable SNRs for even the worst-case scenario if the ROGs were point sources ( nb, the SNR for the point sources in Table 2 refers to the SNR of the brightest pixel). In fact, based on the WFPC2 images the ROGs are extended with typical FWHMs of ~lt0arcs5. The SNRs for the ``extended'' sources in Table 2 assume a size of 0arcs5, and the resulting SNR is the total SNR. With 4 orbits, therefore, we should be able to detect most of the ROGs we target with sufficient signal to determine their morphologies, even if they are extended in the near-infrared. begintable captionSNR considerations for NIC2 F160W observations of ROGs (4 orbits) begincenter begintabularlcr Extent & Flux Level (Jy) & SNR , Point Source & 9.81times10^-7 (H=22.5) & 70 , Point Source & 3.56times10^-8 (H=26.1) & 4 , Extended (0arcs5) & 9.81times10^-7 (H=22.5) & 10 , Extended (0arcs5) & 3.56times10^-8 (H=26.1) & 2 , endtabular endcenter endtable Real Time Justification ----------------------- None. In Spring 1997 we will attempt to get spectra by targeting a few of the ROG candidates with a multislit mask on LRIS on Keck. Calibration Justification ------------------------- We willbe using the standard NICMOS MULTI-ACCUM read patterns, which we expect will be supported, with appropriate dark currents available. Additional Comments ------------------- ------------------------------------------------------------------------------------ 7460( 3) - 05/20/97 15:35 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: 601 Campbell Hall, Berkeley CA 94720- 3411 Ship Via: Email: ------------------------------------------------------------------------------------ 7460( 3) - 05/20/97 15:35 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL- GALAXY,HIGH REDSHIFT RA=14H 17M 42.5266S +/- J2000 V = 25.0+/-1.0 141743+52280 GALAXY 0.2S,DEC=52D 28' 08.140" +/- 8 0.1",PLATE-ID=003A 7460( 3) - 05/20/97 15:35 - [ 5] Visit: 01 Visit Requirements: SCHED 30% ORIENT 315D TO 130D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GAL-141743+ NIC2 MULTIAC NIC2 F160W 1.60000 SAMP-SEQ=STEP256,NSAMP=21 1 DEF PAR 2-3 WITH 1 522808 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 GAL-141743+ NIC1 MULTIAC NIC1 F160W 1.60000 SAMP-SEQ=STEP256,NSAMP=21 1 DEF 522808 CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 GAL-141743+ NIC3 MULTIAC NIC3 F160W 1.60000 SAMP-SEQ=STEP128,NSAMP=20 2 DEF 522808 CUM ------------------------------------------------------------------------------------------------------------------------------------ 11 GAL-141743+ NIC2 MULTIAC NIC2 F160W 1.60000 SAMP-SEQ=STEP256,NSAMP=22, 1 DEF PAR 12-13 WITH 11 POS 522808 CUM PATTERN=SPIRAL-DITH,NUM-POS=3, TARG 0,-1.1 OFFSET=SAM,DITH-SIZE=1.1, PATTERN-ORIENT=DETECTOR ------------------------------------------------------------------------------------------------------------------------------------ 12 GAL-141743+ NIC1 MULTIAC NIC1 F160W 1.60000 SAMP-SEQ=STEP256,NSAMP=22 1 DEF 522808 CUM ------------------------------------------------------------------------------------------------------------------------------------ 13 GAL-141743+ NIC3 MULTIAC NIC3 F160W 1.60000 SAMP-SEQ=STEP128,NSAMP=21 2 DEF 522808 CUM ------------------------------------------------------------------------------------------------------------------------------------ 7460( 3) - 05/20/97 15:35 - [ 6] Summary Form for Proposal 7460 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 NIC1 NIC3 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SAMP-SEQ=STEP256 NSAMP=21 NSAMP=20 PATTERN-ORIENT=DETECTOR NSAMP=22 SAMP-SEQ=STEP128 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SCHED 30% ORIENT 315D TO 130D PAR 2-3 WITH 1 PAR 12-13 WITH 11 POS TARG 0,-1.1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W ------------------------------------------------------------------------------------------------------------------------------------ Target Names GAL-141743+522808 ------------------------------------------------------------------------------------------------------------------------------------