6598( 7) - 03/06/97 09:21 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6598 Version: 7 Check-in Date: 06-Mar-1997 09:18:21 1.Proposal Title: The Reddest Objects in the Universe ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle COSMOLOGY GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: ARJUN DEY KITT PEAK NATIONAL OBSERVATORY CoI: James R. Graham University of California, Berkeley N CoI: Hyron Spinrad University of California, Berkeley N CoI: Kurt Adelberger Caltech N CoI: Charles Steidel Caltech N ------------------------------------------------------------------------------------ 6. Abstract Recent deep K--band imaging surveys have discovered a new population of infrared bright, extremely red (R-K~gt 6), objects (EROS). There are no optical spectra for these bizarre objects on account of their faintness (R ~gt 24.5), and therefore their nature and redshift are uncertain. However we do have some intriguing clues which suggest that HST imaging will be decisive in unraveling this engima. The EROS are common: their surface density is similar to that of luminous quasars. They are just spatially resolved in IR Keck images with 0.''4 seeing, and therefore they are almost certainly distant galaxies. IR spectra from Keck of one object suggests z = 1.44. Very red colors would then follow naturally from shifting of the 4000Angstrom\ break to 1 Mu m. If all the EROS are at moderate redshifts (z~ 1-2), their luminosities are several L^* and their volume space density is comparable to that of active galaxies of similar luminosity. The morphology of the EROS will provide a major clue to their nature -- are they ellipticals, disks or disturbed system? The EROS are small with sizes of about 0.''5 and only HST offers the spatial resolution necessary provide this information. Therefore, we propose to obtain broad band images using the F814W filter in order to determine the morphologies and surface photometry of these objects. This program will complement an ongoing Keck imaging and spectroscopic study of these objects at near infrared wavelengths. ------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 2] Observations Description ------------------------ We propose to image a small sample of very red, radio quiet, galaxies in the F814W filter. The objects in the sample are very faint, and typically have I magnitudes in the range 23 < I < 25. Since some of the objects may be very low surface brightness and diffuse, we estimate that we will require roughly two orbits per target in order to get morphological information on the objects and to aid in cosmic ray removal. We will image each target on a WF CCD and use pixel substepping to slightly increase our sampling and better the resolution. Our choice of using the WF CCD resolution rather than the PC is a compromise between using the better sensitivity of the WF CCDs to diffuse objects, and still regaining some of the resolution if the objects are very centrally nucleated and compact. In 5400s through the F814W filter, we estimate that we should be able to detect (at 5Sigma) surface brightnesses of 24.7 AB mag/sq.arcsec.\\\\\\\\\\\\\\\\ (0.47MuJy/sq.arcsec.) in a 3* 3 pixel (0.''3*0.''3) aperture on the WF2 CCD. Our point source 5Sigma detection threshold will be ~ 27.9 AB mag (0.026MuJy). We therefore request two orbits per target, or a total of 20 orbits for this project. Real Time Justification ----------------------- None. We have begun a near--IR spectroscopic and imaging study of these objects using the W.\\\\\\\\\\\\\\\\ M.\\\\\\\\\\\\\\\\ Keck Telescope. In addition, some HST observations (in bluer bands than those proposed here) of a few of the target fields already exist, but in many cases are of insufficient signal--to-- noise ratio (either because of the observed wavelength or due to the short integration) for a detailed study of the morphology of the red objects. The combination of the spectroscopy (for redshift and possible emission line ratios / continuum break indices), broad band optical and near--IR colors, and optical and IR morphologies at high spatial resolution (~ 0"per1 in the optical with HST, and ~ 0"per5 with NIRC on Keck) will provide us with all the information necessary to understand this high space density population of mysterious objects. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: Dr. Arjun Dey, NOAO/KPNO, 950 N. Cherry Ave., P.O. Box 26732, Tucson, AZ 85726- 6732 Ship Via: Email: dey@noao.edu ------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ERO0424+0204 GALAXY,HIGH REDSHIFT RA=4H 24M 8.54S +/- 0.1S,DEC=2D 2000 R = 24.9 A GALAXY 4' 25.0" +/- 1" Comments: Position listed is for QSO in field 2 ERO0905+3408 GALAXY,HIGH REDSHIFT RA=09H 5M 30.5S +/- 0.1S,DEC=34D 2000 R = 24.4 A GALAXY 8' 9.7" +/- 1" 3 ERO1019+0535 GALAXY,HIGH REDSHIFT RA=10H 19M 32.81S +/- 2000 R = 25.3 A GALAXY 0.1S,DEC=05D 34' 35.2" +/- 1" Comments: Position listed is for ERO 4 ERO1215-0034 GALAXY,HIGH REDSHIFT RA=12H 15M 47.72S +/- 0.1S,DEC=- 2000 R = 24.5 GALAXY 0D 34' 34.4" +/- 1" Comments: Position listed is for ERO R6 5 ERO1645+4626 GALAXY,HIGH REDSHIFT RA=16H 45M 2.35S +/- 2000 R = 25 A GALAXY 0.1S,DEC=46D 26' 26.9" +/- 1" Comments: Position listed is for HR10 6598( 7) - 03/06/97 09:21 - [ 4] Visit: 01 Visit Requirements: ORIENT 90D TO 97D 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 ERO0424+020 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1140 S POS TARG 2.0,0.0 4A Comments: Positioning QSO at the `optimal' WF3 position ------------------------------------------------------------------------------------------------------------------------------------ 2 ERO0424+020 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1140 S SAME POS AS 1 4A ------------------------------------------------------------------------------------------------------------------------------------ 3 ERO0424+020 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1200 S POS TARG 2.55,0.55 4A Comments: Dithering by dX=0.55" from previous position ------------------------------------------------------------------------------------------------------------------------------------ 4 ERO0424+020 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1300 S SAME POS AS 3 4A ------------------------------------------------------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 5] Visit: 02 Visit Requirements: 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 ERO0905+340 WFPC2 IMAGE WF2 F814W CR-SPLIT=NO 1 1200 S 8A Comments: Positioning ERO at optimal WF2 position ------------------------------------------------------------------------------------------------------------------------------------ 2 ERO0905+340 WFPC2 IMAGE WF2 F814W CR-SPLIT=NO 1 1200 S SAME POS AS 1 8A ------------------------------------------------------------------------------------------------------------------------------------ 3 ERO0905+340 WFPC2 IMAGE WF2 F814W CR-SPLIT=NO 1 1300 S POS TARG 0.55,0.55 8A Comments: Dithering by dX=+0.55" from previous position ------------------------------------------------------------------------------------------------------------------------------------ 4 ERO0905+340 WFPC2 IMAGE WF2 F814W CR-SPLIT=NO 1 1300 S SAME POS AS 3 8A ------------------------------------------------------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 6] Visit: 03 Visit Requirements: 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 ERO1019+053 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 1170 S 5A Comments: Positioning ERO at optimal WF3 position ------------------------------------------------------------------------------------------------------------------------------------ 2 ERO1019+053 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 1170 S SAME POS AS 1 5A ------------------------------------------------------------------------------------------------------------------------------------ 3 ERO1019+053 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 1200 S POS TARG 0.55,0.55 5A Comments: Dithering by dX=0.55" from previous position ------------------------------------------------------------------------------------------------------------------------------------ 4 ERO1019+053 WFPC2 IMAGE WF3 F814W CR-SPLIT=NO 1 1300 S SAME POS AS 3 5A ------------------------------------------------------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 7] Visit: 04 Visit Requirements: ORIENT 277D TO 283D 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 ERO1215-003 WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=NO 1 1180 S POS TARG -28.4,27.1 4 Comments: Positioning R6 at (X,Y)=(-28.4",27.1") from WF4-FIX ------------------------------------------------------------------------------------------------------------------------------------ 2 ERO1215-003 WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=NO 1 1180 S SAME POS AS 1 4 ------------------------------------------------------------------------------------------------------------------------------------ 3 ERO1215-003 WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=NO 1 1180 S POS TARG -27.85,26.55 4 Comments: Dithering R6 by dY=-0.55" from previous position ------------------------------------------------------------------------------------------------------------------------------------ 4 ERO1215-003 WFPC2 IMAGE WF4-FIX F814W CR-SPLIT=NO 1 1280 S SAME POS AS 3 4 ------------------------------------------------------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 8] Visit: 05 Visit Requirements: ORIENT 180D TO 213D 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 ERO1645+462 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1300 S POS TARG 2.0,0.0 6A Comments: Positioning HR10 at optimal WF3 position ------------------------------------------------------------------------------------------------------------------------------------ 2 ERO1645+462 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1300 S SAME POS AS 1 6A ------------------------------------------------------------------------------------------------------------------------------------ 3 ERO1645+462 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1300 S POS TARG 2.55,0.55 6A Comments: Dithering by dX=0.55" from previous position ------------------------------------------------------------------------------------------------------------------------------------ 4 ERO1645+462 WFPC2 IMAGE WF3-FIX F814W CR-SPLIT=NO 1 1400 S SAME POS AS 3 6A ------------------------------------------------------------------------------------------------------------------------------------ 6598( 7) - 03/06/97 09:21 - [ 9] Summary Form for Proposal 6598 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COSMOLOGY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 90D TO 97D POS TARG 2.0,0.0 SAME POS AS 1 POS TARG 2.55,0.55 SAME POS AS 3 POS TARG 0.55,0.55 ORIENT 277D TO 283D POS TARG -28.4,27.1 POS TARG -27.85,26.55 ORIENT 180D TO 213D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ERO0424+0204A ERO0905+3408A ERO1019+0535A ERO1215-0034 ERO1645+4626A ------------------------------------------------------------------------------------------------------------------------------------