9438( 12) - 05/01/03 09:47 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9438 Version: 12 Check-in Date: 01-May-2003 09:46:07 1.Proposal Title: The Origin of the Intergalactic Globular Cluster Population in Abell 1185 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Michael West University of Hawaii CoI: Dr. Patrick Cote Rutgers University N CoI: Mr. Andres Jordan Rutgers University N CoI: Dr. Ron Marzke San Francisco State University N ------------------------------------------------------------------------------------ 5. Abstract We request deep V and I observations with ACS to examine the properties of a newly discovered population of intergalactic globular clusters in the core of the rich galaxy cluster Abell 1185. Our previous WFPC2 observations of this field (GO-8164) revealed an excess of five times the number of objects at the expected magnitudes of globular clusters compared to the Hubble Deep Fields. The colors and luminosity function of these intergalactic globular clusters will place strong constraints on their origin, which in turn will yield new insights to the evolution of galaxy populations in dense environments. ------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 2] Observations Description ------------------------ The essential element of this program is high-resolution, multicolor imaging of very faint objects. We will image the x-ray centroid of Abell 1185, the same field that we observed previously with WFPC2 using the F814W filter for our GO- 8164 program, using the F555W (Johnson V) and F814W (Broad I) filters. At the distance of A1185, globular clusters are unresolved even with ACS. We choose to observe with the V and I filters rather than the SDSS filters in order to facilitate comparison with existing datasets on Galactic and extragalactic globular cluster systems, which have been done almost exclusively with this filter system to date. For the I-band observations, our goal is to reach ~ 0.7 mag past the expected turnover of the IGC luminosity function in order to see the turnover at the faint end. For a distance modulus m-M = 35.7 to A1185, and an assumed universal Gaussian globular cluster luminosity function with a characteristic turnover magnitude M_I ~eq -8.4 and a 1Sigma spread of 1.3 (e.g., Harris 1991; Kundu & Whitmore 2001), this requires detecting point sources to I ~eq 28.0. At this depth we will reach ~ 0.5Sigma past the turnover. Based on calculations with the ACS Exposure Time Calculator and assuming a typical globular cluster spectral distribution, we fin d that this can be achieved with a total integration time of 17, 170 seconds with a signal- to-noise ratio S/N=5, which is adequate for reliable separation of resolved and unresolved objects (see, e.g., Elson et al. 1996) and with photometric errors that are small compared to the expected width of the globular cluster luminosity funtion. Our V-band observations do not need to go quite as faint, since their purpose is simply to provide color information for the brighter IGCs. A total integration time of 11, 990 sec in the F555W filter will detect objects down to V ~eq 28.3 with S/N=5. This magnitude limit corresponds to the expected turnover of the globular cluster luminosity function in the V-band (M_V = -7.4), and hence these observations will yield color information on the brightest half of the IGC population. At a declination of Delta = +28^degrees, A1185 has 53 minutes of visibility per orbit. Allowing for target acquisition, CR-SPLITTING, readout, dithering and other o verhead, the total integration time required for this program is 9 orbits in I and 6 orbits in V, for a total request of 15 orbits. We have also been awarded parallel observations with WFPC2. These will complement our ACS observations by allowing us to search for intergalactic globular clusters in another A1185 field. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ABELL1185 CLUSTER OF GALAXIES, RA=11H 10M 45.00S +/- 0', J2000 Z = I = 27.0+/-1.0 RICH CLUSTER DEC=28D 43' 57.0" +/- 0', PLATE- 0.0325 ID=019K Coordinate Source: HST_IMAGE Comments: Our target is a relatively "blank" region in the heart of a rich cluster of galaxies, Abell 1185, and hence there are no pre-selected targets. Our goal is to detect a population of faint intergalactic globular clusters which may be present in this field. The broad band magnitude I~27 is the expected characteristic magnitude of globular clusters at this distance. 9438( 12) - 05/01/03 09:47 - [ 4] Visit: 01 Visit Priority: Visit Requirements: ORIENT 250D TO 280D On Hold Comments: Additional Comments: WFPC2 parallel exposures coordinated with ACS primary exposures Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 110 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2490 S PAR 115 WITH 110 C ------------------------------------------------------------------------------------------------------------------------------------ 115 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 120 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 125 WITH 120 POS TARG C 0.25, 0.08 ------------------------------------------------------------------------------------------------------------------------------------ 125 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 130 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 135 WITH 130 POS TARG C 0.12, 0.22 ------------------------------------------------------------------------------------------------------------------------------------ 135 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 5] Visit: 02 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: WFPC2 parallel exposures coordinated with ACS primary exposures Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 210 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2490 S POS TARG -0.12, 0.15 PAR C 215 WITH 210 ------------------------------------------------------------------------------------------------------------------------------------ 215 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 220 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 225 WITH 220 POS TARG C 0.1, 0.1 ------------------------------------------------------------------------------------------------------------------------------------ 225 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 230 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 235 WITH 230 POS TARG C 0.35, 0.175 ------------------------------------------------------------------------------------------------------------------------------------ 235 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 6] Visit: 03 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: WFPC2 parallel exposures coordinated with ACS primary exposures Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 310 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2490 S POS TARG 0.22, 0.32 PAR C 315 WITH 310 ------------------------------------------------------------------------------------------------------------------------------------ 315 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 320 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 325 WITH 320 POS TARG C 0.03, 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 325 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 330 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2640 S PAR 335 WITH 330 POS TARG C 0.1, 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 335 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 7] Visit: 04 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: WFPC2 parallel exposures coordinated with ACS primary exposures Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 410 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2490 S PAR 415 WITH 410 C ------------------------------------------------------------------------------------------------------------------------------------ 415 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 420 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2640 S PAR 425 WITH 420 POS TARG C 0.25, 0.08 ------------------------------------------------------------------------------------------------------------------------------------ 425 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 430 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2640 S PAR 435 WITH 430 POS TARG C 0.12, 0.22 ------------------------------------------------------------------------------------------------------------------------------------ 435 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 8] Visit: 05 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: WFPC2 parallel exposures coordinated with ACS primary exposures Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 510 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2490 S POS TARG -0.12, 0.15 PAR C 515 WITH 510 ------------------------------------------------------------------------------------------------------------------------------------ 515 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 520 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2640 S PAR 525 WITH 520 POS TARG C 0.1, 0.1 ------------------------------------------------------------------------------------------------------------------------------------ 525 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 530 ABELL1185 ACS/WF ACCUM WFC F555W CR-SPLIT=2 1 2640 S PAR 535 WITH 530 POS TARG C 0.03, 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 535 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 9] Visit: 13 Visit Priority: Visit Requirements: SAME ORIENT AS 01 On Hold Comments: Additional Comments: Repeat of orbit 3 of visit 03. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 330 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=2 1 2490 S PAR 335 WITH 330 POS TARG C 0.1, 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 335 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 2600 S IX ------------------------------------------------------------------------------------------------------------------------------------ 340 ABELL1185 ACS/WF ACCUM WFC F814W CR-SPLIT=NO 1 1320 S PAR 345 WITH 340 POS TARG C 0.03, 0.25 ------------------------------------------------------------------------------------------------------------------------------------ 345 ABELL1185 WFPC2 IMAGE WFALL-F F814W CR-SPLIT=NO 1 1300 S IX ------------------------------------------------------------------------------------------------------------------------------------ 9438( 12) - 05/01/03 09:47 - [ 10] Summary Form for Proposal 9438 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC WFALL-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 CR-SPLIT=0.5 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 250D TO 280D PAR 115 WITH 110 PAR 125 WITH 120 POS TARG 0.25, 0.08 PAR 135 WITH 130 POS TARG 0.12, 0.22 SAME ORIENT AS 01 POS TARG -0.12, 0.15 PAR 215 WITH 210 PAR 225 WITH 220 POS TARG 0.1, 0.1 PAR 235 WITH 230 POS TARG 0.35, 0.175 POS TARG 0.22, 0.32 PAR 315 WITH 310 PAR 325 WITH 320 POS TARG 0.03, 0.25 PAR 335 WITH 330 POS TARG 0.1, 0.0 PAR 415 WITH 410 PAR 425 WITH 420 POS TARG 0.25, 0.08 PAR 435 WITH 430 POS TARG 0.12, 0.22 POS TARG -0.12, 0.15 PAR 515 WITH 510 PAR 525 WITH 520 POS TARG 0.1, 0.1 PAR 535 WITH 530 POS TARG 0.03, 0.25 PAR 345 WITH 340 POS TARG 0.03, 0.25 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ABELL1185 ------------------------------------------------------------------------------------------------------------------------------------