10003( 3) - 09/26/03 14:56 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10003 Version: 3 Check-in Date: 26-Sep-2003 14:55:50 1.Proposal Title: Deep Chandra and Hubble Observations of NGC4697, the Nearest Optically Luminous, X- ray Faint Elliptical Galaxy ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 12 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Dr. Craig L. Sarazin The University of Virginia CoI: Dr. Gregory Sivakoff The University of Virginia N CoI: Dr. Jimmy A. Irwin University of Michigan N CoI: Dr. Patrick Cote Rutgers the State University of New Jersey N CoI: Mr. Andres Jordan Rutgers the State University of New Jersey N ------------------------------------------------------------------------------------ 5. Abstract We propose 4 new Chandra observations of NGC4697, the nearest X-ray-faint, optically-bright elliptical, which was resolved into low mass X-ray binaries (LMXBs) in Cycle 1. We will detect LMXBs at least three times fainter (~1e37 ergs/s) than possible for any luminous E galaxy at present, allowing a direct comparison with the LMXBs in our Galaxy and M31. We will measure the variability of sources on times up to 4.5 yr. Models predict variability for LMXBs in early-type galaxies, which is particularly strong for the brightest black hole sources. We also propose 1 orbit of HST to detect >1500 globular clusters (GCs). If the results for luminous LMXBs continue to low LX, most of the LMXBs will be identified with GCs. We will study the formation history of LMXBs, GCs, and field stars in N4697. ------------------------------------------------------------------------------------ 10003( 3) - 09/26/03 14:56 - [ 2] Observations Description ------------------------ The primary aim of this HST observation of the elliptical galaxy NGC 4697 is to detect and study the globular cluster populations of the galaxy. The globular clusters will be compared to the X-ray binaries detected with Chandra. Studies of other elliptical galaxies have shown that a high fraction of the X-ray binaries (50-70%) are located in globular clusters. NGC4697 is the nearest optically luminous, X-ray faint elliptical galaxy. This makes it the best galaxy to use to study the X-ray binary populution. Our previous Chandra observation detected ~100 X-ray binaries. New observations will increase the Chandra exposure by a factor of about 5. We are also doing a survey of the X- ray binary populations of all bright Virgo early-type galaxies. The globular cluster populations in most of these other galaxies are being determined as part of the HST Cycle 11 Large Project, "The ACS Virgo Cluster Survey", proposal 9401, with Patrick Cote as PI. Cote and Andres Jordan are Co-Is on the present Chandra/HST project. For consistency, the observation of NGC4697 will be done in exactly the same way as the other Virgo galaxies in the ACS Virgo Cluster Survey. Our goal is to obtain a near-complete census of GCs in NGC4697. To first order, the GCLF has a Gaussian form with peak M_V ~ -7.4 and Sigma ~ 1.3 mag (Harris 1991). At NGC4697, the GCLF turnover occurs at V ~ 22.95. Thus, observations to a limiting magnitude of V_lim = 25.75 will reach 2.1 sigma past the GCLF peak and include >98% level of photometric completeness. To reach this limit with a signal-to-noise of S/N = 5 (for both the metal-rich and metal-poor GC populations, and in both filters) we require exposure times of t = 750s in F475W and 1120s in F850LP with the ACS/WFC, or one orbit. Each series will be CR-SPLIT into a pair of exposures to ensure adequate removal of cosmic rays. WFC is preferred over HRC on the basis of its much larger field of view. The nucleus of NGC4697 will be nearly centered on the ACS/WFC, allowing us to measure the luminosity and color profile out to a distance of R ~ 100" with complete azimuthal coverage, and to R ~ 142" with partial coverage. The images of the nucleus will have S/N ~ 150 and 250 per pixel in the g and z bandpasses, respectively. At the position of NGC4697, the target visibility is about 53 min per orbit; guide star acquisition will require 6.1 min. Filter changes, camera setups and readouts will require 4 + 2.5 = 6.5 min per series, or 13 min in total. All exposures exceed 6 min, so there is no penalty for dumping the buffer. Total "on source" integration is then 32.7 min per orbit. The data analysis will be done with the ACS Virgo Cluster Survey pipeline, which is already producing results for the Cycle 11 survey observations. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- The nucleus of NGC4697 will be offset relative to the WFC position by 10" to avoid the gap between the two CCDs. 10003( 3) - 09/26/03 14:56 - [ 3] ------------------------------------------------------------------------------------ 10003( 3) - 09/26/03 14:56 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC4697 GALAXY, ELLIPTICAL RA=12H48M35.91S +/- 1.25", DEC=- J2000 V = V = 9.23 05D48'3.1" +/- 1.25" 1241.0 B = 10.14 Coordinate Source: Other_Source: NED 10003( 3) - 09/26/03 14:56 - [ 5] Visit: 01 Visit Priority: 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 NGC4697 ACS/WF ACCUM WFC F850LP CR-SPLIT=NO 1 90 S POS TARG 0, 10 PAR 4-5 C WITH 1-3 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC4697 ACS/WF ACCUM WFC F850LP CR-SPLIT=2 1 1120 S POS TARG 0, 10 C ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC4697 ACS/WF ACCUM WFC F475W CR-SPLIT=2 1 750 S POS TARG 0, 10 C ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY WFPC2 IMAGE WFALL-F F814W CR-SPLIT=0.5 1 1200 S IX ------------------------------------------------------------------------------------------------------------------------------------ 5 ANY WFPC2 IMAGE WFALL-F F606W CR-SPLIT=0.5 1 700 S IX ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Visit Id| Exp Id |Primary |Secondary |Iteration |CR-SPLIT |Orbit Num |Duration | |Pattern Pos |Pattern Pos |Num |Num | | ------------------------------------------------------------------------------------------------------------------------------------ 01 1 none none none none 1 tbd 01 2 none none none 1 1 tbd 01 2 none none none 2 1 tbd 01 3 none none none 1 1 tbd 01 3 none none none 2 1 tbd 01 4 none none none 1 1 tbd 01 4 none none none 2 1 tbd 01 5 none none none 1 1 tbd 01 5 none none none 2 1 tbd 10003( 3) - 09/26/03 14:56 - [ 6] Summary Form for Proposal 10003 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC WFALL-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO CR-SPLIT=2 CR-SPLIT=0.5 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG 0, 10 PAR 4-5 WITH 1-3 POS TARG 0, 10 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F850LP F475W F814W F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC4697 ANY ------------------------------------------------------------------------------------------------------------------------------------