8214( 3) - 10/04/99 10:49 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8214 Version: 3 Check-in Date: 18-Feb-1999 13:32:52 1.Proposal Title: The Evolution of Globular Cluster Systems In Early-Type Galaxies ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Carl Grillmair SIRTF Science Center CoI: Prof. Jon Holtzman New Mexico State University N CoI: Dr. Rebecca Elson Institute of Astronomy, Cambridge N ------------------------------------------------------------------------------------ 5. Abstract We will measure structural parameters (core radii and concentrations) of globular clusters in three early-type galaxies using deep, four-point dithered observations. We have chosen globular cluster systems which have young, medium-age and old cluster populations, as indicated by cluster colors and luminosities. Our primary goal is to test the hypothesis that globular cluster luminosity functions evolve towards a ``universal'' form. Previous observations have shown that young cluster systems have exponential luminosity functions rather than the characteristic log-normal luminosity function of old cluster systems. We will test to see whether such young system exhibits a wider range of structural parameters than an old systems, and whether and at what rate plausible disruption mechanisms will cause the luminosity function to evolve towards a log-normal form. A simple observational comparison of structural parameters between different age cluster populations and between diff er ent sub-populations within the same galaxy will also provide clues concerning both the formation and destruction mechanisms of star clusters, the distinction between open and globular clusters, and the advisability of using globular cluster luminosity functions as distance indicators. ------------------------------------------------------------------------------------ 8214( 3) - 10/04/99 10:49 - [ 2] Observations Description ------------------------ Observations in each galaxy must probe the cluster population down to masses which are smaller than the mass corresponding to the turnover magnitude in the old GCLFs. To achieve this we will integrate for a total of two orbits in F606 on the Fornax galaxies, and four orbits in NGC 3597. Since most of the globular clusters in the relatively nearby galaxies will be found in the WF chips, we will dither the four orbits at half-pixel spacings to enable better sampling in the Wide Field Cameras. The core radii and concentrations will be determined by simultaneously fitting two-dimensional King models, convolved with an accurate HST point-spread function, to the full set of dithered observations. We use sophisticated models for the WFPC2 PSF which include the effects of both pupil function and aberration variations across the field of view, modulation transfer effects in the CCDs, frame-specific jitter information, and the effects of frame-to-frame differences in focus; our model s are considerably more detailed and accurate than those available with TinyTim. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: SIRTF Science Center, 100-22, 770 South Wilson Ave., Pasadena, CA 91125 Ship Via: Email: ------------------------------------------------------------------------------------ 8214( 3) - 10/04/99 10:49 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1399 GALAXY, Elliptical, BCM RA=3H 38M 29.0S +/- 0.2S, DEC=- J2000 V = SURF(V) = 15.9+/-0.2 35D 27' 0.5" +/- 2.0" +1447 B-V = 0.98 U-B = 0.56 Comments: Surface brightness from WFPC1. 2 NGC1316 GALAXY, Radio Galaxy, RA=3H 22M 41.8S +/- 0.2S, DEC=- J2000 V = SURF(V) = 13.4+/-0.2 Interacting Galaxy 37D 12' 29.8" +/- 2.0" +1793 B-V = 0.93 U-B = 0.47 Comments: Colors from RC3, surface brightness from WFPC1. 3 NGC3597 GALAXY, Interacting RA=11H 14M 41.9S +/- 0.2S, DEC=- J2000 V = SURF(V) = 17.7+/-0.5 Galaxy 23D 43' 46.0" +/- 2.0" +3513 B-V = 0.68 V-R = 0.59 Comments: Surface brightness from Lutz, A&A 245, 31. 8214( 3) - 10/04/99 10:49 - [ 4] 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 NGC1399 WFPC2 IMAGE PC1 F606W DITHER-TYPE=BOX 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 8214( 3) - 10/04/99 10:49 - [ 5] Visit: 02 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 NGC1316 WFPC2 IMAGE PC1 F606W DITHER-TYPE=BOX 1 1100 S ------------------------------------------------------------------------------------------------------------------------------------ 8214( 3) - 10/04/99 10:49 - [ 6] Visit: 03 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 NGC3597 WFPC2 IMAGE PC1 F606W DITHER-TYPE=BOX 1 2300 S ------------------------------------------------------------------------------------------------------------------------------------ 8214( 3) - 10/04/99 10:49 - [ 7] Summary Form for Proposal 8214 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=BOX ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC1399 NGC1316 NGC3597 ------------------------------------------------------------------------------------------------------------------------------------