6423( 3) - 06/05/97 20:22 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6423 Version: 3 Check-in Date: 07-Feb-1996 19:12:31 1.Proposal Title: Structure in the Superstar Clusters in NGC 1569 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle STELLAR POPULATIONS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Deidre Hunter Lowell Observatory CoI: Dr. John Gallagher University of Wisconsin N CoI: Dr. Robert O'Connell University of Virginia N CoI: Dr. Tammy Smecker-Hane University of California-Irvine N ------------------------------------------------------------------------------------ 6. Abstract We propose to use WFPC2 to image the two superstar clusters in NGC 1569. Cycle 1 data showed that these clusters are as luminous and compact as globular clusters are expected to have been at the same age. Thus, the clusters in NGC 1569 could be the closest examples beyond R136 of globular clusters when they were young. However, these clusters are 3--4 magnitudes more luminous than R136. The WFPC2 images will be used to examine the morphology of the clusters, examine the color distribution within the clusters, and resolve the luminous stars in the outer parts of the clusters. From these data we will test the analogy with globular clusters and the assumption of coevality of the clusters. ------------------------------------------------------------------------------------ 6423( 3) - 06/05/97 20:22 - [ 2] Observations Description ------------------------ The galaxy will be placed in the PC for higher resolution and better PSF sampling. The two clusters in NGC 1569 together fit comfortably within the PC field-of-view, and each cluster is about 30 pixels (1.4") in diameter. Thus, the need for HST is obvious. We will obtain F336W, F555W, F814W, and F656N images of the two clusters. The broad-band filters are chosen to be compatible with the resolved stellar photometry that has been done of R136 and other star clusters. The F656N filter is used to subtract gaseous emission from the broad- band filters. Exposure times have been estimated by scaling from Cycle 1 images. We estimate 2*400 s for F336W, 50s, 2*140s, and 2*300s for F555W, and 50s, 2*100s, and 1*300s for F814W. The series of exposures are designed to avoid saturation for the core, just saturate but not bloom for examination of the middle part of the cluster, and go deep for the outer part of the cluster. The pairs of exposures will allow cosmic rays to be identified and removed. The exposure in F656N will fill the remaining time in the second orbit and result in an exposure time of about 30 minutes, broken into two parts. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: ------------------------------------------------------------------------------------ 6423( 3) - 06/05/97 20:22 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1569- EXT-CLUSTER,GLOBULAR RA=04H 30M 48.61S +/- 0.1S, 2000 V=-90 V = 15.4 CLUSTERS CLUSTER DEC=+64D 50' 56" +/- 1", PLATE- SIZE=0.36 ID=01MS E(B-V) = 0.56 V-I = 0.1 6423( 3) - 06/05/97 20:22 - [ 4] Visit: 01 Visit Requirements: ORIENTation 79D TO 286D On Hold Comments: Additional Comments: The ORIENT requirement is to force a nearby 10th mag star onto one of the WF chips. Otherwise it would fall in the missing L of the PC and cause reflections at the several DN level in the PC, where our clusters are. As a result, however, there will be severe saturation on one of the WF CCDs. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC1569-CLU WFPC2 IMAGE PC1-FIX F656N ATD-GAIN=7,CR-SPLIT=NO 2 800 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC1569-CLU WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=7,CR-SPLIT=NO 1 50 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC1569-CLU WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=7,CR-SPLIT=NO 2 140 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC1569-CLU WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=7,CR-SPLIT=NO 1 50 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC1569-CLU WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=7,CR-SPLIT=NO 2 400 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC1569-CLU WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=7,CR-SPLIT=NO 2 100 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC1569-CLU WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=7,CR-SPLIT=NO 1 300 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC1569-CLU WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=7,CR-SPLIT=NO 2 300 S STERS ------------------------------------------------------------------------------------------------------------------------------------ 6423( 3) - 06/05/97 20:22 - [ 5] Summary Form for Proposal 6423 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=7 CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENTation 79D TO 286D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F656N F555W F814W F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC1569-CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------