Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 1017c Report Date: 09-May-96:16:02 Version: ********** Check-in Date: ********** 1.Proposal Title: STELLAR CONTENT OF NGC 6121 AND NGC 6397: FUTURE-CYCLE CONTINUATION ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR POPULATIONS GTO/OS Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. John N. Bahcall INSTITUTE FOR ADVANCED STUDY USA (609) 734-8054 PROF. JOHN BAHCALL ------------------------------------------------------------------------------------ 7. Abstract The stellar content of the cores of the globular clusters NGC 6121 and NGC 6397 will be determined using the WFC. Of special interest will be the observed numbers of white dwarfs, the other ultra-violet excess stars, and the faint red dwarfs. ST observations are needed in order to reach the required faint apparent magnitudes and to provide sufficient spatial resolution to allow accurate photometry. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GLOBULAR CLUSTER, GALACTIC, IMAGING, WHITE DWARF, DWARF, STELLAR POPULATION ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 3.00 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 1017c PI: Dr. John N. Bahcall Proposal Title: STELLAR CONTENT OF NGC 6121 AND NGC 6397: FUTURE-CYCLE CONTINUATION ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ John N. Bahcall INSTITUTE FOR ADVANCED STUDY USA James A. Westphal CALTECH USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. The WFC will be used for one orbit (45 minute) exposures on the core of each globular cluster. The filters to be used are: F555W (30% V); F785LP (I); and F336M (U). Cycle 2 (7-18 months) = Exposures 1-3. Cycle 3+4 (months 19-30) = Exposures 4-5. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. ST observations are necessary in order to reach the required apparent magnitude limits and to provide sufficient spatial resolution to permit accurate photometry. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Would like roll angle for exposures 1-3 t be the same so that can compare simply images on each of the exposures to determine colors. Similarly, want roll angles of exposures 4 and 5 to be the same. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Dark time is required. The success of the program depends upon the ability to study faint stellar images with V>~ 26 mag. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Data reduction and analysis will be performed jointly by John Bahcall (and collaborators) and members of the WF/PC team. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Computing facilities and research associates will be provided as necessary. ------------------------------------------------------------------------------------ 13. The stellar content of the cores of the globular clusters NGC 6121 and NGC 6397 will be determined using the WFC. Of special interest will be the observed numbers of white dwarfs, the other ultra-violet excess stars, and the faint red dwarfs. ------------------------------------------------------------------------------------ 11. Address Information Name: JOHN N. BAHCALL Category: PI Institution: INSTITUTE FOR ADVANCED STUDY Address: OLDEN LANE City: PRINCETON State: NJ Zip Code: 08540 Country: USA Telephone: (609) 734-8054 Telex (or e-mail): 837680 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 1017c [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6121 M4 GALACTIC GLOBULAR RA = 16H 20M 31.4S +/- 0.1S, 1950 1 SURF(V) = 18.0, CLUSTER DEC = -26D 24' 36.4" +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6397 GALACTIC GLOBULAR RA = 17H 36M 37.1S +/- 0.1S, 1950 1 SURF(V) = 16.8, CLUSTER DEC = -53D 38' 52.0" +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 1017c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6397 WFC IMAGE ALL F555W PRE-FLASH=NO 3 700S 1 3 CYCLE 9 / 1-5 CR-SPLIT=NO SEQ 3,3.1,2,1 NO CLOCKS=YES GAP PURGE=YES DARK TIME / 1-5 NON-INT / 1-5 Comments: LINE 1 IS INTENDED TO FIT INTO ONE ORBIT. ADJUST 700S EXPOSURE TIME +/- 20 PERCENT TO ACCOMPLISH. FINAL PURGE ON BRIGHT SIDE AFTER LAST EXPOSURE. ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6397 WFC IMAGE ALL F785LP PRE-FLASH=YES 5 450S 1 3 CR-SPLIT=NO CLOCKS=YES PURGE=YES Comments: LINE 2 IS INTENDED TO FIT INTO ONE ORBIT. ADJUST 450S EXPOSURE TIME +/- 20 PERCENT TO ACCOMPLISH. FINAL PURGE ON BRIGHT SIDE AFTER LAST EXPOSURE. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6397 WFC IMAGE ALL F336W PRE-FLASH=YES 1 500S 1 3 SAME ORIENT FOR 2- CR-SPLIT=NO 3.1 AS 1 CLOCKS=YES PURGE=YES ------------------------------------------------------------------------------------------------------------------------------------ 3.1 ^ ^ ^ ^ ^ PRE-FLASH=YES 1 2000S 1 ^ CR-SPLIT=NO CLOCKS=YES PURGE=YES Comments: LINES 3-3.1 ARE INTENDED TO FIT INTO ONE ORBIT. ADJUST 2000S EXPOSURE TIME +/- 20 PERCENT TO ACCOMPLISH. FINAL PURGE ON BRIGHT SIDE AFTER LAST EXPOSURE. ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6121 WFC IMAGE ALL F555W 3 15M 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC6121 WFC IMAGE ALL F785LP 6 7.5M 1 2 SAME ORIENT FOR 5 AS 4 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 1017c [ 5] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC ^ ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ^ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=NO CR-SPLIT=NO CLOCKS=YES PURGE=YES PRE-FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GTO/OS ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 3.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 9 / 1-5 ; SEQ 3,3.1,2,1 NO GAP ; DARK TIME / 1-5 ; NON-INT / 1-5 SAME ORIENT FOR 2-3.1 AS 1 SAME ORIENT FOR 5 AS 4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F785LP F336W ^ ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6121 M4 NGC6397 ------------------------------------------------------------------------------------------------------------------------------------