Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5672 Report Date: 18-Jul-95:17:50 Version: ********** Check-in Date: ********** 1.Proposal Title: AGES FOR THE OUTERMOST GLOBULAR CLUSTERS: THE FORMATION OF THE GALACTIC HALO: CYCLE 4 HIGH, PART II ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO 5481 Sub Category OLD CLUSTERS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone James E. Hesser 4628 CANADA 604-363-0007 ------------------------------------------------------------------------------------ 7. Abstract We propose observations of globular clusters in the outermost regions of the Galactic halo that will answer fundamental questions about the early epoch of the formation of the Galaxy. We have selected two clusters (NGC 2419 and Pal 4) which lie at Galactocentric distances near 100 kpc. Using deep HST WFPC2 images in the V and I bands, we will reach the main-sequence turnoffs in these clusters with photometric accuracy sufficient to obtain ages (relative to nearby clusters and to clusters in the Galactic bulge) with a precision of better than 1 Gyr. This age comparison will be an essential component in reconstructing the sequence of events during early Galactic formation history, and our project is complementary to HST programs for measuring ages of globular clusters in the Galactic bulge. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0 par: 0 10. Num targs pri: 8 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5672 PI: James E. Hesser Proposal Title: AGES FOR THE OUTERMOST GLOBULAR CLUSTERS: THE FORMATION OF THE GALACTIC HALO: CYCLE 4 HIGH, PART II ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ James E. Hesser 4628 CANADA Roger A. Bell 2620 USA Michael Bolte 1552 USA Howard E. Bond 3470 USA Gregory G. Fahlman 4618 CANADA William E. Harris 4642 CANADA Robert D. Mcclure 4628 CANADA Harvey B. Richer 4618 CANADA Peter B. Stetson 4628 CANADA Don A. Vandenberg 4670 CANADA Sidney Van Den Bergh 4628 CANADA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We will use the PC chip of the WFPC2 to observe two of the most distant known Galactic globular clusters, Pal 4 and NGC 2419, for the purpose of determining and comparing their ages. In both clusters we will observe two separate fields, in order to measure enough stars for the age determinations. In each of the four fields we will obtain eight 1400-sec exposures in F555W ("V") and eight 1300-sec exposures in F814W ("I"). Since there are 8 separate exposures in each filter, we will not do any further CR-SPLITs. We will move the telescope about 1.5 PC pixels between individual exposures, in order to better sample the PSF. The aim of the program is to achieve a precision of 0.06 mag in the V-I color at V = 25, in order to define the stellar sequences in the vicinity of the main-sequence turnoffs for accurate age determinations through comparison with theoretical evolutionary tracks. A second set of short exposures (six 60-sec in V and six 30- sec in I) will be obtained in each field, in order to measure the brighter stars on the red-giant branch and a sample of horizontal-branch stars and assure a proper tie-in to ground-based photometry of the same objects. The telescope will again be moved about 1.5 pixels between individual exposures. The spacecraft roll angle is arbitrary, but all exposures on a given field should be taken at the SAME roll angle. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. (See Phase I proposal.) ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. None. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. None. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. ------------------------------------------------------------------------------------ 9. Description of previous HST work. (See Phase I proposal.) ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). (See Phase I proposal.) Page 3 ------------------------------------------------------------------------------------ 11. Address Information Name: JAMES E. HESSER Category: PI Institution: 4628 Address: DOMINION ASTROPHYSICAL OBSERVATORY 5071 W. Saanich Rd. City: VICTORIA State: BC Zip Code: V8X 4M6 Country: CANADA Telephone: 604-363-0007 Telex (or e-mail): hesser@dao.nrc.ca ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5672 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 4 PAL4-CENTER C,201 RA = 11H 29M 15.86S +/- 1", J2000 1 V=25 DEC = +28D 58' 31.2" +/- 1", PLATE-ID=019K Comments: CENTRAL FIELD IN DISTANT GLOBULAR CLUSTER PAL 4 ------------------------------------------------------------------------------------------------------------------------------------ 5 PAL3-CENTER C,201 RA = 10H 05M 31.4S +/- 1", J2000 1 V=25 DEC = +00D 04' 20.8" +/- 1", PLATE-ID=00JL Comments: CENTRAL FIELD IN DISTANT GLOBULAR CLUSTER PAL 3. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5672 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1600S 1 1 CYCLE 4 / 11-18.2 8-POSNS CLOCKS=NO PCS MODE F / 11- ATD-GAIN=7 18.2 SAME ORIENT FOR 11.1-18.2 AS 11 POS TARG 0.0, 0.0 Comments: THIS SEQUENCE TAKES 8 EXPOSURES SPACED AROUND AN OCTAGONAL PATH WITH 1.5-PIXEL STEPS BETWEEN EXPOSURES. ------------------------------------------------------------------------------------------------------------------------------------ 11.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.0, 0.0 8-POSNS CLOCKS=NO SAME POS FOR 11.1- ATD-GAIN=7 11.2 AS 11.0 ------------------------------------------------------------------------------------------------------------------------------------ 11.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.0, 0.0 8-POSNS CLOCKS=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 12 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.0 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 12.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.0 ATD-GAIN=7 SAME POS FOR 12.1- 12.2 AS 12.0 ------------------------------------------------------------------------------------------------------------------------------------ 12.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.0 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 13 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 13.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 SAME POS FOR 13.1- 13.2 AS 13.0 ------------------------------------------------------------------------------------------------------------------------------------ 13.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 14 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5672 [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 14.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 SAME POS FOR 14.1- 14.2 AS 14.0 ------------------------------------------------------------------------------------------------------------------------------------ 14.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.138, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 15 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 15.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 SAME POS FOR 15.1- 15.2 AS 15.0 ------------------------------------------------------------------------------------------------------------------------------------ 15.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.069, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 16 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG 0.0, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 16.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG 0.0, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 SAME POS FOR 16.1- 16.2 AS 16.0 ------------------------------------------------------------------------------------------------------------------------------------ 16.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG 0.0, 8-POSNS CLOCKS=NO 0.207 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 17 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 17.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 SAME POS FOR 17.1- 17.2 AS 17.0 ------------------------------------------------------------------------------------------------------------------------------------ 17.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.138 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 18 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 1800S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5672 [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 18.1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 60S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 SAME POS FOR 18.1- 18.2 AS 18.0 ------------------------------------------------------------------------------------------------------------------------------------ 18.2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 30S 1 1 POS TARG -0.069, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 21 USE 8- PAL4-CENTER F555W X1 SAME ORIENT FOR 22 POSNS AS 21 Comments: SEQUENCE OF 8 X 1800, 60, 30 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 22 USE 8- PAL4-CENTER F814W X1 POSNS Comments: SEQUENCE OF 8 X 1800, 60, 30 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 41 USE 8- PAL3-CENTER F555W X1 SAME ORIENT FOR 42 POSNS AS 41 Comments: SEQUENCE OF 8 X 1800, 60, 30 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 42 USE 8- PAL3-CENTER F814W X1 POSNS Comments: SEQUENCE OF 8 X 1800, 60, 30 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5672 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO CLOCKS=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category OLD CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4 / 11-18.2; PCS MODE F / 11-18.2; SAME ORIENT FOR 11.1-18.2 AS 11; POS TARG 0.0, 0.0 POS TARG 0.0, 0.0; SAME POS FOR 11.1-11.2 AS 11.0 POS TARG 0.069, 0.0 POS TARG 0.069, 0.0; SAME POS FOR 12.1-12.2 AS 12.0 POS TARG 0.138, 0.069 POS TARG 0.138, 0.069; SAME POS FOR 13.1-13.2 AS 13.0 POS TARG 0.138, 0.138 POS TARG 0.138, 0.138; SAME POS FOR 14.1-14.2 AS 14.0 POS TARG 0.069, 0.207 POS TARG 0.069, 0.207; SAME POS FOR 15.1-15.2 AS 15.0 POS TARG 0.0, 0.207 POS TARG 0.0, 0.207; SAME POS FOR 16.1-16.2 AS 16.0 POS TARG -0.069, 0.138 POS TARG -0.069, 0.138; SAME POS FOR 17.1-17.2 AS 17.0 POS TARG -0.069, 0.069 POS TARG -0.069, 0.069; SAME POS FOR 18.1-18.2 AS 18.0 SAME ORIENT FOR 22 AS 21; SAME ORIENT FOR 42 AS 41 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements # F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PAL4-CENTER PAL3-CENTER ------------------------------------------------------------------------------------------------------------------------------------