Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5481 Report Date: 18-Jul-95:17:30 Version: ********** Check-in Date: ********** 1.Proposal Title: AGES FOR THE OUTERMOST GLOBULAR CLUSTERS: THE FORMATION OF THE GALACTIC HALO: CYCLE 4 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO 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 5481 PI: James E. Hesser Proposal Title: AGES FOR THE OUTERMOST GLOBULAR CLUSTERS: THE FORMATION OF THE GALACTIC HALO: CYCLE 4 HIGH ------------------------------------------------------------------------------------ 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 1/2 pixel 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. Since our deep fields have been carefully selected to be free of bright stars, the pointings for the short exposures will be shifted about half a field diameter toward the cluster center in order to include several brighter stars. The telescope will again be moved about 1/2 pixel 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. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. (See Phase I proposal.) ------------------------------------------------------------------------------------ 8. Additional comments or special requests. None. Page 3 ------------------------------------------------------------------------------------ 9. Description of previous HST work. (See Phase I proposal.) ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). (See Phase I proposal.) ------------------------------------------------------------------------------------ 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 = 5481 [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 PAL4-NORTH C,201 RA = 11H 29M 18.88S +/- 1", J2000 1 V=25 DEC = +28D 59' 03.2" +/- 1", PLATE-ID=019K Comments: NORTHERN FIELD IN DISTANT GLOBULAR CLUSTER PAL 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 PAL4-NORTH- C,201 RA-OFF = 0S +/- 0.08S, J2000 1 V=25 OFF DEC-OFF = -20" +/- 1", FROM 1 Comments: FIELD IN DISTANT GLOBULAR CLUSTER PAL 4, OFFSET 20" SOUTH OF DEEP FIELD TO INCLUDE BRIGHTER STARS. ------------------------------------------------------------------------------------------------------------------------------------ 3 PAL4-SOUTH C,201 RA = 11H 29M 16.47S +/- 1", J2000 1 V=25 DEC = +28D 57' 26.4" +/- 1", PLATE-ID=019K Comments: SOUTHERN FIELD IN DISTANT GLOBULAR CLUSTER PAL 4 ------------------------------------------------------------------------------------------------------------------------------------ 4 PAL4-SOUTH- C,201 RA-OFF = 0S +/- 0.08S, J2000 1 V=25 OFF DEC-OFF = +20" +/- 1", FROM 3 Comments: FIELD IN DISTANT GLOBULAR CLUSTER PAL 4, OFFSET 20" NORTH OF DEEP FIELD TO INCLUDE BRIGHTER STARS. ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC2419- C,201 RA = 07H 38M 09.04S +/- 1", J2000 1 V=25 NORTH DEC = +38D 54' 27.9" +/- 1", PLATE-ID=01H9 Comments: NORTHERN FIELD IN DISTANT GLOBULAR CLUSTER NGC 2419. ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC2419- C,201 RA-OFF = 0S +/- 0.08S, J2000 1 V=25 NORTH-OFF DEC-OFF = -20" +/- 1", FROM 5 Comments: FIELD IN DISTANT GLOBULAR CLUSTER NGC 2419, OFFSET 20" SOUTH OF DEEP FIELD TO INCLUDE BRIGHTER STARS. ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC2419- C,201 RA = 07H 38M 09.21S +/- 1", J2000 1 V=25 SOUTH DEC = +38D 51' 35.4" +/- 1", PLATE-ID=01H9 Comments: SOUTHERN FIELD IN DISTANT GLOBULAR CLUSTER NGC 2419 ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC2419- C,201 RA-OFF = 0S +/- 0.08S, J2000 1 V=25 SOUTH-OFF DEC-OFF = +20" +/- 1", FROM 7 Comments: FIELD IN DISTANT GLOBULAR CLUSTER NGC 2419, OFFSET 20" NORTH OF DEEP FIELD TO INCLUDE BRIGHTER STARS. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5481 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 CYCLE 4 / 1-6 6-POSNS CLOCKS=NO PCS MODE F / 1-6 ATD-GAIN=7 SAME ORIENT FOR 2- 6 AS 1 POS TARG 0., 0. Comments: THIS SEQUENCE TAKES 6 EXPOSURES SPACED AROUND A HEXAGONAL PATH WITH 1/2-PIXEL STEPS BETWEN EXPOSURES. ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.023, 0. 6-POSNS CLOCKS=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.046, 6-POSNS CLOCKS=NO 0.023 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.023, 6-POSNS CLOCKS=NO 0.046 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 5 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.0, 6-POSNS CLOCKS=NO 0.046 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 6 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG -0.023, 6-POSNS CLOCKS=NO 0.023 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 11 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 CYCLE 4 / 11-18 8-POSNS CLOCKS=NO PCS MODE F / 11-18 ATD-GAIN=7 SAME ORIENT FOR 12 -18 AS 11 POS TARG 0., 0. Comments: THIS SEQUENCE TAKES 8 EXPOSURES SPACED AROUND AN OCTAGONAL PATH WITH 1/2-PIXEL STEPS BETWEN EXPOSURES. ------------------------------------------------------------------------------------------------------------------------------------ 12 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.023, 0. 8-POSNS CLOCKS=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 13 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.046, 8-POSNS CLOCKS=NO 0.023 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 14 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.046, 8-POSNS CLOCKS=NO 0.046 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5481 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 15 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.023, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 16 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG 0.0, 8-POSNS CLOCKS=NO 0.069 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 17 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG -0.023, 8-POSNS CLOCKS=NO 0.046 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 18 DEFINE # WFPC2 IMAGE PC1-FIX # CR-SPLIT=NO 1 100S 1 1 POS TARG -0.023, 8-POSNS CLOCKS=NO 0.023 ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ 21 USE 8- PAL4-NORTH F555W X14 SAME ORIENT FOR 22 POSNS AS 21 Comments: SEQUENCE OF 8 X 1400 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 22 USE 8- PAL4-NORTH F814W X13 POSNS Comments: SEQUENCE OF 8 X 1300 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 23 USE 6- PAL4-NORTH- F555W X0.6 SAME ORIENT FOR 23 POSNS OFF -24 AS 21 Comments: SEQUENCE OF 6 X 60 SEC V FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 24 USE 6- PAL4-NORTH- F814W X0.3 POSNS OFF Comments: SEQUENCE OF 6 X 30 SEC I FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 31 USE 8- PAL4-SOUTH F555W X14 SAME ORIENT FOR 32 POSNS AS 31 Comments: SEQUENCE OF 8 X 1400 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 32 USE 8- PAL4-SOUTH F814W X13 POSNS Comments: SEQUENCE OF 8 X 1300 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5481 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 33 USE 6- PAL4-SOUTH- F555W X0.6 SAME ORIENT FOR 33 POSNS OFF -34 AS 31 Comments: SEQUENCE OF 6 X 60 SEC V FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 34 USE 6- PAL4-SOUTH- F814W X0.3 POSNS OFF Comments: SEQUENCE OF 6 X 30 SEC I FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 41 USE 8- NGC2419- F555W X14 SAME ORIENT FOR 42 POSNS NORTH AS 41 Comments: SEQUENCE OF 8 X 1400 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 42 USE 8- NGC2419- F814W X13 POSNS NORTH Comments: SEQUENCE OF 8 X 1300 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 43 USE 6- NGC2419- F555W X0.6 SAME ORIENT FOR 43 POSNS NORTH-OFF -44 AS 41 Comments: SEQUENCE OF 6 X 60 SEC V FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 44 USE 6- NGC2419- F814W X0.3 POSNS NORTH-OFF Comments: SEQUENCE OF 6 X 30 SEC I FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ 51 USE 8- NGC2419- F555W X14 SAME ORIENT FOR 52 POSNS SOUTH AS 51 Comments: SEQUENCE OF 8 X 1400 SEC V FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 52 USE 8- NGC2419- F814W X13 POSNS SOUTH Comments: SEQUENCE OF 8 X 1300 SEC I FRAMES ------------------------------------------------------------------------------------------------------------------------------------ 53 USE 6- NGC2419- F555W X0.6 SAME ORIENT FOR 53 POSNS SOUTH-OFF -54 AS 51 Comments: SEQUENCE OF 6 X 60 SEC V FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5481 [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 54 USE 6- NGC2419- F814W X0.3 POSNS SOUTH-OFF Comments: SEQUENCE OF 6 X 30 SEC I FRAMES , IN FIELD OFFSET TO INCLUDE A FEW BRIGHT STARS. ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5481 [ 9] 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 / 1-6; PCS MODE F / 1-6; SAME ORIENT FOR 2-6 AS 1; POS TARG 0., 0. POS TARG 0.023, 0. POS TARG 0.046, 0.023 POS TARG 0.023, 0.046 POS TARG 0.0, 0.046 POS TARG -0.023, 0.023 CYCLE 4 / 11-18; PCS MODE F / 11-18; SAME ORIENT FOR 12-18 AS 11; POS TARG 0.046, 0.046 POS TARG 0.023, 0.069 POS TARG 0.0, 0.069 POS TARG -0.023, 0.046 SAME ORIENT FOR 22 AS 21 SAME ORIENT FOR 23-24 AS 21 SAME ORIENT FOR 32 AS 31 SAME ORIENT FOR 33-34 AS 31 SAME ORIENT FOR 42 AS 41 SAME ORIENT FOR 43-44 AS 41 SAME ORIENT FOR 52 AS 51 SAME ORIENT FOR 53-54 AS 51 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements # F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names PAL4-NORTH PAL4-NORTH-OFF PAL4-SOUTH PAL4-SOUTH-OFF NGC2419-NORTH NGC2419-NORTH-OFF NGC2419-SOUTH NGC2419-SOUTH-OFF ------------------------------------------------------------------------------------------------------------------------------------