Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5366 Report Date: 18-Jul-95:17:14 Version: ********** Check-in Date: ********** 1.Proposal Title: THE CHRONOLOGY OF THE GALACTIC HALO AND DISK CYCLE4HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GALAXIES & CLUSTERS GO 2419 Sub Category STELLAR POPULATIONS ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Robert J Zinn YALE UNIVERSITY UNITED STA 203-432-3017 ------------------------------------------------------------------------------------ 7. Abstract Observations with the WFPC2 will be used to construct color-magnitude diagrams that precisely determine the magnitude and color of the main-sequence turnoff and lower giant branch, and allow the ages of 7 globular clusters to be derived. Four are metal-rich clusters of the disk population and three are very metal-poor clusters near the galactic center. Only the HST can provide the very high resolution necessary for photometry to the required faint limits in the crowded fields of these clusters. The ages of the clusters will be measured from the c-m diagrams using several techniques, and will be compared with each other and with the ages derived for other clusters from ground-based observations. Our investigation will yield the first chronology of the halo and thick disk clusters near the galactic center, where star formation may have proceeded more rapidly than in the outer, lower density regions. Age differences > 3 Gys. are now known to exist among the globular clusters in the outer halo, and the addition of our results will indicate the timescales of halo and disk formation as functions of galactocentric distance. This will tightly constrain theories of the evolution of the Galaxy. This proposal is a resubmission of a GO proposal that had to be largely deferred until after the repair mission. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 15.30 par: 0 10. Num targs pri: 7 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5366 PI: Robert J Zinn Proposal Title: THE CHRONOLOGY OF THE GALACTIC HALO AND DISK CYCLE4HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Robert Zinn 3900 UNITED STAT Bruce Carney 2990 UNITED STAT Carol Christian 1502 UNITED STAT Gary Da Costa 4110 AUSTRALIA Pierre Demarque 3900 UNITED STAT James Heasley 2192 UNITED STAT Kenneth Janes 1420 UNITED STAT Edward Olszewski 1212 UNITED STAT Patrick Seitzer 2660 UNITED STAT ------------------------------------------------------------------------------------ 3. Description of proposed observations. Our program is designed to obtain high-precision relative photometry for all the stars in the WFPC2 fields. This will allow us to determine the mean positions of the cluster principal sequences with much greater precision than the photometry of an individual star. Since it is the relative locations of these sequences that yield the differences in cluster ages, our major goals can be achieved even if the zero points of our photometry are difficult to determine. The zero points are unlikely to be a problem because they will be set by ground-based observations (see below). The PC chip of the WFPC2 will be used to photometer the regions of highest stellar density, while the WFC chips will record the outer regions and the star fields surrounding the clusters. 3 or 4 long exposures per filter will be taken of a field close to the center of each cluster. The long exposures are designed to achieve S/N > 50 at 2 mag. below the expected turnoffs of the clusters, which should enable us to achieve the required photometric accuracy in these dense fields. Three short exposures at the same positions will provide an extension of the PC's dynamic range to brighter stars in the field (horizontal branch & lower giant branch). We will also take sets of 3 or 4 long and three short exposures per filter of fields offset from the first ones by 20 arcsecs in the directions away from the cluster centers. These observations, which will overlap to some extent with the central sets, will provide important additional information on the principal cluster sequences. Ground-based photometry of the brighter stars in these more radially distant fields, which will be possible given their lower densities, will provide the calibration of the WFPC2 observations. The WFPC2 observations will be made with the F555W and F814W filters, for which straightforward transformations to the V and I bands of the standard Cousins system will be possible. The WFC images of the area around each cluster and ground-based observations of comparison fields outside the tidal radii of the clusters will be used to assess the contamination of the cluster fields by non-cluster members. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Members of our team have constructed c-m diagrams of three of our targets using large ground-based telescopes under excellent conditions, and have achieved only limited success. Heasley, Janes, Christian, and Montgomery (1993, in preparation) observed NGC 6293 with the CFHT and its high resolution camera. Although their data have extremely small images for ground-based observations, 0.5 arcsec FWHM, severe image crowding in the central region of the cluster limited the quality of the photometry. Accurate photometry was possible in the outer regions of the cluster, but there confusion from numerous field stars limits the precision to which the principal sequences of the clusters can be defined. The same problem was encountered by Fullton, Carney, and Seitzer (1993 in preparation) in their investigation of NGC 5927, which they observed in 0.8 arcsec seeing with the CTIO 4m telescope. Again the central regions of the cluster were inaccessible and in the outer regions, where faint photometry was possible, the c-m diagram is swamped by field stars. This problem will be solved by the greater resolution of the WFPC2, which will enable us to do precise photometry to the required faint levels in fields where cluster stars outnumber the field stars. Although our scientific objectives have not been met by our previous photometry of NGC 6293 and 6352 with the PC, these data have shown that the project is feasible with the WFPC2. ------------------------------------------------------------------------------------ 9. Description of previous HST work. Our previous HST work consisted of the Cycle 1 proposal, GO 2419, "The Chronology of the Formation of the Galactic Halo and Disk". The present proposal is a continuation of this earlier project which did receive some telescope time to see if it was feasible with the impaired HST. Hence, this proposal has the same title, scientific objectives, and P.I. and Co-I's as this earlier project. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The computational, image display, and software resources available at Yale, Boston University, Arizona, North Caroline, Hawaii, Michigan, Berkeley, and the Anglo-Australian Observatory (AAO) will be used for the data reduction and analysis. The ground-based observations that are necessary to support this project will be made with the telescopes of Yale, Hawaii, Arizona, and AAO. The resources of Yale's Center for Solar and Space Research will be used for the computation of evolutionary tracks and isochrones. Graduate students will take part in the data reduction, the acquisition of the ground-based observations, and the theoretical computations. ------------------------------------------------------------------------------------ 11. Address Information Name: Robert Zinn Category: PI Institution: 3900 Address: Dept. of Astronomy Yale University Box 6666 260 Whitney Avenue City: New Haven State: CT Zip Code: 06511 Country: United States Telephone: 203-432-3017 Telex (or e-mail): zinn@astro0.astro.yale.edu ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5366 [ 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 NGC5927-POS1 C,201 PLATE-ID = 0619, 2000.0 1 V = 22.2 , TYPE = G0 RA = 15H 27M 59.055S +/- 2", 2 V = 19.6 , TYPE = G0 DEC = -50D 39' 54.99" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5927-POS2 C,201 XI-OFF = +20" +/- 1", 2000.0 1 V = 22.2 , TYPE = G0 ETA-OFF = -20" +/- 1", 2 V = 19.6 , TYPE = G0 FROM 1 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6293-POS1 C,201 PLATE-ID = 067P, 2000.0 1 V = 22.0 , TYPE = G0 RA = 17H 10M 10.239S +/- 2", 2 V = 19.4 , TYPE = G0 DEC = -26D 34' 57.39" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC6293-POS2 C,201 XI-OFF = -20" +/- 1", 2000.0 1 V = 22.0 , TYPE = G0 ETA-OFF = -20" +/- 1", 2 V = 19.4 , TYPE = G0 FROM 3 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC6333-POS1 C,201 PLATE-ID = 06AM, 2000.0 1 V = 21.8 , TYPE = G0 RA = 17H 19M 10.850S +/- 2", 2 V = 19.2 , TYPE = G0 DEC = -18D 31' 08.54" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC6333-POS2 C,201 XI-OFF = -20" +/- 1", 2000.0 1 V = 21.8 , TYPE = G0 ETA-OFF = +20" +/- 1", 2 V = 19.2 , TYPE = G0 FROM 5 ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC6352-POS1 C,201 PLATE-ID = 0689, 2000.0 1 V = 20.7 , TYPE = G0 RA = 17H 25M 27.270S +/- 2", 2 V = 18.1 , TYPE = G0 DEC = -48D 25' 27.55" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC6352-POS2 C,201 XI-OFF = +20" +/- 1", 2000.0 1 V = 20.7 , TYPE = G0 ETA-OFF = -20" +/- 1", 2 V = 18.1 , TYPE = G0 FROM 7 ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC6541-POS1 C,201 PLATE-ID = 06AR, 2000.0 1 V = 20.6 , TYPE = G0 RA = 18H 08M 9.160S +/- 2", 2 V = 18.0 , TYPE = G0 DEC = -43D 41' 52.75" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC6541-POS2 C,201 XI-OFF = -20" +/- 1", 2000.0 1 V = 20.6 , TYPE = G0 ETA-OFF = -20" +/- 1", 2 V = 18.0 , TYPE = G0 FROM 9 ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC6624-POS1 C,201 PLATE-ID = 060E, 2000.0 1 V = 21.6 , TYPE = G0 RA = 18H 23M 44.007S +/- 2", 2 V = 19.0 , TYPE = G0 DEC = -30D 21' 32.86" +/- 2" ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC6624-POS2 C,201 XI-OFF = -28" +/- 1", 2000.0 1 V = 21.6 , TYPE = G0 ETA-OFF = +00" +/- 1", 2 V = 19.0 , TYPE = G0 FROM 11 ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC6637-POS1 C,201 PLATE-ID = 060G, 2000.0 1 V = 21.7 , TYPE = G0 RA = 18H 31M 19.527S +/- 2", 2 V = 19.1 , TYPE = G0 DEC = -32D 21' 17.76" +/- 2", TARGET LIST a) Fixed Targets ID = 5366 [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC6637-POS2 C,201 XI-OFF = +20" +/- 1", 2000.0 1 V = 21.7 , TYPE = G0 ETA-OFF = +20" +/- 1", 2 V = 19.1 , TYPE = G0 FROM 13 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5366 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 DEFINE # WFPC2 IMAGE PC1-FIX F555W SUM=1X1 # 10S 28.9 1 CYCLE 4 V READ=YES CR-SPLIT=NO CLOCKS=NO ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE # WFPC2 IMAGE PC1-FIX F814W SUM=1X1 # 10S 28.9 1 CYCLE 4 I READ=YES CR-SPLIT=NO CLOCKS=NO ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ 3 USE V NGC5927- 3 X5 2 SEQ 3-10 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 4 USE V NGC5927- 4 X60 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 5 USE I NGC5927- 3 X7 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 6 USE I NGC5927- 4 X80 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 7 USE V NGC5927- 3 X5 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 8 USE V NGC5927- 4 X60 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 9 USE I NGC5927- 3 X7 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 10 USE I NGC5927- 4 X80 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 11 USE V NGC6293- 3 X4 2 SEQ 11-18 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 12 USE V NGC6293- 4 X50 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 13 USE I NGC6293- 3 X6 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 14 USE I NGC6293- 4 X70 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 15 USE V NGC6293- 3 X4 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5366 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 16 USE V NGC6293- 4 X50 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 17 USE I NGC6293- 3 X6 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 18 USE I NGC6293- 4 X70 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 19 USE V NGC6333- 3 X3.5 2 SEQ 19-26 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 20 USE V NGC6333- 4 X50 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 21 USE I NGC6333- 3 X5 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 22 USE I NGC6333- 4 X60 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 23 USE V NGC6333- 3 X3.5 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 24 USE V NGC6333- 4 X50 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 25 USE I NGC6333- 3 X5 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 26 USE I NGC6333- 4 X60 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 27 USE V NGC6352- 3 X1.2 2 SEQ 27-36 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 28 USE V NGC6352- 2 X16 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 29 USE I NGC6352- 3 X2 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 30 USE I NGC6352- 2 X26 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 31 USE V NGC6352- 2 X16 1 POS TARG 1.0 , 1.0 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 32 USE I NGC6352- 2 X26 1 POS TARG 1.0 , 1.0 POS1 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5366 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 33 USE V NGC6352- 3 X1.2 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 34 USE V NGC6352- 3 X16 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 35 USE I NGC6352- 3 X2 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 36 USE I NGC6352- 3 X26 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 37 USE V NGC6541- 3 X1.2 2 SEQ 37-44 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 38 USE V NGC6541- 4 X14 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 39 USE I NGC6541- 3 X2 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 40 USE I NGC6541- 3 X26 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 41 USE V NGC6541- 3 X1.2 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 42 USE V NGC6541- 4 X14 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 43 USE I NGC6541- 3 X2 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 44 USE I NGC6541- 4 X26 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 45 USE V NGC6624- 3 X2.6 2 SEQ 45-52 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 46 USE V NGC6624- 4 X35 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 47 USE I NGC6624- 3 X5 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 48 USE I NGC6624- 4 X60 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 49 USE V NGC6624- 3 X2.6 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5366 [ 9] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 50 USE V NGC6624- 4 X35 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 51 USE I NGC6624- 3 X5 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 52 USE I NGC6624- 4 X60 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 53 USE V NGC6637- 3 X3 2 SEQ 53-62 NO GAP POS1 ------------------------------------------------------------------------------------------------------------------------------------ 54 USE V NGC6637- 4 X40 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 55 USE I NGC6637- 3 X6 2 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 56 USE I NGC6637- 4 X70 1 POS1 ------------------------------------------------------------------------------------------------------------------------------------ 57 USE V NGC6637- 3 X3 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 58 USE V NGC6637- 2 X40 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 59 USE I NGC6637- 3 X6 2 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 60 USE I NGC6637- 2 X70 1 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 61 USE V NGC6637- 2 X40 1 POS TARG 1.0 , 1.0 POS2 ------------------------------------------------------------------------------------------------------------------------------------ 62 USE I NGC6637- 2 X70 1 POS TARG 1.0 , 1.0 POS2 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5366 [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SUM=1X1 READ=YES CR-SPLIT=NO CLOCKS=NO ATD-GAIN=15 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 15.30 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category GALAXIES & CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category STELLAR POPULATIONS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; SEQ 3-10 NO GAP; SEQ 11-18 NO GAP; SEQ 19-26 NO GAP; SEQ 27-36 NO GAP; POS TARG 1.0 , 1.0 SEQ 37-44 NO GAP; SEQ 45-52 NO GAP; SEQ 53-62 NO GAP; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5927-POS1 NGC5927-POS2 NGC6293-POS1 NGC6293-POS2 NGC6333-POS1 NGC6333-POS2 NGC6352-POS1 NGC6352-POS2 NGC6541-POS1 NGC6541-POS2 NGC6624-POS1 NGC6624-POS2 NGC6637-POS1 NGC6637-POS2 ------------------------------------------------------------------------------------------------------------------------------------