Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5436 Report Date: 18-Jul-95:17:23 Version: ********** Check-in Date: ********** 1.Proposal Title: AGE AND POPULATIONS OF SUPER METAL RICH GLOBULAR CLUSTERS IN THE GALACTIC BULGE: CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 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 Sergio Ortolani 6470 ITALY 39-49-8293425 ------------------------------------------------------------------------------------ 7. Abstract WFPC2 multicolor observations of THREE among the most metal rich globular clusters in the Galactic Bulge are proposed in order to obtain accurate turnoff luminosities (and then ages) for the three clusters, together with fairly large complete samples of evolved stars. The two main scientific goals of the project are the following. 1) The age determination allows to set stringent constraints on the formation process of the globular cluster system, of the Galactic Bulge, and therefore of the Galaxy as a whole; and 2) The three clusters represent the best available ``Template Stellar Populations'' for super metal rich (SMR), old stellar systems, i.e. for the kind of populations which are likely to dominate the light of giant elliptical galaxies, and the bulge of spirals. In this respect, the present study is meant to obtain well understood stellar templates for the population synthesis of composite stellar systems. The proposed observations will also provide valuable information for such problems as the study of very fast evolutionary stages, and rare (trace) stellar species in SMR clusters (e.g. UV-bright stars, blue stragglers, binaries, etc.) together with their radial distribution. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 1.39 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5436 PI: Sergio Ortolani Proposal Title: AGE AND POPULATIONS OF SUPER METAL RICH GLOBULAR CLUSTERS IN THE GALACTIC BULGE: CYCLE4 MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Sergio Ortolani 6470 ITALY X Alvio Renzini 6460 ITALY X Roberto Gilmozzi 3470 USA X Gianni Marconi 6460 ITALY X Beatriz Barbuy UNIVERSITY OF SAO PAULO BRAZIL Eduardo Bica UNIVERSITY OF PUERTO ALEGRE BRAZIL ------------------------------------------------------------------------------------ 3. Description of proposed observations. For each of the three clusters we propose to obtain WFPC2 exposures through the UVI filters (F336W, F555W, F791W). We propose total exposures times adequate to reach S/N = 25 in V and I, for stars two magnitudes below the TO (V=20 for 6553 and 6528, and around V=22 for Terzan 1), and to reach a limiting magnitude 22 in the U band. This choice keeps the U-band exposures within acceptable limits, while still ensuring the astrophysically relevant information (complete coverage of UV-bright objects that could be present in the clusters: lue HB, SdO and Post- AGB stars. Given its high reddening, no U-band exposures are planned for Terzan 1. Blooming effects must be kept to a minimum in order to prevent losses greater than a few percent in the effective collecting area. Accurate photometry of the brightest cluster members requires short exposures to prevent saturation. The exposures will correspondingly be split into short, and deep exposures. Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST characteristic which is exploited in these proposed observations is its high angular resolution coupled with large field of view. This allows the construction of complete CMDs and luminosity functions to distances from the cluster center much smaller than currently feasible from the ground, thus dramatically reducing to tolerable levels several factors which currently prevent the determination of V(TO) for the target clusters with sufficient accuracy (+/- ~0.1 mag) to yield meaningful cluster ages: i.e. field contamination, and internal crowding. In practice, where the cluster dominates over the field, crowding is so severe that we found impossible to accurately reach the MS turnoff from the ground, even with outstanding seeing (<~= 0.7 arcsec). Conversely, further out where crowding is tolerable for accurate photometry the field contamination is overwhelming. The same argument holds for the derived luminosity functions, as a high photometric accuracy (SIGMA(V-I)~= 0.05 or better) is required, e.g., to unambiguously separate blue stragglers from ordinary MS stars and AGB from RGB stars. We estimate, from the instruction of the WFPC2 manual, that good photometry, with very little statistical and read out noise can be obtained at V=22, with the WFPC2 and F555W filter, in a total integration time of 200 sec., with a dynamical range of almost 5 magnitudes. This meets the requirement of the scientific goals presented in par. 1 and 2. The split of the 200 sec. integration time into two 100 sec. exposures reduces the blooming effect of the brightest stars in the field of view, and allows removing the cosmic ray contamination. An additional short exposure of 15 sec. is required to get optimum photometry at the level of the horizontal branch (V=17) and giant branch (V=14). The same considerations apply to the infrared exposures through the W791W filter for which a total exposure time at V=22.0 and V-I=1.2 is 100 sec. In this case an additional short exposure of 5 sec. is required. In the U-band, 2 x 800 sec. exposures for the clusters NGC 6553 and 6528 are required to reach the limit of U=22.0, which corresponds to the faintest UV objects that we intend to dectect as described in sections 1 and 2. A factor 5 longer exposure (in V) has been adopted for the cluster Terzan 1 to compensate for its higher galactic obscuration. In the I band the calculated total exposure time is 120 sec. For this cluster the U exposures are omitted since they would require unrealistically long exposure times. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ------------------------------------------------------------------------------------ 9. Description of previous HST work. P2579: THE CALIBRATION OF THE WHITE DWARF DISTANCE SCALE FOR GLOBULAR CLUSTERS. (PI A. Renzini) The GO cycle 1 program received 45.80 hours of spacecraft time, with SUPPLEMENTAL priority. The program then completed the Phase 2, and was cleared for the HST observations. Subsequent to the spherical aberration problem the PI asked to DEFER the program to the first HST LINE_6:cycle with fully recovered WF/PC capabilities. In a broad sense, the present proposal is scientifically related to P2579, as they both seek to determine the age of specific globular clusters. In the case of P2579 the target is a cluster in the galactic Halo, here are three clusters in the galactic Bulge. The two projects are complementary to each other. P3449: AGE AND POPULATIONS OF SUPERMETAL RICH GLOBULAR CLUSTERS IN THE GALACTIC BULGE (PI A. Renzini). This GO Cycle 2 program was approved but received SUPPLEMENTAL PRIORITY. No Phase 2 proposal was asked. The present proposal is an update of P3449. Papers: "HST Observations of Two remarkable Planetary Nebula Nuclei", Bond H., Liebert, J., Renzini, A. 1993, in "Science with the Hubble Space Telescope", ed. P. Benvenuti & E. Schreier (Garching: ESO), p. 139. Page 4 ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Resources to be supplied by your institution(s) in support of this project (e.g., data-analysis capabilities, research assistance, students, funds). Computing: Bologna: Our Institute is equipped with one VAX 8530, one VAX 8800, 3 Microvaxes, three Decstations 3100 one of which could be entirely dedicated to the present project (if approved), 5Gby mass memory (of which one private 0.5 Gby disk), one Gould-DeAnza image processor, one Microvax GPX workstation, plus numerous peripherals. There is also ready access to the Cray 2 of the Bologna University. Padova: Our Institute is equipped with one VAX 8530 one Sun station and two Microvax stations. The IHAP package is also available at the HP 1000. Research Assistance and Students: there are typically 10 graduate students in Astronomy at our Department, part of which already work on HST-related projects. Research assistance will be secured. Funds: Bologna, and Padova: Our research grants are sufficient to cover all the expenses conceivably required to complete this together the other HST projects in which we may be involved. The facilities of the ESA/ESO ST-ECF are also available, if needed. ------------------------------------------------------------------------------------ 11. Address Information Name: SERGIO ORTOLANI Category: PI Institution: Address: DIPARTIMENTO DI ASTRONOMIA VICOLO DELL'OSSERVATORIO 5 City: PADOVA State: Zip Code: I-35122 Country: ITALY Telephone: 39-49-8293425 Telex (or e-mail): ASTRPD::ORTOLANI ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5436 [ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC6553 C,201,913; RA = 18H 06M 11.0S +/- 1950 1 V=22.0 +/- 0.1, B-V=+1.7, E(B- 913,A,130 0.05S, 2 V)=0.8 DEC = -25D 55' 1.6" +/- 0.7" 3 V=16.0 +/- 0.1, B-V=+2.0, E(B- 4 V)=0.8 5 I=19.0 +/- 0.1, B-V=+1.7, E(B- V)=0.8 I=13.5 +/- 0.1, B-V=+2.0, E(B- V)=0.8 U=22.0 +/- 0.2, B-V=+0.7, E(B- V)=0.8 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6528 C,201,913; RA = 18H 01M 37.2S +/- 1950 1 V=22.0 +/- 0.1, B-V=+1.7, E(B- 913,A,130 0.08S, 2 V)=0.6 DEC = -30D 03' 34.9" +/- 3 V=16.0 +/- 0.1, B-V=+2.0, E(B- 1.2" 4 V)=0.6 5 I=19.0 +/- 0.1, B-V=+1.7, E(B- V)=0.6 I=13.5 +/- 0.1, B-V=+2.0, E(B- V)=0.6 U=22.0 +/- 0.2, B-V=+0.5, E(B- V)=0.6 ------------------------------------------------------------------------------------------------------------------------------------ 3 TERZAN1 C,201,913; RA = 17H 32M 34.0S +/- 0.2S, 1950 1 V=24.5 +/- 0.2, V-I=4.0, E(B- 913,A,130 DEC = -30D 27' 00.0" +/- 3" 2 V)=1.6 3 V=19.5 +/- 0.2, V-I=+3.8, E(B- V)=1.6 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5436 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC6553 WFPC2 IMAGE WFALL F555W 5550 2 100S 25 1 1 CYCLE 4 200S SAME ORIENT FOR 12 -15 AS 11 ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC6553 WFPC2 IMAGE WFALL F555W 5550 1 15S 100 2 2 SAME ORIENT FOR 12 15S -15 AS 11 CYCLE 4 Comments: AVOID SATURATION AT V=14 ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC6553 WFPC2 IMAGE WFALL F814W 7829 2 50S 25 3 1 CYCLE 4 100S SAME ORIENT FOR 12 -15 AS 11 ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC6553 WFPC2 IMAGE WFALL F814W 7829 1 5S 100 4 2 SAME ORIENT FOR 12 5S -15 AS 11 CYCLE 4 Comments: AVOID SATURATION AT V=14 ------------------------------------------------------------------------------------------------------------------------------------ 15 NGC6553 WFPC2 IMAGE WFALL F336W 3344 2 800S 25 5 3 CYCLE 4 1600S SAME ORIENT FOR 12 -15 AS 11 ------------------------------------------------------------------------------------------------------------------------------------ 16 NGC6528 WFPC2 IMAGE WFALL F555W 5550 2 100S 25 1 1 CYCLE 4 200S SAME ORIENT FOR 17 -20 AS 16 ------------------------------------------------------------------------------------------------------------------------------------ 17 NGC6528 WFPC2 IMAGE WFALL F555W 5550 1 15S 100 2 2 SAME ORIENT FOR 17 15S -20 AS 16 CYCLE 4 Comments: AVOID SATURATION AT V=14 ------------------------------------------------------------------------------------------------------------------------------------ 18 NGC6528 WFPC2 IMAGE WFALL F814W 7829 2 50S 25 3 1 CYCLE 4 100S SAME ORIENT FOR 17 -20 AS 16 ------------------------------------------------------------------------------------------------------------------------------------ 19 NGC6528 WFPC2 IMAGE WFALL F814W 7829 1 5S 100 4 2 CYCLE 4 5S SAME ORIENT FOR 17 -20 AS 16 Comments: AVOID SATURATION AT V=14 ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC6528 WFPC2 IMAGE WFALL F336W 3344 2 800S 25 5 3 CYCLE 4 1600S SAME ORIENT FOR 17 -20 AS 16 ------------------------------------------------------------------------------------------------------------------------------------ 23 TERZAN1 WFPC2 IMAGE WFALL F814W 7829 1 5S 50 2 2 CYCLE 4 5S SAME ORIENT FOR 24 -26 AS 23 Comments: AVOID SATURATION FOR V=14 STARS ------------------------------------------------------------------------------------------------------------------------------------ 24 TERZAN1 WFPC2 IMAGE WFALL F814W 7829 2 60S 25 1 1 CYCLE 4 120S SAME ORIENT FOR 24 -26 AS 23 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5436 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 25 TERZAN1 WFPC2 IMAGE WFALL F555W 5550 2 500S 25 1 1 CYCLE 4 1000S SAME ORIENT FOR 24 -26 AS 23 ------------------------------------------------------------------------------------------------------------------------------------ 26 TERZAN1 WFPC2 IMAGE WFALL F555W 5550 1 30S 40 2 2 CYCLE 4 30S SAME ORIENT FOR 24 -26 AS 23 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5436 [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 1.39 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category OLD CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; SAME ORIENT FOR 12-15 AS 11; SAME ORIENT FOR 12-15 AS 11; CYCLE 4; CYCLE 4; SAME ORIENT FOR 17-20 AS 16; SAME ORIENT FOR 17-20 AS 16; CYCLE 4; CYCLE 4; SAME ORIENT FOR 24-26 AS 23; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F814W F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6553 NGC6528 TERZAN1 ------------------------------------------------------------------------------------------------------------------------------------