Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5496 Report Date: 18-Jul-95:17:31 Version: ********** Check-in Date: ********** 1.Proposal Title: M3: AN IDEAL LABORATORY FOR TESTING STELLAR EVOLUTION AND DYNAMICS: CYCLE4 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 Flavio Fusi pecci 6426 ITALY 39-51-259321 ------------------------------------------------------------------------------------ 7. Abstract We propose WFPC2 observations of the Galactic globular cluster M3 in UVI and the mid -UV (F218W). This will be the first COMPLETE sample of Post-main sequence stars over the entire area of the cluster. It will allow the most stringent test of stellar evolutionary models and will yield crucial observational input for the study of star interactions and dynamics within a cluster. The results should have wide applicability including: (1) the most accurate test of the ``stellar clock'' used in dating globular clusters; (2) a complete survey of very fast evolutionary stages and rare (trace) stellar types (e.g. UV-bright stars, blue stragglers, binaries) along with their radial distributions, which will provide fundamental information for internal cluster dynamics and for the origin of UV light from elliptical galaxies. The cluster M3 is the ideal target for this purpose. We already have ground-based photometry of about 18000 stars: the best complete CMD, the largest complete Luminosity Function for Post-MS stars, and the largest sample of blue straggler stars (BSS) ever obtained for a globular cluster from the ground. The tests we propose require even larger samples which can only be achieved by observing the cluster core which is not resolved from the ground. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 6.39 par: 0.00 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5496 PI: Flavio Fusi pecci Proposal Title: M3: AN IDEAL LABORATORY FOR TESTING STELLAR EVOLUTION AND DYNAMICS: CYCLE4 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Flavio Fusi Pecci 6426 ITALY X Francesco R. Ferraro 6426 ITALY X Carla Cacciari 6426 ITALY X Roberto Buonanno 6436 ITALY X Carlo E. Corsi 6436 ITALY X Robert T. Rood 3730 USA Ben Dorman 3730 USA Greg G. Fahlman 4618 CANADA Harvey B. Richer 4618 CANADA Denis Burgarella 5446 FRANCE X Michel Laget 5446 FRANCE X Guido De Marchi 3470 USA Francesco Paresce 3470 USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. WFPC2 observations of the Galactic globular cluster M3 = NGC 5272 will be taken using 4 filters, i.e. F555W, F814W, F336W, and F218W. In particular, the PC1 will be pointing the cluster center, for each of the 4 filters, while the three WFC mosaics will map adjacent fields in the same bands. Two sets of exposures are planned, separated by a period of time suitable to study photometric variability (ranging from a few days up to a few weeks). Therefore, the second pointing has to be made at a given roll-angle to map the same area of the cluster. Since this program aims at obtaining accurate photometric measurements for all the evolved stars, and not at detecting and measuring the faintest possible objects, the observational strategy is to optimize the degree of completeness (down to a fixed magnitude limit, even at the very cluster center) and the photometric quality of the individual measures. Hence, exposure times for each filter have been computed (based on the WFPC2 Instrument Handbook) (1) to be adequate to reach S/N=15 at about 2 mag below the turnoff, i.e. V=21, in the wide band filters (UVI) and V=19 with F218W, and (2) to be subdivided into sets of appropriate sub-exposures short enough to avoid blooming from the brightest (V=13) giants. In fact, strong charge transfer from highly saturated bright objects would prevent the detection and measure of fainter stars, so decreasing strongly the degree of completeness specially in the very crowded central regions. The exposure times have been computed by adopting a readout noise of rn=14e, E(B-V)=0.01, and the following recipe to estimate the total exposure time (to obtain a desired S/N) and the maximum length of each sub-exposure (to avoid blooming at >100000 counts/central px) Filter Type V S/N Blooming at V Type ------------------------ -------------------------------------------- F555W G0 21 15 13 K0 (GB-tip) F814W G0 21 12 13 K0 (GB-tip) F336W G0 21 10 16 B0 (Bright HB, P-AGB) F218W F0 19 10 16 B0 (Bright HB, P-AGB) Page 3 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The HST characteristics exploited in these observations are the high angular resolution coupled with the large field of view. This will allow to construct the complete luminosity function for all the evolved stars (brighter than the turnoff) including those located in the very central regions, and to detect complete samples of special stars (e.g. blue stragglers and post-AGB) checking also their possible intrinsic variability. By adding to the HST sample the complementary photometric sample we already secured from ground-based observations for the stars located in the external regions of the cluster (about 18000 stars measured so far), we will obtain the first complete sample ranging from the very center out to the cluster outskirts. This sample is at least 3 to 6 times larger than can possibly be obtained in the future from the ground even in extremely good seeing conditions, and by far more extended in spatial coverage than in any GTO program. In essence, only coupling ground based and HST observations one can obtain the complete luminosity function for the whole cluster, a crucial tool for a ``new generation'' of studies on stellar evolution and dynamics. Note that, besides ensuring completeness, the high angular resolution also yields precision photometry of the evolved stars (brighter than turnoff) down to the cluster center. Aiming at reaching S/N > 10 for stars two mag fainter than the turnoff, we guarantee a high photometric accuracy (1sigma < 0.05mag) for magnitudes and colors of all the stars brighter than the turnoff. Such an high internal accuracy is required by the need e.g. to unambiguously separate AGB from RGB stars, to recognize sharp but weak features in the RGB luminosity function (such as the RGB-bump), to accurately determine the maximum RGB and AGB luminosity, to detect BSS candidates, to put into evidence small amplitude variability, etc. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. To avoid the impact of blooming due to the brightest stars in the observed fields, we must subdivide the exposures into many short sub-exposures, which also allows us to check the individual star variability. To increase the time baseline, we have divided the observations into two groups separated by a period of time (from a few days up to a few weeks, depending on the optimization within the HST scheduling system). This implies the need for two visits on the target, with the same roll angle to guarantee the observation of the same fields in the cluster. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. The computing facilities available in Bologna and Rome (see item 10 below) and the photometric package ROMAFOT (Buonanno et al. 1983), specifically prepared to deal with highly accurate photometry in crowded fields and purposely updated to handle HST data, will allow a complete processing of the data using the standard calibration information. This package has already been used to carry out several photometric studies published by our group on the main journals and, in particular, to make all the photometric measures available for the complementary samples of stars located in the external regions of the cluster. Short visits at the STScI or ST-ECF might be necessary to deal with some specific aspects (like calibrations and photometric checks). Reductions of some test fields will be carried out also with alternative packages (e.g., DAOPHOT) for comparison. Page 4 ------------------------------------------------------------------------------------ 9. Description of previous HST work. Two programs have been previously granted HST observing time, namely GO2583 (Cycle 1): ``Color-Magnitude Diagrams of a Sample of Globular Clusters in M31'', and GO3726 (cycle 2): ``Globular Clusters in M31''. These programs (which have been re-submitted and granted observing time in cycle 4) are indirectly related since one of their original goals is a direct measure of the HB star luminosities to be used as standard candles for a precise determination of globular cluster distances and ages. One of the basic aims of the present proposal is indeed the ultimate check of the so-called ``stellar-clock'' which represents the complement to the observables to yield the age of any stellar aggregate. With GO 2583 13 clusters were observed with the FOC/96 + F430W and accurate surface brightness profiles were obtained, along with the related photometric and structural parameters. These results are of far superior quality than what can be obtained from ground-based observations, and are comparable to the results on galactic globular clusters. The two cluster families show very similar characteristics. We have found the first evidence of a PCC cluster in M31. These results was presented at the Workshop ``Science with the Hubble Space Telescope'' held in Baia Chia in July 1992 and in two papers. With GO3726 one cluster was observed with the FOC/96 + F342W and F140W in order to explore the possibility of obtaining a C-M diagram of at least the brightest and hottest stars even in presence of the known HST aberration. The data reduction and analysis is presently being carried on, but it is evident that only the restored HST can provide useful results. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Italy: Computing: our Institutes in Bologna and Rome are equipped with several Workstations (DEC, IBM) and numerous peripherals specifically devoted to the analysis of HST data. Research Assistance and Students: there are typically 10 graduate students in Astronomy in Bologna, part of which already work on HST- related projects. Research assistance will be secured. Funds: Our personal research grants are sufficient to cover all the expenses conceivably required to complete this program along with other HST projects in which we may be involved. The facilities of the ST-ECF are also available, if needed. University of Virginia: Facilities: The Department of Astronomy has several SUN workstations which can be used to assist in data reduction if necessary. These are also adequate to perform the stellar model and population synthesis computations necessary to interpret the data. A very large grid of stellar models has already been computed. Funds: Current funds from a related NASA Long Term Astrophysics Grant are adequate. ------------------------------------------------------------------------------------ 11. Address Information Name: FLAVIO FUSI PECCI Category: PI Institution: 6426 Address: OSSERVATORIO ASTRONOMICO VIA ZAMBONI 33 City: BOLOGNA State: Zip Code: 40126 Country: ITALY Telephone: 39-51-259321 Telex (or e-mail): (SPAN) 37907::FLAVIO, FAX: +39-51-259407 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5496 [ 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 NGC5272 M3 C,201 RA = 13H 39M 52.94S +/- 1950.0 1 SURF-BKG(V)=16.3 +/- 0.1, B-V=0.7 0.1S, 2 V=21, TYPE=G0V, E(B-V)=0.01 DEC = +28D 37' 37.9" +/- 1" 3 V=19, TYPE=F0, E(B-V)=0.01 4 V=26, TYPE=M0, E(B-V)=0.01 Comments: Flux1=central surface brightness in mag/arcsec-2 for ACQ only. Flux2, 3 and 4 are cluster stars for exposure time calculation ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5496 [ 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 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=15 2 3S 3 2 1 CYCLE 4 6S GROUP 1-8 NO GAP SAME ORIENT FOR 1.1-8 AS 1 Comments: 2 EXPOSURES OF 3 SEC EACH TO AVOID BLOOMING FROM V=13 K0 STARS ------------------------------------------------------------------------------------------------------------------------------------ 1.1 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=15 1 100S 50 2 1 CYCLE 4 400S SEQ 1.1-1.4 NO GAP Comments: 4 EXPOSURES OF 100S EACH TO REACH SNR=50 2 MAG BELOW TURNOFF GROUP 1.1-1.4 DITHERED ------------------------------------------------------------------------------------------------------------------------------------ 1.2 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=15 1 100S 50 2 1 CYCLE 4 400S POS TARG +0.07, 0.0 Comments: SAME AS IN LINENUM 1.1 ------------------------------------------------------------------------------------------------------------------------------------ 1.3 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=15 1 100S 50 2 1 CYCLE 4 400S POS TARG 0.0, +0.07 Comments: SAME AS IN LINENUM 1.1 ------------------------------------------------------------------------------------------------------------------------------------ 1.4 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=15 1 100S 50 2 1 CYCLE 4 400S POS TARG +0.07, +0.07 Comments: SAME AS IN LINENUM 1.1 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=15 2 3S 3 2 1 CYCLE 4 6S Comments: 2 EXPOSURES OF 3 SEC EACH TO AVOID BLOOMING FROM V=13 K0 STARS ------------------------------------------------------------------------------------------------------------------------------------ 2.1 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=15 1 140S 50 2 1 CYCLE 4 560S SEQ 2.1-2.4 NO GAP Comments: 4 EXPOSURES OF 140S EACH TO REACH SNR=50 2 MAG BELOW TURNOFF GROUP 2.1-2.4 DITHERED ------------------------------------------------------------------------------------------------------------------------------------ 2.2 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=15 1 140S 50 2 1 CYCLE 4 560S POS TARG +0.07, 0.0 Comments: SAME AS IN LINENUM 2.1 ------------------------------------------------------------------------------------------------------------------------------------ 2.3 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=15 1 140S 50 2 1 CYCLE 4 560S POS TARG 0.0, +0.07 Comments: SAME AS IN LINENUM 2.1 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5496 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 2.4 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=15 1 140S 50 2 1 CYCLE 4 560S POS TARG +0.07, +0.07 Comments: SAME AS IN LINENUM 2.1 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC5272 WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 2 70S 12 3 1 CYCLE 4 140S Comments: 2 EXPOSURES OF 70S EACH TO AVOID BLOOMING FROM V=15 B0 STARS ------------------------------------------------------------------------------------------------------------------------------------ 3.1 NGC5272 WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 800S 20 2 1 CYCLE 4 CR-SPLIT=NO 3200S SEQ 3.1-3.4 NO GAP Comments: 4 EXPOSURES OF 800S EACH GROUP 3.1-3.4 DITHERED ------------------------------------------------------------------------------------------------------------------------------------ 3.2 NGC5272 WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 800S 20 2 1 CYCLE 4 CR-SPLIT=NO 3200S POS TARG +0.07, 0.0 Comments: SAME AS IN LINENUM 3.1 ------------------------------------------------------------------------------------------------------------------------------------ 3.3 NGC5272 WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 800S 20 2 1 CYCLE 4 CR-SPLIT=NO 3200S POS TARG 0.0, +0.07 Comments: SAME AS IN LINENUM 3.1 ------------------------------------------------------------------------------------------------------------------------------------ 3.4 NGC5272 WFPC2 IMAGE PC1-FIX F336W ATD-GAIN=15 1 800S 20 2 1 CYCLE 4 CR-SPLIT=NO 3200S POS TARG +0.07, +0.07 Comments: SAME AS IN LINENUM 3.1 ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC5272 WFPC2 IMAGE PC1-FIX F255W ATD-GAIN=7 1 300S 6 3 1 CYCLE 4 1200S SEQ 4.0-4.3 NO GAP Comments: 4 EXPOSURES OF 300S EACH TO AVOID BLOOMING FROM V=15 B0 STARS GROUP 4.0-4.3 DITHERED ------------------------------------------------------------------------------------------------------------------------------------ 4.1 NGC5272 WFPC2 IMAGE PC1-FIX F255W ATD-GAIN=7 1 300S 6 3 1 CYCLE 4 1200S POS TARG +0.07, 0.0 Comments: SAME AS IN LINENUM 4.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.2 NGC5272 WFPC2 IMAGE PC1-FIX F255W ATD-GAIN=7 1 300S 6 3 1 CYCLE 4 1200S POS TARG 0.0, +0.07 Comments: SAME AS IN LINENUM 4.0 ------------------------------------------------------------------------------------------------------------------------------------ 4.3 NGC5272 WFPC2 IMAGE PC1-FIX F255W ATD-GAIN=7 1 300S 6 3 1 CYCLE 4 1200S POS TARG +0.07, +0.07 Comments: SAME AS IN LINENUM 4.0 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5496 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=7 2 1200s 9 4 1 CYCLE 4 2200S POS TARG 77.78, 77.78 Comments: offset to 110'' from center ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=7 2 600S 9 4 1 CYCLE 4 1200S SAME POS FOR 6 AS 5 Comments: offset to 110'' from center ------------------------------------------------------------------------------------------------------------------------------------ 7 NGC5272 WFPC2 IMAGE PC1-FIX F555W ATD-GAIN=7 2 1200S 9 4 1 CYCLE 4 2200S POS TARG 155.56, 155.56 Comments: offset to 220'' from center ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC5272 WFPC2 IMAGE PC1-FIX F814W ATD-GAIN=7 2 600S 9 4 1 CYCLE 4 1200S SAME POS FOR 8 AS 7 Comments: offset to 220'' from center ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5496 [ 9] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ATD-GAIN=15 ATD-GAIN=15 CR-SPLIT=NO ATD-GAIN=7 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 6.39 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category OLD CLUSTERS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 4; GROUP 1-8 NO GAP; SAME ORIENT FOR 1.1-8 AS 1 CYCLE 4; SEQ 1.1-1.4 NO GAP CYCLE 4; POS TARG +0.07, 0.0 POS TARG 0.0, +0.07 POS TARG +0.07, +0.07 CYCLE 4 CYCLE 4; SEQ 2.1-2.4 NO GAP CYCLE 4; SEQ 3.1-3.4 NO GAP CYCLE 4; SEQ 4.0-4.3 NO GAP POS TARG 77.78, 77.78 SAME POS FOR 6 AS 5 POS TARG 155.56, 155.56 SAME POS FOR 8 AS 7 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F814W F336W F255W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC5272 M3 ------------------------------------------------------------------------------------------------------------------------------------