Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4425c Report Date: 09-May-96:19:36 Version: ********** Check-in Date: ********** 1.Proposal Title: SEARCH FOR OPTICAL COUNTERPARTS OF X-RAY SOURCES IN NEARBY CLUSTERS CYC3-HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID HOT STARS GO Sub Category X-RAY BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Charles D Bailyn YALE UNIVERSITY USA ------------------------------------------------------------------------------------ 7. Abstract We propose deep broadband PC observations of 3 nearby globular clusters (NGC 6397, NGC 6121=M4, and NGC 6656=M22) to search for optical counterparts of low luminosity X-ray sources. ROSAT observations of unprecedented depth are scheduled for these clusters: preliminary data already in hand reveal the presence of multiple sources in the core of NGC 6397. In addition, these HST observations will enable us to search for unusual populations in the cores of these clusters, and determine the main sequence luminosity function, which will provide a test of dynamical models of cluster evolution. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 4.45 par: 0 10. Num targs pri: 3 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4425c PI: Charles D Bailyn Proposal Title: SEARCH FOR OPTICAL COUNTERPARTS OF X-RAY SOURCES IN NEARBY CLUSTERS CYC3-HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Charles D Bailyn YALE UNIVERSITY USA Jonathan E Grindlay CENTER FOR ASTROPHYSICS USA Paul Callanan CENTER FOR ASTROPHYSICS USA Adrienne Cool CENTER FOR ASTROPHYSICS USA Haldan N Cohn INDIANA UNIVERSITY USA Phyllis M Lugger INDIANA UNIVERSITY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. As required by the TAC, we are restricting ourselves to observations of NGC6397, for which X-ray observations have already been obtained. Because our Cycle 2 observations provided less F675W coverage than anticipated (330s total rather than 600s), we will perform one F675W exposure as well as the proposed F439W exposures, to obtain equal depth in F675W and F439W (see details in section 4). Without the additional F675W exposure, additional F439W exposures alone would be useless, since the point of our project is to determine the COLOR of potential optical counterparts of X-ray sources. As proposed, we will also perform one short F439W exposure to analyze bright stars which will be saturated in the longer exposures. The resulting total exposure time of 450s in F675W and 1640s in F439W are somewhat shorter than in our original proposal, but several interesting candidates have already been identified from our Phase 2 results, so we expect that we will be able to achieve our science objectives with the exposures requested here, and detailed below. F439W exposures: 4x400s 1x40s F675W exposure: 120s ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The central regions of globular clusters are too crowded to observe from the ground below the main sequence, hence we require HST observations. By analogy with already analyzed HST observations of M4, we expect our total of 430s of F675W exposures to reach stars 5 to 5.5 magnitudes below the main sequence turnoff (see Phase 1 proposal for details). The F439W filter provides sensitivity of about 1/3 that of the F675W filter. Combined with the red color of most of the stars and the interstellar reddening towards NGC6397, we expect that a factor of approximately 4 more exposure time will be required in the F439W filter to provide equal depth. The proposed 1640s of exposure in the F439W filter will provide the required depth. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. none ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. none ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Data will be reduced at our home institutions, using a slightly modified version of DAOPHOT. Preliminary reductions will be done at Yale, and compared to X-ray maps prepared at the CfA. Workers at Indiana will perform more detailed reductions and comparisons with theoretical models. Page 3 ------------------------------------------------------------------------------------ 8. Additional comments or special requests. ROSAT results for NGC6397 have already been obtained and analyzed. Ground based followup observations will be scheduled using Yale's guaranteed time on the CTIO 1m class telescopes for spring of 1994. A related proposal (proposal number 4571, PI Grindlay) has been accepted as a medium priority cycle 3 proposal, and has also proceeded to phase 2. ------------------------------------------------------------------------------------ 9. Description of previous HST work. GO-2555, PI Grindlay GO-3851, PI Grindlay AR-3793, PI Bailyn All of the above are relevant to this project, results discussed below. GO-2237, PI Bookbinder. This proposal is unrelated to this project, and only preliminary results have been obtained so far. GO-2555: Several interesting candidates have been identified GO-3851: Several interesting candidates have been identified, and are being followed up from the ground, and in proposal 4571. AR-3793: Several conference reports have been published, and a journal paper is in preparation. Several new data reduction techniques have been developed which will be used in the analysis of the data obtained in this project. 4 conference reports have been published. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The CfA, Yale, and Indiana all support extensive networks of scientific workstations which will be sued to reduce the data obtained through this proposal. Telescope time obtained through the agreement governing the use of Yale's 1m telescope by CTIO will be used to obtain ground based data. Summer salary for the PI will be obtained from other grant sources. ------------------------------------------------------------------------------------ 11. Address Information Name: CHARLES D BAILYN Category: PI Institution: Yale University Address: ASTRONOMY DEPT. YALE UNIVERSITY P.O. BOX 6666 City: NEW HAVEN State: CT Zip Code: 06511 Country: USA Telephone: (203) 432-3022 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4425c [ 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 NGC6397 C; 201 RA = 17H 40M 41.74S +/- J2000 1 V=21 +/- 0 0.06S, DEC = -53D 40' 24.94" +/- 0.1S ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4425c [ 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 NGC6397 PC IMAGE PC6-FIX F439W 449.0- CR-SPLIT=NO 1 40S ORIENT 77.5D +/- 450.0 5.0D CYCLE 3 GROUP 1-3 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC6397 PC IMAGE PC6-FIX F439W 449.0- CR-SPLIT=NO 4 400S ORIENT 77.5D +/- 450.0 5.0D CYCLE 3 ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC6397 PC IMAGE PC6-FIX F675W 675.0- CR-SPLIT=NO 1 120S ORIENT 77.5D +/- 676.0 5.0D CYCLE 3 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4425c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 4.45 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category X-RAY BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 77.5D +/- 5.0D; CYCLE 3; GROUP 1-3 NO GAP CYCLE 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F439W F675W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC6397 ------------------------------------------------------------------------------------------------------------------------------------