Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4664c Report Date: 09-May-96:19:46 Version: ********** Check-in Date: ********** 1.Proposal Title: ASTROPHYSICAL STUDY OF BLUE STRAGGLERS IN 47 TUCANAE: CYCLE 3 HIGH ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID GO Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Ronald Gilliland STSCI USA (410)338-4454 ------------------------------------------------------------------------------------ 7. Abstract Through time-series, CCD ensemble photometry of the diverse stellar population in the core of 47 Tucanae, we will detect stellar oscillations of the delta Scuti and dwarf Cepheid type in the blue stragglers. We will also determine the presence and orbital period distribution of contact and cataclysmic binaries in the cluster core. Similar period distributions to those observed in the field would support the suggestion that most cataclysmics and contact binaries were formed in, and ejected from globular clusters. A thorough pulsation study of the about 25 blue stragglers should allow mass determinations in many cases. As the blue stragglers of 47 Tuc are likely the result of stellar collisions, these observations will also yield a thorough survey of the central 66x66 arcsec core region for tightly bound binaries that may serve as precursors to the formation of blue stragglers. We will observe with the PC at a sustained data rate of 3 frames per hour. Since 47 Tuc is in a continuous viewing zone, such observations will be maintained for a 1.5 day period, necessary for detection of low amplitude delta Scuti stars, and to obtain the frequency precisions (8 microHz) needed for detailed interpretation. We expect a total of about 100 frames over 36 hours, each of which will have precision of 4 mag on brightest stars (differential only) at 15th mag, to 0.3 mag at 21st. With some 10000 stars from a most interesting stellar population in this time-series, many serendipitous results may also be expected. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 36.00 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4664c PI: Dr. Ronald Gilliland Proposal Title: ASTROPHYSICAL STUDY OF BLUE STRAGGLERS IN 47 TUCANAE: CYCLE 3 HIGH ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Ronald L Gilliland SPACE TELESCOPE SCIENCE USA INSTITUTE Larry Petro SPACE TELESCOPE SCIENCE USA INSTITUTE Abhijit Saha SPACE TELESCOPE SCIENCE USA INSTITUTE Mike Shara SPACE TELESCOPE SCIENCE USA INSTITUTE ------------------------------------------------------------------------------------ 2. Scientific Justification. Not entered for Phase II. ------------------------------------------------------------------------------------ 3. Description of proposed observations. A primary time-series consisting of some 100 PC exposures most of 17 minutes with F336W. Observations must be obtained when object is well placed in the continuous viewing zone, allowing for dense coverage in a 1.5 day window. Each frame will be taken under conditions as identical as possible to the others. These frames will be used mainly to provide fully differential photometry of some 10000 stars in the 66X66 arcsec field of view. The about 25 blue stragglers are primary targets for detection of stellar pulsations. The frames will also be co- added and analyzed to provide a U magnitude for each star. Use of F336W suppresses the much brighter red giants sufficiently to allow good separation of the blue stragglers. Use of a filter in the UV would not allow sufficiently high count rates for limiting precision work on 16th mag stars. Use of a filter farther to the red would not sufficiently isolate the blue stragglers from the more common stellar types. Astrophysical analysis of any detected pulsating stars is likely to require estimates of luminosity and temperature. A few short B and V band exposures of the primary field are included for this purpose. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. The spatial density of stars in the core of 47 Tuc (or any intrinsically high mass density globular) is very high. Most of the primary program stars have comparably bright neighbors within about 1-2 arcsec in the U band (much worse in B, or redder). High precision time-series photometry in such a crowded field is not feasible with variable seeing as would hold for ground based observations. The primary targets are, however, well separated at the 0.2-0.4 arcsec level (Paresce, Shara et al. 1991). Thus the PSF cores containing about 20% of total energy may be easily measured with PC data. This project makes full use of current WF/PC and HST (as a system) unique capabilities. Our primary goal is detection of stellar pulsations likely to have characteristic frequencies of 60 to 300 microHz (4.6 to 0.9 hours). A frequency resolution of 8 microHz as provided by a 36 hour window should support mode identification for most delta Scuti stars that show both the fundamental and first overtone modes. Reaching the desired overall precision level of a few mmag also requires about 100 frames, consistent with 1.5 days. It would be permissible for the outer limits of the time-series to fall outside the CVZ, thus resulting in small gaps. Some gaps will certainly result from SAA passages. Page 3 ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. TIME-CRITICAL -- our target has only one lengthy CVZ passage in 1993 beginning about 1992.247:22:01. The following information from PIT: GS ACQ (247:19:29) Initial 2 pair fine lock acquisition - BASE2 LINE01 (247:20:24) Reacq followed by 4 900 sec exposures LINE02 (247:22:01) Enter SAA free CVZ period - start taking 1000 sec PC images and keep taking them until next SAA encounter. We should get approx. 32 images. LINE03 (248:08:46) Start SAA passage portion - 3 images per visibility period for 6 orbits. LINE04 (248:18:49) Take 4 900 sec images. LINE05 (248:20:28) Take 4 1000 sec images. Start new obset: LINE06 (248:22:04) Back into SAA free CVZ period. Starting taking 1000 sec images again and keep taking until CVZ exit. Bright earth limb should be set to at least 18 deg for this obset. This time will overlap the SMS boundary and require that the 242 SMS be extended by at least 12 hours. I have received SMS honcho and GSFC's (J. Leibee) approval to do this. Start new obset: LINE08 (249:09:20) Back to observing with short visibility periods for last 6 exposures. These may take up to 6 orbits to obtain due to very bad SAA versus visibility period impact. LINE09 -16: These exposures can be obtained anywhere in the 93.249 SMS. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. No special calibrations required. A decontamination as necessary to maintain relative throughput at 70-80% at F336W would be good. Dense star cluster will provide a mean exposure level of 125 e/1000s exposure removing the need for a pre -flash. Similarly there is no need for CR-SPLIT. ------------------------------------------------------------------------------------ 7. Data reduction and analysis plans. Not given for Phase II. ------------------------------------------------------------------------------------ 8. Additional comments or special requests. This proposal will rely on a single guide star acquisition to support 36 hours of observation. Being centered on 47 Tuc this is a generally crowded field. We request that special attention be paid to the guide star selection to include: 1) sending up 2 guide star pairs instead of the default one, 2) have SPSS generate the guide star candidates ahead of time and have Conrad Sturch visually examine the plate material for these -- this should be noted on the initial SPB Order Form. The CVZ passage straddles an SMS boundary, we request either a special SMS without this break, or an addition of the lost time to the ends of the time series. Priority is to schedule as many exposures, all of same length, as possible in the roughly 36 hour window. It is not desired to maintain even spacings across gaps. Loss of part of a CCD frame at reversals of the tape recorder can be lived with. Attempts should be made to minimize data taking gaps as much as possible. Note on Guide Stars: 47 Tuc was previously observed with the PC at nearly the same roll for the Bahcall program, would a check of what guide stars worked in that case help here? ------------------------------------------------------------------------------------ 9. Description of previous HST work. Not entered for Phase II. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). Not entered for Phase II. ------------------------------------------------------------------------------------ 11. Address Information Page 4 Name: Ronald L Gilliland Category: PI Institution: STSCI Address: 3700 San Martin Dr City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410 338-4454 Telex (or e-mail): ------------------------------------------------------------------------------------ Name: Larry Petro Category: CON Institution: STSCI Address: 3700 San Martin Dr City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410 338-4501 Telex (or e-mail): ------------------------------------------------------------------------------------ Name: Abhijit Saha Category: CON Institution: STSCI Address: 3700 San Martin Dr City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410 338-4806 Telex (or e-mail): ------------------------------------------------------------------------------------ Name: Mike Shara Category: CON Institution: STSCI Address: 3700 San Martin Dr City: Baltimore State: MD Zip Code: 21218 Country: USA Telephone: 410 516-4543 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4664c [ 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 NGC104 47TUC C,201,A,172,175,149 RA=00H 24M 05.90S +/- 0.1S, 2000 1 V = 16.0 +/- 0.1 DEC=-72D 04' 51.2" +/- 1.0" 2 B-V = 0.3 +/- 0.1 3 E(B-V) = 0.04 +/- 0.03 ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC104-OFF1 C,201,A,172,175,149 RA=00H 27M +/- 1S, 2000 DEC=-72D 35M +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC104-OFF2 C,201,A,172,175,149 RA=00H 21M +/- 1S, 2000 DEC=-71D 35M +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC104-OFF3 C,201,A,172,175,149 RA=00H 30M +/- 1S, 2000 DEC=-73D 05M +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC104-OFF4 C,201,A,172,175,149 RA=00H 18M +/- 1S, 2000 DEC=-71D 05M +/- 1" ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4664c [ 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 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 4 900S 200 1 1 AT 6-SEP-93 +/- 4D FIX PRE-FLASH=NO SAME POS FOR 2.0- 16.0 AS 1.0 PCS MODE F / 1.0- 16 CYCLE 3 / 1.0-16 Comments: SCHEDULE PER COMMENTS IN GF 5. SEQ 1-8 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 2 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 32 1000S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME CVZ VIS. ------------------------------------------------------------------------------------------------------------------------------------ 3 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 18 1000S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME 72 MIN VIS. ------------------------------------------------------------------------------------------------------------------------------------ 4 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 4 900S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME 81 MIN VIS. ------------------------------------------------------------------------------------------------------------------------------------ 5 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 4 1000S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME 86 MIN VIS. ------------------------------------------------------------------------------------------------------------------------------------ 6 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 29 1000S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME CVZ VIS. NEW OBSET HERE. SET EARTH LIMB TO 18. ------------------------------------------------------------------------------------------------------------------------------------ 8 NGC104 PC IMAGE PCALL- F336W CR-SPLIT=NO 6 1000S 200 1 1 FIX PRE-FLASH=NO Comments: ASSUME 47 MIN VIS. RESET EARTH LIMB. ------------------------------------------------------------------------------------------------------------------------------------ 9 NGC104 PC IMAGE PCALL- F439W CR-SPLIT=NO 1 20S 50 1 1 AFTER 8 FIX PRE-FLASH=NO SEQ 9-16 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC104 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 8S 50 1 1 FIX PRE-FLASH=NO Comments: (LINES 3.0-10.0) THESE ARE INDEPENDENT OF THE PRIMARY TIME_SERIES IN 1.0-2.0 ------------------------------------------------------------------------------------------------------------------------------------ 11 NGC104 PC IMAGE PCALL- F439W CR-SPLIT=NO 1 35S 70 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 12 NGC104 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 16S 70 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 13 NGC104 PC IMAGE PCALL- F439W CR-SPLIT=NO 1 70S 100 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4664c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 14 NGC104 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 30S 100 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 15 NGC104 PC IMAGE PCALL- F439W CR-SPLIT=NO 1 160S 200 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 16 NGC104 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 60S 200 1 1 FIX PRE-FLASH=NO PURGE=YES ------------------------------------------------------------------------------------------------------------------------------------ 100 NGC104-OFF1 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 40S 1 1 SELECT 1 OF 100 OR FIX PRE-FLASH=NO 101 OR 102 OR 103 COND IF GS AVAIL CYCLE 3/100-103 ------------------------------------------------------------------------------------------------------------------------------------ 101 NGC104-OFF2 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 40S 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 102 NGC104-OFF3 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 40S 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ 103 NGC104-OFF4 PC IMAGE PCALL- F555W CR-SPLIT=NO 1 40S 1 1 FIX PRE-FLASH=NO ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4664c [ 8] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO PRE-FLASH=NO PURGE=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 36.00 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AT 6-SEP-93 +/- 4D; SAME POS FOR 2.0-16.0 AS 1.0; PCS MODE F / 1.0-16; CYCLE 3 / 1.0-16; SEQ 1-8 NO GAP; AFTER 8; SEQ 9-16 NO GAP; SELECT 1 OF 100 OR 101 OR 102 OR 103; COND IF GS AVAIL; CYCLE 3/100-103; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F439W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC104 47TUC NGC104-OFF1 NGC104-OFF2 NGC104-OFF3 NGC104-OFF4 ------------------------------------------------------------------------------------------------------------------------------------