Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4687 Report Date: 18-Jul-95:16:51 Version: ********** Check-in Date: ********** 1.Proposal Title: A CRITICAL TEST OF THE GALACTIC ESCAPE VELOCITY AT R(SUN) -CYCLE4MEDIUM ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID COOL STARS GO 3 Long Term yrs 2428 Sub Category ASTROMETRY ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Darrell J. Macconnell COMPUTER SCIENCES CORPORATIO USA 410-338-4800 ------------------------------------------------------------------------------------ 7. Abstract This is the third cycle of a 3-year program to determine the parallaxes and proper motions of stars having the most extreme velocities known in the galactic rest frame. Such stars constrain the local galactic escape velocity and thus are important for estimating the mass distribution in the galactic disk. The currently accepted value of V(esc) is around 475 k/s (Cudworth 1990), however this result is based on distances dependent on uncertain photometric corrections and reddening estimates. The derived photometric distances for these stars are in the range 180 to 330 pc, so the parallaxes are in the range 3 to 6 milliarsec. If these distances are approximately correct, it will be possible to measure them at the 4-sigma level using the FGS on the HST if care is taken with the observations and reductions. Cudworth has pointed out that even a 10% change in V(esc) produces a significant effect (> 50%) change in the derived galactic mass. Therefore, it is of considerable interest to have reliable distances, hence space vel- ocities, for these stars. ------------------------------------------------------------------------------------ 8. Scientific Key Words: GALACTIC ESCAPE VELOCITY, HIGH-VELOCITY STARS, PARALLAXES, PROPER MOTIONS ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 9.90 par: 0 10. Num targs pri: 16 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FGS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4687 PI: Darrell J. Macconnell Proposal Title: A CRITICAL TEST OF THE GALACTIC ESCAPE VELOCITY AT R(SUN) -CYCLE4MEDIUM ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Pi Darrell J. Macconnell COMPUTER SCIENCES CORPORATION USA Wayne H. Osborn CENTRAL MICHIGAN UNIVERSITY USA ------------------------------------------------------------------------------------ 3. Description of proposed observations. We plan to observe two 13th-mag program stars and 5 to 8 reference stars for each within the 4'x5' field of the FGS-3 'pickle' and its 180-degree inverse. The stars are to be observed during three years (5 epochs) at the maximum parallax factor for each +/- one month. Cycle 1 contains the TRANS- mode scans for duplicity and, for each star, 6 POS-mode observation sequences at the first parallax maximum and 9 at the second. Cycle 2 contains 4 POS-mode sequences at the third epoch and 6 at the fourth. This Cycle 3 request is for the 5 final POS -mode sequences to complete 15 observations at each parallax maximum. Given the expected accuracy of 0.0016 arcsec for a single observation with the FGS, this series should allow parallax determinations with errors of no more than 0.0005 arcsec, which is less than 20% of the expected value of the parallaxes of these stars, and provide proper motions at least as accurate as those currently available. In a separate series of ground-based observations, we plan to obtain photo- metry of the reference stars at one of the national observatories to permit reduction from relative to absolute parallaxes for the program stars. Cycle 1 Primary Hours: 5.4 Parallel Hours: 0.0 Exposures: 273 Cycle 2 Primary Hours: 3.0 Parallel Hours: 0.0 Exposures: 180 Cycle 3 Primary Hours: 1.5 Parallel Hours: 0.0 Exposures: 90 ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. It would not be reasonable to attempt to determine the trigonometric parallaxes of these stars by traditional ground-based methods because the typical errors of the mean would be several times as large as the quantity to be found assuming the photometric distances. While some new astrometric instruments (e.g. Allegheny Observatory MAP, USNO Flagstaff Station CCD) may provide parallaxes near the desired accuracy, the FGS on HST is the only instrument available to us which is capable of carrying out this program. The target stars are too faint for HIPPARCOS observations. We have not explicitly computed the time for the few required TRANS mode observations of Cycle 1. We have assumed an exposure time of 51.2 sec for each POS-mode observation of a star as recommended in the FGS Instrument Handbook. An observational sequence consists of 10 measurements: the parallax star, the 8 reference stars, and the parallax star again. There are 30 such sequences for each parallax star: 15 sequences in Cycle 1, 10 sequences in Cycle 2, and 5 sequences in Cycle 3. For the two stars, this gives a total of 9.9 hours exposure time over the 2.5 years of this project. Cycle 1 and 2 times are those already approved for this project while Cycle 3 is as computed by the phase1_format software. The larger number of Cycle 1 sequences results from the fact the allocated time was for three stars and has now been distri- buted among the remaining two. ------------------------------------------------------------------------------------ 5. Description of special scheduling requirements. Due to the nature of trigonometric parallax observations, our data must be taken every six months +/- one month. Neither target star is near an ecliptic pole, so they must be observed near the extremes of the parallactic ellipse. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. OSF Line Number(s) Instrument Mode Special Calibration Requirement(s) 1.0 - 2.2 FGS POS NONE ------------------------------------------------------------------------------------ 8. Additional comments or special requests. As mentioned earlier, photometry will be obtained for the approximately 16 reference stars from a ground-based observatory to permit the reduction of relative to absolute parallaxes. These observations may be made at any time during or after the HST observational period; simultaneous observations are not required. ------------------------------------------------------------------------------------ 9. Description of previous HST work. P2428 - A Critical Test of the Galactic Escape Velocity at R(Sun) Allocation of 15.0 hours for this program in Cycle 1. Exposures scheduled for execution in 1993 were assigned numbers P4064 (POS-mode) and P4200 (TRANS-mode). P3856 - (Cycle 2 continuation of above) Allocation of 8.3 hours for Cycle 2 TRANS-mode scans of G166-37 show it is single and suitable for parallax determination, while similar observations of G233-27 show that a nearby field star of similar magnitude and color makes POS-mode observations impossible. G233-27 is moving toward this spoiler star during the next decade and so was dropped from the program. G16-25 was substituted for it, and TRANS-mode observations of it show that it is single and therefore suitable for parallax determination. NONE ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). CSC personnel have access to VAX mainframe computers and peripherals at several sites for basic data reduction and analysis. Data analysis software, including STSDAS and spectral analysis packages based on the Interactive Data Language (IDL) are also available. There are a large number of astronomers at CSC available for expert advice to an investi- gator on observational techniques, detector calibration, data analysis, and theoretical modeling. CSC also provides a pool of research assistants and data technicians as well as administrative and secretarial support for research programs. The Co-I's institution will provide student help, partial support for consulting with the PI, and computing support (reduction of ground- based photometry). ------------------------------------------------------------------------------------ 11. Address Information Name: DARRELL J. MACCONNELL Category: PI Institution: COMPUTER SCIENCES CORPORATION Address: SPACE TELESCOPE SCIENCE INSTITUTE 3700 SAN MARTIN DRIVE HOMEWOOD CAMPUS City: BALTIMORE State: MD Zip Code: 21218 Country: USA Telephone: 410-338-4800 Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4687 [ 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 G166-37 R50 A,136 PLATE-ID = 01TM, 2000 V = +369 1 V = 12.66 +/- 0.02 RA = 14H 34M 51.2S +/- 0.1S, 2 B = 13.34 +/- 0.02 DEC = +25D 10' 9" +/- 1" Comments: PARALLAX PROGRAM STAR Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) J 1982.40 -0.0036 +/- 0.0000 -0.3300 +/- 0.0000 0.0055 +/- 0.0020 ------------------------------------------------------------------------------------------------------------------------------------ 2 G166A-REF A,134 PLATE-ID = 01TM, 2000 1 V = 12.7 +/- 0.3 RA = 14H 34M 51.5S +/- 0.2S, DEC = +25D 8' 9" +/- 2" Comments: PARALLAX REFERENCE STAR ------------------------------------------------------------------------------------------------------------------------------------ 3 G166B-REF ^ PLATE-ID = 01TM, 2000 1 V = 16.4 +/- 0.3 RA = 14H 34M 57.6S +/- 0.2S, DEC = +25D 10' 13" +/- 2" Comments: PARALLAX REFERENCE STAR ------------------------------------------------------------------------------------------------------------------------------------ 4 G166L-REF ^ PLATE-ID = 01TM, 2000 1 V = 14.6 +/- 0.3 RA = 14H 34M 57.1S +/- 0.2S, DEC = +25D 11' 46" +/- 2" Comments: PARALLAX REFERENCE STAR ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4687 [ 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 DEFINE G166-37 FGS POS 3 F583W DATA-RATE=32 1 51S 1 SEQ 1-5 NON-INT G166- ORIENT 242.93D +/- SEQ1 0D POS TARG 0,21 SAME POS FOR 2-5 AS 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 DEFINE G166A-REF FGS POS 3 F583W DATA-RATE=32 1 51S 1 DO FOR TARGS 2-4 G166- GROUP-FGS 1-5 SEQ1 WITHIN 50M ------------------------------------------------------------------------------------------------------------------------------------ 3 DEFINE G166-37 FGS POS 3 F583W DATA-RATE=32 1 51S 1 G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 4 DEFINE G166A-REF FGS POS 3 F583W DATA-RATE=32 1 51S 1 DO FOR TARGS 2-4 G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 5 DEFINE G166-37 FGS POS 3 F583W DATA-RATE=32 1 51S 1 G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 6 USE SEQ 7-8 NO GAP G166- AT 20-FEB-95 +/- SEQ1 1D CYCLE 4 / 6-8 Comments: LINES 7-8 NEED TO BE SCHEDULED IN SUCCESSIVE ORBITS TARGET G166-37 TO BE OBSERVED AT START , MIDDLE, AND END OF EACH ORBIT ; BASE1 PCS MODE OK ------------------------------------------------------------------------------------------------------------------------------------ 7 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 8 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 9 USE SEQ 10-13 NO GAP G166- AT 7-APR-95 +/- 1D SEQ1 CYCLE 4 / 9-13 Comments: LINES 10-13 NEED TO BE SCHEDULED IN SUCCESSIVE ORBITS TARGET G166-37 TO BE OBSERVED AT START, MIDDLE, AND END OF EACH ORBIT; BASE1 PCS MODE OK ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4687 [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 10 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 11 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 12 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ 13 USE G166- SEQ1 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4687 [ 7] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes POS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DATA-RATE ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 9.90 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category COOL STARS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ASTROMETRY ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements SEQ 1-5 NON-INT; ORIENT 242.93D +/- 0D; POS TARG 0,21; SAME POS FOR 2-5 AS 1; DO FOR TARGS 2-4; GROUP-FGS 1-5 WITHIN 50M; SEQ 7-8 NO GAP; AT 20-FEB-95 +/- 1D; CYCLE 4 / 6-8; SEQ 10-13 NO GAP; AT 7-APR-95 +/- 1D; CYCLE 4 / 9-13; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F583W ------------------------------------------------------------------------------------------------------------------------------------ Target Names G166-37 R50 G166A-REF G166B-REF G166L-REF ------------------------------------------------------------------------------------------------------------------------------------