8728( 6) - 10/09/00 14:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8728 Version: 6 Check-in Date: 09-Oct-2000 14:57:36 1.Proposal Title: The Low-Mass Multiple System GL 831 (Wolf 922): Definitive Orbit and the Mass- Luminosity Relation ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 9 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Otto Franz Lowell Observatory CoI: Dr. Lawrence Wasserman Lowell Observatory N CoI: Dr. G. Fritz Benedict University of Texas at Austin N CoI: Dr. Todd Henry The Johns Hopkins University N ------------------------------------------------------------------------------------ 5. Abstract GL 831 = Wolf 922 (V = 11.98, B-V = 1.67, PI = 0.1258 +/- 0.0023 arcsec) belongs to the select group of about one dozen nearby multiple sytems suitable for calibrating the empirical mass-luminosity relation for masses below 0.2 Msun\ (Henry et al. 1999), and has been observed 13 times with FGS3 through Cycle 7. However, a 1.93--yr orbital period, HST scheduling constraints, and a safe mode event conspired to yield repeated coverage of a 180--deg arc about apastron, while leaving unobserved the complementary arc containing periastron (Figure 1). Consequently, the orbital period is accurate to 0.2\ major is known at best to 1.0\ these orbital elements yield masses with an accuracy well short of our goal of 5\ Cycle 9 provides the first and only opportunity in the next three years to complete the coverage by TRANS mode measures needed to yield a definitive orbit of GL 831 essential for accurate mass determination. We therefore request five orbits as indicated in Figure 1. New POS mode data, combined with those in hand, will yield the mass ratio and a parallax much more accurate than that currently available. Use of FGS1r should also clarify the location and nature of a fainter third component, possibly of 0.1 Msun, detected in two observations with the less capable FGS3. ------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 2] Observations Description ------------------------ To achieve a definitve orbit for GL 831 and mass determination of its components with 5\ equally spaced in the first half of Cycle 9 as indicated in Figure 1. On each orbit, we will observe the target in both TRANS and POS modes, and four nearby reference stars in POS mode only. Each POS mode set will consist of a sequence of fine--lock measurements of the target itself, the reference stars, and repeat visits to a drift--check star. The first TRANS observation will use scans of 2.5 arcsec length to assure detection of component C should it be at large angular separation and hence in a very long- period orbit, which would make early re--observation unnecessary. Also, this first TRANS observation is, in orbital phase and HST orbital geometry, a replica of the second detection observation of component C. It should, therefore, provide a conclusive test of the distant third--component scenario. The subsequent four TRANS observations will consist of (about) 20 scans of 30 sec duration (1.2 arsec length per FGS axis) and will adequately sample the remainder of the Cycle 9 observing window for GL 831. These observations will fully characterize GL 831, dynamically and photometrically, as a triple system with either a distant or a close and rapidly orbiting third component. Real Time Justification ----------------------- The proposed timing of the five Cycle 9 orbits is essential in order to achieve the goal of the investigation. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 W922 STAR RA=322.812083D +/- 0.000140D, J2000 V = 12.00+/-0.05 DEC= -9.790139D +/- 0.000140D Coordinate Source: OTHER_SOURCE Comments: B-V =1.67 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1953.7 0.079 -0.060 0.134 2 W922-1-REF CALIBRATION, RA=322.86005D +/- 0.00014D, DEC= J2000 V = 13.70+/-0.2 ASTROMETRIC -9.78972D +/- 0.00014D Coordinate Source: GUIDE_STAR_CATALOG Comments: Star 208 on OGF list 3 W922-10-REF CALIBRATION, RA=322.89479D +/- 0.00014D, DEC= J2000 V = 14.30+/-0.2 ASTROMETRIC -9.78936D +/- 0.00014D Coordinate Source: GUIDE_STAR_CATALOG Comments: Star 202 on OGF list 4 W922-3-REF CALIBRATION, RA=322.77817D +/- 0.00014D, DEC= J2000 V = 13.50+/-0.2 ASTROMETRIC -9.77644D +/- 0.00014D Coordinate Source: GUIDE_STAR_CATALOG Comments: Star 185 on OGF list 5 W922-4-REF CALIBRATION, RA=322.76130D +/- 0.00014D, DEC= J2000 V = 15.50+/-0.2 ASTROMETRIC -9.80458D +/- 0.00014D Coordinate Source: GUIDE_STAR_CATALOG Comments: Star 218 on OGF list 8728( 6) - 10/09/00 14:58 - [ 4] Visit: 01 Visit Priority: Visit Requirements: PCS MODE Fine BETWEEN 20-AUG-2000 AND 25-AUG-2000 ORIENT 98D TO 99D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 W922 FGS TRANS 1 F583W SCANS=11,STEP-SIZE=1 1 951.5 S POS TARG 0.0, 0.0 SEQ 10-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 20 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 80 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 90 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 100 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 110 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 120 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 5] Visit: 02 Visit Priority: Visit Requirements: PCS MODE Fine BETWEEN 20-SEP-2000 AND 24-SEP-2000 ORIENT 78D TO 82D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 W922 FGS TRANS 1 F583W SCANS=18,STEP-SIZE=1 1 972 S POS TARG 0.0, 0.0 SEQ 10-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 20 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 80 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 90 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 100 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 110 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 120 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 6] Visit: 03 Visit Priority: Visit Requirements: PCS MODE Fine BETWEEN 20-OCT-2000 AND 24-OCT-2000 ORIENT 78D TO 79D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 W922 FGS TRANS 1 F583W SCANS=18,STEP-SIZE=1 1 972 S POS TARG 0.0, 0.0 SEQ 10-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 20 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 80 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 90 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 100 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 110 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 120 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 7] Visit: 04 Visit Priority: Visit Requirements: PCS MODE Fine BETWEEN 6-NOV-2000 AND 10-NOV-2000 ORIENT 78D TO 84D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 W922 FGS TRANS 1 F583W SCANS=18,STEP-SIZE=1 1 972 S POS TARG 0.0, 0.0 SEQ 10-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 20 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 40 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 80 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 90 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 100 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 110 W922-3-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 120 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 8] Visit: 05 Visit Priority: Visit Requirements: PCS MODE Fine BETWEEN 18-NOV-2000 AND 20-NOV-2000 ORIENT 75D TO 76D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 W922 FGS TRANS 1 F583W SCANS=18,STEP-SIZE=1 1 972 S POS TARG 0.0, 0.0 SEQ 10-120 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 20 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 30 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 50 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 60 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 70 W922 FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 80 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 90 W922-10-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 100 W922-4-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 120 W922-1-REF FGS POS 1 F583W 1 10 S MAX DUR 10S SAME POS AS 10 ------------------------------------------------------------------------------------------------------------------------------------ 8728( 6) - 10/09/00 14:58 - [ 9] Summary Form for Proposal 8728 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations FGS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes TRANS POS ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCANS=11 STEP-SIZE=1 SCANS=18 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PCS MODE Fine BETWEEN 20-AUG-2000 AND 25-AUG-2000 ORIENT 98D TO 99D POS TARG 0.0, 0.0 SEQ 10-120 NON-INT MAX DUR 10S SAME POS AS 10 PCS MODE Fine BETWEEN 20-SEP-2000 AND 24-SEP-2000 ORIENT 78D TO 82D PCS MODE Fine BETWEEN 20-OCT-2000 AND 24-OCT-2000 ORIENT 78D TO 79D PCS MODE Fine BETWEEN 6-NOV-2000 AND 10-NOV-2000 ORIENT 78D TO 84D PCS MODE Fine BETWEEN 18-NOV-2000 AND 20-NOV-2000 ORIENT 75D TO 76D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F583W ------------------------------------------------------------------------------------------------------------------------------------ Target Names W922 W922-1-REF W922-3-REF W922-4-REF W922-10-REF ------------------------------------------------------------------------------------------------------------------------------------