6048( 7) - 04/25/96 13:37 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6048 Version: 7 Check-in Date: 25-Apr-1996 13:30:19 1.Proposal Title: Separate Spectra of Stars of Known Very Low Mass in Nearby Close Binaries ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle Cool Stars GO 5 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. John L. Hershey Computer Sciences Corp. at Space Telescope Science Institute CoI: Don Chance Computer Sciences Corp at Space Telescope N Science Institute ------------------------------------------------------------------------------------ 6. Abstract The Hubble Space Telescope has recently demonstrated its ability in astrometry to separate and measure with high precision the relative orbital position of faint, nearby, low- mass binaries which are barely resolvable by ground based techniques. Since the servicing mission it has the capability of making an even greater advance over ground-based spectroscopy by acquiring separate spectra of the members of faint, close binaries, the only ones where mass can be determined. It is impossible to get these spectra from the ground because the separations of these binaries are too small to be isolated at the spectrograph slit. Knowledge of stellar masses at the ``brown dwarf'' boundary is important in many interrelated areas such as the end of the stellar mass function, theory of stellar evolution,end of the main sequence, and the galactic mass, age and evolution. Currently the objects of low stellar and sub-stellar mass are strong candidates as a source of ``missing'' galactic mass, but a means of estimating the masses of the many known single, low-luminosity and late- type M-dwarf objects is needed. Good separate spectra of these low-mass objects are needed for advancement of the mass calibration of very late-type dwarfs in order to extend the mass function lower. ------------------------------------------------------------------------------------ 6048( 7) - 04/25/96 13:37 - [ 2] Observations Description ------------------------ For the two single reference stars a simple FOS spectrum will be taken as a routine FOS observation. Because the primary targets in this program are closely spaced double stars, great care must be taken in doing the target acquisitions in order to accurately separate each star in the pair. In fact, the majority of the time on each pair must be spent doing the target acquisition. In general, the observing sequence will start by acquiring the brighter of the pair in the large FOS aperture and proceed through a series of target acquisitions to center this star in an ever smaller progression of apertures. This sequence should end with the brighter of the pair centered in the 0.25-pair aperture. A short exposure using the G780H grating will then be taken. An offset maneuver will then be performed to the fainter of the pair. Depending on how well the orbit for the pair is known, a finely spaced peakup target acqusition may be necessary at this point to accurately center the star in the aperture. Finally, a spectrum of the fainter of the pair of stars will be obtained. Simulations provided by FOS instrument scientist A. Keyes have shown that exposure times of about 20 minutes should provide S/N of 20-30 for an M2V star with a V magnitude of 15. Although target acquisition sequence for each pair will follow the general pattern described above, the details will vary slightly in each case. For example, L722-22 has a V magnitude near the limit for use with ACQ/BINARY. Detailed planning and consultation in Phase 2 may indicate it is possible to use ACQ/BINARY rather than ACQ/PEAK for the initial acquisition. This will result in a savings of several minutes and possibly reducing the number of orbits required from 3 to 2. The choice of the 0.25-pair aperture deserves some explanation. While the 0.1-pair aperture would seem at first to be a better choice because of the high spatial resolution required to provide unblended spectra for these close pairs, the 0.25-pair aperture is actually a better choice. The advantages of 0.25-pair aperture over 0.1-pair are listed below: 1. The 0.25-pair aperture gives ~ 2 times greater aperture thoughput. The 0.1 -pair aperture only covers a fraction of the PSF. 2. The 0.25 -pair aperture will be much less affected by spacecraft jitter. 3. The 0.25-pair aperture is better calibrated. No flat fields exist for the 0.1- pair aperture 4. The target acquistion is simplified by use of the larger aperture. Real Time Justification ----------------------- none Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 6048( 7) - 04/25/96 13:37 - [ 3] Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS __Diagnosti Email: , ------------------------------------------------------------------------------------ 6048( 7) - 04/25/96 13:37 - [ 4] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 L722-22A star, M V-IV RA= 3.8640416D +/-0.00139D, J2000 V = 12.62+/-0.5 DEC=-16.1307D +/-0.00139D, PLATE -ID=03Y6 Comments: scientific target GASP coordinate from plate S608 03Y6 Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.8 0.0455 -0.5950 0.1890 2 L722-22B star, M V-IV XI-OFF= -0.28" +/-0.05", ETA- J2000 V = 15.0+/-0.5 OFF= +0.135" +/-0.05", FROM 1, PLATE-ID=03Y6 Comments: GASP coordinate from plate S608 03Y6 Coordinates given for 18-AUG-1996. Coordinates for this star need to be updated when it is known on what SMS it will be scheduled. 3 ROSS-614A Star, M V-IV RA= 97.3440857D +/-0.00139D, J2000 V = 11.1+/-0.5 DEC= -2.8103888D +/-0.00139D, PLATE-ID=02NZ Comments: Scientific Target, GASP coordinate from plate S770 02NZ Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 1983.9 0.04721 -0.7025 0.248 4 ROSS-614B Star, M V-IV XI-OFF= +0.47" +/-0.1", ETA- J2000 V = 14.4+/-0.5 OFF= -0.48" +/-0.1", FROM 3, PLATE-ID=02NZ Comments: GASP coordinate from plate S770 02NZ Coordinates for this star need to be updated when it is known on what SMS it will be scheduled. 6048( 7) - 04/25/96 13:37 - [ 5] Visit: 01 Visit Requirements: BETWEEN 10-AUG-96 AND 1-SEP-96 On Hold Comments: Additional Comments: L722-22B is the fainter companion in a binary with a 4.5 year period. It moves over 0.2" in X and over 0.1" in Y througout the visibility season. The coordinates for L722-22B should be updated when it is known on what SMS this visit will appear. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 L722-22A FOS/RD ACQ/BIN 4.3 MIRROR 1 1.0S ONBOARD ACQuisition FOR 2 ARY Comments: 20,000 counts predicted by the FOS simulator for exposure 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 L722-22A FOS/RD ACQ/PEA 0.25- MIRROR SCAN-STEP- 1 2.0S ONBOARD ACQuisition FOR 3 K PAIR X=0.17,SCAN- STEP- Y=0.17,SEARCH- SIZE-X=5,SEARCH Comments: -SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 3 L722-22A FOS/RD ACCUM 1.0 G780H 1 300.0S ------------------------------------------------------------------------------------------------------------------------------------ 4 L722-22A FOS/RD ACQ/PEA 0.25- MIRROR SCAN-STEP- 1 6.0S ONBOARD ACQuisition FOR 5 K PAIR X=0.052,SCAN- STEP- Y=0.052,SEARCH- SIZE-X=5,SEARCH Comments: -SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 5 L722-22A FOS/RD ACCUM 0.25- G780H STEP- 1 1170.0S PAIR PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 6 L722-22B FOS/RD ACCUM 0.25- G780H STEP- 1 48M PAIR PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 6048( 7) - 04/25/96 13:37 - [ 6] Visit: 02 Visit Requirements: BETWEEN 1-JUL-95 AND 1-DEC-95 On Hold Comments: Additional Comments: Ross-614B is the secondary in a binary with a period of 16.6 years. It moves 0.2" in x and 0.25" in y in a year at this part of its orbit. If it is not observed in the time interval requested in the BETWEEN requirement, the XI-OFF AND ETA-OFF will need to be revised for the target Ross-614B coordinates and a new BETWEEN interval set. Even if it is observed in the BETWEEN period, the coordinates for Ross-614B should be still updated when it is known on what SMS this visit will appear. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 11 ROSS-614A FOS/RD ACQ/PEA 4.3 G650L SCAN-STEP- 1 1.0S ONBOARD ACQuisition FOR 12 K Y=1.23,SEARCH- SIZE-X=1,SEARCH -SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 12 ROSS-614A FOS/RD ACQ/PEA 1.0- G650L SCAN-STEP- 1 1.0S ONBOARD ACQuisition FOR 13 K PAIR X=0.61,SCAN- STEP- Y=0.61,SEARCH- SIZE-X=6,SEARCH Comments: -SIZE-Y=2 ------------------------------------------------------------------------------------------------------------------------------------ 13 ROSS-614A FOS/RD ACQ/PEA 0.25- G650L SCAN-STEP- 1 1.0S ONBOARD ACQuisition FOR 14 K PAIR X=0.17,SCAN- STEP- Y=0.17,SEARCH- SIZE-X=5,SEARCH Comments: -SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 14 ROSS-614A FOS/RD ACQ/PEA 0.25- G650L SCAN-STEP- 1 1.0S ONBOARD ACQuisition FOR 15 K PAIR X=0.052,SCAN- STEP- Y=0.052,SEARCH- SIZE-X=5,SEARCH Comments: -SIZE-Y=5 ------------------------------------------------------------------------------------------------------------------------------------ 15 ROSS-614A FOS/RD ACCUM 0.25- G780H STEP- 1 1190.0S PAIR PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 16 ROSS-614B FOS/RD ACQ/PEA 0.1- MIRROR SCAN-STEP- 1 6.0S ONBOARD ACQuisition FOR 17 K PAIR X=0.052,SCAN- STEP- Y=0.052,SEARCH- SIZE-X=3,SEARCH Comments: -SIZE-Y=3 ------------------------------------------------------------------------------------------------------------------------------------ 17 ROSS-614B FOS/RD ACCUM 0.25- G780H STEP- 1 1700.0S PAIR PATT=SINGLE ------------------------------------------------------------------------------------------------------------------------------------ 6048( 7) - 04/25/96 13:37 - [ 7] Summary Form for Proposal 6048 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/BINARY ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP-X=0.17 SCAN-STEP-Y=0.17 SEARCH-SIZE-X=5 SEARCH-SIZE-Y=5 SCAN-STEP-Y=0.052 STEP-PATT=SINGLE SEARCH-SIZE-Y=3 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.052 SEARCH-SIZE-X=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category Cool Stars ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 10-AUG-96 AND 1-SEP-96 ONBOARD ACQuisition FOR 2 ONBOARD ACQuisition FOR 3 ONBOARD ACQuisition FOR 5 BETWEEN 1-JUL-95 AND 1-DEC-95 ONBOARD ACQuisition FOR 12 ONBOARD ACQuisition FOR 13 ONBOARD ACQuisition FOR 14 ONBOARD ACQuisition FOR 15 ONBOARD ACQuisition FOR 17 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G780H G650L ------------------------------------------------------------------------------------------------------------------------------------ Target Names L722-22A L722-22B ROSS-614A ROSS-614B ------------------------------------------------------------------------------------------------------------------------------------