6642( 8) - 03/28/96 15:06 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 6642 Version: 8 Check-in Date: 28-Mar-1996 15:04:45 1.Proposal Title: White Dwarf Companions to Binary Neutron Stars, Astrometric Frame Ties ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Cycle HOT STARS GO 6 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Roger S. Foster Naval Research Laboratory CoI: Dr. Norbert Zacharias Universities Space Research Association N CoI: Dr. Scott Lundgren Naval Research Laboratory N CoI: Dr. Paul Ray Naval Research Laboratory N CoI: Mr. Theodore Rafferty U.S. Naval Observatory N ------------------------------------------------------------------------------------ 6. Abstract We propose WFPC2 imaging of four white dwarf companions to binary neutron stars for use in radio/optical frame tie measurements. Multiple exposures spaced by several minutes will permit detection of variability due to rotation or pulsation of the white dwarf. Most critically, the astrometry will enable us to measure the rotation of the optical reference frame relative to the radio and dynamical reference frames made from independent pulsar observations. These observations will have direct ties with on going radio pulsar timing experiments and planned very long baseline interferometry observations using the VLBA. As an added benefit the astrometric observations can be used with a second set of observations two Cycles later to measure proper motion of the white dwarfs. Proper motion observations can be used to distinguish between supernova and accretion induced collapse models for the two white-dwarf millisecond pulsars, and provide improved astrometry for all four white dwarf pulsar systems. ------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 2] Observations Description ------------------------ We propose V and I filter observations of 2 binary pulsars and V observations of 2 additional binary pulsars all with white dwarf companions. These filters are chosen for consistency with our own and other ongoing HST studies of cool white dwarfs (Lundgren, et al., in preparation; von Hippel, et al. 1995, MNRAS, 273, L39). Relative astrometry with WFPC2 to 10 mas, requires a S/R of 50. HST can achieve this level in 120--500 seconds for these sources. We will dither our exposures on the chip, if we determine in consultation with WFPC2 instrument specialists that doing so will improve our astrometry (due to the locations of bright stars on the chip or the subpixel source positioning). For each source we have tabulated (Table 2) the four known parameters: distance (d), orbital period (P_orb), spin period and median mass from the mass function (m_wd). For the known magnitudes of these sources, we have estimated the exposure time needed to achieve S/R=50. The balance of each orbit will be filled with multiple observations to search for variability on a timescale of minutes. We have estimated the number of exposures that will fill the orbit including the necessary overhead. Only HST reaches the necessary sensitivity in a short enough time to look for variability on such short timescales. Several of the proposers are familiar with HST astrometric and photometric data analysis from our observations in the previous Cycle. We propose to repeat the same cycle of observations two years later in Cycle 8 to obtain proper motion measurements on the stars and verify any intensity fluctuations or modulations in the white dwarfs. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Media: 8MM Blocking Factor: 10 Ship To: PI_Address Ship Via: UPS Email: , ------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 3] TARGET LIST a) Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-0437- STAR,BINARY RA=04H 37M 15.710S +/- J2000.0 V = 21.0 4715 PULSAR,PULSAR,NEUTRON 0.001S,DEC=-47D 15' 07.998" +/- STAR,LATE-TYPE 0.006" DEGENERATE, 2 STAR- STAR,BINARY RA=07H 00M 37.804S +/- J2000.0 V = 22.2 0700+6418 PULSAR,PULSAR,NEUTRON 0.002S,DEC=64D 18' 11.285" +/- STAR,LATE-TYPE 0.008" DEGENERATE, 3 STAR- STAR,BINARY RA=08H 23M 09.76S +/- J2000.0 V = 22.6 0823+0159 PULSAR,PULSAR,NEUTRON 0.01S,DEC=01D 59' 12.8" +/- 0.5" STAR,LATE-TYPE DEGENERATE, 4 STAR- STAR,BINARY RA=18H 57M 36.393S +/- J2000.0 V = 23.1 1857+0943 PULSAR,PULSAR,NEUTRON 0.001S,DEC=09D 43' 17.323" +/- STAR,LATE-TYPE 0.001" DEGENERATE, 6642( 8) - 03/28/96 15:06 - [ 4] Visit: 10 Visit Requirements: 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 STAR-0437- WFPC2 IMAGE PC1 F555W DITHER-TYPE=BOX 1 140S 4715 ------------------------------------------------------------------------------------------------------------------------------------ 2 STAR-0437- WFPC2 IMAGE PC1 F814W DITHER-TYPE=BOX 1 140S 4715 ------------------------------------------------------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 5] Visit: 11 Visit Requirements: 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 STAR- WFPC2 IMAGE PC1 F555W DITHER-TYPE=BOX 1 300S 0700+6418 ------------------------------------------------------------------------------------------------------------------------------------ 20 STAR- WFPC2 IMAGE PC1 F555W 1 300S POS TARG 0.75,0.75 0700+6418 ------------------------------------------------------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 6] Visit: 12 Visit Requirements: 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 STAR- WFPC2 IMAGE PC1 F555W DITHER-TYPE=BOX 1 400S 0823+0159 ------------------------------------------------------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 7] Visit: 13 Visit Requirements: 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 STAR- WFPC2 IMAGE PC1 F814W DITHER-TYPE=BOX 1 260S 1857+0943 ------------------------------------------------------------------------------------------------------------------------------------ 80 STAR- WFPC2 IMAGE PC1 F814W 1 260S POS TARG 0.75,0.75 1857+0943 ------------------------------------------------------------------------------------------------------------------------------------ 6642( 8) - 03/28/96 15:06 - [ 8] Summary Form for Proposal 6642 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters DITHER-TYPE=BOX ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category HOT STARS ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements POS TARG 0.75,0.75 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F555W F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names STAR-0437-4715 STAR-0700+6418 STAR-0823+0159 STAR-1857+0943 ------------------------------------------------------------------------------------------------------------------------------------