! Proposal 6642, submission 3 ! PI: Dr. Roger S. Foster ! Received Wed Feb 28 15:28:19 EST 1996 ! From: lundgren@spoa.nrl.navy.mil ! +====================+ ! | PED OUTPUT PRODUCT | ! +====================+ ! ! /home/lundgren/oia/proposals/hst/1995b/phase2/6642.prop ! Generated by PREPROCESSOR, version 6.0e ! Date: Wed Feb 28 15:13:30 EST 1996 Proposal_Information Title: White Dwarf Companions to Binary Neutron Stars, Astrometric Frame Ties Proposal_Category: GO Scientific_Category: HOT STARS Cycle: 6 Investigators PI_Name: Dr. Roger S. Foster PI_Institution: Naval Research Laboratory CoI_Name: Dr. Norbert Zacharias CoI_Institution: Universities Space Research Association Contact: CoI_Name: Dr. Scott Lundgren CoI_Institution: Naval Research Laboratory Contact: CoI_Name: Dr. Paul Ray CoI_Institution: Naval Research Laboratory Contact: CoI_Name: Mr. Theodore Rafferty CoI_Institution: U.S. Naval Observatory Contact: 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. Questions Observing_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: Fixed_Targets Target_Number: 1 Target_Name: STAR-0437-4715 Alternate_Names: PSRJ0437-4715 Description: STAR,BINARY PULSAR,PULSAR,NEUTRON STAR,LATE-TYPE DEGENERATE, Position: RA=04H 37M 15.710S +/- 0.001S,DEC=-47D 15' 07.998" +/- 0.006" Equinox: J2000.0 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 21.0 Comments: Target_Number: 2 Target_Name: STAR-0700+6418 Alternate_Names: PSRB0655+64,PSRJ0700+6418 Description: STAR,BINARY PULSAR,PULSAR,NEUTRON STAR,LATE-TYPE DEGENERATE, Position: RA=07H 00M 37.804S +/- 0.002S,DEC=64D 18' 11.285" +/- 0.008" Equinox: J2000.0 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 22.2 Comments: Target_Number: 3 Target_Name: STAR-0823+0159 Alternate_Names: PSRB0820+02,PSRJ0823+0159 Description: STAR,BINARY PULSAR,PULSAR,NEUTRON STAR,LATE-TYPE DEGENERATE, Position: RA=08H 23M 09.76S +/- 0.01S,DEC=01D 59' 12.8" +/- 0.5" Equinox: J2000.0 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 22.6 Comments: Target_Number: 4 Target_Name: STAR-1857+0943 Alternate_Names: PSRB1855+09,PSRJ1857+0943 Description: STAR,BINARY PULSAR,PULSAR,NEUTRON STAR,LATE-TYPE DEGENERATE, Position: RA=18H 57M 36.393S +/- 0.001S,DEC=09D 43' 17.323" +/- 0.001" Equinox: J2000.0 RV_or_Z: RA_PM: Dec_PM: Epoch: Annual_Parallax: Flux: V = 23.1 Comments: Solar_System_Targets Generic_Targets Scan_Data Visits Visit_Number: 10 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 1 Target_Name: STAR-0437-4715 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: DITHER-TYPE=BOX Number_of_Iterations: 1 Time_Per_Exposure: 140S Special_Requirements: Comments: Exposure_Number: 2 Target_Name: STAR-0437-4715 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: DITHER-TYPE=BOX Number_of_Iterations: 1 Time_Per_Exposure: 140S Special_Requirements: Comments: Visit_Number: 11 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 10 Target_Name: STAR-0700+6418 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: DITHER-TYPE=BOX Number_of_Iterations: 1 Time_Per_Exposure: 300S Special_Requirements: Comments: Exposure_Number: 20 Target_Name: STAR-0700+6418 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 300S Special_Requirements: POS TARG 0.75,0.75 Comments: Visit_Number: 12 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 10 Target_Name: STAR-0823+0159 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F555W Wavelength: Optional_Parameters: DITHER-TYPE=BOX Number_of_Iterations: 1 Time_Per_Exposure: 400S Special_Requirements: Comments: Visit_Number: 13 Visit_Requirements: On_Hold_Comments: Visit_Comments: Exposure_Number: 10 Target_Name: STAR-1857+0943 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: DITHER-TYPE=BOX Number_of_Iterations: 1 Time_Per_Exposure: 260S Special_Requirements: Comments: Exposure_Number: 80 Target_Name: STAR-1857+0943 Config: WFPC2 Opmode: IMAGE Aperture: PC1 Sp_Element: F814W Wavelength: Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 260S Special_Requirements: POS TARG 0.75,0.75 Comments: Data_Distribution ! 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