9364( 2) - 02/12/02 07:24 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9364 Version: 2 Check-in Date: 12-Feb-2002 07:22:52 1.Proposal Title: The Parallaxes and Proper Motions of Two Nearby Neutron Stars ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: David Kaplan California Institute of Technology CoI: Prof. S. Kulkarni California Institute of Technology N CoI: Dr. Marten van Kerkwijk Utrecht University N ------------------------------------------------------------------------------------ 5. Abstract We propose to measure the parallax of two nearby neutron stars to the highest possible level of accuracy, ~\.0.5 mas. The primary goal is to determine the neutron -star radius at infinity with better than 1 km precision, and therewith obtain a direct constraint on the equation of state of matter at supra-nuclear density. The required flux and temperature determinations are easiest for the so-called isolated or radio-quiet neutron stars because of their apparently completely thermal spectrum. We argue that the importance of the possible results warrants a study to the best possible level of the best possible sources, and request 24 orbits for the two brightest isolated neutron stars, RX J1856.5-3754 and RX J0720.4-3125. We will also determine whether the enigmatic RX J0720.4-3125 is an old magnetar or an accreting source, based on its luminosity and proper motion. ------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 2] Observations Description ------------------------ Our goal is to determine accurate parallaxes and proper motions of RX J1856.5- 3754 and RX J0720.4-3125. With 8 observations of each source over two years, combined with existing data, we should be able to uniquely and robustly measure the parallax and proper motion. The observations for an individual source should be separated by approximately 3 months, but the technique is sufficiently reliable that the dates need not be very specific; for example, the limited visibility of RX J1856.5-3754 during the winter can be easily accomodated. Having four observations per year and not just two at the parallactic maxima is important not only to allow one to test for possible systematic effects (e.g., brightness dependent position shifts due to CTE), but also to resolve correlations between proper motion and parallax (see Walter 2001). The measurements furthest from parallactic maxima are used to tightly constrain the proper motions of both the source and background stars. We request measurements in two years to demonstrate repeatability, increase the baseline for the background proper motion measurements, and to increase the signal-to-noise ratio of the overall fit. Real Time Justification ----------------------- To properly measure the parallaxes of these sources, we require 4 visits per year to obtain good coverage of parallactic angles. The most important observations are near the parallactic maxima: April and October for RX J0720.4- 3125, and March and September for RX J1856.5-3754. The other two observations are scheduled as close as possible to times 3 months away from the parallactic maxima, but in the case of RX J1856.5-3754 they were moved to accomodate limited visibility. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RXJ1856.5- STAR, NEUTRON STAR RA=18H 56M 35.60S +/- 0.2", DEC= J2000 V = 25.6+/-0.02 3754 -37D 54' 36.2" +/- 0.2" Coordinate Source: HST_IMAGE 2 RXJ0720.4- STAR, NEUTRON STAR RA=07H 20M 24.52S +/- 0.2", DEC= J2000 B = 26.6+/-0.2 3125 -31D 25' 52.4" +/- 0.2" Coordinate Source: OTHER_SOURCE 9364( 2) - 02/12/02 07:24 - [ 4] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 01-Sep-2002 AND 01-Oct-2002 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 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S 754 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0070 754 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0, 0.0620 754 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0690 754 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 5] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 01-Nov-2002 AND 01-Jan-2003 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 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S 754 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0070 754 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0, 0.0620 754 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0690 754 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 6] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 01-Mar-2003 AND 15-Apr-2003 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 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S 754 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0070 754 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0, 0.0620 754 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0690 754 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 7] Visit: 04 Visit Priority: Visit Requirements: BETWEEN 15-May-2003 AND 15-Jul-2003 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 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S 754 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0070 754 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0, 0.0620 754 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ1856.5-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 620 S POS TARG 0.0707, 0.0690 754 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 8] Visit: 10 Visit Priority: Visit Requirements: BETWEEN 15-Jun-2002 AND 30-Jul-2002 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 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S 125 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.0637, 0.0621 125 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1273, 0.1242 125 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1910, 0.1863 125 C ------------------------------------------------------------------------------------------------------------------------------------ 20 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0318, 0.1426 125 C ------------------------------------------------------------------------------------------------------------------------------------ 21 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0955, 0.2047 125 C ------------------------------------------------------------------------------------------------------------------------------------ 22 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.1592, 0.0436 125 C ------------------------------------------------------------------------------------------------------------------------------------ 23 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.2229, 0.1057 125 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 9] Visit: 11 Visit Priority: Visit Requirements: BETWEEN 15-Sep-2002 AND 30-Oct-2002 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 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S 125 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.0637, 0.0621 125 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1273, 0.1242 125 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1910, 0.1863 125 C ------------------------------------------------------------------------------------------------------------------------------------ 20 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0318, 0.1426 125 C ------------------------------------------------------------------------------------------------------------------------------------ 21 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0955, 0.2047 125 C ------------------------------------------------------------------------------------------------------------------------------------ 22 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.1592, 0.0436 125 C ------------------------------------------------------------------------------------------------------------------------------------ 23 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.2229, 0.1057 125 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 10] Visit: 12 Visit Priority: Visit Requirements: BETWEEN 15-Dec-2002 AND 30-Jan-2003 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 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S 125 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.0637, 0.0621 125 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1273, 0.1242 125 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1910, 0.1863 125 C ------------------------------------------------------------------------------------------------------------------------------------ 20 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0318, 0.1426 125 C ------------------------------------------------------------------------------------------------------------------------------------ 21 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0955, 0.2047 125 C ------------------------------------------------------------------------------------------------------------------------------------ 22 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.1592, 0.0436 125 C ------------------------------------------------------------------------------------------------------------------------------------ 23 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.2229, 0.1057 125 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 11] Visit: 13 Visit Priority: Visit Requirements: BETWEEN 15-Mar-2003 AND 30-Apr-2003 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 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S 125 C ------------------------------------------------------------------------------------------------------------------------------------ 11 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.0637, 0.0621 125 C ------------------------------------------------------------------------------------------------------------------------------------ 12 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1273, 0.1242 125 C ------------------------------------------------------------------------------------------------------------------------------------ 13 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 600 S POS TARG 0.1910, 0.1863 125 C ------------------------------------------------------------------------------------------------------------------------------------ 20 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0318, 0.1426 125 C ------------------------------------------------------------------------------------------------------------------------------------ 21 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.0955, 0.2047 125 C ------------------------------------------------------------------------------------------------------------------------------------ 22 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.1592, 0.0436 125 C ------------------------------------------------------------------------------------------------------------------------------------ 23 RXJ0720.4-3 ACS/HR ACCUM HRC F475W CR-SPLIT=NO 1 630 S POS TARG 0.2229, 0.1057 125 C ------------------------------------------------------------------------------------------------------------------------------------ 9364( 2) - 02/12/02 07:24 - [ 12] Summary Form for Proposal 9364 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures HRC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/HRC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-Sep-2002 AND 01-Oct-2002 POS TARG 0.0707, 0.0070 POS TARG 0.0, 0.0620 POS TARG 0.0707, 0.0690 BETWEEN 01-Nov-2002 AND 01-Jan-2003 BETWEEN 01-Mar-2003 AND 15-Apr-2003 BETWEEN 15-May-2003 AND 15-Jul-2003 BETWEEN 15-Jun-2002 AND 30-Jul-2002 POS TARG 0.0637, 0.0621 POS TARG 0.1273, 0.1242 POS TARG 0.1910, 0.1863 POS TARG 0.0318, 0.1426 POS TARG 0.0955, 0.2047 POS TARG 0.1592, 0.0436 POS TARG 0.2229, 0.1057 BETWEEN 15-Sep-2002 AND 30-Oct-2002 BETWEEN 15-Dec-2002 AND 30-Jan-2003 BETWEEN 15-Mar-2003 AND 30-Apr-2003 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F475W ------------------------------------------------------------------------------------------------------------------------------------ Target Names RXJ1856.5-3754 RXJ0720.4-3125 ------------------------------------------------------------------------------------------------------------------------------------