10791( 4) - 03/09/07 10:17 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 10791 Version: 4 Check-in Time: 09-Mar-2007 15:17:09 STScI Edit Number: 0 Title Proper motion may nail counterpart of unique X-ray pulsar ------------------------------------------------------------------------------------ Type Cycle Parallel Pointing Tolerance GO 15 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Andrea DeLuca CNR, Istituto di Astrofisica Spaziale CoI: Dr. Roberto Mignani Mullard Space Science Laboratory Y CoI: Dr. Patrizia A. Caraveo CNR, Istituto di Astrofisica Spaziale N CoI: Prof. Giovanni F. Bignami CESR N CoI: Dr. Sandro Mereghetti CNR, Istituto di Astrofisica Spaziale N ------------------------------------------------------------------------------------ Abstract 1E 1207.4-5209 is one of the most puzzling X-ray compact sources in the Galaxy. Long known to be a radio-quiet Neutron Star (NS) embedded in a young (~7000 y) supernova remnant, it displays a unique phenomenology, including multiple cyclotron absorption features in its thermal X-ray spectrum, as well as a possible non-monotonous evolution of its 424 ms rotational period. A candidate optical counterpart (I~23.4) with very red colours (not consistent with the expected emission of a NS, but rather with a low-mass stellar companion, or a fossil disk) was singled out with HST/ACS in 2003, at the margin of the Chandra error box. In order to test the reality of such an association, we propose to take advantage of the high space velocities characteristics of NSs to search for the expected displacement (~150 mas in the NE direction) of the candidate counterpart over a 3 years time span. One orbit observation, either unveiling the displacement or ruling it out, will settle the problem of the optical identification of 1E1207.4-5209. We stress that a null result would also be important for the understanding of this source. ------------------------------------------------------------------------------------ 10791( 4) - 03/09/07 10:17 - [ 2] Observations Description ------------------------ We plan to performaccurate positioning of the pulsar 1E1207-5209 accurate counterpart with the ACS/WFC Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 10791( 4) - 03/09/07 10:17 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 1E1207-5209 STAR, PULSAR RA=12H10M0.8260S +/- 0.1", DEC=- J2000 V = 26.8+/-0.2 52D26'28.43" +/- 0.1" Reference Frame: ICRS 10791( 4) - 03/09/07 10:17 - [ 4] Visit: 01 Visit Priority: Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 1E1207-5209 WFPC2 IMAGE PC1-FIX F814W 2 1000 S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 1E1207-5209 1 WFPC2 IMAGE PC1-FIX F814W none none 1 1 1 N/A 1E1207-5209 1 WFPC2 IMAGE PC1-FIX F814W none none 1 2 1 N/A 1E1207-5209 1 WFPC2 IMAGE PC1-FIX F814W none none 2 1 1 N/A 1E1207-5209 1 WFPC2 IMAGE PC1-FIX F814W none none 2 2 1 N/A 10791( 4) - 03/09/07 10:17 - [ 5] Summary Form for Proposal 10791 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 1E1207-5209 ------------------------------------------------------------------------------------------------------------------------------------