9467( 2) - 03/08/02 12:58 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9467 Version: 2 Check-in Date: 14-Feb-2002 18:26:28 1.Proposal Title: The Enigmatic Central Object of the RCW 103 Supernova Remnant ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 11 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Divas Sanwal The Pennsylvania State University CoI: Dr. George Pavlov Pennsylvania State University N CoI: Prof. Gordon Garmire Pennsylvania State University N CoI: Dr. Audry Garmire Pennsylvania State University N CoI: Dr. Roberto Mignani European Southern Observatory N ------------------------------------------------------------------------------------ 5. Abstract X-ray observations of the young (2, 000 yrs) supernova remnant RCW 103 have revealed an enigmatic central object, originally claimed to be an isolated neutron star. However, long-term variability and 6-hr periodicity hint that this may be an accreting neutron star or a black hole, perhaps in a low-mass X-ray binary. Previous optical observations with 4-m class telescopes failed to find an optical counterpart (R >~ 24, V >~ 25.5). Recent near-IR observations with the CTIO/OSIRIS and VLT- UT1/ISAAC revealed four objects within about 2'' radius circle around the X-ray position. One of these objects -- which is 0arcs6 from the X-ray source position -- is a plausible candidate for the IR counterpart of the X-ray source. To verify this hypothesis and understand the nature of the X-ray source, we propose deep imaging with NICMOS. An IR counterpart, variable at the X-ray period, and with brightness and broad-band spectrum consistent with a stellar object, would identify the source as an accreting binary with a subluminous companion. This would be the first discovery of a binary system inside a young SNR. Alternatively, a faint counterpart with a peculiar spectrum would indicate the presence of a long-hypothesized residual disk leftover after the supernova explosion. ------------------------------------------------------------------------------------ 9467( 2) - 03/08/02 12:58 - [ 2] Observations Description ------------------------ Because IR observations are much more efficient than optical ones at high extinction, we propose to use the NICMOS. The most suitable camera is NIC2 because it provides a high angular resolution and allows one to observe the target at longer wavelengths (close to the K band). The need to measure the candidate's magnitudes with high S/N, for both accurate absolute photometry and search for small temporal variations, or to go really deep if the candidate appears to be a field star, requires broad filters. We choose F160W (close to H band) as a primary filter to investigate temporal variations because it provides the highest S/N. At the H magnitude of about 20, we reach S/N = 30 in about 300 second exposure with the F160W filter. To avoid the saturation of nearby stars and large diffraction spikes, we propose to limit each exposure to 150 seconds. This will give us 13 exposures per orbit, including overheads (acquisition, readout in the MULTIACCUM mode and dithering), and a S/N ~ 20 for each exposure (which would allow us to pinpoint variations of ~0.05 magnitude). To achieve about 60% phase coverage at the putative six-hour period, eight consecutive orbits are needed, accounting for earth occultations. A large phase coverage is important to look for small amplitude variabilities and to avoid the effects of aliasing in a sparsely sampled light curve. The requested eight orbits with the F160W filter will allow us to search for both periodic and aperiodic variabilities from the counterpart candidate. To measure the colors, we propose to observe the field with two more filters, F110W (close to J) and F205W (close to K), one orbit each. To avoid saturation of the nearby brighter stars, each orbit will be divided into 10 exposures of 200 seconds. This gives a S/N=12 and 20 per exposure and S/N=40 and 60 for the combined data, for the currently estimated J ~ 22.3 and K ~ 19 magnitudes of the counterpart candidate, respectively. If the IR counterpart fades or the candidate turns out to be a field star, we need to go much deeper to detect a counterpart to the X- ray source. In these cases, the combined HST data will allow us to detect the source at S/N = 5 up to the limiting magnitudes J ~ 24.5, H ~ 25, and K ~ 22. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 9467( 2) - 03/08/02 12:58 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 RCW103CCO STAR, X-RAY TRANSIENT, RA=16H 17M 36.26S +/- 1", DEC=- J2000 J = 22.3+/-0.5 NEUTRON STAR 51D 2' 25.0" +/- 1" H = 19.6+/-0.5 K = 18.5+/-0.5 Coordinate Source: OTHER_SOURCE 9467( 2) - 03/08/02 12:58 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type SPIRAL Pattern_Purpose OTHER Number_Of_Points 9 Point_Spacing 2.318 Coordinate_Frame POS-TARG Pattern_Orient 0.4696 Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 9467( 2) - 03/08/02 12:58 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 15D TO 40D ORIENT 60D TO 80D ORIENT 105D TO 130D ORIENT 150D TO 170D ORIENT 195D TO 220D ORIENT 240D TO 260D ORIENT 285D TO 310D ORIENT 330D TO 350D On Hold Comments: Additional Comments: ORIENT constrain is needed to ensure that the diffraction spikes from the nearby bright stars do not fall on the target. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 1 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 2 CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 3 CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 4 CUM ------------------------------------------------------------------------------------------------------------------------------------ 5 RCW103CCO NIC2 MULTIAC NIC2 F110W NSAMP=18,SAMP-SEQ=STEP8 1 DEF PATTERN 1 5 CUM ------------------------------------------------------------------------------------------------------------------------------------ 6 RCW103CCO NIC2 MULTIAC NIC2 F205W NSAMP=12,SAMP-SEQ=STEP8 2 DEF PATTERN 1 6 CUM ------------------------------------------------------------------------------------------------------------------------------------ 9467( 2) - 03/08/02 12:58 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 15D TO 40D ORIENT 105D TO 130D ORIENT 195D TO 220D ORIENT 285D TO 310D ORIENT 60D TO 80D ORIENT 150D TO 170D ORIENT 240D TO 260D ORIENT 330D TO 350D On Hold Comments: Additional Comments: ORIENT constrain is needed to ensure that the diffraction spikes from the nearby bright stars do not fall on the target. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 1 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 2 CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 3 CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 RCW103CCO NIC2 MULTIAC NIC2 F160W NSAMP=15,SAMP-SEQ=STEP16 2 DEF PATTERN 1 4 CUM ------------------------------------------------------------------------------------------------------------------------------------ 5 RCW103CCO NIC2 MULTIAC NIC2 F110W NSAMP=18,SAMP-SEQ=STEP8 1 DEF PATTERN 1 5 CUM ------------------------------------------------------------------------------------------------------------------------------------ 6 RCW103CCO NIC2 MULTIAC NIC2 F205W NSAMP=12,SAMP-SEQ=STEP8 2 DEF PATTERN 1 6 CUM ------------------------------------------------------------------------------------------------------------------------------------ 9467( 2) - 03/08/02 12:58 - [ 7] Summary Form for Proposal 9467 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations NIC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=15 SAMP-SEQ=STEP16 SAMP-SEQ=STEP8 NSAMP=12 NSAMP=18 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 15D TO 40D ORIENT 60D TO 80D ORIENT 105D TO 130D ORIENT 150D TO 170D ORIENT 195D TO 220D ORIENT 240D TO 260D ORIENT 285D TO 310D ORIENT 330D TO 350D PATTERN 1 1 PATTERN 1 2 PATTERN 1 3 PATTERN 1 4 PATTERN 1 5 PATTERN 1 6 ORIENT 15D TO 40D ORIENT 105D TO 130D ORIENT 195D TO 220D ORIENT 285D TO 310D ORIENT 60D TO 80D ORIENT 150D TO 170D ORIENT 240D TO 260D ORIENT 330D TO 350D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W F110W F205W ------------------------------------------------------------------------------------------------------------------------------------ Target Names RCW103CCO ------------------------------------------------------------------------------------------------------------------------------------