Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 3969c Report Date: 09-May-96:19:00 Version: ********** Check-in Date: ********** 1.Proposal Title: OBSERVATIONS OF THE ECLIPSING MILLISECOND PULSAR SCIENCE OBSERVATIONS OF PROGRAM 2237 ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO 2237 Sub Category ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Jay Bookbinder CFA USA (617) 495-7058 ASTROPHYSICIST ------------------------------------------------------------------------------------ 7. Abstract FRUCHTER et al. (1988a) HAVE RECENTLY DISCOVERED a 1.6 MSEC PULSAR (PSR 1957+20) IN A 9.2 HOUR ECLIPSING BINARY SYSTEM. THE UNUSUAL BEHAVIOR OF THE DISPERSION MEASURE AS A FUNCTION OF ORBITAL PHASE, AND THE DISAPPEARANCE OF THE PULSAR SIGNAL FOR 50 MINUTES DURING EACH ORBIT, IMPLIES THAT THE ECLIPSES ARE DUE TO A PULSAR-INDUCED WIND FLOWING OFF OF THE COMPANION. THE OPTICAL COUNTERPART IS A 21ST MAGNITUDE OBJECT WHICH VARIES IN INTENSITY OVER THE BINARY PERIOD; ACCURATE GROUND-BASED OBSERVATIONS ARE PREVENTED BY THE PROXIMITY (0.7") OF A 20TH MAGNITUDE K DWARF. WE PROPOSE TO OBSERVE THE OPTICAL COUNTERPART IN A TWO-PART STUDY. FIRST, THE WF/PC WILL PROVIDE ACCURATE MULTICOLOR PHOTOMETRY, ENABLING US TO DETERMINE UNCONTAMINATED MAGNITUDES AND COLORS BOTH AT MAXIMUM (ANTI-ECLIPSE) AS WELL AS AT MINIMUM (ECLIPSE). SECOND, WE PROPOSE TO OBSERVE THE EXPECTED UV LINE EMISSION WITH FOS, ALLOWING FOR AN INTIAL DETERMINATION OF THE TEMPERATURE AND DENSITY STRUCTURE AND ABUNDANCES OF THE WIND THAT IS BEING ABLATED FROM THE COMPANION. STUDY OF THIS UNIQUE SYSTEM HOLDS ENORMOUS POTENTIAL FOR THE UNDERSTANDING OF THE RADIATION FIELD OF A MILLISECOND PULSAR AND THE EVOLUTION OF LMXRBs AND MSPs IN GENERAL. WE EXPECT THESE OBSERVATIONS TO PLACE VERY SIGNIFICANT CONTRAINTS ON MODELS OF THIS UNIQUE OBJECT. ------------------------------------------------------------------------------------ 8. Scientific Key Words: PULSARS, PULSARS: BINARY, PULSARS: MILLISECOND BINARIES: LOW MASS X-RAY, NEUTRON STARS. ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 7.42 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 3969c PI: Dr. Jay Bookbinder Proposal Title: OBSERVATIONS OF THE ECLIPSING MILLISECOND PULSAR SCIENCE OBSERVATIONS OF PROGRAM 2237 ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Prof. Joseph Taylor PRINCETON UNIVERSITY USA Prof. Phillip D. Judge COLORADO, UNIVERSITY OF USA P.I. Jay Bookbinder CFA USA Charles Bailyn CFA USA Prof. Andrew Fruchter DEPARTMENT OF TERRESTRIAL USA MAGNETISM, CARNEGIE INST. ------------------------------------------------------------------------------------ 3. Description of proposed observations. We are proposing two sets of science observations using the PC and FOS. Our science observations with the PC will be performed to obtain wide-band colors of the companion. RI colors will be obtained using the PC mode and the ``standard'' R, and I filters F675W, F791W. These observations consisting of the ``R'' and ``I'' bands will be obtained at eclipse (optical minimum). The goal of the PC observations is to acquire accurate color temperatures of the pulsar's optical companion. The magnitude and color of the companion at minimum can be used to constrain the geometry of the orbit, under the assumption that there is a lit and unlit face of the secondary. The observations at minimum may also allow us to deduce information about the intrinsic luminosity and nature of the secondary. Second, we propose to obtain a deep, low resolution FOS UV spectrum to obtain the overall flux levels in the UV regime, and to identify lines of C, O, S, Si, N, or He. To obtain this spectrum, we will use the low resolution G160L grating (6.5 A/diode over 1150 A -- 2523 A) and the blue digicon camera on the FOS. This configuration will provide high sensitivity with sufficient spectral resolution for this experiment. This region of the UV spectrum covers the transition region temperature lines of N V, C IV, Si IV, O IV], He II. The range of temperatures sampled is from 7000 to 2 x 10(5). Additionally, several lines that sample plasma at coronal temperatures may be present (e.g., Fe XXI 1354 A (at 10(7)K), Fe XII 1349 A (at 1.6 x 10(6)), OV 1371 A (about 2 x 10(5) K). Standard mode on the FOS will allow us to obtain a spectrum every four minutes. While we are unlikely to detect the pulsar in individual scans, it is possible that variability is present that we would be sensitive to. Page 3 ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. At maximum, the pulsar has a V magnitude of 20.3 (Fruchter et al 1988b), although confusion from the neighboring G star (0.7" away) makes this somewhat uncertain. Estimated exposure times are based on the WF/PC Instrument description, using conservative assumptions regarding both magnitude and flux distribution of the pulsar's optical companion. The requested PC observations at system maximum - 600 seconds with the F569W filter (approx. V-band) - will yield a magnitude error less than 5 percent. Since the magnitude and colors are totally unknown at optical minimum, we will apportion 1000 seconds to each of three I exposures and one R exposures. This will result in at least 5 sigma sensitivity down to 24 magnitude in I. Good astrometry of the field will be required to distinguish between the pulsar's optical counterpart and its near neighbor for the purpose of the FOS observation. This will be accomplished by scheduling the pulsar system maximum PC observations well before the FOS observation. Although our observations must be performed at specific orbital phases, there is a great deal of flexibility in scheduling the primary science observations, since the orbital period is 9.2 hours, and we are insensitive to which orbit(s) are selected for observation. However, we must obtain PC observations both at system maximum and minimum, and FOS observations at system maximum. An accurate ephemeris is available for detailed scheduling information. ------------------------------------------------------------------------------------ 11. Address Information Name: JAY BOOKBINDER Category: PI Institution: SMITHSONIAN ASTROPHYS. OBS. Address: 60 GARDEN STREET City: CAMBRIDGE State: MA Zip Code: 02138 Country: USA Telephone: Telex (or e-mail): ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 3969c [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial |Acqui|FLX| Flux data No | Name | Description | Position |Eqnx | Vel. |Prblm|REF| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 1 PSR1957+20 PULSAR, NEUTRON STAR, RA = 19H 59M 36.77S +/- 2000 COMP 1 B = 21.0 +/- 0.5 ECLIPSING- ECLIPSING BINARY 0.1S, 2 V = 20.3 +/- 0.5 MILLISECOND- INTERACTING BINARY DEC = +20D 48' 15.16" +/- 3 R = 19.4 +/- 0.5 PULSAR 1.0" 4 B-V = 1.0 +/- 0.3 5 A(V) = 1.5 +/- 1.0 6 E(B-V) = 0.5 +/- 0.35 Comments: B, V, R, B-V ARE AT MAX. LIGHT TOTAL VARIATION IS +/- 4 MAG ------------------------------------------------------------------------------------------------------------------------------------ 2 PSR1957+20- PULSAR, NEUTRON STAR, RA-OFF = -0.486S +/- 2000 COMP 1 B = 21.0 +/- 0.5 SPEC ECLIPSING BINARY 0.005S, 2 V = 20.3 +/- 0.5 ECLIPSING- INTERACTING BINARY DEC-OFF = +5.562" +/- 0.01", 3 R = 19.4 +/- 0.5 MILLISECOND- FROM 3 4 B-V = 1.0 +/- 0.3 PULSAR 5 A(V) = 1.5 +/- 1 6 E(B-V) = 0.5 +/- 0.35 Comments: B,V,R,B-V AT MAX. LIGHT TOTAL VARIATION IS +/- 4 MAG OFFSETS*FROM*TARGET*TO*OFFSET STAR ------------------------------------------------------------------------------------------------------------------------------------ 3 SOMESTAR- STAR RA = 19H 59M 36.296S +/- 2000 1 V = 16.00 +/- 0.5 OFFSET 0.01S, DEC = +20D 48' 20.03" +/- 0.02" Comments: STAR "B" ON FINDING CHRTS COORDINATES SUPPLIED BY STSCI FROM REDUCTION OF PC V MAXIMUM IMAGE ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3969c [ 5] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 7 SOMESTAR- FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR OFFSET PEAK 7.02 SPATIAL SCAN SEQ 7-8.1 NO GAP CYCLE 2 / 7.0-14.1 ------------------------------------------------------------------------------------------------------------------------------------ 7.02 SOMESTAR- FOS/BL ACQ/ 1.0 MIRROR 1 15S 1 1 ONBOARD ACQ FOR OFFSET PEAK 7.04 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 7.04 SOMESTAR- FOS/BL ACQ/ 0.5 MIRROR SCAN-STEP=0.35 1 20S 1 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE=3 7.10 ------------------------------------------------------------------------------------------------------------------------------------ 7.1 SOMESTAR- FOS/BL ACQ/ 0.25X2. MIRROR 1 200S 1 1 ONBOARD ACQ FOR OFFSET PEAK 0 8.0-8.1 SPATIAL SCAN Comments: THIS IS A CRITICAL PEAK-UP ------------------------------------------------------------------------------------------------------------------------------------ 8 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 ZERO-PHASE SPEC 0 2524 JD2447245.0846808 +/- 0.0001D PERIOD 33001.9167S +/- 0.0004S PHASE 0.65 +/- Comments: ORIENT +180 OK. OFFSET ANGLE OF 0.05 SLIT WAS 98.19D. PHASE IS FOR ORIENT 143.2D +/- START OF OBS. EXPOSURE MUST 5D OCCUR BETWN PHASES 0.60- DARK TIME 0.90.DARK TIME LESS IMPORTANT SEQ 8-8.1 NO GAP THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 8.1 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 SAME ORIENT FOR SPEC 0 2524 8.1 AS 8 DARK TIME Comments: ORIENT +180 OK. OFFSET ANGLE OF SLIT WAS 98.19D. PHASE IS FOR START OF OBS. EXPOSURE MUST OCCUR BETWN PHASES 0.60- 0.90.DARK TIME LESS IMPORTANT THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 9 SOMESTAR- FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR OFFSET PEAK 9.02 SPATIAL SCAN SEQ 9-10.1 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 9.02 SOMESTAR- FOS/BL ACQ/ 1.0 MIRROR 1 15S 1 1 ONBOARD ACQ FOR OFFSET PEAK 9.04 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 9.04 SOMESTAR- FOS/BL ACQ/ 0.5 MIRROR SCAN-STEP=0.35 1 20S 1 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE=3 9.10 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3969c [ 6] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 9.1 SOMESTAR- FOS/BL ACQ/ 0.25X2. MIRROR 1 200S 1 1 ONBOARD ACQ FOR OFFSET PEAK 0 10.0-10.1 SPATIAL SCAN Comments: THIS IS A CRITICAL PEAK-UP ------------------------------------------------------------------------------------------------------------------------------------ 10 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 ZERO-PHASE SPEC 0 2524 JD2447245.0846808 +/- 0.0001D PERIOD 33001.9167S +/- 0.0004S PHASE 0.65 +/- Comments: ORIENT +180 OK. OFFSET ANGLE OF 0.05 SLIT WAS 98.19D. PHASE IS FOR ORIENT 143.2D +/- START OF OBS. EXPOSURE MUST 5D OCCUR BETWN PHASES 0.60- DARK TIME 0.90.DARK TIME LESS IMPORTANT SEQ 10-10.1 NO GAP THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 10.1 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 SAME ORIENT FOR SPEC 0 2524 10.1 AS 10 DARK TIME Comments: ORIENT +180 OK. OFFSET ANGLE OF SLIT WAS 98.19D. PHASE IS FOR START OF OBS. EXPOSURE MUST OCCUR BETWN PHASES 0.60- 0.90.DARK TIME LESS IMPORTANT THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 11 SOMESTAR- FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR OFFSET PEAK 11.02 SPATIAL SCAN SEQ 11-12.1 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 11.02 SOMESTAR- FOS/BL ACQ/ 1.0 MIRROR 1 15S 1 1 ONBOARD ACQ FOR OFFSET PEAK 11.04 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 11.04 SOMESTAR- FOS/BL ACQ/ 0.5 MIRROR SCAN-STEP=0.35 1 20S 1 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE=3 11.10 ------------------------------------------------------------------------------------------------------------------------------------ 11.1 SOMESTAR- FOS/BL ACQ/ 0.25X2. MIRROR 1 200S 1 1 ONBOARD ACQ FOR OFFSET PEAK 0 12.0-12.1 SPATIAL SCAN Comments: THIS IS A CRITICAL PEAK-UP ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3969c [ 7] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 12 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 ZERO-PHASE SPEC 0 2524 JD2447245.0846808 +/- 0.0001D PERIOD 33001.9167S +/- 0.0004S PHASE 0.65 +/- Comments: ORIENT +180 OK. OFFSET ANGLE OF 0.05 SLIT WAS 98.19D. PHASE IS FOR ORIENT 143.2D +/- START OF OBS. EXPOSURE MUST 5D OCCUR BETWN PHASES 0.60- DARK TIME 0.90.DARK TIME LESS IMPORTANT SEQ 12-12.1 NO GAP THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 12.1 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 SAME ORIENT FOR SPEC 0 2524 12.1 AS 12 DARK TIME Comments: ORIENT +180 OK. OFFSET ANGLE OF SLIT WAS 98.19D. PHASE IS FOR START OF OBS. EXPOSURE MUST OCCUR BETWN PHASES 0.60- 0.90.DARK TIME LESS IMPORTANT THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ 13 SOMESTAR- FOS/BL ACQ/ 4.3 MIRROR 1 10S 1 1 ONBOARD ACQ FOR OFFSET PEAK 13.02 SPATIAL SCAN SEQ 13-14.1 NO GAP ------------------------------------------------------------------------------------------------------------------------------------ 13.02 SOMESTAR- FOS/BL ACQ/ 1.0 MIRROR 1 15S 1 1 ONBOARD ACQ FOR OFFSET PEAK 13.04 SPATIAL SCAN ------------------------------------------------------------------------------------------------------------------------------------ 13.04 SOMESTAR- FOS/BL ACQ/ 0.5 MIRROR SCAN-STEP=0.35 1 20S 1 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE=3 13.10 ------------------------------------------------------------------------------------------------------------------------------------ 13.1 SOMESTAR- FOS/BL ACQ/ 0.25X2. MIRROR 1 200S 1 1 ONBOARD ACQ FOR OFFSET PEAK 0 14.0-14.1 SPATIAL SCAN Comments: THIS IS A CRITICAL PEAK-UP ------------------------------------------------------------------------------------------------------------------------------------ 14 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 ZERO-PHASE SPEC 0 2524 JD2447245.0846808 +/- 0.0001D PERIOD 33001.9167S +/- 0.0004S PHASE 0.65 +/- Comments: ORIENT +180 OK. OFFSET ANGLE OF 0.05 SLIT WAS 98.19D. PHASE IS FOR ORIENT 143.2D +/- START OF OBS. EXPOSURE MUST 5D OCCUR BETWN PHASES 0.60- DARK TIME 0.90.DARK TIME LESS IMPORTANT SEQ 14-14.1 NO GAP THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 3969c [ 8] ------------------------------------------------------------------------------------------------------------------------------------ 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |10 | 11 | 12 |13 |14| 15 ------------------------------------------------------------------------------------------------------------------------------------ Line | Seq | Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | S/N |Flx|Pr| Special Number | Name | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| |Rel. Time|Ref| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 14.1 PSR1957+20- FOS/BL ACCUM 0.25X2. G160L 1150- 1 1320S 4 1 1 SAME ORIENT FOR SPEC 0 2524 14.1 AS 14 DARK TIME Comments: ORIENT +180 OK. OFFSET ANGLE OF SLIT WAS 98.19D. PHASE IS FOR START OF OBS. EXPOSURE MUST OCCUR BETWN PHASES 0.60- 0.90.DARK TIME LESS IMPORTANT THAN PHASE, ORIENT ------------------------------------------------------------------------------------------------------------------------------------ Scan Paramters Form Proposal ID: 3969c [ 9] ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 1 Exposure Logsheet lines: 7.0, 9.0, 11.0, 13.0 FGS Scan: DWELL Dwell Only: dwell points/line: 3 Seconds per dwell: 1.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 2.8000 Angle between sides (degrees) 90.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 0.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.4000 Width Offset (arc-sec): 0.000 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 2 Exposure Logsheet lines: 7.02, 9.02, 11.02, 13 FGS Scan: DWELL Dwell Only: dwell points/line: 6 Seconds per dwell: 1.00 Scan width (arc-secs): 0.7000 Scan length (arc-secs): 3.5000 Angle between sides (degrees) 90.00 Number of lines: 2 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 1.7500 Width Offset (arc-sec): 0.3500 ------------------------------------------------------------------------------------------------------------------------------------ Data ID: 3 Exposure Logsheet lines: 7.1, 9.1, 11.1, 13.1 FGS Scan: DWELL Dwell Only: dwell points/line: 7 Seconds per dwell: 1.00 Scan width (arc-secs): 0.0000 Scan length (arc-secs): 0.4000 Angle between sides (degrees) 0.00 Number of lines: 1 Scan rate (arc-sec/sec): 0.0000 PA of first scan line (degrees) 90.000 Scan frame (CEL or S/C): S/C Length Offset (arc-sec): 0.2000 Width Offset (arc-sec): 0.00 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 3969c [ 10] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/BL ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SCAN-STEP=0.35 SEARCH-SIZE=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 7.42 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 7.02; SPATIAL SCAN; SEQ 7-8.1 NO GAP; CYCLE 2 / 7.0-14.1 ONBOARD ACQ FOR 7.04; SPATIAL SCAN ONBOARD ACQ FOR 7.10 ONBOARD ACQ FOR 8.0-8.1; ZERO-PHASE JD2447245.0846808 +/- 0.0001D; PERIOD 33001.9167S +/- 0.0004S; PHASE 0.65 +/- 0.05; ORIENT 143.2D +/- 5D; DARK TIME; SEQ 8-8.1 NO GAP; SAME ORIENT FOR 8.1 AS 8; ONBOARD ACQ FOR 9.02; SEQ 9-10.1 NO GAP ONBOARD ACQ FOR 9.04; ONBOARD ACQ FOR 9.10 ONBOARD ACQ FOR 10.0-10.1; SEQ 10-10.1 NO GAP; SAME ORIENT FOR 10.1 AS 10; ONBOARD ACQ FOR 11.02; SEQ 11-12.1 NO GAP ONBOARD ACQ FOR 11.04; ONBOARD ACQ FOR 11.10 ONBOARD ACQ FOR 12.0-12.1; SEQ 12-12.1 NO GAP; SAME ORIENT FOR 12.1 AS 12; ONBOARD ACQ FOR 13.02; SEQ 13-14.1 NO GAP ONBOARD ACQ FOR 13.04; ONBOARD ACQ FOR 13.10 ONBOARD ACQ FOR 14.0-14.1; SEQ 14-14.1 NO GAP; SAME ORIENT FOR 14.1 AS 14; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G160L ------------------------------------------------------------------------------------------------------------------------------------ Target Names PSR1957+20 ECLIPSING-MILLISECOND-PULSAR PSR1957+20-SPEC SOMESTAR-OFFSET ------------------------------------------------------------------------------------------------------------------------------------