! File: 3579C.PROP ! Database: PEPDB ! Date: 19-FEB-1994:12:40:41 coverpage: title_1: THE UV ORBITAL LIGHT CURVE OF THE X-RAY BINARY X1822-371 sci_cat: STELLAR ASTROPHYSICS sci_subcat: X-RAY BINARIES proposal_for: GO pi_fname: KEITH pi_mi: O. pi_lname: MASON pi_inst: MULLARD SPACE SCIENCE LABORATORY pi_country: UK pi_phone: 44-483-274111 hours_pri: 6.00 num_pri: 1 fos: Y funds_amount: 47070 funds_length: 12 off_fname: J. off_mi: L. off_lname: CULHANE off_title: DIRECTOR off_inst: MULLARD SPACE SCIENCE LABORATORY off_addr_1: HOLMBURY ST.MARY off_addr_2: DORKING off_city: SURREY off_state: RH5 off_zip: 6NT off_country: UK off_phone: (44) 483 274111 ! end of coverpage abstract: line_1: We are proposing to obtain the first far-UV orbital light curve of line_2: an eclipsing low-mass X-ray binary by making FOS observations of line_3: the V=15 system X1822-371. The shape of the UV light curve as a line_4: function of energy will be used to determine the geometry of the line_5: hottest, X-ray illuminated parts of the accretion disk and will line_6: provide information that is crucial to determining whether line_7: the disk in this X-ray binary has a thick, structured rim. line_8: The FOS data will also permit us to construct light curves of the line_9: flux in the high excitation UV emission lines such as CIV 1549 and line_10: NV 1249, allowing us to determine where they are formed in the line_11: system and investigate how they are excited. This will be the line_12: first detailed study of UV orbital variations in a member of this line_13: important class of X-ray binary, and can only be done with HST. line_14: This proposal was approved at supplemental priority in cycle~1 line_15: but has not yet been scheduled. ! ! end of abstract general_form_proposers: lname: MASON fname: KEITH title: PI mi: O. inst: MULLARD SPACE SCIENCE LABORATORY country: U.K. esa: Y ! lname: CHARLES fname: PHILIP mi: A. inst: UNIVERSITY OF OXFORD country: U.K. esa: Y ! lname: CORDOVA fname: FRANCE mi: A. inst: PENNSYLVANIA STATE UNIVERSITY country: U.S.A. esa: N ! lname: ILOVAISKY fname: SERGIO inst: OBSERVATOIRE HAUTE PROVINCE country: FRANCE esa: Y ! lname: VAN PARADIJS fname: JAN inst: UNIVERSITY OF AMSTERDAM country: NETHERLANDS esa: Y ! lname: THORSTENSEN fname: JOHN inst: DARTMOUTH COLLEGE country: U.S.A. ! ! end of general_form_proposers block general_form_text: question: 3 section: 1 line_1: WE WISH TO USE THE FOS WITH BLUE DIGICON AND G160L DISPERSER TO line_2: MEASURE THE 1200-2400A SPECTRUM OF THE LOW MASS X-RAY BINARY line_3: X1822-371 AS A FUNCTION OF PHASE IN ITS 5.57H ORBITAL CYCLE. WE line_4: ARE PRIMARILY INTERESTED IN CONTINUUM VARIATIONS SO WILL USE THE line_5: 4.3 ARCSEC APERTURE. UNIFORM PHASE COVERAGE OF THE BINARY IS line_6: HIGHLY DESIRABLE AND CAN BE ACHIEVED WITHOUT TIME CRITICAL line_7: OBSERVATIONS BY OBSERVING IN CONTIGUOUS HST ORBITS. THIS IS line_8: BECAUSE THE X1822-371 BINARY PERIOD AND THE HST ORBITAL PERIOD line_9: ARE NOT COMMENSURATE; THEIR RATIO IS ABOUT 3.7. THUS ASSUMING line_10: A 50% DUTY CYCLE, UNIFORM PHASE COVERAGE WILL BE GUARANTEED BY line_11: OBSERVATIONS IN A CONTIGUOUS SET OF 8-9 HST ORBITS. I.E. GAPS IN line_12: THE BINARY PHASE COVERAGE ON THE FIRST SET OF FOUR CONTIGUOUS HST line_13: ORBITS WILL BE MOSTLY FILLED IN ON THE NEXT FOUR, WHICH ARE 1 line_14: BINARY CYCLE LATER. IF CONTIGUOUS ORBITS ARE NOT AVAILABLE THEN line_15: MANY OF THE SCIENTIFIC AIMS ARE LIKELY TO BE ACHIEVED BY line_16: OBSERVATIONS IN RANDOMLY DISTRIBUTED ORBITS, BUT UNIFORM PHASE line_17: COVERAGE IS UNLIKELY. HAVING AS MANY CONTIGUOUS HST ORBITS AS line_18: POSSIBLE IS ALWAYS DESIRABLE THOUGH. line_19: IN THE OPTICAL X1822-371 VARIES BETWEEN V=15.2 AND V=16.2 WITH A line_20: QUASI-SINUSOIDAL LIGHT CURVE. NOTE THAT THE TOTAL OBSERVING TIME line_21: IS DETERMINED BY THE NEED TO COVER THE 5.57 HOUR BINARY CYCLE line_22: RATHER THAN S/N CONSIDERATIONS. ! question: 4 section: 1 line_1: The investigation we propose can only be done in the UV where there line_2: is no contamination from cool disk radiation, and it therefore must line_3: be done from space. We have already tried using IUE to measure the line_4: UV continuum and line-flux light curves of X1822-371 (Mason and line_5: Cordova 1982a), but the best time resolution possible with that line_6: instrument for a source as faint as X1822-371 (V=15.5) was line_7: sufficient only to divide the 5.57 hour orbital cycle into 3 phase line_8: bins. The resulting data are consistent with the type of behavior we line_9: expect, indicating that our ideas are not widely wrong, but the line_10: crude phase resolution is not sufficient to advance our line_11: understanding of the source further. The only way to make line_12: significant progress with this problem is to observe with HST. ! question: 5 section: 1 line_1: No special scheduling or constraints are required, although line_2: contiguous spacecraft orbits are very desirable to ensure uniform line_3: orbital phase coverage as discussed in Q3. ! question: 6 section: 1 line_1: None other than already discussed in Q3 and Q5. ! question: 7 section: 1 line_1: Standard techniques for wavelength and flux calibration of the FOS line_2: spectra should be adequate. We will use the modelling code developed line_3: by Hellier and Mason (1989) to aid interpretation of the data. ! question: 8 section: 1 line_1: Ground based photometry will be scheduled as near as possible to the line_2: time of the HST observation to check for long-term variations in the line_3: light curve (although none have been seen in ~12 years of monitoring line_4: of the source thus far) and to update the ephemeris for optimum line_5: comparison of the light curves in the various wavelength bands. line_6: Since members of the consortium have regular access to ground-based line_7: telescopes this will not impact the HST scheduling. ! question: 9 section: 1 line_1: N/A ! question: 10 section: 1 line_1: All members of the consortium routinely have access to DEC Vax line_2: computers and/or Sun workstations dedicated to astronomical data line_3: reduction, and running IRAF or equivalent data analysis environments line_4: capable of supporting SDAS. All members are linked by computer line_5: networks and have considerable experience of working closely line_6: together `at a distance'. A number of us supervise graduate students line_7: who can be involved in reducing and analyzing HST observations. We line_8: anticipate a 2-3 day visit by (2 of) the team to familiarize line_9: ourselves with the SDAS environment and the latest data analysis line_10: techniques for FOS data. All members of the consortium have line_11: considerable experience working in X-ray binary research. ! !end of general form text general_form_address: lname: MASON fname: KEITH mi: O. category: PI inst: MULLARD SPACE SCIENCE LABORATORY addr_1: HOLMBURY ST.MARY addr_2: DORKING city: SURREY state: SU zip: RH5 6NT country: UK phone: (44) 483 274111 telex: 859185 ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: X1822-371 name_2: V691CRA descr_1: A, 165, 906 pos_1: RA = 18H 25M 46.75S +/- 0.03S, pos_2: DEC = -37D 06' 19.8" +/- 0.5", pos_3: PLATE-ID=060G equinox: J2000 pos_epoch_bj: J pos_epoch_yr: 1984.00 comment_1: MEAN FLUXES QUOTED. comment_2: ERRORS ON FLUX VALUES REFLECT comment_3: RANGE OF STAR'S ORBITAL comment_4: VARIABILITY. fluxnum_1: 1 fluxval_1: V=15.7 +/- 0.5 fluxnum_2: 2 fluxval_2: F-CONT(1300) = 2.5 +/- 1.0 E-14 fluxnum_3: 3 fluxval_3: F-CONT(1900) = 1.8 +/- 1.0 E-14 fluxnum_4: 4 fluxval_4: E(B-V) = 0.2 +/- 0.1 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: X1822-371 config: FOS/BL opmode: ACQ/BINARY aperture: 4.3 sp_element: MIRROR num_exp: 1 time_per_exp: 5.5S fluxnum_1: 1 fluxnum_2: 4 priority: 1 req_1: CYCLE 2; req_2: ONBOARD ACQ FOR 2-10; comment_1: TARGET ACQUISITION. comment_2: EFFECTIVE TEMPERATURE OF B2 STAR comment_3: ASSUMED. NOTE STAR IS VARIABLE BY comment_4: +/- 0.5 MAG ABOUT THE MEAN USED. ! linenum: 2.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: GROUP 2-10 NO GAP; req_2: CYCLE 2; comment_1: REF NO GAP REQUIREMENT: CONTIGUOUS comment_2: S/C ORBITS YIELD OPTIMUM BINARY PHASE comment_3: COVERAGE AND ARE THUS VERY DESIRABLE. comment_4: SEE Q3 FOR MORE DETAIL. comment_5: EXPOSURE TIME DICTATED BY LENGTH OF comment_6: BINARY CYCLE RATHER THAN BY S/N. ! linenum: 3.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 4.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 5.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 6.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 7.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 8.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 9.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 40M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! linenum: 10.000 targname: X1822-371 config: FOS/BL opmode: RAPID aperture: 4.3 sp_element: G160L wavelength: 1850 num_exp: 1 time_per_exp: 39M s_to_n: 5.5 s_to_n_time: 4M fluxnum_1: 2 priority: 1 param_1: READ-TIME = 60 req_1: CYCLE 2; ! ! end of exposure logsheet ! No scan data records found