! File: 4165C.PROP ! Database: PEPDB ! Date: 20-FEB-1994:11:41:23 coverpage: title_1: ASTROMETRY OF THE 4U1543-47 X-RAY title_2: TRANSIENT OPTICAL COUNTERPART sci_cat: STELLAR ASTROPHYSICS sci_subcat: X-RAY BINARIES proposal_for: GO/DD targ_of_opp: Y pi_title: DR. pi_fname: SERGIO pi_mi: A. pi_lname: ILOVAISKY pi_inst: OBSERVATOIRE DE HAUTE-PROVENCE pi_country: FRANCE pi_phone: (33)92706400 keywords_1: X-RAY TRANSIENTS, OPTICAL COUNTERPARTS keywords_2: ASTROMETRY hours_pri: 0.28 num_pri: 1 wf_pc: Y pi_position: DIRECT. DE RECHERCHE off_fname: PHILIPPE off_lname: VERON off_title: DR. off_inst: OBSERVATOIRE DE HAUTE-PROVENCE off_city: ST.MICHEL L'OBSERV. off_zip: 04870 off_country: FRANCE off_phone: (33)92706400 off_telex: 410690F ! end of coverpage abstract: line_1: We propose to obtain relative WF/PC astrometry line_2: of the optical counterpart of the 4U1543-47 line_3: soft X-ray transient, currently in outburst. line_4: Ground-based observations made in 1989 during line_5: the quiescent state show that an apparently line_6: normal V=16.7 A-type star is located (within line_7: +/- 0.1 arc-sec) at the position of the V=14.6 line_8: image seen during outburst. While it is highly line_9: unlikely that the A star is the companion of line_10: the X-ray source, it appears nevertheless to be line_11: located at the same distance from us. Accurate line_12: relative astrometry between images obtained line_13: with the WF/PC during outburst and later, during line_14: quiescence, will allow us to find whether or not, line_15: on the basis of position alone, the A-star is line_16: somehow related to the X-ray source. If not, the line_17: images may allow us to discover the true optical line_18: counterpart of 4U1543-47. ! ! end of abstract general_form_proposers: lname: CHEVALIER fname: CLAUDE title: DR. inst: OBSERVATOIRE DE HAUTE-PROVENCE country: FRANCE esa: Y ! lname: PEDERSEN fname: HOLGER title: DR. inst: COPENHAGEN UNIVERSITY OBSERVATORY country: DANEMARK esa: Y ! ! end of general_form_proposers block general_form_text: question: 2 section: 1 line_1: 4U1543-47 is an X-ray transient which has been line_2: observed in outburst in 1971 and 1983. It is now line_3: (May 1992) in outburst again (IAUC 5512). From its line_4: ultra soft X-ray spectrum it is considered a black line_5: hole candidate, similar to A0620-00 and GS2000+25. line_6: During the 1983 outburst EXOSAT observed the source line_7: (Blisset 1983, van der Woerd et al. 1989) and it line_8: was subsequently identified by Pedersen et al. line_9: (1983) with a V=14.6 object with the characteristic line_10: emission lines of low-mass X-ray binaries. line_11: However, comparison with ESO Schmidt plates taken line_12: during quiescence showed that the object had line_13: brightened by only 1 magnitude. This was line_14: surprising for such a type of transient where line_15: optical amplitudes of 6 magnitudes or more are line_16: common. ! question: 2 section: 2 line_1: Optical observations made by us at ESO during line_2: quiescence in 1989 (Chevalier 1989) reveal that line_3: the V=16.7 star appearing at the location of the line_4: outburst image is a normal-looking A-type star. line_5: Spectra show interstellar features remarkably line_6: similar to those seen in the outburst spectrum, line_7: suggesting that both the A-star and the X-ray line_8: source are located at 4kpc (or beyond). line_9: Astrometry made by comparing the 1983 and 1989 line_10: CCD frames taken at the 1.54m Danish telescope line_11: shows that the two stellar images coincide to line_12: within 0.2 pixel (0.1 arc-sec). The outburst line_13: spectra also show shallow Balmer absorption line_14: lines due to the contribution from the A star. ! question: 2 section: 3 line_1: What is the nature of this source ? Is the A star line_2: an interloper in the line of sight or a third line_3: member in the binary system ? If the A star is line_4: not in the line of sight to the source, we can line_5: detect the true optical counterpart with higher line_6: resolving power observations. ! question: 2 section: 4 line_1: Chevalier, C. (1989) ESA SP-296 p.341 line_2: Pedersen, H. et al. (1983) IAUC 3858 line_3: van der Woerd et al. (1989) Ap.J. 344,320 line_4: Della Valle et al. (1992) IAUC 5512 line_5: Harmon et al. (1992) IAUC 5504 line_6: Blissett (1983 IAUC 3858 ! question: 3 section: 1 line_1: We propose to obtain WF/PC images of the 4U1543-47 line_2: field using the PC mode through two different line_3: filters: F555W to compare with ground-based line_4: observations and F336W to maximize the line_5: contribution from the X-ray source while line_6: minimizing the influence of the A-star and of the line_7: bright V=11.7 star a few arc-seconds away. line_8: Two exposures of different duration will be line_9: needed per filter to insure detection of the line_10: counterpart in case it has decreased in line_11: brightness (Maximum emission was on April 20). ! question: 4 section: 1 line_1: Existing ground-based observations do not allow line_2: us to answer the question of whether the A-star line_3: is associated to the X-ray source or not. Only line_4: much higher resolving power observations with the line_5: WF/PC during the current outburst will allow line_6: a direct attack on this problem. Next chance line_7: may be 10 years from now. ! !end of general form text general_form_address: lname: ILOVAISKY fname: SERGIO mi: A. title: DR. category: PI inst: OBSERVATOIRE DE HAUTE-PROVENCE city: ST.MICHEL L'OBSERVATOIRE zip: 04870 country: FRANCE phone: (33)92706400 telex: 410690F ! ! end of general_form_address records fixed_targets: targnum: 1 name_1: 4U1543-47 descr_1: (A, 164) pos_1: RA = 15H 43M 33.72S +/- 0.05S, pos_2: DEC = -47D 30' 56.6" +/- 0.5" equinox: 1950 acqpr_1: COMP comment_1: BRIGHT STAR (V=11.7) 5"7 WEST comment_2: AND 2"3 NORTH FROM TARGET fluxnum_1: 1 fluxval_1: V=14.6 fluxnum_2: 2 fluxval_2: B=15.3 fluxnum_3: 3 fluxval_3: E(B-V)=0.7 ! ! end of fixed targets ! No solar system records found ! No generic target records found exposure_logsheet: linenum: 1.000 targname: 4U1543-47 config: PC opmode: IMAGE aperture: P6 sp_element: F336W num_exp: 1 time_per_exp: 160S s_to_n: 100 fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=YES req_1: CYCLE 2 ! linenum: 2.000 targname: 4U1543-47 config: PC opmode: IMAGE aperture: P6 sp_element: F336W num_exp: 1 time_per_exp: 800S s_to_n: 100 fluxnum_1: 1 priority: 1 param_1: PRE-FLASH=YES req_1: CYCLE 2 ! linenum: 3.000 targname: 4U1543-47 config: PC opmode: IMAGE aperture: P6 sp_element: F555W num_exp: 1 time_per_exp: 10S s_to_n: 100 fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=YES req_1: CYCLE 2 ! linenum: 4.000 targname: 4U1543-47 config: PC opmode: IMAGE aperture: P6 sp_element: F555W num_exp: 1 time_per_exp: 50S s_to_n: 100 fluxnum_1: 1 priority: 2 param_1: PRE-FLASH=YES req_1: CYCLE 2 ! ! end of exposure logsheet ! No scan data records found