Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 4165c Report Date: 09-May-96:19:22 Version: ********** Check-in Date: ********** 1.Proposal Title: ASTROMETRY OF THE 4U1543-47 X-RAY TRANSIENT OPTICAL COUNTERPART ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/DD Target of Oppt. Sub Category X-RAY BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Dr. Sergio A. Ilovaisky OBSERVATOIRE DE HAUTE-PROVEN FRANCE (33)92706400 DIRECT. DE RECHERCHE ------------------------------------------------------------------------------------ 7. Abstract We propose to obtain relative WF/PC astrometry of the optical counterpart of the 4U1543-47 soft X-ray transient, currently in outburst. Ground-based observations made in 1989 during the quiescent state show that an apparently normal V=16.7 A-type star is located (within +/- 0.1 arc-sec) at the position of the V=14.6 image seen during outburst. While it is highly unlikely that the A star is the companion of the X-ray source, it appears nevertheless to be located at the same distance from us. Accurate relative astrometry between images obtained with the WF/PC during outburst and later, during quiescence, will allow us to find whether or not, on the basis of position alone, the A-star is somehow related to the X-ray source. If not, the images may allow us to discover the true optical counterpart of 4U1543-47. ------------------------------------------------------------------------------------ 8. Scientific Key Words: X-RAY TRANSIENTS, OPTICAL COUNTERPARTS ASTROMETRY ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 0.28 par: 0 10. Num targs pri: 1 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: WF/PC ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 4165c PI: Dr. Sergio A. Ilovaisky Proposal Title: ASTROMETRY OF THE 4U1543-47 X-RAY TRANSIENT OPTICAL COUNTERPART ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Dr. Claude Chevalier OBSERVATOIRE DE HAUTE-PROVENCE FRANCE X Dr. Holger Pedersen COPENHAGEN UNIVERSITY DANEMARK X OBSERVATORY ------------------------------------------------------------------------------------ 2. Scientific Justification. 4U1543-47 is an X-ray transient which has been observed in outburst in 1971 and 1983. It is now (May 1992) in outburst again (IAUC 5512). From its ultra soft X- ray spectrum it is considered a black hole candidate, similar to A0620-00 and GS2000+25. During the 1983 outburst EXOSAT observed the source (Blisset 1983, van der Woerd et al. 1989) and it was subsequently identified by Pedersen et al. (1983) with a V=14.6 object with the characteristic emission lines of low-mass X- ray binaries. However, comparison with ESO Schmidt plates taken during quiescence showed that the object had brightened by only 1 magnitude. This was surprising for such a type of transient where optical amplitudes of 6 magnitudes or more are common. Optical observations made by us at ESO during quiescence in 1989 (Chevalier 1989) reveal that the V=16.7 star appearing at the location of the outburst image is a normal-looking A-type star. Spectra show interstellar features remarkably similar to those seen in the outburst spectrum, suggesting that both the A-star and the X-ray source are located at 4kpc (or beyond). Astrometry made by comparing the 1983 and 1989 CCD frames taken at the 1.54m Danish telescope shows that the two stellar images coincide to within 0.2 pixel (0.1 arc-sec). The outburst spectra also show shallow Balmer absorption lines due to the contribution from the A star. What is the nature of this source ? Is the A star an interloper in the line of sight or a third member in the binary system ? If the A star is not in the line of sight to the source, we can detect the true optical counterpart with higher resolving power observations. Chevalier, C. (1989) ESA SP-296 p.341 Pedersen, H. et al. (1983) IAUC 3858 van der Woerd et al. (1989) Ap.J. 344,320 Della Valle et al. (1992) IAUC 5512 Harmon et al. (1992) IAUC 5504 Blissett (1983 IAUC 3858 ------------------------------------------------------------------------------------ 3. Description of proposed observations. We propose to obtain WF/PC images of the 4U1543-47 field using the PC mode through two different filters: F555W to compare with ground-based observations and F336W to maximize the contribution from the X-ray source while minimizing the influence of the A-star and of the bright V=11.7 star a few arc-seconds away. Two exposures of different duration will be needed per filter to insure detection of the counterpart in case it has decreased in brightness (Maximum emission was on April 20). ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. Existing ground-based observations do not allow us to answer the question of whether the A-star is associated to the X-ray source or not. Only much higher resolving power observations with the WF/PC during the current outburst will allow a direct attack on this problem. Next chance may be 10 years from now. ------------------------------------------------------------------------------------ 11. Address Information Page 3 Name: SERGIO A. ILOVAISKY Category: PI Institution: OBSERVATOIRE DE HAUTE-PROVENCE Address: City: ST.MICHEL L'OBSERVATOIRE State: Zip Code: 04870 Country: FRANCE Telephone: (33)92706400 Telex (or e-mail): 410690F ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 4165c [ 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 4U1543-47 (A, 164) RA = 15H 43M 33.72S +/- 1950 COMP 1 V=14.6 0.05S, 2 B=15.3 DEC = -47D 30' 56.6" +/- 3 E(B-V)=0.7 0.5" Comments: BRIGHT STAR (V=11.7) 5"7 WEST AND 2"3 NORTH FROM TARGET ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 4165c [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 1 4U1543-47 PC IMAGE P6 F336W PRE-FLASH=YES 1 160S 100 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 2 4U1543-47 PC IMAGE P6 F336W PRE-FLASH=YES 1 800S 100 1 1 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 4U1543-47 PC IMAGE P6 F555W PRE-FLASH=YES 1 10S 100 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ 4 4U1543-47 PC IMAGE P6 F555W PRE-FLASH=YES 1 50S 100 1 2 CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 4165c [ 6] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations PC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters PRE-FLASH=YES ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/DD ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 0.28 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category X-RAY BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements CYCLE 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F555W ------------------------------------------------------------------------------------------------------------------------------------ Target Names 4U1543-47 ------------------------------------------------------------------------------------------------------------------------------------