Page 1 PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID 5697 Report Date: 18-Jul-95:17:52 Version: ********** Check-in Date: ********** 1.Proposal Title: CIR-X1 REVISITED: SPECTROSCOPY THROUGHOUT THE 16.6 DAY CYCLE OF THE REAL OPTICAL CANDIDATE: CYCLE 4 CARRYOVER ------------------------------------------------------------------------------------ 2. Scientific Category 3. Proposal For 4. Proposal Type 5. Continuation ID STELLAR ASTROPHYSICS GO/CAR 4930 Sub Category X-RAY BINARIES ------------------------------------------------------------------------------------ 6. Principal Investigator Institution Country Telephone Patrizia A Caraveo ISTITUTO DI FISICA COSMICA D ITALY 39-2-2367587 ------------------------------------------------------------------------------------ 7. Abstract Circinus X-1 is a very strong and highly variable X-ray, IR and radio source. Its optical identification was, until very recently, wrongly attributed to a star which recent NTT observations, done in superb seeing, have resolved in three objects.Of these one, very red, coincides with the accurate VLA position for the radio source (varying in phase with the X-ray), and is thus the real candidate. Only HST can now do meaningful work on the true counterpart of Cir X-1: even small seeing conditions variations would render incomparable measurements taken from the ground over the 16.6 day (binary\?) source cycle. A new FOS spectrum, taken at critical time during the cycle, will help to understand this 17-19 mag variable object, responsible for a truly bizarre X-ray/radio object. ------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------ 9. Est obs time (hours) pri: 2.80 par: 0 10. Num targs pri: 2 par: 0 ------------------------------------------------------------------------------------ 11. Instruments requested: FOS ------------------------------------------------------------------------------------ 12. Special sched req: Time Critical obs. ------------------------------------------------------------------------------------ Page 2 I. GENERAL FORM Proposal 5697 PI: Patrizia A Caraveo Proposal Title: CIR-X1 REVISITED: SPECTROSCOPY THROUGHOUT THE 16.6 DAY CYCLE OF THE REAL OPTICAL CANDIDATE: CYCLE 4 CARRYOVER ------------------------------------------------------------------------------------ 1. Proposers: Proposers Institution Country ESA ------------------------------------------------------------------------------------ Giovanni F Bignami ISTITUTO DI FISICA COSMICA DEL ITALY X CNR Pi Patrizia A Caraveo ISTITUTO DI FISICA COSMICA DEL ITALY X CNR ------------------------------------------------------------------------------------ 3. Description of proposed observations. We plan to use the red detector of the FOS with the grism G570H using a 0.5 arcsec aperture to obtain a spectrum of the proposed counterpart of Cir X-1. We have chosen this set-up in order to cover Halpha as well as the most prominent ISM absorption features which could give and independent measure of the source distance. We need to use the small aperture in order to avoid contamination from the nearby (about 1.5 arcsec) field stars. ------------------------------------------------------------------------------------ 4. Justification of need for HST observations. In order to study the temporal behaviour of the Cir X1 optical counterpart, now known to lye 1.5 arcsec from two unrelated objects,one needs EXCELLENT and CONSTANT SEEING CONDITIONS. Clearly this can only be achievable with HST whose angular resolution is both very good and stable. ------------------------------------------------------------------------------------ 6. Description of special calibration exposures. Since the strong and clearly correlated X-ray,Radio,IR flux variabilities of Cir X-1 are known to follow a 16.6 day cyclic behaviour. For this corryover, we propose to observe the source during the X-ray maximum. ------------------------------------------------------------------------------------ 9. Description of previous HST work. 3432 and 4930: same title cycle 2. 3432 Early acquisition, using WFPC, to compute the offset parameters needed to point our faint target. 4930 three FOS spectra taken using the PRISM as disperser: not satisfactory owing to non linear dispersion and very poor resolution in the red part of the spectrum. ------------------------------------------------------------------------------------ 10. Resources to be supplied by investigator's institution(s). The Istituto di Fisica Cosmica has SUN WS equipped with MIDAS and IRAF (with STSDAS). Students from the Istituto di Fisica of the Milano University normally take active part in the data analysis. Funds will be provided by the Agenzia Spaziale Italiana and by CNR ------------------------------------------------------------------------------------ 11. Address Information Name: PATRIZIA A CARAVEO Category: PI Institution: ISTITUTO DI FISICA COSMICA DEL CN Address: VIA BASSINI, 15 City: MILANO 20133 State: Zip Code: Country: ITALY Telephone: 39-2-2367587 Telex (or e-mail): 313839 ------------------------------------------------------------------------------------ TARGET LIST a) Fixed Targets ID = 5697 [ 3] ------------------------------------------------------------------------------------------------------------------------------------ 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| | | | | | | | | ------------------------------------------------------------------------------------------------------------------------------------ 2 CIR-X1- I,603 RA = 15H 20M 39.683S +/- 2000 1 R = 18.7 +/- 0.5 OFFSET 0.1", DEC =-57D 09' 16.42"+/- 0.1" Comments: OFFSET STAR ------------------------------------------------------------------------------------------------------------------------------------ 3 STAR-1520- B,165 RA-OFF = 1.173S +/- 0.1S, 2000 1 R = 19.0 +/- 0.5 5710- DEC-OFF = -43.379" +/- 0.1", 1 V = 20.0 +/- 0.5 SPECTRUM CIR FROM 2 1 I = 18.6 +/- 0.5 -X1 Comments: OFFSET FROM 2 ------------------------------------------------------------------------------------------------------------------------------------ EXPOSURE LOGSHEET ID = 5697 [ 4] ------------------------------------------------------------------------------------------------------------------------------------ 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 ------------------------------------------------------------------------------------------------------------------------------------ 8 CIR-X1- FOS/RD ACQ/ 4.3 MIRROR SEARCH-SIZE-X=1 1 25S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=3 8.1 SCAN-STEP- CYCLE 4/8-9 Y=1.204 Comments: ASSUME A K5 V STAR FOR THE OFFSET STAR. ------------------------------------------------------------------------------------------------------------------------------------ 8.1 CIR-X1- FOS/RD ACQ/ 1.0 MIRROR SEARCH-SIZE-X=6 1 25S 1 ONBOARD ACQ FOR OFFSET PEAK SEARCH-SIZE-Y=2 8.2 SCAN-STEP- X=0.602 SCAN-STEP- Y=0.602 ------------------------------------------------------------------------------------------------------------------------------------ 8.2 STAR-1520- FOS/RD ACQ/ 0.5 MIRROR SEARCH-SIZE-X=3 1 35S 1 ONBOARD ACQ FOR 5710- PEAK SEARCH-SIZE-Y=3 8.3 SPECTRUM SCAN-STEP- X=0.29 SCAN-STEP- Y=0.29 ------------------------------------------------------------------------------------------------------------------------------------ 8.3 STAR-1520- FOS/RD ACQ/ 0.3 MIRROR SEARCH-SIZE-X=4 1 50S 1 ONBOARD ACQ FOR 9 5710- PEAK SEARCH-SIZE-Y=4 SPECTRUM SCAN-STEP- X=0.11 SCAN-STEP- Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ 9 STAR-1520- FOS/RD ACCUM 0.5 G570H 4571- 1 86M 10 1 1 PHASE 0.0 +/- 0.1 5710- 6820 PERIOD 16.5678D +/ SPECTRUM - 0.0000353D ZERO-PHASE JD 2443076.87 +/- 0.01D ------------------------------------------------------------------------------------------------------------------------------------ Summary Form for Proposal 5697 [ 5] Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Configurations FOS/RD ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ/PEAK ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters SEARCH-SIZE-X=1 SEARCH-SIZE-Y=3 SCAN-STEP-Y=1.204 SEARCH-SIZE-X=6 SEARCH-SIZE-Y=2 SCAN-STEP-X=0.602 SCAN-STEP-Y=0.602 SEARCH-SIZE-X=3 SCAN-STEP-X=0.29 SCAN-STEP-Y=0.29 SEARCH-SIZE-X=4 SEARCH-SIZE-Y=4 SCAN-STEP-X=0.11 SCAN-STEP-Y=0.11 ------------------------------------------------------------------------------------------------------------------------------------ Proposal for GO/CAR ------------------------------------------------------------------------------------------------------------------------------------ S/C Hours 2.80 ------------------------------------------------------------------------------------------------------------------------------------ Scientific Category STELLAR ASTROPHYSICS ------------------------------------------------------------------------------------------------------------------------------------ Scientific Sub-category X-RAY BINARIES ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ONBOARD ACQ FOR 8.1; CYCLE 4/8-9; ONBOARD ACQ FOR 8.2; ONBOARD ACQ FOR 8.3; ONBOARD ACQ FOR 9; PHASE 0.0 +/- 0.1; PERIOD 16.5678D +/- 0.0000353D; ZERO-PHASE JD 2443076.87 +/- 0.01D; ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G570H ------------------------------------------------------------------------------------------------------------------------------------ Target Names CIR-X1-OFFSET STAR-1520-5710-SPECTRUM CIR-X1 ------------------------------------------------------------------------------------------------------------------------------------