8343( 5) - 06/23/00 14:47 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 8343 Version: 5 Check-in Date: 06-Mar-2000 16:01:10 1.Proposal Title: Structure and evolution of the globular cluster low mass X-ray binary AC211 in M15 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 8 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Philip Charles Oxford University CoI: Mr. Lee Homer University of Oxford N CoI: Mr. Zach Ioannou Keele University N CoI: Prof. Bruce Margon University of Washington N CoI: Dr. Tim Naylor Keele University N ------------------------------------------------------------------------------------ 5. Abstract Our Cycle 7 STIS UV spectra of AC211, the optical counterpart of the bright X-ray binary X2127+119 in the core of M15, have revealed strong HeII Lambda1648 and CIV Lambda1550 emission together with many broad absorption lines including LyAlpha. The temporal information through primary eclipse will enable us to map the disc and wind of this accretion disc corona source. Recently Homer & Charles (1998) have shown that the 17.1 hr X-ray light curve is stable on long timescales and reveals secondary dip structure around phase 0.5 which we presume to be associated with the disc rim. We are therefore proposing here for additional time-resolved UV spectrophotometry covering phases 0.15-0.7 so as to investigate the complex interaction of the mass transfer stream with the accretion disc. AC211 is optically the most luminous of all the globular cluster X-ray sources and, with its high inclination, is the ideal object for such a study. ------------------------------------------------------------------------------------ 8343( 5) - 06/23/00 14:47 - [ 2] Observations Description ------------------------ We propose to obtain UV spectrophotometry of AC211 through orbital phases 0.15- 0.7. This will cover the secondary minimum and together with our Cycle 7 data provide complete orbital phase coverage. We will observe AC211 using the strategy which was successful for proposal 7613. With STIS, the FUV MAMA detectors and G140L we cover from Lyman Alpha to HeII Lambda1640, with adequate continuum on either side of these lines. By using the 0.5 arcsec slit we ensure that we obtain good spectrophotometry (see Fig. reffig:spec). Considering the source is in the centre of a globular cluster the acquisition sequence is deceptively simple, and we know it works. We first use the CCD and MIRROR for an ACQ of a 14th magnitude offset star. We then move to AC211, and switch to the FUV MAMA, 0.5 arcsecond slit and G140L grating. This whole sequence takes less than the 52 minutes of target visibility, allowing 1 exposure of around 10 minutes on the target in the first orbit, and four each orbi t thereafter. AC211 has a continuu m flux at 1500Angstrom\ of f_Lambda ~ 1* 10^-14 ergs s^-1 cm^-2 AA^-1. In a ten minute exposure this gives a signal-to-noise of about 15 per resolution element. We wish to cover 0.55 in phase, for which experience with our previous proposal suggests we need 10 S/C orbits. The SAA means that this will have to be split into 2 visits, each of 5 orbits. As described above, most of the first S/C orbit is spent acquiring the target, which means the coverage of a visit is really four S/C orbits, or 0.37 in phase. To make the observations schedulable, we have to give a phase slot of about 0.1 in phase for where the observations can start. Thus up to 0.1 of the phase coverage may be ``lost'' as overlap with phases covered in other observations. So with two 5 orbit visits we can be certain to cover the remaining phases. Real Time Justification ----------------------- We require our two visits to start close to specific orbital phases. Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ Data Distribution Paper Products: NO Media: ELECTRONIC Blocking Factor: 10 Ship To: PI_Address Ship Via: Email: ------------------------------------------------------------------------------------ 8343( 5) - 06/23/00 14:47 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NGC7078- STAR RA=21H 29M 56.556S +/- 0.01S, J2000 V = 14.1+/-0.2 OFFSET DEC=12D 10' 7.270" +/- 0.1" U-V = 1.3+/-0.2 Coordinate Source: Comments: Offset star. Position updated based on early-acq WF/PC image obtained in prior cycle 3 proposal. 2 NGC7078-STAR STAR, LMXB RA-OFF=1.796S+/- 0.01S, DEC-OFF= J2000 V = 17.0+/-0.2 -3.879"+/- 0.1", FROM 1 B-V = +0.4+/-0.2 Coordinate Source: Comments: Variable star. Position updated based on early-acq WF/PC image obtained in prior cycle 3 proposal. 8343( 5) - 06/23/00 14:47 - [ 4] Visit: 01 Visit Priority: Visit Requirements: PERIOD 0.713021 D AND ZERO-PHASE JD2447790.963000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 NGC7078-OFF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S SET CD P Comments: Star will saturate in around 5 seconds, and give S:N of 80 in about 0.1 seconds. ------------------------------------------------------------------------------------------------------------------------------------ 20 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 1 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 20, 30 A NON-INT PHASE 0.2 TO 0.3 ------------------------------------------------------------------------------------------------------------------------------------ 30 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 3 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 20, 30 A NON-INT ------------------------------------------------------------------------------------------------------------------------------------ 40 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 6 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 40 NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 50 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 6 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 50 NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 60 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 6 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 60 NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 70 NGC7078-STA STIS/F ACCUM 52X0.5 G140L 1425 6 421 S EXPAND MAX DUR 10 M MIN R UV-MAM DUR 5 M SEQ 70 NON-INT A ------------------------------------------------------------------------------------------------------------------------------------ 8343( 5) - 06/23/00 14:47 - [ 5] Visit: 02 Visit Priority: Visit Requirements: PERIOD 0.713021 D AND ZERO-PHASE JD2447790.963000 On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 110 NGC7078-OFF STIS/C ACQ F28X50L MIRROR ACQTYPE=POINT 1 0.2 S SET CD P Comments: Star will saturate in around 5 seconds, and give S:N of 80 in about 0.1 seconds. ------------------------------------------------------------------------------------------------------------------------------------ 120 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 SIZEAXIS1=1060,SIZEAXIS2=100, 1 12 M EXPAND MAX DUR 18 M MIN R CD CR-SPLIT=3 DUR 9 M SEQ 120, 130 NON-INT PHASE 0.7 TO 0.8 ------------------------------------------------------------------------------------------------------------------------------------ 130 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 PATTERN=ALONG-SLIT,NUM-POS=2, 1 8 M EXPAND MAX DUR 12 M MIN R CD STEP-SIZE=0.5, DUR 6 M SEQ 120, 130 PATTERN-DIRECTION=PLUS, NON-INT SIZEAXIS2=100,SIZEAXIS1=1060 ------------------------------------------------------------------------------------------------------------------------------------ 140 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 SIZEAXIS1=1060,SIZEAXIS2=100, 1 15 M EXPAND MAX DUR 20 M MIN R CD PATTERN=ALONG-SLIT,NUM-POS=3, DUR 10 M NO SPLIT STEP-SIZE=0.5, PATTERN-DIRECTION=PLUS,CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ 150 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 SIZEAXIS1=1060,SIZEAXIS2=100, 1 15 M EXPAND MAX DUR 20 M MIN R CD PATTERN=ALONG-SLIT,NUM-POS=3, DUR 10 M NO SPLIT STEP-SIZE=0.5, PATTERN-DIRECTION=PLUS,CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ 160 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 SIZEAXIS1=1060,SIZEAXIS2=100, 1 15 M EXPAND MAX DUR 20 M MIN R CD PATTERN=ALONG-SLIT,NUM-POS=3, DUR 10 M NO SPLIT STEP-SIZE=0.5, PATTERN-DIRECTION=PLUS,CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ 170 NGC7078-STA STIS/C ACCUM 52X0.2 G750M 6581 SIZEAXIS1=1060,SIZEAXIS2=100, 1 15 M EXPAND MAX DUR 20 M MIN R CD PATTERN=ALONG-SLIT,NUM-POS=3, DUR 10 M NO SPLIT STEP-SIZE=0.5, PATTERN-DIRECTION=PLUS,CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ 8343( 5) - 06/23/00 14:47 - [ 6] Summary Form for Proposal 8343 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures F28X50LP 52X0.5 52X0.2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD STIS/FUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ACQTYPE=POINT CR-SPLIT=3 SIZEAXIS1=1060 CR-SPLIT=2 PATTERN-DIRECTION=PLUS STEP-SIZE=0.5 NUM-POS=3 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PERIOD 0.713021 D AND ZERO-PHASE JD2447790.963000 EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 20, 30 NON-INT PHASE 0.2 TO 0.3 EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 20, 30 NON-INT EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 40 NON-INT EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 50 NON-INT EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 60 NON-INT EXPAND MAX DUR 10 M MIN DUR 5 M SEQ 70 NON-INT EXPAND MAX DUR 18 M MIN DUR 9 M SEQ 120, 130 NON-INT PHASE 0.7 TO 0.8 EXPAND MAX DUR 12 M MIN DUR 6 M SEQ 120, 130 NON-INT EXPAND MAX DUR 20 M MIN DUR 10 M NO SPLIT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements MIRROR G140L G750M ------------------------------------------------------------------------------------------------------------------------------------ Target Names NGC7078-OFFSET NGC7078-STAR ------------------------------------------------------------------------------------------------------------------------------------ Wavelengths 1425 6581 ------------------------------------------------------------------------------------------------------------------------------------