! Hubble Space Telescope Cycle 5 (1995) Phase II Proposal Template ! $Id: 5867,v 6.1 1996/01/26 03:47:59 pepsa Exp $ ! ! Refer to the HST Phase II Proposal Instructions to fill this out ! ! Anything after a "!" is ignored, and may be deleted ! ! All keywords with multiple entries are comma delimited except the ! Visit_Requirements and Special_Requirements keywords which can be ! delimited with carriage returns or semi-colons, but not commas ! ! For help call your Program Coordinator: Karla Peterson ! Phone: 410 338-4774, E-mail: peterson@stsci.edu ! ! This partially completed template was generated from your Phase I proposal. ! Proposal_Information ! Section 4 Title: UV spectroscopy of the Low Mass X-ray Binary SCO-X1 Proposal_Category: GO Scientific_Category: Hot Stars Cycle: 5 Investigators PI_name: Timothy Kallman PI_Institution: Laboratory for High Energy Astrophysics CoI_Name: Saequa Vrtilek CoI_Institution: University of Maryland Contact: ! Y or N (designate at most one contact) CoI_Name: Richard McCray CoI_Institution: Joint Institute for Laboratory Astrophysics Contact: ! Y or N (designate at most one contact) CoI_Name: Bram Boroson CoI_Institution: Joint Institute for Laboratory Astrophysics Contact: ! Y or N (designate at most one contact) CoI_Name: Fumiaki Nagase CoI_Institution: ISAS Contact: ! Y or N (designate at most one contact) CoI_Name: John Raymond CoI_Institution: Smithsonian Astrophysical Observatory Contact: ! Y or N (designate at most one contact) Abstract: ! Free format text (please update) We propose to observe the UV spectrum of SCO-X1 with the GHRS on HST. This will provide a probe into the structure and dynamics of the accretion flow, enable us to test models of the UV emission, and explore the circumstellar environment and evolution. We will observe with the GHRS G140L at high data rate with time resolution of 50 ms in order to test for short timescale variability in the UV lines and continuum. A high frequency cutoff in the power spectrum of the variability in the UV lines will provide a measure of the size of the UV emitting region. We will also observe at medium and high spectral resolution in the vicinity of the strong lines LAlpha, C IV Lambda1550 and N V Lambda1240 in order to better measure the interstellar column density toward SCO-X1 and to test for evidence of X-ray ionization and winds. The UV spectral region is necessary for studying the effects of X-ray ionization; optical emission lines and continuum are much less sensitive to ionization effects. Neither the high time- resolution nor the high spectral resolution observations are feasible with IUE. Questions ! Free format text (please update) Observing_Description: We propose to observe SCO-X1 for a total of 6 satellite orbits. First will be with the GHRS 140L grating in the wavelength region 1300 -- 1580 Angstrom (i.e. including both the Si IV Lambda 1400 and C IV Lambda 1550 resonance lines) for one satellite orbit. The goal is to test for UV continuum and line strength variability at frequencies up to 10 Hz. We will utilize the RAPID mode with data readout every 50 ms. The flux observed from IUE at the C IV line is F_Lambda~eq 5 * 10^-13 erg cm^-2 s^-1 AA^-1, corresponding to a counting rate of 3.3 counts s^-1 diode^-1. Since we measure the width of the C IV emission line to be approximately 4 Angstrom, by summing the diodes over the line we expect a counting rate of approximately 23 counts s^-1. The time estimate for the G140L observation is based on the requirements for time-series analysis. In order to measure the power spectrum at a frequency f (in Hz) we require an observing time given by the formula T = (4n^2f)/(F^2r^4), where n is the number of ``sigmas'' of the detection, F is the count rate, and r is the fractional amplitude of the variability. In the space of the 20 minutes of data accumulation time available to a high time resolution observation per orbit, we can expect a ~eq5Sigma detection of variability at 10 Hz if r=0.2. At 1 Hz we will be sensitive to r=0.1 variability with comparable statistics. By binning up the entire bandpass of the G140L we expect a counting rate of 1660 s^-1, giving sensitivity to r=0.02 variations at ~eq5Sigma up to the limiting frequency of 20 Hz. Next, we will use the G160M grating in the vicinity of the L Alpha (1200-1233 Angstrom), N V (1220-1253 Angstrom) and C IV (1535 -1568 Angstrom) lines for one satellite orbit each to measure the damping wings of the interstellar LAlpha absorption and hence the interstellar column, and to measure the profiles of the N V and C IV emission lines. We expect counting rates of at least 0.05 counts s^-1 diode^-1 near these lines. This assumes the lowest line fluxes recorded by IUE ('horizontal branch'), which are a factor of ~2 lower than average. Thus, during one satellite orbit (43 minutes after subtracting reaquisitions and overhead) we can obtain at least 130 counts per diode from SCO-X1, and most probably several times more than this. This corresponds to a signal-to-noise ratio of approximately 11 for each diode. This compares favorably with the value obtained by IUE high resolution of approximately 4 when the source was in a high state. Finally, we will use the Echelle A grating in the vicinity of the N V Lambda1240 (order 45) and C IV Lambda1550 (order 36) lines for one satellite orbit each to search for narrow absorption components due to photoionized interstellar gas and a possible wind-blown bubble. We expect counting rates of at least .02 counts s^-1 diode^-1 near the N V and C IV lines, again using the most pessimistic estimates for the UV fluxes in these lines. With one satellite orbit each these observations will yield at least 53 counts diode^-1. We will therefore be sensitive to narrow (3 Km s^-1) absorption features superimposed on the broader intrinsic emission lines if they have optical depth Tau>= 0.7 at the 3Sigma level. If the source is in a brighter state, near its average flux, the sensitivity improves to Tau>= 0.3. Real_Time_Justification: No special requirements. Calibration_Justification: ! Move appropriate text from Real_Time_Justification Additional_Comments: We request that this visit be scheduled after 1 Sep, 1995. This because we wish to schedule a simultaneous observation with XTE which will be launched on 1 Aug, 1995. XTE has a flexible scheduling policy, and so will schedule following the HST schedule as long as the date of the HST observation can be fixed one month in advance. Fixed_Targets Target_Number: 1 Target_Name: SCO-X1 Alternate_Names: X1617-155,GSC6202-00919 Description: STAR,LMXB Position: RA = 16H 19M 55.07S +/- 0.08S, DEC = -15D 38' 24.6" +/- 1.2", PLATE-ID = 02C3 Equinox: J2000 RV_or_Z: RA_PM: -0.00044 +/- 0.00015 ! Units are seconds of time per year Dec_PM: -0.0201 +/- 0.0022 ! Units are seconds of arc per year Epoch: 1983.500 Annual_Parallax: Flux: V=12.4,B-V=0.2, F-LINE(1500)= 7 +/- 4 E-12, A(V)=1.2 +/-0.2, F-CONT(1500)= 5 +/- 1 E-13 ! Include at least V and B-V Comments: Coordinates are from GSC ! This is a template for a single visit containing a single exposure ! Repeat exposure and visit blocks as needed Visits Visit_Number: 1 Visit_Requirements: BETWEEN 17-JAN-1996 AND 10-MAR-1996 On_Hold_Comments: Visit_Comments: We request that this visit be scheduled after 1 Sep, 1995. This because we wish to schedule a simultaneous observation with XTE which will be launched on 1 Aug, 1995. XTE has a flexible scheduling policy, and so will schedule following the HST schedule as long as the date of the HST observation can be fixed one month in advance. ! first the rapid mode acquisition Exposure_Number: 1 ! Section 6.5 Target_Name: SCO-X1 Config: HRS Opmode: ACQ Aperture: 2.0 Sp_Element: MIRROR-N2 Wavelength: Optional_Parameters: BRIGHT=RETURN Number_of_Iterations: 1 Time_Per_Exposure: 9S Special_Requirements: ONBOARD ACQuisition FOR 2-8 Comments: STEP-TIME=1S ! the G160M accum at L alpha Exposure_Number: 2 Target_Name: SCO-X1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1216. Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2420.8S Special_Requirements: Comments: Exposure time is 40.3M ! the G160M accum at C IV Exposure_Number: 3 Target_Name: SCO-X1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1550. Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2420.8S Special_Requirements: ! the G160M accum at N V Exposure_Number: 4 Target_Name: SCO-X1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: G160M Wavelength: 1240. Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2420.8S Special_Requirements: ! second the rapid mode observation Exposure_Number: 5 ! Section 6.5 Target_Name: SCO-X1 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G140L Wavelength: 1400. Optional_Parameters: SAMPLE-TIME=0.1 Number_of_Iterations: 1 Time_Per_Exposure: 14.5M Special_Requirements: Exposure_Number: 6 Target_Name: SCO-X1 Config: HRS Opmode: RAPID Aperture: 2.0 Sp_Element: G140L Wavelength: 1400. Optional_Parameters: SAMPLE-TIME=0.1 Number_of_Iterations: 1 Time_Per_Exposure: 14.5M Special_Requirements: ! the ECH A accum at N V Exposure_Number: 7 Target_Name: SCO-X1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A Wavelength: 1240. Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2638.4S Special_Requirements: Comments: Exposure time is 44M ! the ECH A accum at C IV Exposure_Number: 8 Target_Name: SCO-X1 Config: HRS Opmode: ACCUM Aperture: 2.0 Sp_Element: ECH-A Wavelength: 1550. Optional_Parameters: Number_of_Iterations: 1 Time_Per_Exposure: 2638.4S Special_Requirements: ! Uncomment or copy exposure level special requirements needed ! INTeractive ACQuisition FOR ! ONBOARD ACQuisition FOR ! POSition TARGet , ! SAME POSition AS ! DO FOR TARGets ! FGS only ! PARallel WITH ! GROUP-FGS WITHIN