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J/ApJS/96/303       Calibrating Broad Band X-ray Telescope    (Weaver+ 1995)
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Calibrating the broad band X-ray telescope.
    Weaver K.A., Arnaud K.A., Boldt E.A., Christian D., Corcoran M.,
    Holt S.S., Jahoda K., Kelley R., Marshall F.E., Mushotzky R.F.,
    Petre R., Rawley G., Serlemitsos P.J., Schlegel E.M., Smale A.P.,
    Swank J.H., Szymkowiak A.E.
   <Astrophys. J. Suppl. Ser. 96, 303 (1995)>
   =1995ApJS...96..303W      (SIMBAD/NED BibCode)
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ADC_Keywords: X-ray sources
Keywords: instrumentation: detectors - space vehicles - X-rays: general

Abstract:
    This paper describes the calibration of the two solid-state Si(Li)
    X-ray detectors and the X-ray telescopes that flew as part of Goddard
    Space Flight Center's Broad Band X-Ray Telescope (BBXRT) experiment on
    board the space shuttle Columbia in 1990 December. During the 9 day
    shuttle mission, BBXRT performed ~150 observations of 82 celestial
    sources. The content of the archive is summarised here. Although BBXRT
    had a relatively short life, it stands as a milestone in X-ray
    astronomy as being the first instrument to offer moderate spectral
    resolution over a wide bandpass (0.3-12.0keV). Among other things,
    this paper discusses the effective area calibration of the instrument,
    the flux calibration and flux corrections for off-axis observations,
    the detector background, and optimal background subtraction
    techniques. The on-axis effective area calibration for the central
    detector elements was performed using data from the Crab Nebula, while
    other carefully selected targets were used for calibration of the
    outer detector elements. The remaining systematic uncertainties in the
    effective area calibration for point sources observed both on and off
    axis are generally less than 5%-10%. The energy scale is known to
    better than 0.5% at 6.0 keV for both detectors. The results presented
    here have an impact on the calibration of other medium resolution
    X-ray experiments such as the CCDs on board ASCA (Astro-D) as well as
    the Advanced X-Ray Astrophysics Facility detectors.

File Summary:
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  FileName     Lrecl  Records   Explanations
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ReadMe          80        .   This file
table1          98      155   Broad Band X-Ray Telescope (BBXRT) observation Log
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Byte-by-byte Description of file: table1
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   Bytes Format Units   Label     Explanations
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   1-  9  A9    ---     Source    Source name
  11- 18  F8.4  deg     RAdeg     Nominal right ascension (1950.0)
  20- 26  F7.3  deg     DEdeg     Nominal declination (1950.0)
  28- 33  F6.3  deg     DRA       ? Offset in right ascension (1)
  35- 40  F6.3  deg     DDE       ? Offset in declination (1)
  42- 46  F5.1  deg     Roll      Roll angle of the A-system telescope (phi) (2)
  48- 53  F6.4  d       Start     Start time of MET measured from
                                   1990 December 2, 06:49:01 UT
  55- 60  F6.1  s       ExpTime   Exposure time
  62- 63  A2    ---     D/N       [MND B] Indicator of shuttle day or night (3)
  65- 70  F6.1  ---     GR        Mean detector guard rate (4)
  72- 75  F4.1  arcmin  Angle     Average off-axis angle (5)
  77- 83  F7.2  ct/s    Rate      Total count rate in all 10 pixels.
  85- 98  A14   ---     Class     Type of object.
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Note (1): Offset of the pointing direction of the A-system telescope 
    from the nominal RA and DE (epoch 1950.0), given as RAnom - RAaspect,
    and DEnom - DEaspect. Numbers are supplied only if there exists an
    aspect solution derived from data taken with the aspect camera.
    Specific details about aspect solutions can be obtained through the
    HEASARC at GSFC.
Note (2): If no aspect solution exists, the roll angle is only 
    an approximate value.
Note (3): N = night
          D = day
         MN = mostly night (>75%)
         MD = mostly day (>75%)
          B = both, mixed
Note (4): Parameter that measures the rate of particle interactions 
     with the guard.
Note (5): Average off-axis angle (THETA) as derived rom the nominal and 
    aspect RA.s and DE.s (cols. [2]-[5]). When an angle but no RA or DE
    offset is given, that angle is derived from ray tracing. A value of 
    -1 indicates that the angle has not yet been calculated. A ray-tracing
    program is available from the HEASARC that allows observers to
    determine their own off-axis angles and to confirm our aspect
    solutions.
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History: Prepared via OCR at CDS.
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(End)                           James Marcout, Patricia Bauer [CDS]  28-Aug-1997