J/ApJS/96/303 Calibrating Broad Band X-ray Telescope (Weaver+ 1995)
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 1995ApJS...96..303W (SIMBAD/NED BibCode)
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.
(End) James Marcout, Patricia Bauer [CDS] 28-Aug-1997