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Last modified: 26 October 2016

URL: http://cxc.harvard.edu/ciao/data_products_guide/misc.html

Bias, Parameter Block, & Orbit Ephemeris Files

Data Products Guide

Filename Description Content SDP Pipeline
acis_bias0.fits ACIS bias maps BIAS0 ACIS0
acis_pbk0.fits ACIS parameter block PBK ACIS0
orbit_eph1.fits orbit ephemeris ORBITEPHEM1 EPHEM1

ACIS Bias Maps

Filename Description Content SDP Pipeline
acis_bias0.fits ACIS bias maps BIAS0 ACIS0

Description:

When the bad pixel list is created, each bias map is searched for pixels whose bias values are either too low or too high. There is one 1024x1024 pixel bias map image for each ACIS chip that was used for the observation.

There are no creator tools; the bias maps are generated internally.


ACIS Parameter Block

Filename Description Content SDP Pipeline
acis_pbk0.fits ACIS parameter block PBK ACIS0

Description:

The parameter block file is needed in conjunction with the bias maps when creating a new bad pixel list. It is used to determine observational parameters, such as which CCDs are active, the READMODE and DATAMODE, etc.

There are no creator tools; the parameter block solution file is generated internally.

Columns:

Column Name Units Description
CCD_ID CCD ID
FEP_ID Front End Processor ID
VIDRESP CCD video chain response selection, 0 for 1:1
EVT_THR[4] adu Event thresholds for nodes A-D
SPL_THR[4] adu Split thresholds for output nodes A-D
BCMPSLOT Slot identifier for bias map compression tab
BIASALG Bias algorithm is. 1:whole frame; 2:strip
BIASARG0 Bias arguement 0
BIASARG1 Bias arguement 1
BIASARG2 Bias arguement 2
BIASARG3 Bias arguement 3
BIASARG4 Bias arguement 4
VID_OFF[4] Video offsets for CCD output nodes A-D

ACIS Exposure Statistics

Filename Description Content SDP Pipeline
acis_stat1.fits Exp. Stats EXPSTATS ACIS1

Description:

The ACIS exposure statistics file contains one extension that contains various statistics about each good ACIS exposure, and then has one extension for each CCD_ID that contains minimal information about dropped exposures (due to telemetry saturation).

Users will note that since the CCD's are clocked out asynchronously that the same exposure number, EXPNO, will have a different TIME value.

Creator tool: acis_format_events

Columns:

Column Name Units Description
TIME s Time
CCD_ID CCD ID number
EXPTIME s Exposure time
EXPNO Exposure Number
EVTSENT Number of events telemetered
THR_PIX Number of pixels above threshold
DROP_AMP Number of events outside energy filter
DROP_POS Number of events outside window
DROP_GRD Number of events with bad grades
BERR_SUM Number of bias parity errors
OVRCLOCK adu Mean overclock for each node

Orbit Ephemeris

Filename Description Content SDP Pipeline
orbit_eph1.fits orbit ephemeris ORBITEPHEM1 EPHEM1

Description:

The definitive orbit ephemeris information for the observation. The coordinates are recorded as Earth-centered Cartesian ICRS coordinates.

There are no creator tools; the orbit ephemeris file is generated internally.

Columns:

Column Name Units Description
Time s Time
X m X coordinate
Y m Y coordinate
Z m Z coordinate
Vx m/s Velocity in the X direction
Vy m/s Velocity in the Y direction
Vz m/s Velocity in the Z direction

Last modified: 26 October 2016
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