Region Files
Bad Pixel List
Description:
A list of pixels identified as "bad"; criteria for flagging a
pixel are listed in the Bad Pixels
dictionary entry. Any tool that reads this file
will exclude the bad pixels from its calculations.
ACIS Columns:
| Column Name |
Units |
Description |
| SHAPE | | region shape |
| COMPONENT | | Component number |
| CHIP(CHIPX,CHIPY)[2] | pixel | CHIP X location |
| TIME | s | Time pixel went bad |
| TIME_STOP | s | Time pixel went bad |
| STATUS[4] | coded | Badpixel status code |
HRC Columns:
| Column Name |
Units |
Description |
| CHIP_ID | | Chip ID |
| SHAPE | | shape of bad element |
| COMPONENT | | component index |
| CHIPX[2] | pixel | chip X |
| CHIPY[2] | pixel | chip Y |
| STATUS | | Status Bitarray |
Imaging Source List
The src2.fits files are no longer created as of DS
8.4 (June 2011).
Description:
The imaging source candidate list is obtained from a single run
of celldetect with S/N threshold equal to 3 and should
not be used directly in analysis. Users interested in spatial
analysis should perform their own detection runs with one of the
three Chandra Detect tools: celldetect,
wavdetect, and vtpdetect. The Detect Manual
describes which tool is suited to a particular analysis.
Columns:
| Column Name |
Units |
Description |
| RA | deg | Source Right Ascension |
| DEC | deg | Source Declination |
| RA_ERR | deg | Source Right Ascension Error |
| DEC_ERR | deg | Source Declination Error |
| POS(X,Y) | pixel | Physical coordinates |
| X_ERR | pixel | Source X position error |
| Y_ERR | pixel | Source Y position error |
| CELLPOS(CELL_X,CELL_Y) | pixel | Physical coordinates |
| DETSIZE | pixel | source cell size |
| BKGSIZE | pixel | background cell size |
| NPIXSOU | pixel | pixels in source cell |
| NPIXBKG | pixel | pixels in background cell |
| NET_COUNTS | count | Net source counts |
| NET_COUNTS_ERR | count | Error in net source counts |
| BKG_COUNTS | count | Background counts (scaled to source cell) |
| BKG_COUNTS_ERR | count | Error in BKG_COUNTS |
| NET_RATE | count/s | Source count rate |
| NET_RATE_ERR | count/s | Source count rate error |
| BKG_RATE | count/s | Background count rate |
| BKG_RATE_ERR | count/s/pixel | Background count rate error |
| EXPTIME | s | Effective exposure time |
| SNR | | Signal-to-Noise ratio |
| SHAPE | | Shape of source region |
| R[2] | pixel | Radii of source region source |
| ROTANG | deg | Rotation angle of source region |
| PSFRATIO | | ratio of source ellipse size to PSF size |
| BLOCK | | blocking factor |
| COMPONENT | | Source Number |
| EXPO_RATIO | | ratio of average background and detect cell exp |
| DOUBLE | | double detection flag |
| DOUBLE_ID | | double source component |
Field of View
Description:
The field-of-view file contains regions which describe the edges
of each instrument chip (one polygon per chip). This region file
can be used to filter event files or images to contain specific
chips.
Creator tool: skyfov
Columns:
| Column Name |
Units |
Description |
| POS(X,Y)[13] | pixel | Position |
| SHAPE | | Region shape type |
| R[2] | pixel | Radius |
| ROTANG[2] | pixel | Angle |
| COMPONENT | | Component number |
| CCD_ID | | CCD ID |
Detector Mask
Description:
The mask file records the valid part of the detector element -
ACIS CCD or HRC plate - used for the observation (i.e. the
portion for which events can be telemetered). The active portion
of an element may be smaller than the default regions if an
observation was performed using subarrays or custom windows
Creator tool: acis_build_mask, hrc_build_mask
Columns:
| Column Name |
Units |
Description |
| SHAPE | | region shape |
| COMPONENT | | Component index |
| CHIP(CHIPX,CHIPY)[2] | pixel | CHIP position |
| SAMP_CYC | | sampling cycle |
| PHAMIN | | minimum pulse height |
| PHAMAX | | maximum pulse height |
For ACIS, each CCD is 1024x1024 pixels. The mask file for a standard full-frame
observation will contain 3 rows. The first row will SAMP_CYC=1 and will
have X and Y values 2:1023. The 2nd and 3rd rows will have SAMP_CYC=0,
indicating that no events are recorded there; row2 will have X and Y values
going from 1:1024, row3 will have X and Y values going from 2:1023
with the shape set to "!rectangle". This is logic used to specify that
no events are detected in the 1 pixel border around the chip.
Grating Source List
Description:
The zero-order centroid location for grating observations. if
there are multiple observation intervals (OBIs), then the
table is formed by merging each OBI's table with the previous
using source-matching to form a unique source identifier
column.
Creator tools: celldetect, tgidselectsrc, tgmatchsrc
Columns:
| Column Name |
Units |
Description |
| RA | deg | Source Right Ascension |
| DEC | deg | Source Declination |
| RA_ERR | deg | Source Right Ascension Error |
| DEC_ERR | deg | Source Declination Error |
| POS(X,Y) | pixel | Physical coordinates |
| X_ERR | pixel | Source X position error |
| Y_ERR | pixel | Source Y position error |
| CELLPOS(CELL_X,CELL_Y) | pixel | Physical coordinates |
| DETSIZE | pixel | source cell size |
| BKGSIZE | pixel | background cell size |
| NPIXSOU | pixel | pixels in source cell |
| NPIXBKG | pixel | pixels in background cell |
| NET_COUNTS | count | Net source counts |
| NET_COUNTS_ERR | count | Error in net source counts |
| BKG_COUNTS | count | Background counts (scaled to source cell) |
| BKG_COUNTS_ERR | count | Error in BKG_COUNTS |
| NET_RATE | count/s | Source count rate |
| NET_RATE_ERR | count/s | Source count rate error |
| BKG_RATE | count/s | Background count rate |
| BKG_RATE_ERR | count/s/pixel | Background count rate error |
| EXPTIME | s | Effective exposure time |
| SNR | | Signal-to-Noise ratio |
| SHAPE | | Shape of source region |
| R[2] | pixel | Radii of source region source |
| ROTANG | deg | Rotation angle of source region |
| PSFRATIO | | ratio of source ellipse size to PSF size |
| BLOCK | | blocking factor |
| COMPONENT | | Source Number |
| EXPO_RATIO | | ratio of average background and detect cell exp |
| DOUBLE | | double detection flag |
| DOUBLE_ID | | double source component |
| TG_SRCID | | |