batcelldetect - perform source detection using the sliding cell method
batcelldetect infile outfile snrthresh
batcelldetect performs source detection on a sky image. The sliding
cell method is used to locate regions of the image which are
significantly different from the background.
This tool is more appropriate for coded aperture imaging because: (1)
it assumes Gaussian fluctuations, not Poissonian; (2) it measures the
local background; and (3) it measures the local background standard
deviation. A source is detected at a pixel if that pixel's value
exceeds the background by more than "snrthresh" times the background
standard deviation. Users can increase the significance of a
detection and reduce false detections by requiring more than one
adjacent pixel exceed the threshold, using the "nadjpix" parameter.
The "nullborder" and "bkgpcodethresh" parameters can also be used to
exclude false positives near the edge of the image.
This tool performs analysis in two stages. In the first stage, new
sources are detected using a sliding cell method. In the second
stage, the fluxes and positions of both new and previously known
sources are refined by fitting the point spread function.
In the first stage, the background and pixel significances are
estimated by using a sliding window region method. The shape of the
window is either a circular annulus or "square annulus," depending on
the 'bkgwindowtype' parameter. The outer radius of the circle (or
half-width of the square) is specified by the bkgradius parameter.
The window region does not include the centermost portion (whose
radius is the srcradius parameter). This portion should be the size
of a typical source, so that the fluxes from sources do not
contaminate the background estimate. For source detection, the pixel
significance is estimated as the raw pixel value divided by the local
standard deviation calculated using this method.
In a single iteration, the sliding cell algorithm is less sensitive in
a region around bright sources, because the background standard
deviation becomes biased. To avoid this, the algorithm can be run in
multiple iterations (controlled by the 'niter' parameter). After each
iteration, the detected pixels are removed, and thus the bias can be
At the second stage, batcelldetect fits a point spread function to
regions of the image where sources are detected. For new sources,
this aids in refining the centroid of the source position, as well as
in estimating uncertainties.
The default output is a catalog list of detected sources, plus various
statistics about them. The output flux column is either COUNTS or
RATE, depending on the input image units. The tool can optionally
output the background map, the background fluctuation map, and a
IMPORTANT NOTE: if the keepbadsources parameter is 'YES', then
the output catalog may contain some sources which failed processing
for one reason or another. Information on the success or failure on a
source-by-source basis is recorded in the DETECT_STATUS column.
The user can also supply an input catalog. Sources in the input
catalog, which are within the field of view of the image, are assumed
to be fixed at their known positions, and fitted during the
PSF-fitting stage for intensity only (unless posfit=NO). Additional
detected sources are also written to the output catalog.
This task can operate on multiple images, as produced by batfftimage.
If the images vary only in their energy range, and are otherwise
identical in their coordinate systems and exposures, then the
'vectorflux' parameter can be set to YES. When vectorflux=YES, each
source has only one catalog row, and multiple fluxes are recorded in a
vector table cell. When vectorflux=NO, a source will appear multiple
times in the catalog, with a single flux in each entry. Note that if
the input images do not match exactly their coordinate system or
exposures, then you must specify vectorflux=NO.
To avoid spurious detections at the edge of the field of view, a
partial coding threshold can be specified (see 'pcodefile' and
'pcodethresh'). If a partial coding map is provided, then by default
sources must be at least 1% coded.
This routine uses a relatively straightforward brute-force convolution
by FFT to compute the sliding-cell averages. Users should have a
about a factor of eight more memory than the size of the image.
Fitting For Position and Flux
batcelldetect has several options to fit the positions and fluxes
of sources. Newly detected and previously known sources are treated
differently. By default, the positions of newly detected sources are
allowed to vary and the those of previously known sources are held
fixed. This behavior depends on the input parameters and the input
The following behaviors are possible:
As of May 2007, the BAT team recommends using the GAUSSIAN point
spread function (FWHM=0.37413) for all BAT data throughout the
mission. The previous recommendation to use the "PYRAMID" shape was
- Perform source detection only. For all
sources, neither position nor flux are fit. For new sources, the
positions are taken from the source detection stage. For previously
known sources, the values are transferred from the input catalog
- srcfit=YES; posfit=NO (DEFAULT)
- Hold the position of known
sources fixed, but fit for the positions of new sources. The fluxes
of all sources are fitted.
- srcfit=YES; posfit=YES; posfitwindow=0.0
- Fit for the positions
of all sources. The positions of known sources are allowed to vary
within a window which is 3 times the ERR_RAD value from the input
catalog. Thus, if ERR_RAD = 0, the position is held fixed. Special
cases: if an individual value of ERR_RAD is null, the position of that
source is allowed to vary. If the ERR_RAD column is missing entirely,
the positions are assumed to be fixed. The fluxes of all sources are
- srcfit=YES; posfit=YES; posfitwindow > 0
- As above,
except the positions of known sources are allowed to vary by +/-
3*ERR_RAD or +/- posfitwindow, whichever is larger.
The output catalog contains the following columns. Other input
columns are copied to the output unchanged. For new sources entries,
the row is filled with null value before writing batcelldetect-derived
Note that while the input catalog is only required to have the NAME,
RA_OBJ and DEC_OBJ columns, they must have the units and
dimensions listed below. Any input catalog columns that match the
list below, must also have the specified units.
The data type should be either "D" (double) or "J" (integer);
the NAME column can be up to a 30-character string. The word
"Vector" indicates which output catalog columns will be a vector if
vectorflux=YES and multiple images are analyzed.
- Start time of image (Mission Elapsed Time). Type=D, Unit=s.
- Stop time of image (Mission Elapsed Time). Type=D, Unit=s.
- EXPOSURE time of image. Type=D, Unit=s.
- Catalog identification number. For known sources, this number is copied from input catalog. For new sources, the number is determined by the 'newsrcind' parameter. Type=J.
- Source name. For known sources, this name is copied from input catalog. For new sources, the name will be 'UNKNOWN'. Type=30A (string).
- IMX Tangent plane coordinate (instrument X). Type=D.
- IMY Tangent plane coordinate (instrument Y). Type=D.
- IMX formal uncertainty. Type=D.
- IMY formal uncertainty. Type=D.
- IMX pixel coordinate (instrument X). FITS coordinate pixels label the center of the first pixel as IMXPIX=1.0. Type=D, Unit=pixel.
- IMY pixel coordinate (instrument Y). FITS coordinate pixels label the center of the first pixel as IMYPIX=1.0. Type=D, Unit=pixel.
- RA_OBJ / GLON_OBJ
- Source celestial longitude (equatorial or galactic). The presence of output celestial coordinates depends on the WCS coordinate system embedded in the input image. Type=D, Unit=deg.
- DEC_OBJ / GLAT_OBJ
- Source celestial latitude (equatorial or galactic). Type=D, Unit=deg.
- RA_OBJ_ERR / GLON_OBJ_ERR
- Source celestial longitude formal uncertainty (1 sigma). Type=D, Unit=deg.
- DEC_OBJ_ERR / GLAT_OBJ_ERR
- Source celestial latitude formal uncertainty (1 sigma). Type=D, Unit=deg.
- Estimated error radius (formal; 1 sigma). Type=D, Unit=deg.
- Instrumental PSF X full width at half-max (tangent plane coords). Type=D.
- Instrumental PSF Y full width at half-max (tangent plane coords). Type=D.
- Instrumental PSF X FWHM formal uncertainty (1 sigma). Type=D.
- Instrumental PSF Y FWHM formal uncertainty (1 sigma). Type=D.
- Source angle from instrumental boresight. Type=D, Unit=deg.
- Source instrumental longitude. Type=D, Unit=deg.
- BAT simulator longitude. Type=D, Unit=deg.
- BAT simulator latitude. Type=D, Unit=deg.
- Background-subtracted source count rate (units from image BUNIT keyword)
RATE is used if the image has rate-like units. Type=D, Vector.
- Source count rate formal uncertainty (1 sigma; units from image). Type=D, Vector.
- Background-subtractd source count rate derived from the pixel nearest to the output catalog position. Type=D, Vector.
- Estimated count rate due to all sources except this source; a measure of contamination due to diffuse background and nearby confusing sources. Type=D, Vector.
- Background-subtracted source counts (units from image BUNIT keyword)
COUNTS is used if the image does not have rate-like units. Type=D, Vector.
- Source counts formal uncertainty (1 sigma; units from image). Type=D, Vector.
- Background-subtracted source counts derived from the pixel nearest to the output catalog position. Type=D, Vector.
- Estimated counts due to all sources except this source; a measure of contamination due to diffuse background and nearby confusing sources. Type=D, Vector.
- Local diffuse background intensity, ignoring any nearby point sources. This is the value used for background-subtraction of sources. The BKG column is filled with data from either the BKG_FIT or the BKG_CELL column. (units from image BUNIT keyword). Type=D, Vector.
- Local background intensity formal uncertainty (1 sigma; units from image). Type=D, Vector.
- Local background standard deviation (units from image). Type=D, Vector.
- Local diffuse background intensity, as estimated using the PSF fitting technique. (units from image BUNIT keyword). Type=D, Vector.
- Local diffuse background intensity, as estimated using the sliding cell technique. (units from image BUNIT keyword). Type=D, Vector.
- Source signal to noise ratio (defined as RATE/BKG_VAR). Type=D, Vector.
- Source signal to noise ratio (defined as CENT_RATE/BKG_VAR). Type=D, Vector.
- Number of valid pixels in the source window. Type=J, Unit=pixel.
- Number of valid pixels in the background window. Type=J, Unit=pixel.
- Method used for source detection:
4=Position calculated from multiple vector images
- Chi2 value in PSF fit. Type=D, Vector.
- Number of degrees of freedom in PSF fit. Type=D, Vector.
- Reduced Chi2 value in PSF fit. Type=D, Vector.
- Source detection status code; entries with non-zero DETECT_STATUS are deleted when keepbadsources='NO'; One of:
-1=Too many pixels detected;
-2=No pixels detected;
-3=Source touches border of image;
-4=Source error radius did not fit in source window.
-5=PSF fit failed (source was likely out of bounds)
- PSF fitting constraint flag; Describes which parameters of the PSF model were fixed; Sum of:
8=PSF width fixed.
- Source window radius . Type=J, Unit=pixel.
- Background window radius . Type=J, Unit=pixel.
- Number of good detectors (copied from input image). Type=J, Unit=pixel.
- Near-field source height (ground testing only; coped from input image). Type=D, Unit=cm.
- Partial coding fraction of source. Type=D.
- Derivative of x position with respect to IMX. Type=D, Unit=deg.
- Derivative of x position with respect to IMY. Type=D, Unit=deg.
- Keywords copied from input image via the 'keepkeywords' parameter.
For the columns which refer to intensity --- namely RATE, COUNTS,
CENT_RATE and/or CENT_COUNTS --- batcelldetect performs background
subtraction. The source of the background estimate depends on the setting of
the 'bkgfit' parameter. If 'bkgfit=NO', then the background is
derived from the nearest pixel of the estimated background map. If
'bkgfit=YES', then the background is estimated during the PSF fitting
process, as an additional constant level.
Whichever background method is chosen, the estimated background is
subtracted from the raw intensity value before it is reported in the
output catalog. The background value that was used is reported in the
output catalog column named BKG. Hence, this equation holds for
RATE, RAW_RATE = RATE + BKG, where RAW_RATE is the
raw image peak height. In addition, the values derived from the two
different methods are reported in the BKG_CELL and BKG_FIT catalog
columns, corresponding to the background map and fitted PSF techniques
The background level is considered to be a contaminating source, and
thus is added to the reported CONTAM_FLUX value.
Batcelldetect can correct for systematic non-linear centroid shifts in
the image. It is assumed that all catalog celestial positions (input
and output) are in "true" undistorted coordinates. All distortion
corrections occur at the pixel level within batcelldetect. The
distortion correction occurs if the 'distfile' parameter points to a
- infile [filename]
- Input file name containing one or more sky maps. Each sky map
should be stored as one image extension. (Avoid using the CFITSIO
syntax to select image extensions; individual images extensions can be
selected from the file using the 'rows' parameter).
- outfile [filename]
- Output source list.
- snrthresh [real]
- Signal to noise threshold for detection of sources. A value of
6.0 indicates that an excess must be 6 sigma above the background
level to be considered a detection. Here 1 sigma is the standard
deviation of the background. Note: for performance reasons users
should choose snrthresh > 3.5. Also, if nadjpix > 1, then the
effective threshold will be higher than snrthresh.
- (incatalog=NONE) [string]
- Name of input catalog of known sources. This catalog must have at
least the columns RA and DEC, in degrees (J2000). Additional columns
are also copied to outfile (however see above about required units). A
value of "NONE" indicates that no a priori catalog should be used.
Specifying this incatalog=NONE by itself does not prevent the
cell-detection based source detection algorithm from being applied.
- (pcodefile=NONE) [string]
- Name of optional partial coding map file. This may be any image
with exactly the same dimensions and coordinate system as infile. Any
region where the partial coding map exceeds pcodethresh is searched
for sources; any region where it is below pcodethresh is ignored. The
map need not be an actual partial coding map; any quantity that can be
thresholded (even a map of 0s and 1s) can be used. If pcode file is
"NONE", then the entire image is searched.
- (pcodethresh=0.01) [real]
- Partial coding threshold for source detection. This threshold is
applied to the map specified in pcodefile. Any partial coding value
greater than pcodethresh is considered active for the purposes of
- (bkgpcodethresh=-1) [real]
- Partial coding threshold for background analysis. This threshold
is applied to the map specified in pcodefile. Any partial coding
value greater than bkgpcodethresh is considered active for the purposes
of measuring the backgroud and its variance. A value of -1 indicates
that bkgpcodethresh should be set to pcodethresh. The "source" and
"background" thresholds are kept separately so that background
analysis can be done over a wider area than the source acceptance
- (pospeaks=YES) [boolean]
- Constrain newly detected peaks to be positve. If NO, then
significant positive or negative deviations will be searched
for. Known catalogged sources are permitted to have a negative fitted
flux regardless of pospeaks.
- (posfluxfit=NO) [boolean]
- If YES, constrain the flux to be positive during the PSF fitting
stage. If NO, fluxes are allowed to be positive or negative.
- (vectorflux=NO) [boolean]
- If YES, then output flux values for a given source as a vector,
one element for each input image. If NO, then output one catalog rows
for each source in each input image. Note, for vectorflux=YES, the
input images must all match their coordinate systems, exposure, and
instrument configuration exactly.
- (rows = "-") [string]
- An index list of images to operate on. This is a standard
comma-separated list of image ranges, starting with image number 1.
Image number 1 corresponds to the primary extension of the input FITS
file, 2 to the next extension, and so on. A range of "-" indicates all
images should be processed. Thus, this parameter really selects
image extension numbers to operate on rather than binary table
- (niter=2) [integer]
- Number of iterations of source detection to perform. niter=0 is
allowed; in that case the sources in the input catalog (if any) which
are in the field of view are transferred to the output catalog.
- (carryover=YES) [boolean]
- For the analysis of multiple images. If YES, then carry over the
sources detected in the analysis of earlier images to the analysis of
later images. Positions of previously detected new sources are held
fixed as described above. If NO, then the analysis of each image
begins from scratch, excluding any previously detected sources. Note
that carryover=NO and vectorflux=YES are contradictory.
- (nadjpix=3) [integer]
- Minimum number of adjacent pixels required for source detection.
This serves to decrease the number of false detections. This quantity
is somewhat dependent on the image oversampling used.
- (nullborder=NO) [boolean]
- Allow sources which fall on the border of the image? If no, then
sources whose "source window" overlaps with the edge of the image are
ignored. The edge of the image is defined by the partial coding
threshold. These sources may still appear in the output catalog with
a DETECT_STATUS value of -3.
- (bkgwindowtype="circle") [string]
- Background window type, one of "circle", "smooth_circle" or
"square". A "circle" is an annular background region with sharp inner
and outer edges. A "smooth_circle" has the same shape but the edges
are tapered in order to reduce noise fluctuations. A "square" is a
square region with sharp inner and outer edges.
- (bkgradius=30) [integer]
- Background window radius in pixels. For a window of "circle", the
bkgradius parameter is the radius of the circle. For a "square"
window, the bkgradius is the half-width of the square. Actual
diameter of circle or square is 2*bkgradius+1.
- (regionfile=NONE) [string]
- Optional name of source detection region file. Upon output,
sources listed in the outfile catalog are also written to an ASCII
"region" file, which can then be read into image display programs such
as fv/POW or SAO ds9. Output units are degrees. The radius of the
circle is twice the PSF gaussian sigma radius.
- (srcradius=6) [integer]
- Source radius in pixels. If 0, then the full background window is
used to estimate the background and its standard deviation. Actual
diameter of circle or square is 2*srcradius+1.
- (srcdetect=YES) [boolean]
- If srcdetect is set to "YES", then batcelldetect will attempt to
detect new sources. If "NO", then source detection is disabled, but
source fitting of previously cataloged sources may still be performed
(depending on the value of 'srcfit').
- (srcfit=YES) [boolean]
- If srcfit is set to "YES", then batcelldetect will fit newly
detected and previously cataloged sources (if any) as described above.
If "NO", then previously determined positions and intensities are
output. See "Fitting For Position and Flux" above.
- (posfit=NO) [boolean]
- Posfit specifies whether batcelldetect fits the position of
already known sources. See "Fitting For Position and Flux"
above. Also, the parameter 'posfitwindow' may override this parameter.
- (bkgfit=YES) [boolean]
- Fit the background for each source individually? If yes, then
during the PSF fitting stage, each source has an independent
background level. If no, a fixed background is subtracted.
- (psfshape="GAUSSIAN") [string]
- Shape of the point spread function to use. It should be one of
"GAUSSIAN", "PYRAMID" or "TRUNCONE". "GAUSSIAN" is a two-dimensional
gaussian function (which more closely matches the Swift/BAT point
spread function in a single image); "PYRAMID" is a two-dimensional
pyramidal frustum with a square base (no longer recommended);
"TRUNCONE" is a truncated cone (no longer recommended).
- (psffwhm="0.37413") [string]
- Full-width at half maximum of the point spread function, in units
of degrees. By default, this is held fixed, but if ":FIT" is
appended, then the width is fitted. The default value listed above
applies to the BAT point spread function.
- (psftopwidth="0.04584") [string]
- For the pyramidal point spread function, the full width of the top
of the truncated pyramid, in units of degrees. By default, this is
held fixed, but if ":FIT" is appended, then the width is fitted. The
default value listed above applies to the BAT point spread function.
- (newsrcname="UNKNOWN") [string]
- Name to be used for newly detected sources. This can be a C
format string, whose interpretation depends on the value of the
newsrcind parameter. If newsrcind is greater than or equal to zero,
then newsrcname may contain a single "%d"-style C format code. Each
new source is given a unique source number, starting with index
newsrcind. If newsrcind is -1, then newsrcname may contain two "%f" C
format codes for the RA and DEC position, in degrees.
- (newsrcind=1) [integer]
- Starting index number to be used to label new sources (see
newsrcname). If -1, then sources are labeled by their position on the
- (signifmap=NONE) [string]
- Optional output file name for the significance map.
- (bkgmap=NONE) [string]
- Optional output file name for the mean background map.
- (bkgvarmap=NONE) [string]
- Optional output file name for the background fluctuation map.
- (inbkgmap=NONE) [string]
- Optional background map which overrides the internally-calculated
background. The map or maps must have exactly the same structure and
number of images as the input image file. If inbkgmap=ZERO, then the
background is explicitly set to zero in the source detection stage.
- (inbkgvarmap=NONE) [string]
- Optional background variation map which overrides the
internally-calculated variation map. The map or maps must have
exactly the same structure and number of images as the input image
- (distfile=CALDB) [string]
The 'distfile' parameter should point to a FITS file containing an
MxNx2 image (or CALDB to use the default instrument correction in the
calibration database). The two planes of the image are the non-linear
distortion of the BAT "plate scale" as a function of position in the
sky image. The values are offsets in tangent plane coordinates
(IMX,IMY), and therefore unitless. The first plane of the image cube
is the IMX offset, and the second plane is the IMY offset. The sense
of the offset is (TRUE-APPARENT), i.e. for a measured position in
tangent plane coordinates, the offset values should be *added* to
arrive at the true position in tangent plane coordinates. The images
are low-resolution versions of the BAT field of view in instrumental
sky coordinates, and are meant to be interpolated to the desired
sampling. The WCS keywords must specify the image coordinate systems.
- (keepbits = "ALL") [string]
- Integer number of bits of precision to keep in the output images.
A value of ALL means keep all bits. A positive value indicates that
'keepbits' bits of precision should be preserved, and the other bits
should be set to zero. Fewer kept bits means the output images are
more compressible, at the expense of lost precision. For background
and variance maps, a straight number of bits are kept (thus preserving
the same relative precision across the map). For significance maps,
'keepbits' prescribes the number of
noise bits to keep; more bits may be kept if a pixel is
significantly above the noise (thus preserving the same noise
quantization error across the map).
- (npixthresh=20) [integer]
- Minimum number of pixels in the background window to enable source
detection. Setting this parameter to a high number will prevent
detections based on only a few background pixels.
- (posfitwindow=0) [real]
- The position 'window' radius, in degrees, used for all position
fits, including known sources. The window is the allowed region over
which the centroid position is allowed to vary during the position
fit, regardless of the error radius specified for the source.
Typically, this parameter will only be used if the attitude solution
is suspected to be incorrect. A value of zero indicates that the
window size is determined by the error radius specified in the
catalog, if any. WARNING: This parameter is basically an override for
the ERR_RAD column and the 'posfit' parameter. See "Fitting For
Position and Flux" above.
- (possyserr=0) [real]
- Systematic position error, in degrees, to be added in quadrature
to each position error radius reported in the output catalog. This
parameter allows one to specify a minimum systematic position error
for every reported detection (which is separate from posfitwindow,
which controls the position determination process itself).
- (vectorposmeth=AVERAGE) [string]
- Specify which source position is reported when the source position
is fitted and vectorflux=YES. The output catalog has only one
position for each source. If position fitting is allowed and
vectorflux=YES, then it is possible for multiple positions to be
derived. This parameter describes what to do with multiple positions.
The allowed values are: "FIRST" or "FIXFIRST" - report the fitted
position in the first image; "LAST" - report the fitted position in
the last image; "AVERAGE" - report the weighted average fitted
position; "MAX_SNR" - report the fitted position for the image with
highest signal-to-noise ratio. "FIXFIRST" is different than "FIRST"
in that once a fitted source position is found, its position is held
fixed for subsequent images. If the fitted position does not exceed
'snrthresh' then it will not be included in these calculations. When
positions are combined using one of the above methods, then the
DETECT_METHOD column will be flagged with a multiple of 4.
- (keepkeywords="*APP,CLEANLEV") [string]
- A comma separated list of keywords or keyword wildcard patterns.
The matching keywords are transferred to the output catalog, under a
column of the same name. This is a way to automatically keep track of
corrections that have been applied to the input image. The CFITSIO
wildcard patterns are: '?' will match any single character at that
position in the keyword name; '*' will match any length (including
zero) string of characters; and '#' will match any consecutive string
of decimal digits (0 - 9).
- (hduclasses="-VIGNETTING,-BKG_VARIANCE,-BKG_STDDEV,-SIGNIFICANCE") [string]
- List of comma-separated image type filters, used to accept or
reject images based on their HDUCLASn keywords. This is useful for
files that contain different kinds of image extensions. A minus sign
"-" indicates exclusion. Each image is checked for each of the
HDUCLASn keywords. If any of the keyword values matches an excluded
list member, then that image is rejected for analysis. List members
without a minus sign must be present. A value of NONE
indicates no filtering (i.e. all images are accepted).
- (sortcolumns="-KNOWN,-SNR/UNKNOWN,RA_OBJ") [string]
- Controls the sort order of the table displayed on the console.
Note that this does not affect the FITS table, which can be sorted
using ftsort or fsort. The string should be a comma-separated list of
sort keys, or "NONE" for arbitrary printed order. The first key
listed is the primary sort key, the next is the secondary and so on.
By default, values are printed from lowest to highest, but a preceding
'-' sign indicates highest to lowest. The following sort keys are
available: NAME; RA_OBJ; DEC_OBJ; SNR; RATE; COUNTS; FLUX (all three
of these keys are synonymous); KNOWN (if the sources appears in the
input catalog or not); IMX; IMY; PCODEFR; CATNUM; THETA; PHI;
SNR/UNKNOWN. Most sort keys are identical to their corresponding
catalog column, described above. "SNR/UNKNOWN" is a special sort key,
indicating to sort only previously unknown columns by SNR. The
default sortcolumns indicate to arrange the table by printing the
known sources first, sorted by RA, and then the unknown sources,
arranged in descending order by signal to noise ratio.
- (keepbadsources = NO) [boolean]
- If yes, then individual sources are kept in the output catalog,
even if DETECT_STATUS is non-zero, indicating a failure of some kind.
If no, then any output catalog entry with DETECT_STATUS non-zero is
- (ptcorrel = "NONE") [string]
- Account for pixel to pixel correlations during the fit.
Either NONE (straight PSF fitting); PSF (use PSF for correlations);
or GAUSSIAN[x] (where x is the FWHM of the correlation function in
NOTE: This parameter is not tested and may produce unexpected results!
- (clobber = NO) [boolean]
- If the output file already exists, then setting "clobber = yes" will cause it to be overwritten.
- (chatter = 2) [integer, 0 - 5]
- Controls the amount of informative text written to standard
output. Setting chatter = 1 produces a basic summary, including a
list of detected sources; chatter = 2 (default) additionally prints a
summary of input parameters; chatter = 5 prints debugging information.
- (history = YES) [boolean]
- If history = YES, then a set of HISTORY keywords will be written to
the header of the specified HDU in the output file to record the value
of all the task parameters that were used to produce the output
1. Performs source detection on skyimage.img, finding those sources which
exceed the background by 6 sigma. The output is written to srclist.fits.
The default circular background window is used.
batcelldetect skyimage.img srclist.fits 6.0
2. Same as example 1, but use a square background window of half-width
batcelldetect skyimage.img srclist.fits 6.0 \
3. Same as example 1, but outputs the significance image to
signif.img as well.
batcelldetect skyimage.img srclist.fits 6.0 signifmap=signif.img
The fitting library, MPFIT, is based on MINPACK. This product
includes software developed by the University of Chicago, as Operator
of Argonne National Laboratory. See 'fhelp batcelldetect-mpfit' for