Last modified: 3 April 2024

Contextual List of Ahelp Files

Context Topic Summary
ahelp ahelp Access the CIAO help documentation.

calibration ardlib Analysis Reference Data Library
caldb CALibration DataBase (CALDB)

chandra coords Coordinate systems used in Chandra analysis
eventdef Column definition in Chandra event files
level Describes the amount of processing performed to create a given product.
mtl A description of the Mission Time Line (MTL)
pileup An overview of pileup in the Chandra ACIS detector.
times "Times" used in Chandra datasets and Chandra data analysis

concept autoname Autonaming is a feature available in various tools for automatically naming an output file based upon the name of an input file.
ciao-install Download and install CIAO, CALDB, and the contributed script files
ciaorc (OBSOLETE) The .ciaorc file provides user-configuration options for CIAO
ciao Chandra Interactive Analysis of Observations
dmmath Syntax used for writing mathematical operations in dmtcalc, dmimgcalc, and dmgti
history A record of the tools that were run, along with the parameter settings, on a file.
merging_rules A description of the merging rules used when combining header information.
parameter Describes the parameter interface used by CIAO.
stack How to set a parameter to more than one value using a stack.
subspace Describes the filtering applied to a file

contrib add_colvals Add a column to a crate given a name and array of values
cda_data Download public data by ObsId from the Chandra archive (Python interface).
cda_search Find publicly-available Chandra ObsIds from the Chandra archive (Python interface).
check_caldb_version Check whether the locally-installed version of the Chandra Calibration DataBase (CALDB) is up to date
ciao_caldb Utility routines for the CIAO CALDB (CIAO contributed package).
ciao_contrib Useful Python routines for CIAO.
ciao_proptools Experimental interface to the Chandra proposal tools (CIAO contributed package).
ciao_runtool Run CIAO tools from Python as if they were functions (CIAO contributed package).
ciao_smooth Simple smoothing routines for 2D data
ciao_stacklib Support routines for using stacks in CIAO (CIAO contributed package).
ciao_utils Utility routines for CIAO (CIAO contributed package).
coords_chandra Utility routines for working with Chandra Coordinates
coords_format Convert between string and numeric formats for Astronomical positions.
coords_gratings Object to convert to/from Chandra grating coordinates.
coords_utils Utility routines for working with Astronomical positions.
crates_contrib Contributed CIAO routines for Crates.
crates_images Image-related routines for Crates (CIAO contributed package).
crates_utils Utility routines for Crates (CIAO contributed package).
FOVFiles Check which FOV files contains the specified RA,Dec location.
get_caldb Access various information about the Chandra Calibration DataBase (CALDB)
identify_name Find the position of an astronomical object using NED or CDS.
imextent Create a linear 2D transformation for the axes of an image
lc_clean lc_clean - remove periods of high (or low) count rates using the same technique as the ACIS background files
lc_sigma_clip lc_sigma_clip - remove flares from a light curve using an iterative sigma-clipping algorithm
lightcurves lightcurves - routines to remove periods of anomalously high (or low) count rates in a lightcurve
make_image_crate Create an IMAGECrate from an array.
make_table_crate Create a TABLECrate from a set of arrays, a dictionary, or a structured array.
read_ds9_contours Read in the contours from a ds9 *.con file with optional coordinate conversion.
scale_image_crate Scale the pixel values in an IMAGE crate.
simplecoordtransform Convert between the different coordinate systems of an image.
simple_hist Create a one-dimensional histogram of a data array
simple_stats Calculate several basic statistic values for a data array
smooth_image_crate Smooth the pixel values in an IMAGE crate.
write_arrays Write arrays to an ASCII file
write_columns Write out arrays (columns) to a file as a table (ASCII or FITS format).

crates add_col Add a column to a crate.
add_crate Add a crate to a dataset.
add_key Add a keyword to a crate given a CrateKey object.
add_piximg Add an image to a crate.
col_exists Determine if a column exists in a crate.
copy_colvals Copy the column values from a crate.
copy_piximgvals Copy the image values from a crate.
cratedataset The CrateDataset object is used to read and write files with multiple blocks.
cratedata The CrateData object is used to store column or image data.
cratekey The CrateKey object is used to represent a header item (keyword and value) for a file.
crates Reading, writing, and changing ASCII and FITS files in Python
crate The TABLECrate and IMAGECrate objects represent a block in a file.
create_vector_column Create a vector column.
create_virtual_column Create a virtual column.
delete_col Delete a column from a crate.
delete_key Delete a keyword from a crate.
delete_piximg Delete an image from a crate.
get_axis_transform Return the axis transform from an IMAGECrate.
get_colvals Get the column values from a crate.
get_col_names Return an array of the column names in a crate.
get_col Return a CrateData object of a column from a crate.
get_crate_item_type Return the type of the crate item as a string.
get_crate_type Return the type of the crate as a string.
get_crate Get a crate from a dataset.
get_keyval Return the value of a keyword in a crate.
get_key_names Return an array of the keywords in a crate.
get_key Return a CrateKey object of a keyword from a crate.
get_number_cols Return the number of columns in a crate.
get_number_rows Return the number of rows in a crate.
get_piximgvals Get the pixel values from an image crate.
get_piximg_shape Get the dimensions of the image stored in the IMAGECrate.
get_piximg Return a CrateData object of an image from a crate.
get_transform_matrix Extract the transform matrix from a crate.
get_transform Extract the coordinate transform from a crate.
is_pha Determine if the crate dataset contains a PHA file and its type.
is_rmf Determine if the crate dataset contains an RMF.
is_virtual Determine if the input column from the crate is a virtual column.
key_exists Determine if the keyword exists in the crate.
print_crate_names Display information on data from a crate.
read_dataset Read all contents of a file.
read_file Read FITS or ASCII data into a crate.
read_pha Load a PHA file into a PHACrateDataset.
read_rmf Load an RMF file into a RMFCrateDataset.
set_colvals Set the values of a column in a crate.
set_keyval Set the keyword value in a crate.
set_key Add a keyword to a crate given a name and a value.
set_piximgvals Set the pixel values in an image crate.
write_dataset Write a dataset to an output file.
write_file Write a crate to an output file.
write_pha Write a PHACrateDataset to a file.
write_rmf Write an RMFCrateDataset to a file.

dm dmascii Using the Data Model with text files
dmbinning The CIAO binning syntax
dmfiltering Filtering tables and images with the Data Model
dmmasks CIAO mask filtering syntax
dmopt Controlling Data Model internal options
dmregions CIAO region filtering syntax
dm CIAO Data Model: syntax for filtering and binning files

group group Provides the Python interface to the CXC grouping library
grpAdaptiveSnr Adaptively group an array by signal to noise.
grpAdaptive Group an array by the number of counts per group using an adaptive scheme.
grpBinFile Group an array using the grouping applied to another dataset.
grpBinWidth Group an array into a set of equal-width groups (by group width).
grpBin Group an array using low and high boundaries.
grpGetChansPerGroup Calculate the number of channels (elements) in each group.
grpGetGroupSum Apply the supplied grouping to an array.
grpGetGrpNum Calculate the group number for each element in the array.
grpMaxSlope Group an array so that its absolute gradient is above a user-defined limit.
grpMinSlope Group an array so that its absolute gradient is below a user-defined limit.
grpNumBins Group an array into a set of equal-width groups (by number of groups).
grpNumCounts Group an array by the number of counts per group.
grpSnr Group an array by signal to noise.

paramio paccess Returns the path to the specified parameter file.
paramclose Close a parameter file opened by paramopen.
paramio The Python interface to the CXC parameter system
paramopen Open a parameter file.
pgets Read/write individual parameter values.
pget Get a parameter value as a string.
plist Get list of parameter names.
pquery Query a parameter value.
pset Set a parameter value.
punlearn Restore the system defaults for a parameter file.

proposaltools colden COLDEN is an interactive program to evaluate the neutral hydrogen column density at a given direction on the sky
dates DATES is an interactive calendar and time conversion tool.
obsvis ObsVis is the Observation Visualizer created at the Chandra Science Center in Cambridge Massachusetts, USA.
pimms PIMMS (Portable, Interactive Multi-Mission Simulator) converts source fluxes and count rates between missions.
precess PRECESS is an interactive astronomical coordinate conversion program. It provides precession of equatorial coordinates and conversion between equatorial, ecliptic, galactic, and supergalactic coordinates.
prop-coords Defines available coordinate systems for Chandra Proposal Tools
prop-time Defines available calendars and timescales for command line versions of Chandra Proposal Tools
prop-tools Tools that aid in the preparation and submission of Chandra proposals

psf psf A Python module to calculate the size or enclosed-counts fraction of the Chandra PSF

region regArea *DEPRECATED* Calculate the area enclosed by a region.
regExtent *DEPRECTATED* Calculate the bounding box of a region.
regInsideRegion *DEPRECATED* Is a point (or set of points) inside a region?
region-old *DEPRECATED* Provides the Python interface to the CXC region library
region Provides a Python interface to the CXC region library
regParse *DEPRECATED* Parse a region for use by the routines in the region library
regPrintRegion *DEPRECATED* Print out diagnostic details about a region.
regRegionString *DEPRECATED* Converts a region object into a string.

scripting python Python is a dynamic object-oriented programming language used by CIAO

tools::acis acisreadcorr Flag and relocate out-of-time CCD events
acis_build_badpix Create an observation-specific bad-pixel file
acis_check_pha_range Compute approximate energy range for on-orbit PHA filter.
acis_clear_status_bits Clear (set to 0) ACIS status bits before reprocessing with acis_process_events
acis_detect_afterglow Identify and flag cosmic ray afterglows
acis_find_afterglow Identify cosmic-ray afterglows and hot pixels for TIMED mode observations
acis_process_events Produce or update the time, coordinate, pulse-height, grade, and status information in ACIS event files
acis_streak_map Generate high frequency background maps (streakmaps) which identify ACIS streaks caused when bright source photons are applied to the wrong pixel during readout.
destreak Remove streak events from ACIS data
multi_chip_gti Create a combined GTI file for multiple ACIS chips

tools::aspect asphist Bin the aspect solution into a 3D histogram of duration vs pointing offset and roll offset.
asp_offaxis_corr Applies off-axis boresight correction to an L1 Aspect solution file (ASPSOL).
correct_periscope_drift Correct a Chandra aspect solution for temporal drift calculated from a fit of the drift in the sky positions of the events in a supplied circle region.
dither_region Compute fraction of region area that covers chips
get_dither_parameters Determine the approximate dither period and amplitude used during an observation.
monitor_photom Generate a photometric lightcurve from ACA monitor data.

tools::background acis_bkgrnd_lookup Find the matching ACIS "blank-sky" dataset for an observation
blanksky_image Create scaled background and background-subtracted images given an observation-specific blanksky background file and a reference image.
blanksky_sample Create a scaled background events file by using the scale factor calculated by and sampling the blanksky background file generated by the "blanksky" script for an observation.
blanksky Tailor an unscaled blanksky background file to be compatible with a given events file; combining and reprojecting the necessary background files from the CalDB.
create_bkg_map Create a background map for ACIS and HRC from the event files.
hrc_bkgrnd_lookup Find the matching HRC "blank-sky" dataset (event file or spectrum) for an observation
readout_bkg Approximate the Out Of Time source contribution to the background.

tools::caldb calindex Create an index file or append data on an existing one of calibration database (CALDB) products.
calmerge Merge index files of calibration database (CALDB) products.
calquiz Find calibration files in the CALDB
calvalid Validate index file of calibration database (CALDB) products.

tools::composite chandra_repro Reprocess a Chandra dataset
combine_grating_spectra Combine Chandra gratings PHA files and their associated response files.
combine_spectra Combine PHA files and their associated response files.
dax Run CIAO tasks from the ds9 Analysis menu
fluximage Create exposure-corrected images and exposure maps for an observation.
flux_obs Combine reprojected observations to create an exposure-corrected image.
merge_obs Reproject and combine multiple observations to create a merged event file and exposure-corrected images.
reproject_obs Reproject a set of observations to a common tangent point and create a merged event file.
specextract Create source and optional background spectra for Chandra imaging-mode and zeroth-order grating data.
srcextent Determine if a source is extended within a confidence interval.
srcflux Calculate the net count rates and fluxes, including uncertainties, of sources in a Chandra observation.

tools::coordinates dmcoords Convert between Chandra coordinate systems
reproject_aspect Modify aspect solution file RA, Dec, and roll or updfile WCS to minimize position differences between two source lists.
reproject_events Regrid an event file to a different tangent point
reproject_image_grid Projects image(s) from one WCS to another
reproject_image Projects image from one WCS to another
sky2tdet Project an image in SKY coordinates to TDET coordinates
sso_freeze Reproject sky x and y coordinates into a Solar System Object centered reference frame.
wcs_match Create a frame transformation to minimize the aspect difference between data from the same sky region.
wcs_update Modify aspect solution file RA and Dec or infile WCS based on a transformation matrix.

tools::core dmappend Append multiple blocks/extensions to an existing output file.
dmcopy Filter and bin tables and images.
dmdiff Compare values in two files.
dmextract Make a histogram table file (e.g. PHA file, lightcurve file) from a table column. Generate count histogram on supplied regions for a spatial table or image file.
dmlist List contents or structure of a file.

tools::detect celldetect Use a "sliding cell" to search for sources
get_src_region Outputs regions that have counts higher than background
vtpdetect Voronoi Tessellation and Percolation (VTP) source detection
wavdetect Mexican-Hat Wavelet source detection (wtransform+wrecon)
wrecon Combine wavelet transform coefficients into sources
wtransform Obtain wavelet transform coefficients for poisson image data

tools::download download_chandra_obsid Download public data by ObsId from the Chandra archive.
download_obsid_caldb Download the CALDB files required to analyze an OBS_ID
find_chandra_obsid Find, and optionally download, publicly-available Chandra ObsIds from the Chandra archive.
install_marx Automatically download and install MARX
obsid_search_csc Search the Chandra Source Catalog by OBS_ID
search_csc Perform a position search on the Chandra Source Catalog

tools::gratings detilt Correct the time-dependent tilt of LETG/HRC-S spectra by adjusting TG_D.
dewiggle Straighten LETG/HRC-S spectra by applying tg_d adjustments.
symmetrize Adjust the tg_d values of LETG/HRC-S evt2 data to make cross-dispersion profiles more symmetric
tgdetect2 Bundles three programs: tg_findzo, tg_choose_method, and tgdetect into one in order to provide a more convenient interface for determination of the zeroth order centroid.
tgdetect Detect and centroid the zero order image in a spatial sub-region of a grating event list.
tgextract2 Bin event list grating wavelengths column into a one-dimensional counts histogram, by source, grating part, and diffraction order. Optionally bin background spectrum.
tgextract Bin event list grating wavelengths column into a one-dimensional counts histogram, by source, grating part, and diffraction order.
tgidselectsrc Filter an input source list based upon a SNR threshold.
tgmask2reg Customize grating extaction region file for use with tgextract2
tgmatchsrc Match sources between two source lists by their 2-D separation files.
tgsplit Split a TYPE:II grating PHA file into several TYPE:I files
tg_bkg Creates a PHA background file for use in XSPEC
tg_choose_method Automatically choose between tgdetect and tg_findzo for determining the zeroth order centroid
tg_create_mask Create a region file to define spectrum sky boundaries
tg_findzo Find the zeroth order sky X,Y centroid for bright sources observed using HETG or LETG gratings with the ACIS-S detector.
tg_resolve_events Assign grating events to spectral orders; use detector energy resolution for order separation, if available.

tools::header dmhedit Edit datamodel file headers
dmhistory Extracts the tool history from the file header
dmkeypar Retrieve information about a keyword from an input file
dmmakepar Write header keywords to a parameter file
dmreadpar Create header keywords from a parameter file

tools::hrc hrc_build_badpix Create observation-specific bad pixel file for HRC
hrc_dtfstats Calculate statistics from hrc_calc_dead_time and a GTI
hrc_process_events Correct HRC event positions, times, PHA, etc.

tools::image aconvolve Convolve an N-dimensional image with a kernel
acrosscorr Cross-correlate two N-dimensional images or autocorrelate an image
apowerspectrum Compute the power spectrum of an N-dimensional input array, or from two columns (independent/dependent variable) in an input file
arestore Restore image resolution using deconvolution techniques
centroid_map Adaptively bin an image using centroid map algorithm
csmooth Adaptively smooth a 2-D image
dmfilth Replace pixel values in source regions of an image with values interpolated from surrounding background regions
dmimg2jpg Make a color JPEG image (or EPS) from three image files
dmimgadapt Adaptively smoothes an image based on number of counts
dmimgblob Identifies groups of pixels above/below threshold
dmimgcalc Perform arithmetic on images
dmimgdist Computes the distance transform of image
dmimgfilt Performs various non-linear image filtering techniques.
dmimghist Create a histogram of the pixel values in a 2-D image
dmimgpick Maps image values to rows in a table
dmimgpm Compute a low frequency spatial (modified poisson mean) background map
dmimgproject Project image along axis
dmimgreproject Replicates table value along axis of image
dmimgthresh Set low (or high) intensity or exposure regions of an image to a constant value.
dmmaskbin Bins an image based on input mask
dmmaskfill Replaces mask values with those found in lookup table
dmnautilus Perform a quad-tree adaptive binning on 2D images
dmradar Perform polar quad-tree adaptive binning on 2D images
dmregrid2 shift, rotate, scale images
dmregrid Rebin a stack of 2-dimensional images.
energy_hue_map Creates a true color image using median-energy map and counts image.
evalpos Get image values at a specified (RA,DEC)
hexgrid Create a regular hexagonal grid and apply to input image
map2reg Convert a map file into a region file.
merge_too_small Adjust input map file to meet some minimum criteria
mkregmap Create map from stack of input regions.
pathfinder Group pixels by steepest gradient ascent to local maximum
vtbin Create adaptive bin image using Voronoi Tessellation

tools::parameter paccess Gives the location of a tool's parameter file
pdump Dumps the values of the parameters, with one parameter per line.
pget Get parameter values
pline Display the parameter values, with all parameters on a single line
plist List the contents of a parameter file.
pquery Query whether a parameter exists and, if so, get and return its value.
pset Set parameter values on the command line
punlearn Restore system default parameter values

tools::region bkg_fixed_counts Create a background region with a fixed number of counts
convert_ds9_region_to_ciao_stack Convert ds9 region file containing special shapes to CIAO stack.
dmcontour Make contour regions from a 2-D image
dmellipse Finds ellipse for specified fraction
dmgroupreg Translates DS9 regions and groups to CIAO format.
dmimghull Create convex polygon around pixels in an image
dmimglasso Draw region around point with similar values
dmmakereg Convert the format of a region file (swap between ASCII and CXC FITS)
psfsize_srcs Compute the size of a circle enclosing a specified fraction of PSF.
psf_contour Create a source region file from a simulated PSF
rank_roi Assign overlapping region area to highest ranking source.
regphystocel Convert regions in physical coordinates to ds9 format regions in celestial (fk5) coordinates.
roi Generates source and background regions from source list
skyfov Make a field-of-view region in sky coordinates
splitroi Convert the output of roi into a format usable by dmfilth

tools::response acis_fef_lookup Find the FITS Embedded Function file for use by mkrmf
acis_set_ardlib Sets the bad pixel parameters of the ardlib file to the given file
addresp Add multiple RMFs, weighted by ARFs and exposures; add mutiple ARFs, weighted by exposures.
arfcorr Calculate a point source aperture correction, either as a single-energy image or as an energy-dependent correction to the ARF file.
color_color Creates a Color-Color diagram
dmarfadd Add multiple grating ARF files together, weighting by exposure.
ecf_calc Obtain the encircled counts fraction of an object as a function of radius.
eff2evt Compute the flux and look up the QE & effective area for event positions
find_mono_energy Compute monochromatic for energy band given input spectrum and responses.
fullgarf Create a grating ARF for a particular order and grating for a given observation.
make_instmap_weights make_instmap_weights - produces a weighted spectrum file usable with mkinstmap in order to create a weighted exposure map.
make_psf_asymmetry_region Create a region that shows the location of the HRMA PSF asymmetry for a source
mean_energy_map Creates an image whose pixels are the mean energy of the events
mkacisrmf Generate an RMF for Chandra imaging data
mkarf Generate an ARF for Chandra imaging data (and grating 0th order)
mkexpmap Generate a Chandra imaging exposure map (effective area vs. sky position)
mkgarf Generate a Chandra Grating ARF for one detector element.
mkgrmf Generate an RMF for Chandra grating data
mkinstmap Generate a Chandra instrument map (effective area vs. detector position)
mkpsfmap Look up the radius of the PSF for each pixel in an image
mkrmf Generate an RMF for Chandra imaging data
mktgresp Create ARF and RMF files for each spectral order and grating arm in a TypeII PHA file
mkwarf Generate a weighted ARF.
modelflux Calculate model flux or count rate
pileup_map Compute image that gives indication of pileup.
psf_project_ray Project rays generated by ChaRT onto a semi-infinite detector plane.
rmfimg Create a simple image of an RMF or ARF file
simulate_psf Simulate the Chandra PSF
src_psffrac Compute approximate PSF fraction in circular source region

tools::stacks stk_build stk_build is used to build a stack from a user-defined string. The output is to stdout, stderr, or a file.
stk_count stk_count is used to count the number of items in a stack. The output is to the stk_count parameter file.
stk_read_num stk_read_num is used to read one element of a user-defined stack. The output is to the outelement field of the stk_read_num parameter file.
stk_where stk_where finds the location of an item in a stack

tools::statistics aplimits Compute upper limits for the detection of a source, using data obtained from background apertures in event lists, images, and exposure maps.
aprates Compute net counts, rate, and/or flux, plus credible intervals, for a point source, using data obtained from source and background apertures in event lists, images, and exposure maps.
dmstat Compute statistics for images and columns in tables.
imgmoment Computes image moments (sum, mean, size, angle, etc).
lim_sens Create an output limiting sensitivity map with the same blocking factor, dimensions and WCS
statmap Compute simple statistics for events in each map region.

tools::table dmgroup Group a specified column in a table with various options
dmjoin Join two files whose sampling is different.
dmmerge Merge two or more compatible tables (e.g. event files) into one.
dmpaste Add new columns to a table.
dmsort Sort a table.
dmtabfilt Apply non-linear filters to columns in table
dmtcalc Modify and create columns in a table
dmtype2split Split up an array column into multiple files (e.g. PHA type 2 to PHA type 1).

tools::timing axbary Apply barycentric corrections to event times, GTIs, and header values.
deflare deflare - remove flares from light curves using lc_clean or lc_sigma_clip
dmgti Create a Good Time Interval from limits placed on time-based files (event and Mission Time Line files).
glvary Search for variability using Gregory-Loredo algorithm.
gti_align Align GTI to ACIS exposure times
mtl_build_gti Create Good Time Interval from Mission Time Line and limits
pfold Folds events into multiple periods

tools::utilities apply_fov_limits Create an image that matches the FOV file for the observation
check_ciao_caldb A tool to test the installation of the CIAO Calibration Database (CALDB)
check_ciao_version Check that the CIAO and CALDB installations are up to date.
convert_xspec_script Convert a XSPEC save file to Sherpa commands *experimental*
convert_xspec_user_model Compile a XSPEC user model for use in Sherpa *experimental*
get_fov_limits Find the region (bounding box) covered by a FOV file in sky coordinates
get_sky_limits Find the region covered by an image in sky coordinates
r4_header_update Update file header with various keywords to match latest archive processing
splitobs `splitobs' separates the data products for Multi-Obi and ACIS interleaved observations
summarize_status_bits Summarize the status bits in a Chandra event file.

transform apply_transform Apply a transform to the given data.
copy_transform Copy the transform.
get_transform_type Return the flavor of the input Transform object.
transform TRANSFORMS - Coordinate transforms in Python