Chandra X-Ray Observatory
Skip to the navigation links
Last modified: 21 July 2017

Alphabetical List of Ahelp Files

    Topic Context Summary
A acisreadcorr tools Flag and relocate out-of-time CCD events
acis_bkgrnd_lookup tools Find the matching ACIS "blank-sky" dataset for an observation
acis_build_badpix tools Create an observation-specific bad-pixel file
acis_clear_status_bits tools Clear (set to 0) ACIS status bits before reprocessing with acis_process_events
acis_detect_afterglow tools Identify and flag cosmic ray afterglows
acis_fef_lookup tools Find the FITS Embedded Function file for use by mkrmf
acis_find_afterglow tools Identify cosmic-ray afterglows and hot pixels for TIMED mode observations
acis_process_events tools Produce or update the time, coordinate, pulse-height, grade, and status information in ACIS event files
acis_set_ardlib tools Sets the bad pixel parameters of the ardlib file to the given file
acis_streak_map tools Generate high frequency background maps (streakmaps) which identify ACIS streaks caused when bright source photons are applied to the wrong pixel during readout.
aconvolve tools Convolve an N-dimensional image with a kernel
acrosscorr tools Cross-correlate two N-dimensional images or autocorrelate an image
addresp tools Add multiple RMFs, weighted by ARFs and exposures; add mutiple ARFs, weighted by exposures.
add_colvals contrib Add a column to a crate given a name and array of values
add_col crates Add a column to a crate.
add_crate crates Add a crate to a dataset.
add_ds9_contours contrib Add the contours from a ds9 *.con file to a ChIPS plot (with optional coordinate conversion).
add_key crates Add a keyword to a crate given a CrateKey object.
add_piximg crates Add an image to a crate.
ahelp ahelp Access the CIAO help documentation.
analysis-menu gui Run commands from the "Analysis" menu in CIAO GUIs
apowerspectrum tools Compute the power spectrum of an N-dimensional input array, or from two columns (independent/dependent variable) in an input file
apply_fov_limits tools Create an image that matches the FOV file for the observation
apply_transform transform Apply a transform to the given data.
aprates tools Compute net counts, rate, and/or flux, plus confidence regions, for a point source, using data obtained from source and background apertures in event lists, images, and exposure maps.
ardlib calibration Analysis Reference Data Library
arestore tools Restore image resolution using deconvolution techniques
arfcorr tools Calculate a point source aperture correction, either as a single-energy image or as an energy-dependent correction to the ARF file.
asphist tools Bin the aspect solution into a 3D histogram of duration vs pointing offset and roll offset.
autoname concept Autonaming is a feature available in various tools for automatically naming an output file based upon the name of an input file.
axbary tools Apply barycentric corrections to event times, GTIs, and header values.

B blanksky_image tools Create scaled background and background-subtracted images given an observation-specific blanksky background file and a reference image.
blanksky tools Tailor an unscaled blanksky background file to be compatible with a given events file; combining and reprojecting the necessary background files from the CalDB.

C caldb calibration CALibration DataBase (CALDB)
calindex tools Create an index file or append data on an existing one of calibration database (CALDB) products.
calmerge tools Merge index files of calibration database (CALDB) products.
calquiz tools Find calibration files in the CALDB
calvalid tools Validate index file of calibration database (CALDB) products.
cda_data contrib Download public data by ObsId from the Chandra archive (Python interface).
cda_search contrib Find publicly-available Chandra ObsIds from the Chandra archive (Python interface).
celldetect tools Use a "sliding cell" to search for sources
chandra_repro tools Reprocess a Chandra dataset
check_caldb_version contrib Check whether the locally-installed version of the Chandra Calibration DataBase (CALDB) is up to date
check_ciao_caldb tools A tool to test the installation of the CIAO Calibration Database (CALDB)
check_ciao_version tools Check that the CIAO and CALDB installations are up to date.
ciao-install concept Download and install CIAO, CALDB, and the contributed script files
ciaorc concept The .ciaorc file provides user-configuration options for CIAO
ciao_caldb contrib Utility routines for the CIAO CALDB (CIAO contributed package).
ciao_contrib contrib Contributed Crates, ChIPS, and Sherpa routines for CIAO.
ciao_proptools contrib Experimental interface to the Chandra proposal tools (CIAO contributed package).
ciao_runtool contrib Run CIAO tools from Python as if they were functions (CIAO contributed package).
ciao_smooth contrib Simple smoothing routines for 2D data
ciao_stacklib contrib Support routines for using stacks in CIAO (CIAO contributed package).
ciao_utils contrib Utility routines for CIAO (CIAO contributed package).
ciao concept Chandra Interactive Analysis of Observations
colden proposaltools COLDEN is an interactive program to evaluate the neutral hydrogen column density at a given direction on the sky
col_exists crates Determine if a column exists in a crate.
combine_grating_spectra tools Combine Chandra gratings PHA files and their associated response files.
combine_spectra tools Combine PHA files and their associated response files.
convert_xspec_user_model tools Compile a XSPEC user model for use in Sherpa *experimental*
coords_chandra contrib Utility routines for working with Chandra Coordinates
coords_format contrib Convert between string and numeric formats for Astronomical positions.
coords_utils contrib Utility routines for working with Astronomical positions.
coords chandra Coordinate systems used in Chandra analysis
copy_colvals crates Copy the column values from a crate.
copy_piximgvals crates Copy the image values from a crate.
copy_transform transform Copy the transform.
correct_periscope_drift tools 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.
cratedataset crates The CrateDataset object is used to read and write files with multiple blocks.
cratedata crates The CrateData object is used to store column or image data.
cratekey crates The CrateKey object is used to represent a header item (keyword and value) for a file.
crates_contrib contrib Contributed CIAO routines for Crates.
crates_images contrib Image-related routines for Crates (CIAO contributed package).
crates_utils contrib Utility routines for Crates (CIAO contributed package).
crates crates Reading, writing, and changing ASCII and FITS files in Python
crate crates The TABLECrate and IMAGECrate objects represent a block in a file.
create_bkg_map tools Create a background map for ACIS and HRC from the event files.
create_vector_column crates Create a vector column.
create_virtual_column crates Create a virtual column.
csmooth tools Adaptively smooth a 2-D image

D dates proposaltools DATES is an interactive calendar and time conversion tool.
dax tools Run CIAO tasks from the ds9 Analysis menu
deflare tools deflare - remove flares from light curves using lc_clean or lc_sigma_clip
delete_col crates Delete a column from a crate.
delete_key crates Delete a keyword from a crate.
delete_piximg crates Delete an image from a crate.
destreak tools Remove streak events from ACIS data
detilt tools Correct the time-dependent tilt of LETG/HRC-S spectra by adjusting TG_D.
dewiggle tools Straighten LETG/HRC-S spectra by applying tg_d adjustments.
dither_region tools Compute fraction of region area that covers chips
dmappend tools Append multiple blocks/extensions to an existing output file.
dmarfadd tools Add multiple grating ARF files together, weighting by exposure.
dmascii dm Using the Data Model with text files
dmbinning dm The CIAO binning syntax
dmcontour tools Make contour regions from a 2-D image
dmcoords tools Convert between Chandra coordinate systems
dmcopy tools Filter and bin tables and images.
dmdiff tools Compare values in two files.
dmellipse tools Finds ellipse for specified fraction
dmextract tools 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.
dmfiltering dm Filtering tables and images with the Data Model
dmfilth tools Replace pixel values in source regions of an image with values interpolated from surrounding background regions
dmgroupreg tools Translates DS9 regions and groups to CIAO format.
dmgroup tools Group a specified column in a table with various options
dmgti tools Create a Good Time Interval from limits placed on time-based files (event and Mission Time Line files).
dmhedit tools Edit datamodel file headers
dmhistory tools Extracts the tool history from the file header
dmimg2jpg tools Make a color JPEG image (or EPS) from three image files
dmimgadapt tools Adaptively smoothes an image based on number of counts
dmimgblob tools Identifies groups of pixels above/below threshold
dmimgcalc tools Perform arithmetic on images
dmimgdist tools Computes the distance transform of image
dmimgfilt tools Performs various non-linear image filtering techniques.
dmimghist tools Create a histogram of the pixel values in a 2-D image
dmimghull tools Create convex polygon around pixels in an image
dmimglasso tools Draw region around point with similar values
dmimgpick tools Maps image values to rows in a table
dmimgpm tools Compute a low frequency spatial (modified poisson mean) background map
dmimgproject tools Project image along axis
dmimgreproject tools Replicates table value along axis of image
dmimgthresh tools Set low (or high) intensity or exposure regions of an image to a constant value.
dmjoin tools Join two files whose sampling is different.
dmkeypar tools Retrieve information about a keyword from an input file
dmlist tools List contents or structure of a file.
dmmakepar tools Write header keywords to a parameter file
dmmakereg tools Convert the format of a region file (swap between ASCII and CXC FITS)
dmmaskbin tools Bins an image based on input mask
dmmaskfill tools Replaces mask values with those found in lookup table
dmmath tools Syntax used for writing mathematical operations in dmtcalc, dmimgcalc, and dmgti
dmmerge tools Merge two or more compatible tables (e.g. event files) into one.
dmnautilus tools Perform a quad-tree adaptive binning on 2D images
dmopt dm Controlling Data Model internal options
dmpaste tools Add new columns to a table.
dmreadpar tools Create header keywords from a parameter file
dmregions dm CIAO region filtering syntax
dmregrid2 tools shift, rotate, scale images
dmregrid tools Rebin a stack of 2-dimensional images.
dmsort tools Sort a table.
dmstat tools Compute statistics for images and columns in tables.
dmtabfilt tools Apply non-linear filters to columns in table
dmtcalc tools Modify and create columns in a table
dmtype2split tools Split up an array column into multiple files (e.g. PHA type 2 to PHA type 1).
dm dm CIAO Data Model: syntax for filtering and binning files
download_chandra_obsid tools Download public data by ObsId from the Chandra archive.
download_obsid_caldb tools Download the CALDB files required to analyze an OBS_ID

E ecf_calc tools Obtain the encircled counts fraction of an object as a function of radius.
eff2evt tools Compute the flux and look up the QE & effective area for event positions
evalpos tools Get image values at a specified (RA,DEC)
eventdef chandra Column definition in Chandra event files

F find_chandra_obsid tools Find, and optionally download, publicly-available Chandra ObsIds from the Chandra archive.
fluximage tools Create exposure-corrected images and exposure maps for an observation.
flux_obs tools Combine reprojected observations to create an exposure-corrected image.
FOVFiles contrib Check which FOV files contains the specified RA,Dec location.
fullgarf tools Create a grating ARF for a particular order and grating for a given observation.

G get_axis_transform crates Return the axis transform from an IMAGECrate.
get_caldb contrib Access various information about the Chandra Calibration DataBase (CALDB)
get_colvals crates Get the column values from a crate.
get_col_names crates Return an array of the column names in a crate.
get_col crates Return a CrateData object of a column from a crate.
get_crate_item_type crates Return the type of the crate item as a string.
get_crate_type crates Return the type of the crate as a string.
get_crate crates Get a crate from a dataset.
get_fov_limits tools Find the region (bounding box) covered by a FOV file in sky coordinates
get_keyval crates Return the value of a keyword in a crate.
get_key_names crates Return an array of the keywords in a crate.
get_key crates Return a CrateKey object of a keyword from a crate.
get_number_cols crates Return the number of columns in a crate.
get_number_rows crates Return the number of rows in a crate.
get_piximgvals crates Get the pixel values from an image crate.
get_piximg_shape crates Get the dimensions of the image stored in the IMAGECrate.
get_piximg crates Return a CrateData object of an image from a crate.
get_sky_limits tools Find the region covered by an image in sky coordinates
get_src_region tools Outputs regions that have counts higher than background
get_transform_matrix crates Extract the transform matrix from a crate.
get_transform_type transform Return the flavor of the input Transform object.
get_transform crates Extract the coordinate transform from a crate.
glvary tools Search for variability using Gregory-Loredo algorithm.
group group Provides the Python interface to the CXC grouping library
grpAdaptiveSnr group Adaptively group an array by signal to noise.
grpAdaptive group Group an array by the number of counts per group using an adaptive scheme.
grpBinFile group Group an array using the grouping applied to another dataset.
grpBinWidth group Group an array into a set of equal-width groups (by group width).
grpBin group Group an array using low and high boundaries.
grpGetChansPerGroup group Calculate the number of channels (elements) in each group.
grpGetGroupSum group Apply the supplied grouping to an array.
grpGetGrpNum group Calculate the group number for each element in the array.
grpMaxSlope group Group an array so that its absolute gradient is above a user-defined limit.
grpMinSlope group Group an array so that its absolute gradient is below a user-defined limit.
grpNumBins group Group an array into a set of equal-width groups (by number of groups).
grpNumCounts group Group an array by the number of counts per group.
grpSnr group Group an array by signal to noise.
gti_align tools Align GTI to ACIS exposure times
gui gui Graphical User Interface (GUI)

H hrc_bkgrnd_lookup tools Find the matching HRC "blank-sky" dataset (event file or spectrum) for an observation
hrc_build_badpix tools Create observation-specific bad pixel file for HRC
hrc_dtfstats tools Calculate statistics from hrc_calc_dead_time and a GTI
hrc_process_events tools Correct HRC event positions, times, PHA, etc.

I identify_name contrib Find the position of an astronomical object using NED or CDS.
imextent contrib Create a linear 2D transformation for the axes of an image
imgmoment tools Computes image moments (sum, mean, size, angle, etc).
install_marx tools Automatically download and install MARX
is_pha crates Determine if the crate dataset contains a PHA file and its type.
is_rmf crates Determine if the crate dataset contains an RMF.
is_virtual crates Determine if the input column from the crate is a virtual column.

K key_exists crates Determine if the keyword exists in the crate.

L lc_clean contrib lc_clean - remove periods of high (or low) count rates using the same technique as the ACIS background files
lc_sigma_clip contrib lc_sigma_clip - remove flares from a light curve using an iterative sigma-clipping algorithm
level chandra Describes the amount of processing performed to create a given product.
lightcurves contrib lightcurves - routines to remove periods of anomalously high (or low) count rates in a lightcurve
lim_sens tools Create an output limiting sensitivity map with the same blocking factor, dimensions and WCS
list_datasetid tools List the LaTeX dataset identifier macros for a set of files.

M make_image_crate contrib Create an IMAGECrate from an array.
make_instmap_weights tools make_instmap_weights - produces a weighted spectrum file usable with mkinstmap in order to create a weighted exposure map.
make_psf_asymmetry_region tools Create a region that shows the location of the HRMA PSF asymmetry for a source
make_table_crate contrib Create a TABLECrate from a set of arrays, a dictionary, or a structured array.
mean_energy_map tools Creates an image whose pixels are the mean energy of the events
merge_obs tools Reproject and combine multiple observations to create a merged event file and exposure-corrected images.
merging_rules concept A description of the merging rules used when combining header information.
mkacisrmf tools Generate an RMF for Chandra imaging data
mkarf tools Generate an ARF for Chandra imaging data (and grating 0th order)
mkbgreg tools Creates a stack of background regions for a given source list
mkexpmap tools Generate a Chandra imaging exposure map (effective area vs. sky position)
mkgarf tools Generate a Chandra Grating ARF for one detector element.
mkgrmf tools Generate an RMF for Chandra grating data
mkinstmap tools Generate a Chandra instrument map (effective area vs. detector position)
mkpsfmap tools Look up the PSF-size for each pixel in an image
mkrmf tools Generate an RMF for Chandra imaging data
mksubbgreg tools Subtracts source regions from background regions
mktgresp tools Create ARF and RMF files for each spectral order and grating arm in a TypeII PHA file
mkwarf tools Generate a weighted ARF.
modelflux tools Calculate model flux or count rate
monitor_photom tools Generate a photometric lightcurve from ACA monitor data.
mtl_build_gti tools Create Good Time Interval from Mission Time Line and limits
mtl chandra A description of the Mission Time Line (MTL)
multi_chip_gti tools Create a combined GTI file for multiple ACIS chips

O obsid_search_csc tools Search the Chandra Source Catalog by OBS_ID
obsvis proposaltools ObsVis is the Observation Visualizer created at the Chandra Science Center in Cambridge Massachusetts, USA.

P paccess paramio Returns the path to the specified parameter file.
paccess tools Gives the location of a tool's parameter file
paramclose paramio Close a parameter file opened by paramopen.
parameter concept Describes the parameter interface used by CIAO.
paramio paramio The Python interface to the CXC parameter system
paramopen paramio Open a parameter file.
pdump tools Dumps the values of the parameters, with one parameter per line.
peg gui PEG: the parameter editor GUI (for CXCDS parameter interface)
pfold tools Folds events into multiple periods
pgets paramio Read/write individual parameter values.
pget paramio Get a parameter value as a string.
pget tools Get parameter values
pileup_map tools Compute image that gives indication of pileup.
pileup chandra An overview of pileup in the Chandra ACIS detector.
pimms proposaltools PIMMS (Portable, Interactive Multi-Mission Simulator) converts source fluxes and count rates between missions.
pline tools Display the parameter values, with all parameters on a single line
plist paramio Get list of parameter names.
plist tools List the contents of a parameter file.
pquery paramio Query a parameter value.
pquery tools Query whether a parameter exists and, if so, get and return its value.
precess proposaltools PRECESS is an interactive astronomical coordinate conversion program. It provides precession of equatorial coordinates and conversion between equatorial, ecliptic, galactic, and supergalactic coordinates.
print_crate_names crates Display information on data from a crate.
prism gui Format-independent file browsing GUI
prop-coords proposaltools Defines available coordinate systems for Chandra Proposal Tools
prop-time proposaltools Defines available calendars and timescales for command line versions of Chandra Proposal Tools
prop-tools proposaltools Tools that aid in the preparation and submission of Chandra proposals
pset paramio Set a parameter value.
pset tools Set parameter values on the command line
psextract tools [REMOVED FROM CIAO 4.4]
psfsize_srcs tools Compute the size of a circle enclosing a specified fraction of PSF.
psf_project_ray tools Project rays generated by ChaRT onto a semi-infinite detector plane.
psf psf A Python module to calculate the size or enclosed-counts fraction of the Chandra PSF
punlearn paramio Restore the system defaults for a parameter file.
punlearn tools Restore system default parameter values
python scripting Python is a dynamic object-oriented programming language used by CIAO

R r4_header_update tools Update file header with various keywords to match latest archive processing
readout_bkg tools Approximate the Out Of Time source contribution to the background.
read_ds9_contours contrib Read in the contours from a ds9 *.con file with optional coordinate conversion.
read_file crates Read FITS or ASCII data into a crate.
read_pha crates Load a PHA file into a PHACrateDataset.
read_rmf crates Load an RMF file into a RMFCrateDataset.
regArea region Calculate the area enclosed by a region.
regExtent region Calculate the bounding box of a region.
regInsideRegion region Is a point (or set of points) inside a region?
region region Provides the Python interface to the CXC region library
regParse region Parse a region for use by the routines in the region library
regPrintRegion region Print out diagnostic details about a region.
regRegionString region Converts a region object into a string.
reproject_aspect tools Modify aspect solution file RA, Dec, and roll or updfile WCS to minimize position differences between two source lists.
reproject_events tools Regrid an event file to a different tangent point
reproject_image_grid tools Projects image(s) from one WCS to another
reproject_image tools Projects image from one WCS to another
reproject_obs tools Reproject a set of observations to a common tangent point and create a merged event file.
rmfimg tools Create a simple image of an RMF or ARF file
roi tools Generates source and background regions from source list

S scale_image_crate contrib Scale the pixel values in an IMAGE crate (useful for the ChIPS add_image command)
search_csc tools Perform a position search on the Chandra Source Catalog
set_colvals crates Set the values of a column in a crate.
set_keyval crates Set the keyword value in a crate.
set_key crates Add a keyword to a crate given a name and a value.
set_piximgvals crates Set the pixel values in an image crate.
simplecoordtransform contrib Convert between the different coordinate systems of an image.
simple_hist contrib Create a one-dimensional histogram of a data array
simple_stats contrib Calculate several basic statistic values for a data array
simulate_psf tools Simulate the Chandra PSF
sky2tdet tools Project an image in SKY coordinates to TDET coordinates
skyfov tools Make a field-of-view region in sky coordinates
smooth_image_crate contrib Smooth the pixel values in an IMAGE crate (useful for add_image)
specextract tools Create source and optional background spectra for Chandra imaging-mode and zeroth-order grating data.
splitobs tools `splitobs' separates the data products for Multi-Obi and ACIS interleaved observations
splitroi tools Convert the output of roi into a format usable by dmfilth
srcextent tools Determine if a source is extended within a confidence interval.
srcflux tools Calculate the net count rates and fluxes, including uncertainties, of sources in a Chandra observation.
src_psffrac tools Compute approximate PSF fraction in circular source region
sso_freeze tools Reproject sky x and y coordinates into a Solar System Object centered reference frame.
stack concept How to set a parameter to more than one value using a stack.
stk_build tools stk_build is used to build a stack from a user-defined string. The output is to stdout, stderr, or a file.
stk_count tools 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 tools 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 tools stk_where finds the location of an item in a stack
subspace concept Describes the filtering applied to a file
summarize_status_bits tools Summarize the status bits in a Chandra event file.
symmetrize tools Adjust the tg_d values of LETG/HRC-S evt2 data to make cross-dispersion profiles more symmetric

T taskmonitor gui GUI to run a task as a background process and display the output
tgdetect2 tools 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 tools Detect and centroid the zero order image in a spatial sub-region of a grating event list.
tgextract2 tools Bin event list grating wavelengths column into a one-dimensional counts histogram, by source, grating part, and diffraction order. Optionally bin background spectrum.
tgextract tools Bin event list grating wavelengths column into a one-dimensional counts histogram, by source, grating part, and diffraction order.
tgidselectsrc tools Filter an input source list based upon a SNR threshold.
tgmask2reg tools Customize grating extaction region file for use with tgextract2
tgmatchsrc tools Match sources between two source lists by their 2-D separation files.
tgsplit tools Split a TYPE:II grating PHA file into several TYPE:I files
tg_bkg tools Creates a PHA background file for use in XSPEC
tg_choose_method tools Automatically choose between tgdetect and tg_findzo for determining the zeroth order centroid
tg_create_mask tools Create a region file to define spectrum sky boundaries
tg_findzo tools 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 tools Assign grating events to spectral orders; use detector energy resolution for order separation, if available.
times chandra "Times" used in Chandra datasets and Chandra data analysis
transform transform TRANSFORMS - Coordinate transforms in Python

V vtpdetect tools Voronoi Tessellation and Percolation (VTP) source detection

W wavdetect tools Mexican-Hat Wavelet source detection (wtransform+wrecon)
wcs_match tools Create a frame transformation to minimize the aspect difference between data from the same sky region.
wcs_update tools Modify aspect solution file RA and Dec or infile WCS based on a transformation matrix.
wrecon tools Combine wavelet transform coefficients into sources
write_arrays contrib Write arrays to an ASCII file
write_columns contrib Write out arrays (columns) to a file as a table (ASCII or FITS format).
write_file crates Write a crate to an output file.
write_pha crates Write a PHACrateDataset to a file.
write_rmf crates Write an RMFCrateDataset to a file.
wtransform tools Obtain wavelet transform coefficients for poisson image data

Last modified: 21 July 2017
Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: Smithsonian Institution, Copyright © 1998-2017. All rights reserved.