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Last modified: 2 January 2024

URL: https://cxc.cfa.harvard.edu/ciao/ahelp/index.html

Ahelp for CIAO

List of all Ahelp files: alphabetical or by context.

To learn how to use the help system for CIAO, type:

unix% ahelp

The help documents are accessed by subject (a single word, case insensitive). To get help on the tool dmextract:

To search on a word, use ahelp -k which will bring up a list of all matching documents or - if there is only one match - display that document. Here we look for any document that mentions "merging":

unix% ahelp -k merging
--------------------------------------------------------------------------------
|       SUBJECT        |      CONTEXT       |             SYNOPSIS             |
|----------------------|--------------------|----------------------------------|
| addresp              | tools::response    | Add multiple RMFs, weighted by   |
|                      |                    | ARFs and exposures; add mutiple  |
|                      |                    | ARFs, weighted by exposures.     |
|----------------------|--------------------|----------------------------------|
| dmappend             | tools::core        | Append multiple blocks/extension |
|                      |                    | s to an existing output file.    |
|----------------------|--------------------|----------------------------------|
| dmpaste              | tools::table       | Add new columns to a table.      |
|----------------------|--------------------|----------------------------------|
| dmregrid             | tools::image       | Rebin a stack of 2-dimensional   |
|                      |                    | images.                          |
|----------------------|--------------------|----------------------------------|
| dmregrid2            | tools::image       | shift, rotate, scale images      |
|----------------------|--------------------|----------------------------------|
| flux_obs             | tools::composite   | Combine reprojected              |
|                      |                    | observations to create an        |
|                      |                    | exposure-corrected image.        |
|----------------------|--------------------|----------------------------------|
| fluximage            | tools::composite   | Create exposure-corrected        |
|                      |                    | images and exposure maps for an  |
|                      |                    | observation.                     |
|----------------------|--------------------|----------------------------------|
| merge_obs            | tools::composite   | Reproject and combine multiple   |
|                      |                    | observations to create a merged  |
|                      |                    | event file and exposure-correcte |
|                      |                    | d images.                        |
|----------------------|--------------------|----------------------------------|
| merging_rules        | concept            | A description of the merging     |
|                      |                    | rules used when combining        |
|                      |                    | header information.              |
|----------------------|--------------------|----------------------------------|
| reproject_events     | tools::coordinates | Regrid an event file to a        |
|                      |                    | different tangent point          |
|----------------------|--------------------|----------------------------------|
| reproject_image      | tools::coordinates | Projects image from one WCS to   |
|                      |                    | another                          |
|----------------------|--------------------|----------------------------------|
| reproject_image_grid | tools::coordinates | Projects image(s) from one WCS   |
|                      |                    | to another                       |
|----------------------|--------------------|----------------------------------|
| reproject_obs        | tools::composite   | Reproject a set of observations  |
|                      |                    | to a common tangent point and    |
|                      |                    | create a merged event file.      |
--------------------------------------------------------------------------------

Use "ahelp subject" ("ahelp context subject" for non-unique cases) e.g.: 
 ahelp reproject_obs
 ahelp tools::composite reproject_obs

In general you will be now be able to say "ahelp <subject>" to read the help for that document. However, if the same subject matches different contexts, you have to say "ahelp <context> <subject>" as described at the end of the list of matches (e.g. "ahelp tools dmregrid").

Read the ahelp document for more information on the ahelp system, such as reading parts of the document - e.g. only the examples or the parameter list.