aimfind: Select images containing catalog objects

Package: astcat

Usage

aimfind images output imfile

Parameters

images

The input image list. The input images must contain a valid fits world coordinate system which is used to determine the catalog extraction region.

output

The list of output astrometry file names. The number of output file names must be equal to the number of input images. Output files are only created if at least one catalog object is in the image. By default the output files are assigned names of the form "image.cat.#", e.g. "image.cat.1".

imfile

The list of images containing catalog data.

catalogs = ")_.catalogs"

The input astrometry catalog. By default the catalog name is set to the value of the package parameter catalogs.

standard = yes

Output a standard astrometry file ? If standard = yes then a header describing the format of the astrometry file is written to the output file. The astcat package tasks use this information to decode the file. If standard = no, no header is written and the user must instruct the astcat tasks how to decode the file.

filter = no

Filter the results of the catalog query before writing the final results to the output astrometry file ?

afiltpars = ""

The astrometry file filtering parameter set. These parameters permit the user to sort the output on a field or field expression, select or reject catalog records using a boolean expression, select or reject fields to output, add new fields that are expressions of existing fields to the output, and perform simple coordinate transformations.

append = no

By default the predicted pixel coordinates are prepended to each selected output file record. If append = yes they are appended to each selected record instead.

update = no

Update the default values of the algorithm parameters, e.g. aregpars and afiltpars, at task termination ?

verbose = yes

Print status messages on the terminal as the task proceeds ?

catdb = ")_.catdb"

The catalog configuration file. Catdb defaults to the value of the package parameter catdb. The default catalog configuration file is "astcat$lib/catdb.dat".

Description

Aimfind selects those images from the input image list images which contain one or more catalog catalogs objects and writes the resulting catalog records along with predicted pixel coordinates to output and the selected image name to imfile. The input images must contain a valid FITs wcs.

For each input image aimfind determines the region of the sky covered by the image, formats the appropriate catalog query, makes a local or remote connection to the catalog server using the catalog description in the catalog configuration file catdb, and captures the results. Catalog names must be of the form catalog@site, e.g. lan92@noao.

If filter = yes, the captured results are filtered using the values of the parameters in the filtering parameter set afiltpars. The afilterpars parameters permit the user to sort the query results by setting the sort field parameter fsort, select or reject catalog records by setting the selection expression parameter fexpr, select or reject fields for output by setting the output field list parameter fields, and change the coordinate system, units, and format of the catalog coordinates by setting the fosystem, foraunits, fodecunits, foraformat, and fodecformat parameters. At present the names, data types, units, and format of the predicted pixel coordinates computed by aimfind are fixed at "xp,yp", "d,d", "pixels,pixels", and "%10.3f,%10.3f" respectively. A more detailed description of the region filtering parameters can be obtained by typing "help afiltpars".

If standard = yes a header is written to the output astrometry file which defines the contents and format of the output object list. The astcat tasks use this header to decode the input catalog files. If it is missing or has been modified by non-astcat tasks the user must use the acatpars parameters to define the astrometry file format. Most non-astcat tasks will interpret the astrometry file header as documentation and skip it.

If append = no then the values of the predicted pixel coordinates are prepended to each selected catalog record. If append = tes they are appended instead.

If update = yes the values of the aregpars and afilterpars parameters will be updated at task termination. If verbose = yes then detailed status reports are issued as the task executes.

Examples

1. Determine which images in the input image list contain Landolt standards.

cl> aimfind *.imh "" imlist catalogs=lan92@noao
cl> page imlist

2. Repeat the previous example but write an output astrometry file for each selected image.

cl> aimfind *.imh default imlist catalogs=lan92@noao

3. Repeat example 2 but sort the output on a field called v.

cl> aimfind *.imh default filter+ fsort="v"

4. Repeat example 2 but transform the catalog coordinates to the B1950 system.

cl> aimfind *.imh default filter+ fosystem="B1950"

Time requirements

Bugs

See also

aclist, adumpcat, agetcat, afiltpars