build-astrometry-index (1)

NAME

build-astrometry-index - Create astrometry.net index files

SYNOPSIS

build-astrometry-index [options] -i catalog -o file -P scale

DESCRIPTION

build-astrometry-index takes a FITS catalog table containing at least RA, DEC, and magnitude columns and converts it into an index file that can be used by the astrometry.net programs like solve-index (1).

OPTIONS

-i catalog

Input FITS catalog: source RA,DEC, etc.

-e extension

FITS extension to read when -i is specified.

-1 index

Share another index's stars (alternatively to -i/-e).

-o file

Output filename for index

-N nside

Healpix Nside for quad-building

-l size

Minimum quad size (arcminutes)

-u size

Maximum quad size (arcminutes)

-P number

Use 'preset' values for -N, -l, and -u. The scale-number is the last two digits of the pre-cooked index filename -- eg., index-205 is -P 5.

-P 0 should be good for images about 6 arcmin in size and it goes in steps of sqrt(2), so:

-P 2 should work for images about 12 arcmin across

-P 4 should work for images about 24 arcmin across

-P 6 should work for images about 1 degree across

-P 8 should work for images about 2 degree across

-P 10 should work for images about 4 degree across etc... up to -P 19

-S column

Sort column (default: assume the input file is already sorted)

-f

Sort in descending order (eg, for FLUX); default ascending (eg, for MAG)

-A column

Specify the RA column name in the input FITS table (default "RA")

-D column

Specify the Dec column name in the input FITS table (default "Dec")

-B val

Cut any object whose sort-column value is less than val; for mags this is a bright limit

-U

Healpix Nside for uniformization (default: same as -n)

-H big healpix

Big healpix; default is all-sky

-s Nside

Big healpix Nside; default is 1

-m margin

Add a margin of margin healpixels; default 0

-n sweeps

Sweeps (ie, number of stars per fine healpix grid cell); default 10

-r radius

Deduplication radius in arcseconds; default no deduplication

-j jitter

Positional error of stars in the reference catalog (in arcsec; default 1)

-d dimquads

Number of stars in a "quad" (default 4).

-p passes

Number of rounds of quad-building (ie, number of quads per healpix cell, default 16)

-R reuse

Number of times a star can be used (default: 8)

-L max-reuses

Make extra passes through the healpixes, increasing the -r reuse limit each time, up to max-reuses.

-E

Scan through the catalog, checking which healpixes are occupied.

-I id

Set the unique ID of this index

-M

In-memory (don't use temp files)

-T

Don't delete temp files

-t dir

Use this temp directory (default: /tmp)

-v

Add verbosity.

AUTHOR

The Astrometry.net team. Principal investigators are David W. Hogg (NYU) and Dustin Lang (CMU).

SEE ALSO

hpsplit (1), solve-field (1)
For a tutorial, see astrometry.net/doc/build-index.html