tristarid1 - find correction to rotate observed objects onto reference objects


tristarid1 ref.path=<filename> obs.path=<filename>


This tool attempts a triplet-based match of observations onto reference objects.

See [1] for a description of triplet matching. tristarid1 is meant to run quickly; it makes no attempt to optimize the distribution of the triplet index. The two features it uses for indexing triplets are the separation between the stars making up one edge of the triangle, and the opening angle of one vertex.

The input reference and observation position files contain object identifier, Right Ascension, Declination, magnitude, and type fields. Objects without known magnitudes are allowed.


ref.path [filename]
Input file holding reference information.

obs.path [filename]
Input file holding observation information.

(out.path = NONE) [filename]
Output file to write the processing information or NONE.

(ref.deg = no) [boolean]
Are reference positions in degrees?

(obs.deg = no) [boolean]
Are observation positions in degrees?

(fov = 1) [deg]
Size of field of view.

(n.reference = 30) [integer]
The maximum number of reference objects to use during triplet matching. The brightest objects are used.

(n.observation = 20) [integer]
The maximum number of observed objects to use during triplet matching. The brightest objects are used.

(n.primary = 40) [integer]
Size of the primary index.

(n.secondary = 40) [integer]
Size of the secondary index.

(doublet.min = 60) [real]
Minimum separation between two stars making up a doublet [arcsec].

(doublet.err = 3) [real]
Estimate of error in doublets [arcsec].

(triplet.min = 10) [real]
Minimum opening angle of sides of a triplet [deg].

(mag.min = 10) [real]
Minimum (brightest) magnitude to include in triplet matching.

(mag.max = 30) [real]
Maximum (faintest) magnitude to include in triplet matching.

(mag.err = 2) [real]
Largest magnitude error.

(group.angle = 3) [real]
Maximum separation between matches during grouping [arcsec].

( = 3) [integer]
Required difference in size between two largest groups for the largest to be considered correct.

(min.matches = 3) [integer]
Required number of matches.

(n.catalog = 3) [integer]
Catalog blocking factor.

(rot.err = 3) [real]
Maximum input rotation error [arcmin]. The special value -1 indicates no rotation knowledge.

(filter.ignore = 0.1) [real, 0-1]
Match fraction to ignore. Each match between observed and reference objects occurs a certain number of times. If an ambiguous match occurs less times than this fraction of the strongest match, it is ignored.

(filter.base = 1) [real]
Base value for filtering matches [arcsec]. After a correction is found and applied to the observed positions, the residual offsets are found. Matches with residual offsets larger than the median offset plus this parameter are discarded.

(cleanup = yes) [boolean]
Clean up temporary files?

(clobber = no) [boolean]
Standard HEAdas clobber parameter.

(chatter = 3) [integer, 0-5]
Standard HEAdas chatter parameter.


The following example illustrates running tristarid1

1. run tristarid1 on given source lists

      tristarid1 ref.path=sources.ref obs.path=source.obs



   [1] IAF-98.A.6.05 
   Development and Validation of a Fast and Reliable Star Sensor Algorithm
   with Reduced Data Base
   E.J. v.d. Heide, M. Kruijff, S.R. Douma, D. Oude Lansink


September 2005