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Last Updated Jan 2001

Copyright © 2001 The Association of Universities for Research in Astronomy, Inc. All Rights Reserved.

Purpose :

Classify objects in the GSC 2 pipeline using a decision tree. Objects are classified as 1) stars, 2) nonstars, or 3) defects, with probabilities for each class. For use with the final GSC 2 catalog or for GSC 2 pipeline tasks such as the centroider or photosol.

Procedure :

The GSC2 pipeline classification of plate objects is broken into two programs, RANK_FEATURES and CLASSIFY. RANK_FEATURES divides a plate into multiple sections, or regions, and then ranks object features for each region based on all objects in a region. Only 101 rank values are stored for each feature, from the lowest to the highest feature value in a region, in 1% increments. The CLASSIFY program reads the rank file written by RANK_FEATURES, and reading objects from an OOP or FEA file, classifies them by ranking their features (interpolating with the tables from the rank file) and using a decision tree. The new classifications are either written back to the original OOP file, or to a new copy of the OOP file, called a CLS file.

Calling Sequence :

CLASSIFY oopfile
[/XRANGE=(lx,ux)]
[/YRANGE=(ly,uy)]
[/NEW] Create new DID file
[/STATS] Create a detailed statistics file
[/FEA] Read input from FEA file instead of default OOP file
[/CLS] Write classifications to new CLS file instead of def OOP
[/MINOBJ=] If region contains fewer objects than MINOBJ, take ranks from nearest neighbor region {def=1000}
[/DTREEDIR=] Specify directory name and (optional) file name for decision tree (must be .dat file) {def task_pars:dtree.dat}
[/TRAIN] Write ranks to training set file instead of writing classifications to pipeline OOP or CLS file
[/COMMENT] Add comment to DID file
[/DEBUG] Run Debug mode

Availability :

  • GSSS AXP - yes
  • GSSS VAX - yes
  • PIXELS - no

History/Author :

  • Original Implementation - George Hawkins