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Practically all kinds of astronomical images, containing a number of stars
and/or galaxies, can be treated with the INVENTORY commands. Up to now
INVENTORY has been
used or tested on data from the following instruments:
Schmidt plates, CCD-frames taken with
several telescopes, direct unaided and electronographic plates taken with
the ESO 3.6m telescope.
The applicability of INVENTORY commands is limited to frames that
contain more than say 100 and less than 8000 objects. The lower limit concerns
a single frame. If one has a number of frames each containing 20 or even a
smaller number of objects, it is still worthwhile to use INVENTORY.
A CLASSIFY/INV command requires:
- at least 20 stars and 20 galaxies
to work at all, and
- at least 100 objects on a good clean CCD-frame, or
- at least 300 objects on a Schmidt frame
in order to work well. The upper limit is set by the dimensions of some
internal arrays. Frames containing more than 8000 objects should be divided
onto smaller subframes to be run separately.
Note
The CPU time required depends approximately linearly on the total
number of pixels and on the total number of found objects
(including defects).
The demo frame with little over 100000 pixels and 200 objects needs
12.4, 10.7, and 2.5 sec of CPU time for executing the SEARCH/INV
command, the base version of ANALYSE/INV command, and the
CLASSIFY/INV command respectively with the use of the ESO
VAX 8600 computer.
Next: Procedures to Follow
Up: Object Search and Classification
Previous: General Information
Petra Nass
1999-06-15