The Bright Object Tool. Ron Downes August 2007. Outline. Documentation High-level assumptions Limitations How it works (the guts) Basic processing Low-level assumptions Use of other catalogs (GALEX, 2MASS) Sample output Table view Graphical (Aladin) view
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The Bright Object Tool
For WFC3/IR objects with only a J mag, an extended search is performed around the position and the F mag of the object is assumed to be equal to the faintest F mag detected. This conservative assumption allows us to process and clear many objects that would otherwise require "manual" processing.
For ACS/SBC, STIS/MAMA, and COS objects that have only an F mag, an extended search is performed around the position and the J mag of the object is assumed to be equal to the faintest J mag detected. This conservative assumption allows us to process and clear many objects that would otherwise require "manual" processing.
For WFC3/IR objects that have only an F mag, assume the object is an M2V star (with appropriate J-F), and continue processing.
For ACS/SBC, STIS/MAMA, WFC3, and COS, the GSC2 flag indicating the object is not a star is ignored for all faint (detector-specific cutoffs) objects. This is due to the fact that the reason most of these objects have the flag set due to the poor S/N in the PSF. While this issue is important in determining if the object can be used as a guide star, it is not relevant for bright object checking. Failure to do this results in a large number of "unknown" objects appearing in many fields, which then need to be "manually" cleared.
Note that an additional step has been proposed to handle cases with only 1 magnitude (will discuss later).
For ACS/SBC, STIS/MAMA, and COS, all objects with B-V<+0.1 are assumed to be O5V stars. This assumption is necessary due to the near degeneracy in the spectral type-color relation at the blue end.
For ACS/SBC, STIS/MAMA, and COS, all objects brighter than a Vcrit value (spectral element dependent) are assumed to be O5V stars. This assumption is necessary due to the lack of reddening information.
For COS and STIS spectroscopy, the aperture throughput is taken into account.