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Introduction
The thread explains how to perform interactive photometry in OM images
previously processed.
Expected Outcome
Users will learn how to add an undetected source to the
list produced by
omichain
or how to improve the photometry of individual sources interactively.
SAS Tasks to be Used
Prerequisites
Using of
omsource
to perform photometry interactively requires that the
corresponding OM images have been already processed with
omichain.
Then new,
non detected sources can be selected with the cursor, or the measuring
parameters of detected sources can be modified to improve the results.
A proper SAS set up is required.
Useful Links
Caveats
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Procedure
If the results obtained after running
omichain
are not satisfactory, e.g. an interesting source has not been detected,
the user can perform the photometry in a fully interactive way.
Invoking
omsource
will allow us to select the desired source and
to adjust the aperture and background region sizes so as to
obtain its count rate and magnitude with all the necessary corrections.
A detailed description of this task can be found in the SAS
documentation, both in HTML and Postscript format.
The input for
omsource
is an image file that
has gone through all steps of the image processing up to source
detection (
see OM image processing threads). This input image can be entered in the
command line as a parameter, or it can be selected from a pop-up menu.
omsource
imageset=/path_to_your_data/proc/P0125321001OMS006IMAGE_0000.FIT [optional parameter] \
currentsrclistset=/path_to_your_data/proc/a_name_for_my_current_list.FIT [optional parameter] \
oldsrclistset=/path_to_your_data/proc/P0125321001OMS006SWSRLI0000.FIT [optional parameter]
The user can provide an existing source list. Then, the existing
sources can be modified and/or current sources can be added
interactively.
The image MUST NOT have been processed by
omatt.
In other words, north aligned images produced by the Pipeline or by using
omatt
are not valid for
omsource
The image is displayed by DS9, and an interactive menu allows us
to start the source selection:
The first menu allows the user to enter an existing source list
[Load source-list], or to start
selecting targets with the cursor
[Select sources]. When
list loading or current sources selection is completed, then a second
menu will appear and the photometric
parameters for each source can be changed. Final computation is
achieved by pushing the
[Compute Photometry] button.
Upon Exit, we shall be prompted for a name for the current source list, if
it was not given in the command line.
Last Updated: 16 April 2010
