[News] Chip class modifications

[John P. McFarland]

Hi All,

In order to allow inclusion of instruments with multiple CCD geometry 
configurations into Astro-WISE, the Chip class will be fundamentally modified. 
This e-mail is to notify the community of these impending changes, 
particularly for those who write scripts that access Chip methods directly. 
If you are not interested in these changes, read no further as all the changes 
necessary to the main opipe checkout will be made in the near future and will 
be transparent to most users.  Below is a detailed description of the changes.


The NAXIS1 and NAXIS2 attributes of Chip will be moved from the chip attribute 
of BaseFrame-derived classes (where applicable) to attributes of the Frame 
itself for _all_ objects in the database.  These values will be taken directly 
from the associated files.  Where the file does not exist, the values will be 
-1.  The procedure is equivalent to setting all RawFrame NAXIS1, NAXIS2 values 
to chip.NAXIS1, chip.NAXIS2, respectively, and to setting all non-RawFrame 
NAXIS1, NAXIS2 values to the values returned by the chip.get_trimmed_size() 
method.

The PRSCX, PRSCY, OVSCX, OVSCY values will be moved from the chip attribute of 
RawFrame-derived classes, to attributes of the Frame itself (again for all 
objects and from the associated files).  The methods:

get_trim_region
get_trimmed_size
get_prescan_x_region
has_prescan_x_region
get_prescan_y_region
has_prescan_y_region
get_overscan_x_region
has_overscan_x_region
get_overscan_y_region
has_overscan_y_region

will be moved from Chip to RawFrame as most of the attributes they use will be 
moved there.

It should be noted that one major use of these methods is of get_trimmed_size 
to determine the actual size of a non-RawFrame.  In most cases, this method 
will no longer be necessary as the desired values will be in the NAXIS1 and 
NAXIS2 attributes of the Frame itself.

Furthermore, RegriddedFrame and CoaddedRegriddedFrame will gain the NAXIS1, 
NAXIS2 attributes, allowing methods requiring image sizes (in pixel- or 
world-coordinates) to access these values directly.  There will no longer be a 
need to retrieve a possibly enormous file just to determine its geometry.

All methods of the classes and Tasks in the opipe checkout have been modified 
locally to reflect the above described changes and have been tested to the 
fullest extent of the unittests.  They will be committed once the database 
administrators are satisfied that the system is ready for them.  Stay tuned 
for the announcement of the implementation of these changes, perhaps as early 
as this Thursday.

Thank you for your attention.

Cheers,


-=John