id	summary	reporter	owner	description	type	status	priority	milestone	component	version	severity	resolution	keywords	cc
122	Some more Astrometry questions	gusciora@…	Paul Price	"psCellinChip() What is the proper way to determine if an (x,y) pair is valid
for a cell?  Can I simply check if (x,y) is between 0 and however many
rows/columns that image has?  Can I assume all readouts for the cell are the
same size, and therefore, that I only have to check one readout?

psCoordChiptoCell(): The psFPA struct has two transformation members:
    fromTangentPlane
    toTangentPlane
The psChip struct has two similar transformation members:
    toFPA;
    fromFPA;
However the psCell struct only has one such member
    toChip
Can we add a ""fromChip"" member to the psCell struct?  This is needed by
psCoordChiptoCell().

When I transform between the FP and TP, I must use a 4-D transformation with
the magnitude and color of the object being additional elements.  Where do I
get the magnitude and color from?  Do these vary at each coordinate in the
focal plane?  Or, is this a constant for an entire exposure?

There is an element of the psCell struct:
    psPlaneTransform* toSky;
This is of type ""psPlaneTransform"", however the intent is to produce sky
coordinates which are, of course, spherical coordinates.  That doesn't seem
right.  But since it's a ""quick"" transform, I'm not sure.  Can you expand on that?

psCoordCelltoSkyQuick(): uses the ""toSky"" transformation in the psCell struct
that I mentioned above, which is a linear transformation.  If that transform
should indeed be linear, how should I produce the spherical coordinates from
it that this function requires?

psCoordSkytoCell(): where do I get the grommit info?

psCoordSkytoCellQuick(): this transform is not specified anywhere, as far
as I can tell.

psCoordCelltoSky(): I implement by doing:
    1: cell to FPA transformation.
    2: FPA to tangent plane transformation.
    3: tangent plane to sky transformation.
In order to do step 3, I have to create a grommit for this function which is
only used once, then discarded.  Maybe we should make the grommit a member
in the psFPA structure?"	defect	closed	high		IPP SDRS	unspecified	normal	fixed