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-rw-r--r--lib/stwcs/wcsutil/hstwcs.py26
1 files changed, 24 insertions, 2 deletions
diff --git a/lib/stwcs/wcsutil/hstwcs.py b/lib/stwcs/wcsutil/hstwcs.py
index 11c1f42..1e0e23d 100644
--- a/lib/stwcs/wcsutil/hstwcs.py
+++ b/lib/stwcs/wcsutil/hstwcs.py
@@ -134,7 +134,7 @@ class HSTWCS(WCS):
to a CD matrix, if reasonable, by running pc2.cd() method.\n \
The plate scale can be set then by calling setPscale() method.\n"
self.pscale = None
-
+
def setOrient(self):
"""
Computes ORIENTAT from the CD matrix
@@ -239,13 +239,35 @@ class HSTWCS(WCS):
chip=self.chip, direction='forward', date=self.date_obs,
filter1=self.filter1, filter2=self.filter2,
offtab=self.offtab, binned=self.binned)
+
+ if self.ltv1 != 0. or self.ltv2 != 0.:
+ self.resetLTV()
if update:
if header==None:
print 'Update header with IDC model kw requested but header was not provided\n.'
else:
self._updatehdr(header)
-
+
+ def resetLTV(self):
+ """
+ Reset LTV values for polarizer data
+
+ The polarizer field is smaller than the detector field.
+ The distortion coefficients are defined for the entire
+ polarizer field and the LTV values are set as with subarray
+ data. This may also be true for other special filters.
+ This is a special case when the observation is considered
+ a subarray in terms of detector field but a full frame in
+ terms of distortion model.
+ To avoid shifting the distortion coefficients the LTV values
+ are reset to 0.
+ """
+ if self.naxis1 == self.idcmodel.refpix['XSIZE'] and \
+ self.naxis2 == self.idcmodel.refpix['YSIZE']:
+ self.ltv1 = 0.
+ self.ltv2 = 0.
+
def wcs2header(self, sip2hdr=False, idc2hdr=True):
"""
Create a pyfits.Header object from WCS keywords.