MatchOptimisticBTask¶
MatchOptimisticBTask
matches sources to reference objects. This is often done
as a preliminary step to fitting an astrometric or photometric solution.
Optimistic Pattern Matching is described in [Tabur2007]
Processing summary¶
MatchOptimisticBTask
runs this sequence of operations:
Flags sources with bad centroids and low signal to noise and remove them from the matching.
Match the usable sources with an input reference catalog using the V. Tabur 2007 algorithm.
Further remove sources detected on the edge of the image and those that are saturated.
Return these sources matched to the references.
Python API summary¶
from lsst.meas.astrom.matchOptimisticBTask import MatchOptimisticBTask
-
class
MatchOptimisticBTask
(**kwargs) Match sources to reference objects using the Optimistic Pattern Matcher B algorithm of Tabur 2007
...
- attributeconfig
Access configuration fields and retargetable subtasks.
See also
See the MatchOptimisticBTask
API reference for complete details.
Retargetable subtasks¶
No subtasks.
Configuration fields¶
allowedNonperpDeg¶
- Default
0.2
- Field type
- Range
[-inf,45.0)
Allowed non-perpendicularity of x and y (degree)
maxDeterminant¶
maximum determinant of linear transformation matrix for a usable solution
maxMatchDistArcSec¶
- Default
2.0
- Field type
- Range
[0,inf)
Maximum separation between reference objects and sources beyond which they will not be considered a match (arcsec)
maxOffsetPix¶
- Default
250
- Field type
- Range
[-inf,4000)
Maximum allowed shift of WCS, due to matching (pixel). When changing this value, the LoadReferenceObjectsConfig.pixelMargin should also be updated.
maxRotationDeg¶
- Default
1.0
- Field type
- Range
[-inf,6.0)
Rotation angle allowed between sources and position reference objects (degrees)
minFracMatchedPairs¶
- Default
0.3
- Field type
- Range
[0,1)
Minimum number of matched pairs as a fraction of the smaller of the number of reference stars or the number of good sources; the actual minimum is the smaller of this value or minMatchedPairs
minMatchedPairs¶
- Default
30
- Field type
- Range
[2,inf)
Minimum number of matched pairs; see also minFracMatchedPairs
numBrightStars¶
- Default
150
- Field type
- Range
[2,inf)
Maximum number of bright stars to use in fit.
numPointsForShape¶
number of points to define a shape for matching
Debugging¶
The lsst.pipe.base.cmdLineTask.CmdLineTask
command line task interface supports a flag -d to import debug.py from your PYTHONPATH; see lsstDebug for more about debug.py files.
The available variables in MatchOptimisticB are
- display (bool)
If True display information at three stages: after finding reference objects, after matching sources to reference objects, and after fitting the WCS; defaults to False
- frame (int)
frame to use to display the reference objects; the next two frames are used to display the match list and the results of the final WCS; defaults to 0
To investigate the meas_astrom_astrometry_Debug, put something like
import lsstDebug
def DebugInfo(name):
debug = lsstDebug.getInfo(name) # N.b. lsstDebug.Info(name) would call us recursively
if name == "lsst.meas.astrom.astrometry":
debug.display = True
return debug
lsstDebug.Info = DebugInfo
into your debug.py file and run this task with the --debug
flag.