obs_strategies¶
ChopNodCombiner¶
Creates and combines 4 images for each of the chop/nod positions.
AA : original position
(dx, dy) = (0, 0)
AB : chop position
(dx, dy) = chop_offsets
BA : nod position
(dx, dy) = nod_offsets
BB : chop-nod position
(dx, dy) = nod_offsets + chop_offsets
Images are combined using:
im_combined = (AA - AB) - (BA - BB)
If no nod_offset
is given, it is set to the inverse of chop_offset
.
ChopNodCombiner
is a detector effect and should be placed last in thedetector yaml (after the noise effects).
Keyword Arguments¶
- chop_offsetstuple, optional
[arcsec] (dx, dy) offset of chop position relative to AA
- nod_offsetstuple, optional
[arcsec] (dx, dy) offset of nod position relative to AA
Example yaml entry¶
name: perpendicular_chop_nod_slanted_pattern
description: chop throw to (+5, 0) and nod throw to (-7, +10) arcsec
class: ChopNodCombiner
include: True
kwargs:
pixel_scale : "!INST.pixel_scale"
chop_offsets : (5, 0)
nod_offsets : (-7, 10)