User manual

WHIRC Data Reduction Manual Version 2.0, 2014 June 26 20
Figure 2.16: Average of sky images in the Paβ filter (left panel), showing evident
fringes. Same image after subtraction of dark frame (right panel).
3. At this point most of the dark current will be removed, except for occasional
mavericks, but the frame still has the low spatial frequency structure and the central pupil
ghost. Dividing by the dome flat and running fixpix with the bad pixel mask (Fig. 2.9)
will remove most of the structure and clean up the image (Fig. 2.18a).
4. The fringe template for rmfringe has (ideally) a minimum value near zero, so one can
at this point subtract off a constant value to achieve this. Running
fmedian (Fig. 2.17)
with a fairly small box (3 × 3) appears to enhance the S/N without affecting the spatial
resolution of the template (Fig. 2.18b).
Figure 2.17: IRAF parameter list for the task
fmedian, with a smaller (3 × 3)
smoothing box than used for the pupil ghost template.