Sigma QUick Infrared Camera User Manual download pdf (Page 4)

WHIRC Data Reduction Manual Version 2.0, 2014 June 26 4

obtained within a fairly narrow time window. We strongly suggest that observers who

generate sky flats also obtain dome flats as a backup.

2. Science Observations: These can be a series of dithered observations on the source

field (for standards and pointlike sources) or a set of dithered observations on the source

and a set of dithered observations at an off-source sky location.

3. Darks: These are not really required for data reduction, because the process of sky

subtraction will also subtract out any dark current or bias structure. However, a series of

at least 10 short (5 s) darks is a useful diagnostic for evaluating the read noise. If one

generates sky flats, darks at the same integration time are needed.

2.1 Initial Steps

Independent of the reduction platform or individual techniques used for reduction, there

are several steps which should be carried out on all of the data frames prior to any

reduction. Using the wprep.cl script (step 5) will automatically carry out steps 1 – 4,

and is recommended.

1. Trimming: The raw data frames are 2144 × 2050 pixels in size, with 96 columns of

reference pixels (Fig. 2.1) on the right side and two rows at the top which are presently of

no use and will just make things ugly during the reduction. We suggest trimming these

off of all of the data frames; e.g.,

imcopy *.fits[1:2048,1:2048] *.%fits%tr.fits%

Figure 2.1: Raw Ks band image before (left panel) and after (right panel) trimming.

There is one bad column [97] and row [286] on the detector. The bright spot in the

center of the field is the pupil ghost.

1 2 3 4 5 6 7 8 9 ... 39 40

No comments

Sigma QUick Infrared Camera User Manual Page 4