lirisdr - An IRAF package for LIRIS data reduction

The problem of observing in the near infrared range using ground-based telescopes:

The main trouble to solve is the high background coming from the Earth atmosphere, there are different terms of contribution: the OH emission lines and the airglow produced in the high layers of the atmosphere dominating in the H band, the thermal radiation originated at the telescope and its environment, increasing as moving to the red extreme of the K band.

Initial steps:

    The first step is to subtract the bias level. Each pixel of common infrared detectors are usually read following the scheme: reset-read-integrate-read.  In general data are stored after subtraction of the first read level.  If this is not the case one has to perform this step.
Currently, in the case of LIRIS data  there is a pixel mapping problem which has to be corrected before any other processing steps. There is a C routine which performs this correction for a single file. This routine can also be called from IRAF for a list of files, for example:
lirisdr> lcpixmap @inframes "c" out=outframes 

Imaging mode

The most common observing mode is to follow a dithern pattern. The reduction steps to be followed are:
An sky image can be obtained as the median value for each pixel from the whole set of  frames. 
The program which perform the whole process is called ldedither.