-- RunaBriguglio - 03 Aug 2011

Here, we will give a short resume of the data collection operations, trying to identify the critical points (and figure out how to fix them)

Creation of a PISCES image

1. Fits files are created with a procedure that is provided by LBTO. Such procedure is integrated with a dithering script.
2. After creation, each file is (must be) processed with the CORQUAD function: such function corrects the crosstalk among the CCD quadrants and converts the fits array from unsigned int to float, also changing the "bitpix" keyword in the header from 16 to -32.
3. A set of n corquadded frames is assembled together into a fits cube.
4. The cube contains (is supposed to contain) images taken on the same target with the same filter, exposure time, dithering positions and position angle. The fits header is unique for the whole cube, so that no extra informations are provided for each frame in the cube.
5. To collect a dark frame, an empty field is imaged, closed to the scientific target.

So far, so good. This procedure was executed until June 13th, then the sampling became a bit more messy.

General problems on the fits files as produced by the sampling procedure

1. Integration time may change within the data cube
2. when naxis=3, data are typically in the form 1024x1024x n, but also n x1024x1024 cubes have been found
3. if bitpix = 16, then the corquad operation was not performed of the frame, or failed
4. some fits header contains non readable characters, so that corquad fails
5. 5 types of fits header were found.

1HEADFITS

ERROR - Extension past EOF Input header does not contain required SIMPLE keyword