Detrend Images

The Elixir Team provides master detrend frames as part of the QSO package. The master frames are created using an iterative process. First all the original detrend frames are averaged to create the master. That master is then used to individually flatten the original images creating a residual image. A member of the Elixir team will identify which of these residual images should be included in the master and exclude those that don't belong. This step involves an analysis of the median standard deviation and the clipped standard deviation as well as the general appearance of the flattened detrend image. The process is performed until the Elixir team is satisfied with the resulting master detrend image. These master detrend frames have been used to flatten your science data.

Only the master detrend frames have been provided on this distribution. The individual flat, bias, and dark frames are NOT included. The detrend frames follow the naming convention:


CameraRun is a runid corresponding to the run which this detrend image is applicable to.
[flat|dark|bias] Describes what type of detrend frame.
[etime|filter] This will be the etime for darks, 0 for biases, and the filter for flats.
chip If the master detrend files are created in SPLIT format, this is the chip. If the frame is MEF then this is the number of extensions
exp Often more than one detrend image applies to a Camera Run, this field identifies which image this file belongs to.

The Master Detrend table contains all the information used by elixir for determining which master flat to apply to a science image, primarily the date, filter, and version columns.

Note: A scattered light correction was applied to the master flats. As a result, the name of the actual master flats used differs in the exp extension.