This section describes both the data format for all Gemini instruments, including GMOS, and the Gemini IRAF Package, which supports imaging, and long-slit, multi-object, and IFU data from both GMOS-N and GMOS-S.

• Gemini Data Format
• Data Reduction: Gemini IRAF package

GMOS Data Format

Each of the three chips in the GMOS-N and GMOS-S arrays can be read out through one or two amplifiers (left and right). In the two-amplifier mode the output data file then contains 6 fits extensions (see diagram below). Each of the six image sections has an accompanying overscan region 32 pixels wide. In one-amp mode the data file contains three extensions, one per chip, again with a 32-pixel wide overscan section. The one-amplifier mode is the most used for science applications.

Binning: When pixel binning is used, the resulting datafile still contains overscan regions that are 32 samples wide.

Layout of GMOS detector array and structure of the output data file, when reading out in 6-amp mode, with unbinned pixels.

Layout of GMOS detector array and structure of the output data file, when reading out in 3-amp mode (using the 'best' three amps, R,R,L). Note the overscan regions are not in the same place for each chip.