Our spectrograph, and its dedicated camera are both made by the Santa Barbara Instrument Group (SBIG, hereafter). The spectrograph is an SBIG SGS, and the camera is an SBIG 8E. The imaging (or main) CCD in the camera is a Kodak KAF1602E. The guide CCD is a Texas Instruments TC211. Copies of the documentation from both SBIG and Kodak are available in the Andreas Control Room. These documents are useful for understanding the general properties of the camera and detector systems. This document is intended to provide observers with detailed information about how our detector and our camera behave in conjunction with our spectrograph and our telescope. Such information is crucial for planning the details of an observing campaign and for understanding how best to calibrate data obtained with the available instrument configurations.
The CCD has a full size of 1530x1020 pixels. The pixels are 9 microns square. The SBIG software allows the chip to be read out with a variety of binning. The choice of whether or not to bin the detector is driven by several factors, including the quality of the seeing, the importance of spatial sampling, and the relative importance of read noise to the overall noise budget. Unless otherwise stated, all discussion in this manual refers to unbinned images. Data from the pixels are recorded as 16-bit unsigned integers. The detector gain is 2.3 electrons per "Analog to Digital Unit" (more compactly, 2.3 e- /ADU), and the full-well capacity is 50,000 e- or about 20,000 ADU. ADUs are also commonly referred to as "counts" or as "Data Numbers" (DNs).
The guide CCD has a full size of 190x162 pixels. The pixels are rectangular, with dimension 13.75x16 microns, producing a square field of view (fov, hereafter). For most observing projects, the guider images are useful only for making sure the target is on the slit, and are thus not saved. However, for projects involving observation of extended sources, the guide CCD images are useful for understanding the sampling of the target by the slit. I will thus discuss the basic reduction of the guide CCD images.
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