This is an old revision of the document!
The focalplane layout of the 4 CCDs as it is on sky and in quick look is shown below.
The platescale is 0.455 arcsec per 15 micron pixel.
The gap between CCDs is ROUGHLY 55 arcsec in Dec and 170 arcsec in RA.
The ampifiers are arranged as follows: ◦CCD1: Amps 1-4 ◦CCD2: Amps 5-8 ◦CCD3: Amps 9-12 ◦CCD4: Amps 13-16
Layout Drawings (still old)
◦Physical layout, but old ◦View into dewar window
Fringing
These backside-illuminated CCDs fringe a small amount at the wavelength of SDSS r’ filter, even more at SDSS i’, and even more at SDSS z’. You need to take appropriate data to create and later subtract scaled fringe frames. Remember that the 8000-10000 Angstrom sky is highly variable with changing emission lines, thus changing relative intensity of fringes in the fringe pattern.
Offsets
Offset from center of the 4 CCDs (the center of gutter) to center of CCD 1: ◦move the telescope1006 arcsec SOUTH (ie, -1006) ◦move 908 the telescope arcsec WEST (ie, -908)