MDM Facility CCD Detectors


MDM Observatory has six facility CCDs available for general use. These CCDs can be used in imaging mode at either telescope, and on the Modular and MkIII spectrographs. All are Leach GenI controller systems operated by the ccdcom package.

The 8K Mosaic camera and the OSU CCD spectrograph have their own CCDS and the user is referred to the appropriate documentation.

CCD name	format		pixel size	Notes
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Charlotte	1024x1024	24 micron	thinned, backside ill.
						manufacturer: SITE

Templeton	1024x1024	24 micron	thinned, backside ill.
						manufacturer: SITE

Echelle		2048x2048	24 micron	thinned, backside ill.
						manufacturer: SITE

Nellie		2048x2048	21 micron	thick, frontside
						manufacturer: STIS

Wilbur		2048x2048	15 micron	thick, frontside
						manufacturer: LORAL

Lurvy		512x1024	24 micron	thick, frontside 
						manufacturer: Lincoln Labs (Not used any more)
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Templeton and Echelle have the best response overall, and are the ones to use in the ultraviolet. Charlotte and Templeton use a common dewar body so they can not be used at the same time. Nellie and Wilbur have limited response at Johnson B, and have a higher cosmic ray rate than the thinned devices.

QE curves are available for Charlotte and Echelle.

Readout times are typically 30-31 seconds for the 1024x1024 devices (unbinned). Wilbur and Nellie take approximately 100 seconds when read out in the full 2048x2048 format, and the Echelle takes 120 seconds when read in the full 2048x2048 format. All devices are read through a single amplifier.

All CCDs produce 16 bit unsigned data: 0-65535 DN. Nominal values for gain and readnoise as determined during the fall of 1995 are:

CCD name	gain (e/DN)	readnoise (e rms)
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Charlotte	3.16		5.45
Templeton	3.47		5.33	(measured Oct 1996)
Echelle		1.3/2.7		7.9	(measured April 1997)
Nellie		2.94		4.38
Wilbur		2.25		4.73	
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The following table gives the angular size ("/pixel) and the field of view (arc-minutes) for these CCDs when used in direct imaging at the various foci of the MDM telescopes. These are computed using the scale factors given in the telescope manuals. They are not measured values.
2.4m Hiltner telescope

		f/7.5	11.528"/mm	f/13.5 	6.399"/mm
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Charlotte	0.28	4.72		0.15	2.62
Templeton	0.28	4.72		0.15	2.62
Echelle		0.28	9.44		0.15	5.24
Nellie		0.24	8.26		0.13	4.59
Wilbur		0.17	5.90		0.10	3.28
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1.3m McGraw-Hill telescope

		f/7.6	20.72"/mm	f/13.5 11.81"/mm
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Charlotte	0.50	8.49		0.28	4.84
Templeton	0.50	8.49		0.28	4.84
Echelle		0.50	16.98		0.28	9.68
Nellie		0.44	14.85		0.25	8.47
Wilbur		0.31	10.61		0.18	6.05
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Updated: 2006 Dec 1