Description of the MDM Observatory's 8K CCD array project based at Columbia Astrophysics Laboratory
If you questions or comments regarding this document, please contact Arlin Crotts ( (Telephone: (212) 854-7899).

Under Construction! Under Construction!

This document describes the 8192x8192 pixel imaging CCD array operating at MDM Observatory's 2.4-meter and 1.3-meter telescopes. The MDM 8K was built by Columbia University with the able assistance of Ohio State's Imaging Sciences Laboratory and the Instrument Shop of Dartmouth College's Department of Physics. GL Scientific (Dr. Gerald Luppino, owner) was the prime subcontractor and Arlin Crotts was the designer, in part, and project manager, and is currently instrument scientist.

Thumbnail description of the MDM 8K:
(Some numbers in this section are preliminary, but all are approximately correct.)

The detector plane is 8192x8192 pixels in a 4x2 mosaic of thinned 2048x4096 SITe ST002A CCDs. This is identical in description to the KPNO MOSAIC, although the MDM 8K is somewhat superior, cosmetically.

The field of view is 25 arcmin on the 2.4-meter and 46 arcmin on the 1.3-meter with a pixel scale of 0.18 arcsec on the 2.4-meter and 0.34 arcsec on the 1.3-meter. Image correction is well subarcsecond on the 2.4-meter for U-Z bands, but not as good on the 1.3-meter.

Currently, overhead time for a full frame image at full resolution is 110s (within a sequence of exposures). For many applications, binning 2x2 will be preferred, which takes about 30s overhead per exposure. The fastest exposure currently is 3s, but times of 1s or shorter will soon be available.

Filters available now are MDM standard Bessell U, Harris B, Harris V, Harris R, I ("Arizona I"), gunn Z, a broad R: ("Rjt": 560-720nm) and H-alpha on-band and off-band. Filters are 5.75-inches square in a 6-position filter wheel.

Full format images are 134 MBytes before processing and can be stored to tape on a DDS3 4mm ("DAT") tape drive as multi-extension FITS or 8 individual FITS files.
A more thorough description is found below.


Basic Startup/Shutdown Procedures
Taking Exposures
DetCom Help Page
Description of Link between MDM 8K and TCS (Telescope Control System)
Observer's Guide for CFH 12K - similar in operation to MDM 8K



The Telescope - MDM 2.4m at f/7.5:
- Field of View
- Optical parameters
- Seeing performance

Basic System Characteristics:
- Field and image quality
- Filters
- System overview & basic layout
- Summary of system on 1.3m - preliminary

The Detectors - 2 by 4 array of 4Kx2K CCDs:
- The new CCD upgrade - preliminary
- Focal plane assembly

The Optics -- Wide-Field Corrector:
- Overview and prescription
- Layout and ray diagrams
- Imaging performance & spot diagrams

The Dewar & Cryostat:
- Basic overview
- Dewar and cryostat performance

Control Electronics:
- Basic overview
- System computer
- Controller performance

Readout and I/O:
- Basic overview
- Readout & I/O performance
- Tape and disk drives

Auxiliary System Components:
- Filter wheel
- Shutter

The Guider:
- Guider field and imaging performance
- Detector characteristics
- Mechanical considerations
- Control and readout

The New MIS - Modular Instrument System - preliminary
- Basic layout
- Room for additions

Overall System Parameters:
- System weight
- System power