Kottamia's New CCD System

Kottamia Observatory is commissioning a new CCD system for its newly refurbished 1.9-m reflector. The new CCD system comprises a science camera and an acquisition/offset guide camera. Both CCDs are controlled by '486-class microcomputers and Imager2 software. The new instrument can be used at either the Newtonian or the Cassegrain focus.

The chip employed in the science camera is housed in a liquid nitrogen cooled vacuum dewar and controlled by a Digital Driver Electronics control unit (type DDE 4202) and Imager 2 software. The chip is manufactured by SITe (formerly Tektronix). It is a thinned back-illuminated chip, which is protected by a removable window provided with an anti-reflection coating to enhance the chip response from the UV to IR. The quantum efficiency (QE) reaches its maximum value (80%) at room temperature between 6000-7000 Å. This detector is characterized by high dynamic range, excellent charge transfer efficiency at low signal level, low dark current and maximum readout flexibility.

This acquisition/guide camera detector is a thermoelectrically cooled Kodak KAF-1300 CCD, also controlled by a DDE 4202 controller unit and Imager 2 software. The chip is a front-illuminated CCD with spectral response from blue to near infrared with maximum QE of 50% at around 8000 Å. A long pass-band filter (RG610, 6100 Å) is installed at the front of the camera to improve the signal-to-noise ratio. The light path is folded into the camera using a 45-degree tilted mirror. The camera is mounted on a short rail to facilitate motion in or out along the optical axis. Such motion is achieved employing a DC motor.