Obvious changes - the array has been changed; you will not be able to use flats or bad pixel masks from previous (pre-Feb 96) observing. The electronics have been upgraded; the time for a single read is about 2.4 seconds. The "dummy read" may not be necessary for broad-band imaging. Not using a dummy read causes the first three lines of each quadrant to be slightly unstable with respect to the rest of the array on the level of 5-10 ADU's. For narrow-band imaging, this may be a significant effect. The conservative approach is to use the dummy read. This will add 5 seconds overhead to each image.
The ADU scaling is different. Hard saturation occurs at 50,000 ADU's. It is probably wise to keep the peak value in the image well below 40,000 to stay below this limit. The scaling is now about 1.85 electrons/ADU. The plate scale was measured to be 0.1886 arcsec/pixel at f/10, with a rotation in the nominal position of 0.883 degrees CCW (e.g., N is rotated 0.883 deg E of vertical when displayed in the normal way).
The motor for the second filter wheel failed in the lab so at the present time only the original wheel is in QUIRC with 8 filters. Replacement cryogenic motors are being procured and will be installed as soon as possible. The current filters are:
The dewar now has a temperature sensor and heater. For normal operation, the temperature controller should be used to set the detector temperature to 80.0K. If the controller is not used, drifts can occur as the telescope is moved, resulting in dark current instabilities in the array. The new array is not thought to be more sensitive to these effects than the previous detector, but some of the anomalies previously seen by observers with the original QUIRC detector may have been due to this effect.
Last modified 14 February 1996