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CCD and Controller News (1Dec92)
(from CTIO, NOAO Newsletter No. 32, 1 December 1992)

Reticon has delivered the Grade 1 1200J CCD (1200 x 400, 27 um pixels),
on order for more than two years. This is a thinned device upon which a
flashgate and AR coating have been deposited by Lloyd Robinson (Lick
Observatory). The quantum efficiency is much higher than that of our
present Reticon #2, especially in the blue (75% vs. 40% at 4000 A), and
read noise is expected to be about 3 electrons rms. We plan to swap the
new CCD (Reticon #3) for Reticon #2 during November. As a reminder, the
Reticon is installed in a special dewar dedicated to the Blue Air
Schmidt camera, which sees use with the three 4-m spectrographs (ARGUS,
R-C and Echelle).

A second, similar dewar contains an EEV CCD (576 x 384, 22 um pixels)
which is dedicated for use with the Red Air Schmidt camera. This CCD
has QE little inferior to the Reticon in the far red, and being a
front-illuminated CCD, does not suffer from fringing. We have increased
the versatility of this option by substituting a coated CCD which is
sensitive shortwards of the 4800 cutoff of the uncoated device.
Secondly, a field flattener has been installed which has a multi-layer
broad-band AR coating.  The useful wavelength range of this combination
is approximately 3800-10000 A.

Work to convert our CCDs to operate with the new ARCON controllers is
proceeding apace. As discussed in previous Newsletters (No. 30 p. 8,
No. 31 p. 10), a prototype version (ARCON 2.1) has been successfully
taking data at the Schmidt telescope this year, and will be offered for
visitor use at that telescope next semester. Three production ARCONs
are being produced almost in parallel; one of these is a laboratory
system, and the other two will operate a Tek 1024 and Tek 2048. We
expect to begin using these at the telescopes during November and
December. Although we warned (Newsletter No. 30, p. 8) that the
conversion to ARCONs would mean a restriction in the types of CCD
offered at the 0.9-m telescope, in actuality we will need to keep the
old VEB controllers in service for a few more months just to operate
the filters and preflash. At this time we plan to switch over to using
a new motor controller, and the VEB and LSI-11 computer will be
retired. Until this time CCDs at the 0.9-m can in principle be operated
with either the old or new controllers. Notwithstanding, we plan to
restrict as much as possible the changing of CCDs at the 0.9-m, and the
ARCON-based Tek 1024 #2 will be the default detector.

Alistair Walker

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