Previous Article
Next Article
Table of Contents

4-m Prime Focus CCD (1Mar93)
(from CTIO, NOAO Newsletter No. 33, 1 March 1993)

The new Large-Format PFCCD imager was completed on schedule and went
for its first engineering run on December 18. It is designed to
accommodate CCDs or mosaics up to 75 mm square, and has two filter
wheels capable of holding five 102 mm square filters. The CCDTV camera
is on a stage which permits short-scanning, while there are facilities
for easy tilt and rotation of the dewar so that large CCDs can be
accurately aligned with the focal plane. It works either with the
triplet correctors or with the soon-to-be-installed ADC. Instrument
control uses DC or DC servo motors via a STD-Bus box. Apart from the
ability to use large CCDs at the 4-m, the images are expected to be
significantly improved (especially with the ADC) since the present
arrangement has the CCD centered well off-axis of the doublet
corrector.

The above-mentioned engineering night was also the first on which an
ARCON-based controller had been tried at the 4-m telescope, and it was
also the first time a CCDTV camera had been used at PF for acquisition
and guiding.  Installation went extremely smoothly, focussing took
place soon after dark, and by 2 AM all the engineers had vanished! The
equipment functioned well, but some system integration work remains to
be done to make all the computers (ARCON, TCS, Motor-control) talk (and
listen) to each other. With the red triplet and a CCD with 0.35 arcsec
pixels, the images had 1.1-1.3 arcsec FWHM on a night when the other
telescopes reported 1.5-1.7 arcsec FWHM, whereas on following nights
with the old PFCCD system the FWHM was the same as the other
telescopes. This rather meager statistic suggests that image quality
has improved with the new system. Another engineering night is
scheduled in February, and it is hoped that the instrument will be
available for visitor use starting with the April prime focus run.

Alistair Walker, Tom Ingerson,
Andres Montane, Javier Rojas, Rodolfo Cardemil

Previous Article
Next Article
Table of Contents