CCD Mosaic Imager Status Report
(from KPNO, NOAO Newsletter No. 51, September 1997)
Mosaic Imager Status
During the months of May, June and July, the CCD Mosaic Imager
continued to evolve toward a user-class facility instrument.
We had engineering runs at the 0.9-m and 4-m in June and July.
The engineering nights were followed by shared-risk science
observing. Two groups of observers used the instrument at
each telescope. The observers achieved a high degree of
scientific success with the Mosaic. In turn, the Mosaic team
received valuable feedback from the observers, and a number
of issues raised by the observers are being addressed this
summer.
Some highlights of the May and June runs were:
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Excellent image quality was seen on several occasions during
the 4-m run. The tightest images had FWHM of 0.65 arcsec (2.6 pixels)
in the R band. This demonstrates that the new
4-m Corrector and ADC are performing very well in demanding conditions.
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The IRAF Data Capture Agent,
which automatically transfers
images from the data acquisition computer to the data reduction
computer, was used routinely during the most recent 4-m and 0.9-m
runs. The image is available for examination and analysis within
seconds of the readout completing (125 seconds for an unbinned
exposure).
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Commands for obtaining multiple dithered exposures have
been added to the Arcon IRAF user interface: mosdither and mosgrid.
This software automatically offsets the telescope over a dither
pattern or grid, takes exposures, and assists with recordkeeping
and guider control. The default dither pattern that is designed
to fill in the gaps between the Mosaic CCDs proved quite popular.
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We received two new Mosaic filters,
I and H
(6563/75), and tested them at the telescope. These join B, V and R.
We are scheduled to take delivery and test six other Mosaic filters
over the summer (three H redshifted (6603/80, 6643/80,
6683/80), [OIII] (5007/50), [OIII] off (5300/250), and [SII] (6723/80)).
However, deliveries have been running somewhat behind schedule.
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As described in the last Newsletter article, we decided to
embrace digital linear tape technology in order to record the vast
amount of data produced by the CCD Mosaic Imager.
A DLT-7000 tape drive
has been installed on the data reduction computer, and a second drive
is present downtown on ursa. IRAF can write the multi-extension FITS
files produced by Mosaic to the DLT-7000. We were pleased by the speed
of one Mosaic image per minute to the DLT. We continue to offer two
Exabyte 8505 drives on the data reduction computer as well.
[In late-breaking news, we just received two H filters redshifted
by +1800 and +3600 km/s, but these new filters have not been tested yet.]
Science Grade CCD Status
As discussed in previous Newsletter articles, we are awaiting the
thinned science-grade CCDs from SITe, in order to replace the current
engineering-grade CCDs. As of late July, none has been delivered.
User Manuals
We continue to work on documenting the CCD Mosaic Imager for users.
Particular progress has been made on the manual sections describing the
acquisition software
(author Steve Heathcote) and the
data reduction
software (author Frank Valdes). This documentation is being made
available in draft form on the
Mosaic Web page
(http://www.noao.edu/kpno/mosaic/mosaic.html).
Applying for Time With Mosaic
The CCD Mosaic Imager will continue to be offered for shared-risk
observing during the spring semester (see the list of available
instruments in the SCOPE section for guidelines and constraints). For
more information about Mosaic status or performance, see the Mosaic Web
page or contact one of the undersigned.
[From the "SCOPE" section of this Newsletter]
To minimize the number of instrument installations, the CCD Mosaic
Imager will be available for block-scheduled, shared-risk observing on
the 4-m and 0.9-m telescopes, with priority given to 4-m use. Check
the CCD Mosaic WWW page for updates concerning new filters and progress
toward replacing the current engineering-grade CCDs (the default for
all of semester II 1997) with science-grade CCDs.
For updates on the progress of the Mosaic project, check out the
Mosaic web page
at http://www.noao.edu/kpno/mosaic/mosaic.html
George Jacoby gjacoby@noao.edu
Taft Armandroff tarmandroff@noao.edu
Todd Boroson tboroson@noao.edu
For the Mosaic Team ...