Newsletter - 15 February 1994
This is another update concerning the current status of instruments
at CFHT. Comments and suggestions about the newsletter may be
emailed to newsletter@cfht.hawaii.edu or newsletter@uhcfht.bitnet
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CFHT World Wide Web (via mosaic) Home Page Now Available
The world wide web home page in use at CFHT is now available to the Internet.
The CFHT URL is: "http://www.cfht.hawaii.edu/". The URL, uniform resource
locator, is a special pointer to a file which may be anywhere on the Internet.
The home page is simply the first "www" page to be viewed at a site.
Mosaic is an Internet-based global hypermedia browser for which www is made
available free for academic, research, and internal commercial use from the
National Center for Supercomputing Applications at the University of Illinois.
Send questions or comments via email to xmosaic-admin@cfht.hawaii.edu.
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Data Acquisition News
1. The follwing FITS cards have been added to the FITS headers:
DETSIZE1= -9999 / detector size in axis 1 direction
DETSIZE2= -9999 / detector size in axis 2 direction
PIXSIZE = -9999 / pixel size (microns)
INTTIMER= -9999.9 / integration time requested (seconds)
XPROBE = -9999.9 / X position of guide probe
YPROBE = -9999.9 / Y position of guide probe
ZPROBE = -9999.9 / Z position of guide probe
ZEROPIX = 'Null ' / illegal zero-valued pixels detected
The detector size keywords indicate the "raw" detector size,
independent of subrasters, binning, or overscan, selected for the image.
The INTTIMER was added because the INTTIME given by the system is not yet
accurate reflection of the time the shutter was open. The X, Y, and
ZPROBE were added to ease reobservations of objects and to provide
more relevent "focus" values for prime focus. The ZEROPIX indicates
that illegal pixel values were detected during CCD readout (see the
next news notes!)
2. It has been noted that data taken in the past with the Loral3 CCD
occasionally have extra pixels (intensity equal to zero ADC units)
added to the data stream going to disk. This occurs at random, and
but has the effect of shifting the subsequent data by one pixel for
each occurance. It is seen visually by looking at a two-dimensional
display of an image and examining the border between the data and the
"overscan" region at the end of each line (row.) This border will
shift further and further to the right as one looks towards increasing
Y values (increasing row number.) The extra pixels are easily
identified because they are zero valued, and correcting the image is
straightfoward. Contact your support astronomer or the Directors via
email to directors@cfht.hawaii.edu for assistance, if needed.
Since January 25, 1994, the data acquisition software automatically
detects the zero value pixels and corrects the images for the problem
(the only lost data is a small number of pixels at the end of the last
line that fill out the complete frame.) The file
/pub/ccdnews/zeropix.list is available through anonymous ftp to
ftp.cfht.hawaii.edu. This identifies images for which "zero" pixels have been
detected but HAVE NOT been corrected between Sept 24, 1993 and Jan 25,
1994, if anyone suspects they may have such data.
3. Either 8mm (exabyte) and DAT drives are selectable for saving
image files from the Pegasus sessions, as either "tar" archive files
or as individual FITS file format (but the latter is inefficient for
tape usage.) NOTE: the use of round, 9 track 1/2 inch tapes is being
discontinued effective immediately. Please contact your support
astronomer if this causes a problem. 9 track drives are still
available at the Waimea Headquarters.
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The following items are reprinted from the "UPDATE INFORMATION"
page inserted in the CFHT Proposal form
1. Service observing requests will be accepted for observations
requiring no more than 5 hours of data, including
calibrations, using FOCAM with a 2048x2048 pixel CCD, and the
Redeye cameras (narrow and wide field). Each proposal must be
accompanied by a full set of exposure request forms identical
to that in the attached template, one form per exposure. The
template may be downloaded by anonymous ftp to
(ftp.cfht.hawaii.edu). The template is in file
/pub/cfht-manuals/cfhform/service.tex.
2. Following discussions with the SAC and the acceptance of the
corresponding SAC recommendation by the Board of Directors,
CFHT will only schedule instruments for runs of FOUR (4) nights
or more. Should less than four nights be recommended by the
national Time Allocation Committees, additional nights to make
a four night run will be added and charged to the national
TAC(s) requesting the time.
3. SAC has recommended, and it was accepted by the Board of
Directors and the CFHT Executive, that the Herzberg
spectrograph will be decommissioned at the end of the 94II
semester. Should a significant number of nights be scheduled
during 94II, the date of decommissioning would be reviewed.
4. July 1994 Jupiter-Comet Schoemaker-Levy Collision
A Special Procedure for Allocation of Time Related to the
Crash of Comet 1993e on Jupiter in July 1994 has been
established. The event is still open to proposal submission.
The reason for this exceptional procedure is that additional
information is needed about the sizes of bodies and the exact
dates of collisions. This will be better known after
observation of the comet in 1994, and computer simulations of
the collision. In agreement with SAC and TAC, we are adopting
the following procedure:
The time between Sunday afternoon, 17 July, and Thursday
morning, 28 July 1994, will be reserved for observations at
the F/35 focus of the events related to the crash of the comet
Shoemaker-Levy 9 onto Jupiter.
The detailed schedule of the observations will be decided at
the TAC meeting during the third week of May 1994.
We are calling for requests for allocation of time related to
the comet/Jupiter event that use the f/35 focus, or backup programs
which will make use of the same instrument planne for the comet
encounter observations, with a special deadline 1 April 1994.
These special requests will be collected by the agencies in the same
way as normal requests, except for the unusual deadline date.
CFHT would prefer not to change the instrumental configuration
during the event, since there is always the danger of losing
time on the sky because of technical problems during a change
of instruments. We intend, at the very least, to minimize the
number of changes. Before presenting a request, we encourage
PIs to exchange information with other potential candidates in
order to optimize the use of the telescope during this period.
5. SIS guider
A replacement detector unit is currently being fabricated for
the SIS fast-guider system to extend its sensitivity well
beyond the existing limit of magnitude 15.5. This new system
will be implemented and tested early in April, 1994. To assist us in
scheduling SIS for the 94II semester, please specify in
Section 3 (Instruments) if you require SIS for imaging and/or
for spectroscopy, whether or not your program requires the
fast-guiding capabilities, and what is the brightest guide
star available. Should the upgrade of the SIS guider be unsuccessful,
SIS imaging programs could be scheduled to use HRCam.
Note also that SAC and the CFHT Executive agree that if the upgrade is
successful, CFHT will no longer support HRCam runs, but would
schedule the high resolution imaging runs with SIS, which has a larger
field of view.
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Redeye+FTS = "BEAR" not available during 94II
The combination of the Redeye (HgCdTe) array as the detector on
the FTS, which is considered a visitor instrument, will not be available
under CFHT responsibility during the 94II semester. Due to staff changes
in the CFHT Resident Astronomers occuring during 94I, support for the
complicated data reduction will be impossible.
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