Hi Paul,
I've gathered together everything on this web page for you.
Firstly, if you were to show only 1 overhead of ULTRACAM during your talk,
it should be this one...
ULTRACAM - postscript version
ULTRACAM - html version
ULTRACAM - jpg version
ULTRACAM - gif version
It summarises the most important aspects of ULTRACAM and its possible use
on the VLT. Hopefully, you should be able to print at least one of these
out on your system. If you can't, please let me know.
If you have more time, you might want to select some additional
overheads from these ones...
- introduction - a brief summary overhead.
- high-speed astrophysics - a brief
listing of the science we would like to do with ULTRACAM as a function
of astrophysical timescale.
- ULTRACAM requirements - the scientific
requirements of ULTRACAM. These are pretty much the same requirements
one would obtain if one were to design a "perfect" photometer (i.e. one
which combines the strengths of both CCD and photo-electric
photometers).
- ULTRACAM optical design - a schematic
of the optical path of ULTRACAM. The focus of the telescope is shown at
the top. The light is then collimated and the blue (u') light then reflected
off a dichroic, through a filter and then re-imaged onto a frame-transfer
CCD. The rest of the light goes straight through and the green (g') light
is then reflected off a second dichroic onto a second CCD. The remaining
red (r'/i'/z') light passes straight through and falls onto a third CCD.
The plot on the right shows the filter bandpass of the SDSS set, the
dichroic cut-points and the CCD QE curves. Note that you can use other
filters (e.g. UBVRIZ) if you really want to.
- ULTRACAM mechanical design - the mechanical
chassis which holds everything (optics, CCDs, CCD controller, etc), is
a "double octopod" design made out of aluminium and carbon fibre. It is
approximately 70cm in length (and about 50cm at its widest) and weighs
approximately 75 kg. Note that the instrument shown here is the one which
will go on the WHT - the VLT one will probably have to be a little larger
(but not that much).
- ULTRACAM detectors - these are of the highest
quality (grade 0), and are frame transfer devices with exceptional
QE (97% at peak!) and good noise performance. There are 3 such devices
in ULTRACAM, each one with a different coating to optimise performance in the
wavelength band it is being used for. The optics we have currently got
designed give a plate scale of 0.3 arcseconds/pixel and hence a field of
view of 5 arcminutes on each chip. This gives an approximately 97%
probability of
finding a 13th magnitude star somewhere in the field to use as a comparison
star for differential photometry (which is obviously pretty essential).
- ULTRACAM data acquisition - this is a key part of
ULTRACAM. The system will be able to handle data rates of up to 5 Mbytes
all night. In other words, ULTRACAM
will be able to record millisecond frame rates continuously without stopping
for an entire night. Not only that, these data will be both archived and
fully reduced in real-time. In other words, the user will see a light curve
in real-time and will never have to stop taking data in a night in order
to allow the disks/tapes/data reduction/etc to catch up with the data taking
(thereby avoiding horrible gaps in time-series data and the resulting aliasing
one gets in power spectra).
Another key aspect of the system design is that it is using the very latest
in hardware/software technology (e.g. RTLinux/SDSU-PCI/GPS/RAID array, etc) and is
hence fairly future-proof. Another important aspect is that the system is
standalone and requires NO software/electronic interfacing with the telescope
(i.e. it does not need to talk to the telescope at all). This makes it a
simple matter to commission on a new telescope (as one only needs to worry
about the mechanical interface).
- ULTRACAM sensitivity - these curves
assume pretty much the same (fairly realistic) parameters I detailed in my
earlier email to you.
- ULTRACAM speed - this shows the minimum exposure
time one can go to with a 100x100 window. The "max (...)" statements are
fortran type statements which show you that the maximum dead-time between
exposures will be the largest of the two numbers in the brackets. In other
words, with a 100x100 window in drift mode (the fastest mode), the dead
time between exposures will be 0.5 milliseconds unless the exposure time
is shorter than 56 milliseconds, in which case the deadtime will be
56 milliseconds minus whatever the exposure time is. By using on-chip
binning and smaller windows (perfectly feasible), we can reach our
requirement of 1 millisecond exposure times with negligible dead time.
Note that all exposures are time stamped to an absolute accuracy of
0.01 milliseconds using a GPS receiver.
- ULTRACAM on the VLT - a few points it might be
worth making at the end of your talk. The really key one is that we can have an ULTRACAM on the
VLT in an incredibly short time and incredibly cheaply (when compared
to the other instruments currently being planned for the telescope).
This must surely be worth doing, especially given the huge number of
VLT focii which have to be filled with instruments!
Finally, if you want more background information, try...
- This talk on ULTRACAM, which I gave
at a conference on high-time resolution astrophysics at Galway earlier
this year (click on the pointers to "science", "design", "performance"
and "milestones" on the bottom-right of the page).
- The ULTRACAM web-site,
which has loads of additional information on the instrument.
- Phoning me at work (+44-114-222-4528) next week. You can also email
me, of course, on
vik.dhillon@shef.ac.uk
(I will be checking my email regularly over the weekend).
Many thanks for all your efforts with this - I think it is great that
you are raising the profile of high time-resolution work on the VLT
(which is clearly an important area which ESO should be looking to exploit).
Regards,
Vik.