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Robert Davis
October 13th 03, 04:08 AM
Hi All,

I am an electronics and computer engineer. I design gamma ray cameras
for a living. I would like to design a CCD camera around the TI TC253 CCD.
With the charge amplifier register it is capable of counting individual
photons. I have experience designing high speed low noise analog and
digital circuits with FPGAs, microcontrollers and USB comunications. The
readout noise on this CCD is less 1 electron rms when using high gain (300
or greater). I read about a group using a similar CCD (Marconi in England)
for the NOT telescope in Norway. One of my colleagues, who wants to help,
designs extremely low noise analog circuits that process signals in the
hundreds of electrons.
Do any one have any experience using this CCD? Is there any thing I need
to know that would crumple my sails before I get under way. The idea of
using this CCD is to gather frames at a very high rate (50 frames per
second) and to analyze the FWHM (full width half max) of a sample star in
the frame to determine the sharpness of each frame. Since perfect seeing
(transparent atmosphere) comes and goes very rapidly only the best frames
(2-10 percent) are use to construct the final image. Since this CCD is so
sensitive, I don't think total exposure periods will be excessively long.
Also, since each frame has such a short integration period, guiding
requirements are loosened because frame are shifted and stacked for the
resulting image. Has anybody made this type of camera in the US. Is such a
camera available already? Is this idea all wet? I would be very interested
in your opinions. If there is one thing I have learned over the years, it
is that experienced advice is invaluable. Incidently, I want to use the
camera with my Celestron C8. I am not an optical engineer, so any advice on
focal length and pixel size would be helpful.

Thank you,
Bob Davis

Phil Hobbs
October 13th 03, 04:22 AM
Robert Davis wrote:
>
> Hi All,
>
> Do any one have any experience using this CCD? Is there any thing I need
> to know that would crumple my sails before I get under way.

Get hold of the archives of the ccd-world mailing list, available at
http://www.not.iac.es/CCD-world.

Cheers,

Phil Hobbs

Chris L Peterson
October 13th 03, 05:35 AM
On Mon, 13 Oct 2003 03:08:19 GMT, "Robert Davis" > wrote:

> Do any one have any experience using this CCD?...

Not this particular device, but what you want to do is very reasonable. I built
a camera with a Marconi device having essentially zero readout noise. With this
camera I have collected deep images with subsecond frames. It is very cool to
just watch the image appear on the screen, and to stop it when the desired S/N
is reached. I've also derived a real-time guide signal from the subimages, and
stacked each image after a shift, essentially emulating a mechanical tip/tilt
system. Although I haven't done real-time analysis of quality as a tool for
adaptive optics, I've done this on saved series. My only comment would be that
it isn't enough to look at the FWHM of a single star- seeing varies across the
FOV and you want to look at many places in order to determine if the frame will
be kept.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Carsten A. Arnholm
October 14th 03, 03:52 PM
Robert Davis wrote:
> [snip]
> I read about a
> group using a similar CCD (Marconi in England) for the NOT telescope
> in Norway.

The NOT (Nordic Optical Telescope) is unfortunately NOT in Norway
http://www.astro.utu.fi/tuorla/new/report/not.shtml
(It is NOT in Finland either, but at La Palma, Spain)

> Incidently, I want to use the camera with my
> Celestron C8. I am not an optical engineer, so any advice on focal
> length and pixel size would be helpful.
>
> Thank you,
> Bob Davis

--
Carsten A. Arnholm
http://home.online.no/~arnholm/astro/astro.htm
Celestron C8 owner in Norway (NOT Spain)

Robert Davis
October 15th 03, 04:59 AM
Dear Carsten,

I appologize. I just assumed the Nordic meant Norway. Thank you for
correcting me.

Bob Davis

"Carsten A. Arnholm" > wrote in message
...
> Robert Davis wrote:
> > [snip]
> > I read about a
> > group using a similar CCD (Marconi in England) for the NOT telescope
> > in Norway.
>
> The NOT (Nordic Optical Telescope) is unfortunately NOT in Norway
> http://www.astro.utu.fi/tuorla/new/report/not.shtml
> (It is NOT in Finland either, but at La Palma, Spain)
>
> > Incidently, I want to use the camera with my
> > Celestron C8. I am not an optical engineer, so any advice on focal
> > length and pixel size would be helpful.
> >
> > Thank you,
> > Bob Davis
>
> --
> Carsten A. Arnholm
> http://home.online.no/~arnholm/astro/astro.htm
> Celestron C8 owner in Norway (NOT Spain)
>
>