ASNNE

Notes on imager I’ll put here until website is in operation.

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Notes for tonight oct 13 2009

top posting here, read down for earlier posts.

Camera is running on by remote, going to make library of dark frames, as camera is on sunporch, and getting good and cold.

Links are from Gateway 450rog,  (the one I usually bring to observatory)  wifi to router.  One of router cat5 cable outputs goes to a hub, then to Dragon (my multimedia test bed box) and by cable the STS1.2, as it has no wifi due to damaged internal wifi.

Imager Hardware notes.

SBIG (Santa Barbara Instruments Group) ST-2000XCM One Shot Color Camera

It uses a Kodak Model xxx CCD chip for imaging, and a separate chip solely for guiding. The guide chip is as good as some imagers alone.

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Features:

2 chip system, this takes load off imager chip for faster and better quality operation.

Self guiding chip allows the camera to control the Meade, in place of or in addition to a computer hookup, it will also compensate for scope tracking errors.

One shot color, no three filter switcher needed. Capture the image, and process the data to color later

Binning is available for some real sensitivity.

Nice dynamic range, pixel wells are deep!

Built in Peltier cooler. Except on really warm nights, sky noise will be higher than chip noise!

For serious stuff on warm nights, water cooling hookup is available, and I have a suitable water pump. (Brings back memories of working with water cooled IR lasers).

Shutter, for easy dark frames.

Progress:

Installed software provided by SBIG website, CCDOps, V5.49  on various computers.

The STS-1 computer, the box built for the observatory was originally going to run the Linux programs available from SBIG. As an experiment I put the Windows 7 OS in it and the camera works fine.

In spring I set it up on my lx200gps and got the Hercules cluster without even trying. I set my scope to goto m13 and did not check with the eyepiece. I saw something in the imager, focused and shot. got m13 as first light.

90914720. cont.

Last summer installed recessed cap screws in the tripod mount size threads in imager. These are used instead of the cable tie mounts I used to tie it to scope as a safety harness.

A mini bungie cord can be used in place of string.

The cylinder of the eyepiece mount is slightly too small as noted in the internet, so a wrap of tape is used, or it will rock.

Be sure the unit is tight before moving the scope.

Tried to get Jupiter spots one night, but was having trouble with exposure etc, seemed it was overloading either chip or software. Switched to Meade LPI imager I got with my scope. Got Jupiter, but not sure if my time was right, and looks like image would not have enough res.

I am taking and storing dark frames tonight at various shutter speeds and chip temperatures.

When first receiving unit in Spring, I removed and baked the desiccant capsule in an oven for several hours.

After running it all day, today I see no frost on chip at -12 degrees C.

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HOWTO notes on making a howto for club members.

For now, use scope and camera independent of computer.

Acquire image in a club scope. Remove eyepiece.

Mount imager using a spacer, or maybe spacer will have to be on eyepiece. In other words we want to be able to swap out camera and eyepiece and have focus close. Mind any scope balance needs.

Imager will be set up and running from previous use.

CCDOps will be running on club or other computer.

Be sure cooling power is around 85%. If not adjust imager cooler for higher or lower temp to achieve it.

go to ‘camera-grab’ Exposure window will come up. Take a test exposure without ‘dark frame also’ selection, or you will double your work time.

Later you can take a dark frame in addition, or use the stored frames in the club database.

Do not goto the scope unless you can prevent the camera and cables from impacting the fork, or stretching cables.

Have someone at the Meade to hit ‘enter’ to stop scope if camera is about to contact anything due to operator or scope error. And immediatly to hit power switch if  ‘enter’ doesn’t work.

Once procedures are used to, the Meade has automatic stop limits to use.

Eventually I would like to install mechanical stop switches in case software stops fail.

I’ll be working on cable management of the Meade this week.

Secured cables to camera for strain relief, ease of use.

– Tech notes

Make separate folder called darks to pre store dark frame data. This is good for most imaging, and only needs to be updated every few months to compensate for migrating pixels.

Need to make flat field shots through scopes. Possibly twilight area of sky. This compensates for any unevenness in optics.

Orientation of camera is that when the connectors are toward Earth, the camera image is right side up.

Saving rgb will only be 8 bits with CCDOps, but there are hoops to jump to get 16 bit.  Somewhere I read this surprises people with ‘fat’ stars.

save rgb as usual, then extract a luminance frame and save as 16 bit .tif.

Take several images for stacking.

Later in GIMP or Photoshop, it will be processed to a final image. Even two shots will make a big difference.

GIMP is on the sts-1

Keep original uncompressed image to later work with, but the instant color can be used for casual imaging.

TODO 90915

Bring imager to meeting

.active USB extensions

.mini bungies

.laptop or sts1

.mouse

.extension cord, power