Monthly Archives: February 2010

Surprise clear sky, recalibrated focuser

It wasn’t supposed to be clear tonight (or any night for the next week) but I looked outside at about 7:00 PM to see clear sky and stars! I quickly changed my plans for the evening and spent a couple of hours outside doing some calibration.

I had re-installed the observatory computer, camera, and focuser this past weekend (in daylight) and hadn’t yet had a chance to calibrate, so I just used my couple of hours outdoors to do multiple V-Curve runs with FocusMax and the focuser. The computer also worked well, although I discovered I had not properly re-installed PinPoint and the Guide Star Catalog when I set things up, so I fixed that too.

It’s clear that I also have to re-calibrate the mount parameters, time, slew limits, etc., as it made a couple of stupid slewing decisions, and ran into slew limits a couple of times. Since this wasn’t an imaging session I didn’t worry about it, but next time I have a couple of hours I think I’ll use it to do a cold start and carefully re-build the sky model and slew limits for the mount.

Packed it in about 9:30, cold hands, but pleased at the surprise clear evening.

Saturday, February 13, 2010

Journal Page: February 13

I reinstalled the CCD camera and filter wheel today, after having cleaned the camera’s CCD window.

Installed a permanent observatory PC. Specs on this machine:

  • an older Dell computer running XP, so all the drivers should work well;
  • main C: drive replaced with a solid-state drive, so there are no moving parts except the fan. I’m hoping this will mean it can run in cold temperatures with no problems.
  • Wireless link back to the house for access to network-based storage

It took a while to get all the drivers configured, serial ports properly lined up, etc., but everything seems to be working. Now it’s forecast to be cloudy for at least a week, so it will be a while before testing this new setup.

Initial Design for Outdoor PC

My first thoughts on a PC that can work outdoors:

  • I’m hoping the mere fact that it gets cold and then later warms up is not a problem.  Laptops get cold in aircraft holds and survive. Starting while cold will be a challenge.
  • I think moving parts may be a problem when cold.
  • I’m especially concerned about the rotating hard drive.
    • First, a cold component will have tighter fit and may bind, drag, or burn out.
    • Second, I am especially concerned about condensation or frost forming inside the drive mechanism, which I think would almost certainly destroy the drive.

Continue reading

Designing a PC for Outdoor Storage

I hope to keep a PC permanently installed in the observatory to speed setup, and avoid any more incidents where I drop and break my laptop when cold and stupid.

A PC stored in the observatory would be sheltered from rain, but would go through temperature and humidity extremes. I would think there could be trouble from

  • Starting it up when it has been sitting cold in the winter – possibly at temperatures as low as -15 to -20°C.  Moving parts will be tight, lubricants will be viscous, etc.
  • Shutting it down in the cold after it has warmed up. Will the cooling parts become damp with condensation, and what will such moisture do?
  • Performance of LCD monitor in the cold (I know from other appliances that LCD displayes fade in the cold).
  • Infiltration of insects into parts.

I’m going to try to design a PC that can work in these conditions, and will keep a diary of the attempt here.

Flat Frame Illumination Panel for C9.25

I made a flat frame panel for the C9.25 SCT today.

Making the flat-frame light box for the SV80 involved a fair amount of construction, of a box and a set of diffusers for an LED light source. For the C9.25 I took a different approach and it was simple.

I ordered an electroluminescent panel from GlowHut. This is amazing – a thin sheet of flexible plastic that is a dull pink colour on one side and dull gray on the other. When 100V voltage is applied, using the supplied transformer, the pink side lights up a bright flat white.

I just sandwiched this sheet between two pieces of lexan and taped it shut with duct tape, then put some peel-n-stick foam strips on the illuminated side to make spacers that will hold it against the C9.25 tube. It took about 30 minutes to do the whole thing.

I’m hoping I can just point the C9.25 upwards and sit the frame on top for taking flats.

I’m not in a position to test it yet. It looks like it will work very well as a flat light source, but I’m a little worried that it may be too bright and require some kind of further masking to reduce the intensity – we’ll see once the weather allows me to try it out. If it does require further masking, I’ll just put some sheets of vellum over the illuminated side.