Monday, March 28, 2011

video astronomy night (Toronto)

I wanted to make a video record of an occultation (even though I was not in the shadow). And I wanted to try a long exposure of a deep sky object with the StellaCam3.
Intrument: Celestron 8-inch SCT
Mount: Vixen Super Polaris
Method: star hopping
4:29 PM, 27 Mar 2011. The telescope, mount, and tripod were outside. It put the 'scope down on the deck floor, out of the Sun, to cool. I put the tripod a little bit closer to house to afford a bit more room around the south end of the porch. Remembered, for a change, to put a portable weather station outside. Put the poles for the light blind outside. I had an observing list ready. I had other accessories ready.

7:31 PM. I finally figured out StellaCam integration settings! Damn! At long last. I learned that each frame represents 1/30th of a second. I had thought it 1/60th. That explained a lot. It confirmed that the integration setting 9, of 256 frames, was 8.5 seconds. It meant that settings 1 through 3 were about 1/30th, 1/15th, and 1/7th of a second. Fine enough, fast enough, for many occultations. It was all suddenly clear now. What a relief.

8:19. I now had the OTA and mount on the tripod. I had the power cord through the window.

8:25. It was cold. Environment Canada said it was -4.3°C but it felt way colder than that.

I had the mount motor running. The dew heaters were running (including the coffee cup heater on the finder scope). The SCT adapter was reinstalled to the visual back. The WO 2" mirror was installed.

8:36. I finished aligning on the NCP. Polaris just at edge of roof, from the new tripod position. I left the 'scope on Sirius to gauge the tracking. Did some periodic checks over the next 20 minutes and the alignment seemed OK. Not perfect but OK for a video record. I know I'd need a better alignment for long exposures. I could do drift alignment analyses.

9:00. I began the long star hop. I paused at δ1 (delta) CMi. There were a lot of tree branches in the way. I put up the light shield, a bit higher this time. It was great!

9:18. Continuing the star hop, I landed on star HD 57902. There was a big branch in the way now. I'd have to wait a bit for the star to clear. I could start setting up occultation gear. Well, except for the camera.

9:24. I had the rig outside. The GPS sensor was ready. I had the StellaCam3 installed in Vixen flip mirror, at the proper depth (to be parfocal) and set it aside. Still had the Williams Optics mirror attached to the SCT. I checked the time. It was less than 1 hour to go.

9:37. I continued the star hop. I knew that I was less than a degree from the target. But I found the tree in the way again.

9:49. At last, I found and centred on the target star. I bumped to the 26mm eyepiece. I was ready to put the flip mirror in. I powered the rig. Oops. Knew I'd forget something. I connected control pad (on the fly)! I centred on the star and flipped the mirror. I had it! Went inside to get the camcorder. Started recording.

10:09. Everything was ready. I double-checked everything. Just when the tape ran out! Ha ha. I had actually briefly wondered where I was on the tape. Now I knew. Considered for a moment drumming up another tape but I wasn't exactly sure where I had put them. So, I rewound to beginning and resumed recording.

The drift error was fairly pronounced so I rotated the flip mirror about 90 deg to take advantage of field width.

I noted this time that I get the microphone feedback when camcorder display open. It immediately stopped when I closed the little LCD.

Double-checked everything once again. And same, for the second time, I had a GPS error. I simply reinitialised the Kiwi and it started up fine.

This is it...

I didn't see anything blink out at 22:16:16. I recorded for another 2 minutes.

10:21. While I monitored the star on the Oslon LCD, I did not see it blink out. So I unofficially called it an observed miss. As I expected.

I would still have to examine the video record of course...

I was a little perturbed by the polar alignment being off. I wanted to check it via ST3 again. I tried redoing it but I saw, on the screen, I was still drifting. It was actually very interesting having a live video feed. With the 8 second integration, I dialled out the drift.

I removed power from the Kiwi to clean up the display.

I star hopped, classic style, to M81 and M82 using the Pocket Sky Atlas. I was confused for a moment until I remembered that the new finder scope didn't rotate the field of view.

12:23 AM, 28 Mar 2011. I just finished imaging M82, with the gain at 50%. I did manual exposures at 15, 20, 30, and 60 sec. I was pleased that there was very little trailing.

12:41 AM. Tried a 90 second shot but there was lots of trailing.

I inspected the Oregon Scientific weather station: -5.7°C, 43% humidity, the pressure was rising.

I did a rapid tear down. I tried pressing LED on CCD camera to turn off the cooling but it didn't move.

1:07. I was very very curious. I transferred a still image over from the camcorder and played with it briefly in Fireworks. Got lots o' learnin' to do...

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