Monday, March 19, 2012

measured Castor (Toronto)

Thought of Manuel. He talked about imaging from his deck. And the RASC Toronto Centre peeps heading to Long Sault, following piper Stu. Hoped everyone would find good skies. The Clear Sky Alarm Clock email had said good seeing but bad transparency. So a potential excellent night for planets and double stars...

Via the Yahoo!Group I reminded people to contribute to the Globe At Night project.

Even though I did not have an early morning commitment, I was kind of on the fence about doing anything. Trying to image was on my mind, given that I didn't fire up the SKYnyx last week... In particular, I was thinking about imaging some double stars. Refining procedures for measuring them, once again, with BinStar.

I looked in SkyTools 3 Pro at my "rapid movers" list. Checked what was visible given the date and my location... Wow. There were about a dozen double stars suggested! Lots of options. Ah. But how would they appear in the camera's field of view. When I had checked last week, if I remember correctly for Alula Australis, the stars were merged. No point.

So I reviewed some of the wide ones... Ah. Stuff in Boötes, over 100" about. Oh ho. And Gemini! Castor. How about that... I knew Castor was a double (er, multiple) star system but I didn't know it was a fast mover. ST3P said the orbital period for AB was about 500 years. OK. Not in my life time. But then slow enough that I should be able to verify methods. About 4" apart.

Launched the Interactive Atlas, selected the current date and time, set the location. Clicked the Context Viewer button and set the Celestron telescope and chose the Lumenera camera. Looked in the camera menu again and noticed that the doubler was not available. So I jumped back to the list window and added 2x magnification in the telescope-camera profile. OK. And would you look at that! Nicely split stars. This would work!

Considered a reference double in the area, an optical pair, so that I could calibrate or compare. I found HD 59848 with a 6" sep. No apparent orbit. Not too far away... Good.

All of a sudden, my heart was in it. I was ready to do some astronomical imaging. OK. Let's do this! I setup rapidly.

8:36 PM. Aligned on Polaris. Viewed Jupiter quickly in the baader 36mm. The planet was flanked by two moons each side. Hints of cloud bands.

9:05. The 'scope seemed to be drifting. Even though I thought I had a pretty good polar alignment. I tried again. I went to a different part of the sky and chose ζ (zeta) UMa.

I considered that if I wanted to image double star drifts, and I wanted better results than the last time, well... I should do a very good polar align. Prepared my drift alignment tips in Evernote.

Put the red film on the iPod.

9:20. I confirmed that the polar alignment was OK. I think it was just a controller gremlin and not tracking before. Was the battery low? I checked the level meter (by street light). It seemed fine.

Put the Meade calibrated eyepiece in with the Celestron 2x Barlow. The seeing went rock steady. At times... But then went away... Ooh. Yuk.

Got out the SKYnyx monochrome camera and cable. Grabbed the last piece of red film for the laptop LCD. Fetched the laptop and supply.

10:02. Took the Meade out (and forgot to turn off the red LED right away).

Did some tests and checks.

Put the camera on Mizar, with the doubler still installed. Couldn't focus. Removed the doubler. Found Mizar. Focused and centred. Put the doubler back in. Focused. Set the Orion finder scope accurately. Went to Castor. Started LuCam Capture and turned on the Preview. Centred and focused (with the focus mask). Shut down LuCam; started AmCap. Did a quick little recording to test. Was a little confused for a moment on naming files.

Thought it better to focus on a single star. So hunted for a bright one. Focused with the Bahtinov mask. Refined the finder scope aligned. Let the laptop restart--after it protested many times. I was ready now to go to my test subject star.

Just as Castor went behind a thick tree branch...

10:57. Completed the Castor capture.

frame rate 60 fps
exposure 10ms
gain 8.840
2x doubler

I had a fairly good polar alignment. The star would stay in the same general area of the FOV (at this high power) for quite some time. But the seeing was not so great. The prediction had been wrong...

Earlier, I had put the Oregon Scientific portable weather station out to get a reading. The air had felt damp to me. And I thought I was seeing haze or moisture about the street lamps. Fog? When I went to check the OS unit, I found the screen blank. When I tapped it, it rebooted! Damn. The values that immediately appeared were 77% for humidity and 11.5°C for temperature. I wondered if those values were accurate. Certainly I had been holding the unit for a moment...

11:00. Finished recording 3 or 4 movies.

Checked the OS again: 74% and 11.4°C.

11:19. Packed up. Put the laptop in the office. Ready to reduce some data.

Put the silver weather station on the desk. Noticed it showing the low battery icon. Looks like a trip to The Source is due...

11:25. Reviewed the movies on the laptop. Movies 3, 4, and 5 are drifts of Castor. Incredible vibration in them. 3 and 5 are quite bad. Despite during 4 and 5 standing well back from the tripod... I wonder where this was coming from... At the time, I thought it was me. Was it the power supply fan perhaps?! I had it sitting under the tripod. Maybe the motor was sending vibration into one of the planks on the deck.

I was not real happy with the session. I had been unsuccessful at finding the token sample star to measure against. The mount seemed to have a tracking problem. Was the motor struggling against the weight. Did I have poor balance? The OS station died. The whole reason for putting it out side was to get current local conditions. Who knows if the readings were right. I was also a little disappointed that I was not better prepared. I had not researched suggestions for exposure, fps, gamma, gain, etc. So I wasted telescope time fiddling. And the final video quality I thought poor, particularly the vibration.

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