Friday, August 27, 2010

missed both ISS passes (Blue Mountains)

Sorta missed.

I mean, they happened, we saw (and enjoyed) them. But I couldn't get the Paramount to precisely track them...


4:00 PM. When I arrived at the RASC Toronto Centre Carr Astronomical Observatory, while I was here sort of "on business," I was thinking about the ISS...

Now that the ISS had phased, once again, into evenings for Ontario, I wanted to see if I could image the International Space Station with the MallinCam. Or perhaps record a little movie!

I began to set up the telescope and camera. The immediate plan was to choose a bright target to establish alignment and focus.

Entered data from Heavens Above for the CAO location into my palmtop calendar. Set alarms.

Used my Sony voice recorder to capture my log notes.

5:15. I had been in the Geoff Brown Observatory for an hour or so, using the Paramount ME with TheSky6 software.

Just recorded a little movie to test the AVerMediaTV hardware and software. Worked good.

I looked at Venus with the Celestron 14" SCT with the Tele Vue 27mm eyepiece (yielding 144 power). Venus was a big disk! Huge in this 'scope. Quarter phase. Very nice. Pretty well centred.

I had hooked up the MallinCam Hyper Color with the black photo extension tube. I found it pretty well aligned. Venus was a small shape on the monitor though. Bit of a let down compared to the eyepiece view though. Ironically, I thought I'd turn the camera's zoom feature on but found it already set. Ha! At least that meant the alignment was very good.

Focus remains a challenge. I recorded the amount of the focuser tube exposed using a piece of paper, to measure later (2-1/8"). Tony had previously estimated the shaft position (1-3/8") but that was when we were still using the mirror diagonal. I will need to update my MallinCam notes...

5:25. Used my personal Celestron Ultima 2x doubler with the MallinCam. It worked! This was good news. It means that we can functionally double the image size of small objects. It still doesn't explain why the Centre's PowerMate 4x doesn't work.

7:18. I took my doubler out of the MallinCam setup as I wanted to have as wide a field as possible, for my ISS tracking/imaging test. That said, I did turn the zoom on.

Did a quick test. Told TheSky6 to go to a different object. Then I slewed back to Venus. It appeared in the MallinCam view. Yeh. Alignment of the TV101 was good!

OK. It was a good time to be hands-off. No more screwing around with the configuration... I had good focus, good camera settings, good alignment, cabling good, ready to image or record, ready to view optically.

8:35. I readied myself for ISS pass. I had TheSky6 programmed with the satellite ISS Zarya.

This flyover was to go overhead. I wondered how the Paramount would do with respect to crossing the meridian off to the north... That is, would it act any differently than a southern sky flyover?

My palmtop alarm went off. It was about 15 minutes to go for the flyover.

Tim came out to the observatory with his binoculars. As we waited for the ISS, we looked at the planets in the west. I read off the magnitudes from TheSky6: Mars 1.5, Saturn 1.0, Venus -4.4. Checked the positions: Mars was up and to the right of Venus; Saturn was almost the same elevation as Venus but much further to the right.

8:40. I said, "This is so exciting. It better work!" I was clearly anxious about the ISS pass.

8:42. I spotted Mars naked eye. It was about 4° away from Venus. A little later, with Tim's help, I spotted Saturn, without optical aid. It was tough to see though, fading in and out, with distant cloud. Or thick air.

8:45. Showed Tim the plot of the ISS in TheSky6 software.

Tim has a funny sense of humour...

8:48. I yawned. Lack of sleep. I must nap.

8:49. After a couple of attempts, I started the satellite tracking feature in TheSky6. Told Tim it would become visible 10° up in the south-west.

8:50. Atop the little white stepladder, peering over the west wall, I spotted the ISS visually, going straight up. The 'scopes couldn't see it though, based on the elevation and azimuth, with the south wall door flaps up.

8:51. At this time, I thought the MallinCam rig should be able to clearly see the ISS. But there was nothing on the monitor. There was also nothing in the eyepiece. Too much power? I checked the computer settings. It showed it had it. The mount was clearly making a good path.

I asked Tim if he wanted to take a look through the eyepiece, as I checked the computer. He too did not see the station; he did observe stars whizzing past. I wondered if I had the wrong data.

8:54. The 'mount shut off, having reached the meridian. I was disappointed.

I asked Tim if he could see any detail in his "bins." He replied negatively.

8:57. Visually watched the ISS fade out in the north-east. That was a long pass, horizon to horizon!

9:00. Rebooted the Paramount ME and TheSky6 as they were not operating correctly after driving fast into the meridian no-fly zone.

I wondered out loud how to verify the orbital element data was correct...


10:38. The second ISS pass was a flop too.

Both times the mount was tracking well, starting in the proper area, following the correct general path through the sky through to the end. But off. Off by a degree or so. I wondered again if it was bad or old TLE data. If the space station orbit was boosted during the day, then the TLE data would probably be incorrect, off a little.

It's always going to be an issue.

Made a mental note to read about adjusting the mount's alignment, on the fly...


Weird. My attempts on Jul 9 and Jul 10 were successful. Very successful. Why was it not working now?

Was I lucky?

Is the norm to be off a little?

Thank goodness there was not a huge crowd tonight! That would have been a big let down...


I noticed some distance numbers in Heavens Above, on the detailed pass page, with the overhead map. Never noticed these values before. It was very interesting to note that the ISS was about 2000 kilometres away when it would first become visible. At zenith, a mere 350.

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