Cassiopeia Observatory

ISS-Sun Transit Dry Run; Meteorite Gift

Posted: 28 December 2012

The sky started out clear on Thursday morning, 27 December 2012, so I decided I would take advantage of it and do a "dry run" of the ISS-Sun transit, predicted by CalSky to occur at my location on Monday, 31 December, at 0932 MST. Even though the current weather forecast for Monday is not good:

I wanted to determine the D7000 DSLR HD video exposure settings that I would use to capture the transit. Unfortunately, by the time the sun rose over the hill to the east and was visible from the observatory, clouds had moved in. Late in the afternoon on Thursday there was a brief rain shower, followed by some snow flurries. Shortly after sunset the sky had cleared to partly cloudy. I decided I would go out to the observatory for some Jupiter and Full Moon observing, however, by the time I was ready (changed to warm outdoor clothes), clouds had increased. I went to the observatory anyway only to discover that there was a lot of ice on the dome (temperature 32°F). Since the ice would have needed to be cleared off (in the dark) before opening the dome, and since the cloud cover seemed to be increasing, I returned to the (warm) house. No observing.

Friday, 28 December, dawned clear (and cold). This image from my Live Webcam shows the view towards to the observatory with the "Belt of Venus" visible above the Earth's shadow in the western sky before sunrise:

I opened the observatory at 0858 MST, 45°F, to do HD video test recordings of the sun at prime focus of the 8" LX200-ACF using the D7000 DSLR. Before opening the dome, I had to clear off ice:

I also had to rotate the dome to get the portion that was in shadow into the sunlight to melt some of the ice. While the ice was melting, I prepared the D7000 DSLR for imaging. Once the dome was clear of ice and water, it was opened at 0913 MST. I synced the observatory clock to WWV. I then attached the Orion full-aperture solar filter to the Meade 8" LX200-ACF. I then did a GOTO the sun (using the "Sun as Asteroid" technique). The camera was then attached at prime focus + visual back and focused using a small sunspot.

At 0930 MST, I began a series of HD video test recordings, about 10 seconds each, at 1/2000sec using various ISO settings. This is a frame from the ISO 1600 video, which is what I will use for the ISS-Sun transit:

East is at the top and south on the left. Some sunspots are visible near the eastern limb.

I also did a series of HD video recordings at prime focus + 2X Barlow Lens but I won't use that since I won't be able to get full coverage of the ISS transit. This is a frame from a 1/1250sec, ISO 3200, HD video recording:

I also did some still imaging of the two sunspots at prime focus + 2X Barlow Lens, 1/400sec, ISO 2000:

I completed imaging tests at 0942 MST and did some brief solar viewing. First tried 154X but the seeing was not good enough. I also tried the 2" 9mm 100° eyepiece (222X) but as expected, the view was not very good due to the poor seeing. The best view was at 77X.

So, I'm ready for the ISS-Sun transit. Unfortunately, Monday's forecast is getting worse; now partly cloudy with "scattered showers" during the morning.

Since I had some short video recordings of the sun, I decided to stack them using Keith's Image Stacker and see how well the resulting images compared to the above images. The upper image below is a stack of 231 frames from the prime focus, 1/2000sec, ISO 1600, video. The bottom image is a stack of 243 frames from the prime focus + 2X Barlow Lens, 1/1250sec, ISO 3200, video.

In November 2012, I purchased an Explore Scientific 2" 9mm 100° eyepiece from OPT. I registered the eyepiece on the Explore Scientific web site. The day after Christmas I received a gift from Explore Scientific for registering the eyepiece. It was a meteorite:

It might be small (about 1/2" long) but it is definitely an appropriate gift. Thanks Explore Scientific!

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