Wednesday, December 30, 2015

Just One More, And Then Another...

Tonight's title comes from a song.  Our movie buddy Larry makes a mix tape every holiday and we were lucky enough to get one last year. One country-tinged song, called "Just One More" by Tim O'Brien and Darrell Scott has the words: One more drink of wine/ And if you're still on my mind/ One drink, just one more, and then another". So it goes for my sunset sojourns - a week ago I said I was done with them for the season, but the more I thought of it, the more I wanted to go up again and chase the alignment further down the hill. Perhaps I should have done what the song suggests - stay home and drink, but after a two day trip to Mexico for Christmas, I again headed up the Mount Lemmon Highway in search of celestial alignments.

Using the Heavens-Above website to calculate the Sun's declination, it was obvious I would miss the alignment at my usual setup point (from my experience the week before), so it was time to bias my position to realign the sun and Observatory profile. TAAA member Jim O'Connor stayed on the turn, biased as far south as he could set up, and I went south a bit and up a hill a couple hundred yards to "Thimble Peak Vista". There, among the hordes of folks going down the road after playing in the snow atop the mountain, I set up the scope for imaging the sunset. Note from the left image that observing any further south isn't allowed as the side of the hill about 1km away would block the view... So this night was perhaps the REAL last chance for an alignment.

With the sun barely in the field of the telescope, I quickly checked focus and exposure, then started the sequence using an intervalometer, taking frames every 2 seconds. Once started, there was really nothing for me to do other than watch, so took a couple frames with Melinda's camera and 300mm lens (without filter) at left. I knew the sun would be overexposed, but wanted to catch the other mountains that aren't visible through the solar filter. This shot is F/10 and 1/2500 second. It turns out that the alignment was perfect! Shown at right is about the most-centered frame. All together, 142 frames were included in the sequence from start to finish, so I went through them all, cropped each down to the center 60% of the frame and fine-tuned levels slightly. No color or sharpening was done, otherwise straight shots through the Baader solar filter, TEC 140 scope and 1/80th second exposures at ISO 200.

Putting all the frames together, I made another GIF, but the artifacts similar to the last version bothered me, so I uploaded it to Youtube after making a clip in Moviemaker.  In this video I also added a couple frames where I ID the profile of the main scopes at Kitt Peak.  Here it is with 2 loops through the frames - full screen and HD if you can:

Unfortunately, while I had a perfect set of data, Jim O'Connor had some software issues and didn't catch an alignment on the usual curve.  Looking at some frames that his wife Susan took, I'm thinking they could have caught it there too.

And of course, in the theme of "Just one more, and then another", I decided that perfect wasn't good enough! I felt bad about chickening out about trying 1 frame/second for the intervalometer, so wanted to push that, and also wondered if I could catch one more alignment from the Thimble Peak Vista. The quick answers are yes and no.  Yes, if I didn't overload the camera by trying to write raw files, it seemed to write jpegs just fine at 1/second. But unfortunately, while the data streamed in quickly at 1/second for over 4 minutes, the alignment couldn't be seen a full week after Solstice. Examining the image at left, you can see the sun is north enough that it doesn't ever cover all the scopes at once, though it does over a period of several seconds. So in my book, the alignment season's limits are +/- 1 week. I'll likely write up a compendium of all this information for future alignment chasers - so look for that if you are interested...

1 comment:

Anonymous said...

forget the crossed fingers! Praise God for continued success battling that cancer. amen