The Lumen Occultation - Dec 28, 2013

....Where everything went wrong, wrong, wrong. It started with the night before. A birthday party for buddy Jim at Dave and Diane's. Lots of beer was sampled. Beers with names like "Arrogant Bastard", and everything in between chocolate beers and beers so high octane and hoppy they make your eyes water. Before that, I'd finished up my swim yardage goal for '13 with a couple thousand yards in the pool, and a leg workout. So, I was tired. Got home, did some more work reducing the Honoria occultation of last week, then packed my stuff and headed to the observatory at midnight. And realized as I arrived that I'd forgotten my down sleeping bag. Doh! Had to settle for the thin Aussie summer bag. So I didn't get to sleep till 1am, and when the 4am alarm went off, I was not in top form. First mistake, taking the time to open up and set up the 12" dome scope for doing a star trail image of the occultation. The stars were not focused so it took an extra 12 minutes to do digital focusing. I should have set that up before going to sleep, and letting it just track for the remaining 3 hours. So I had only a half hour by the time that was done, to set up the 10" and get on-target with the video camera. I still had mounted on it the Owl 0.5x reducer and decided to leave it this way. Leaving, too, the scope at it's prior focus which was in-focus for the Owl. The target didn't seem to me to be that hard to find, and at 10.1 magnitude and with a similar star right next to it, it should be straightforward. Well, it wasn't. There are two similar "double stars" in the general area; Xi Cancri and it's companion, and another about a half degree away. I found one in my videocamera, but couldn't tell which one it was. Next, the scope clearly wasn't targeting very well. Often I can get an object in a 22mm eyepiece with the 'go to' feature after a 2-star alignment. I aligned on Capella and Spica; opposites on the sky and that's good. But it still didn't point to M44 very well. Just too much slop in the gears after all the years of wear/tear. I gave up trying to target with just the video (Derek's always telling me how easy it is to do on his 12" scope w/ f/6 and Owl and 1/2" chip). I pulled out the video and put on the 22mm Nagler and tried to figure out where it was pointing, but time was just too short. It was now 5:13am and just 5 min to go. I gave up and went with "Plan B", which was to take a 1-min star trail. I ran in to the main observatory building, positioned the target star at the bottom of the frame as I'd done the prior successful star trail shot, waited, and then clicked off "track" and started "grab". But CCDOPS 5 came up with a message about it being in binned mode and color info would be lost and did I really want to take this exposure? YES!, but I'd already lost the precise moment of starting the exposure; I was about 1.5 seconds late. I waited the full 60 seconds of the grab shot and when it downloaded and presented, it didn't look anything like I'd expected. Turns out since the star was in the WEST, the meridian flip meant I needed to have positioned the target star at the TOP of the frame, not the bottom, as the prior Eastern sky events had required! If I'd had more time to practice even a bit, or not been so bleary-brained, I'd have at least verified that toggling on/off the tracking would show me how the star trailed. Instead I went from memory and not reason. Always a mistake, as I'm fond of telling my students. So, I got nothing. No timing, no visual, no nothing on the brightest "sure thing" asteroid event of 2013. Grrr!

Adding to the frustration - it seems this may be a newly discovered double-asteroid, given Tony George's observations in Arizona.

What did I learn?
1. Position the 12" scope on target BEFORE going to sleep
2. Verify which direction the star trails by clicking on/off tracking after doing any necessary meridian flip
3. Write that computer program which will allow you to make a properly flipped, oriented star chart with a rectangle showing your FOV
4. Set up the TV again, for targeting. With switch to power off so it doesn't drain off any video signal during recording.

This is a 5 second grab taken about 20 minutes after the event. Lumen is the

A close up of the previous slide, showing the bright target star right next to fainter Lumen


Post Mortem

It looks like the star trail idea was doomed anyway; the target star turned out to be binary and so the depth of the events was much less than expected. Given the look of the Washingtonia event's star trail, it was probably not going to be visible. The video was the answer. I will make sure this sort of thing doesn't happen in the future. Grrr.