Breaking news! Variable star U Geminorum in outburst!


A few weeks ago, I saw an online article about U Gem being due for a flareup. It's kind of a weird variable star, because it has a lot of uncertainty. It could flare up any day, or it might take another 3 months. Who knows? I figured I'd take some reference pictures so that I'd be prepared.

Of course, like other long-period variables, I tend to forget about them! I took images of U Gem on March 27th, 29th, and 30th, and then lost interest. I told myself that I would try and remember to come back and follow up later. I even put a Post-It note on my computer monitor to remind me, but somehow, I ignored it.

Tonight, I finally remembered. Oh, yeah.... I should check in and see what ol' U Gem is doing! And wow! Was I in for a surprise! It was several magnitudes brighter than the last time I shot it!

I hope I'm not in trouble for using the copyrighted AAVSO chart. I thought it would be cool to show a direct comparison of their finder chart with the two images of my animated GIF. The numbers beside the stars are magnitudes to use for a reference. Traditionally, they don't use decimals, so that the decimal points won't be confused with stars in the chart. So, for instance, "139" and "143" are meant to show stars of 13.9 and 14.3 magnitude, respectively. When U Gem was at minimum brightness in the March 31st (Universal Time) image, you can compare its brightness to 13th and 14th magnitude stars. And for tonight's image when it's in outburst, you can compare it to 9th and 10th magnitude stars. 

I don't consider myself to be very good at judging magnitudes, but for what it's worth, in my opinion, the minimum brightness that I captured was about 14th magnitude, while tonight's outburst appears to be around 10th magnitude. Maybe a tad brighter. I think it definitely looks dimmer than the 8.6-mag star, and it looks brighter than the 10.7-mag star. Not sure about the 9.3-mg. star, but I would say it's dimmer than mag. 9.3. What do you think?

In my previous post, I talked about the "time filter" and U Gem is a perfect example of an astronomical object that needs to be shot using that filter! When U Gem is at minimum brightness for many weeks, you could shoot it with special color filters and take 50-hour exposures of it to impress your friends. But if you don't happen to come back around and shoot U Gem at maximum brightness and blink the two images, you'll miss the whole point!

April 15 update:

U Geminorum's outburst was holding steady last night when I took another look at it. See below.



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