PM Sun. February 26 - AM Mon. February 27, 2012 - Observing Notes

This was just the 2nd night out in 2012 with the 10" f/4. This was also an opportunity to observe two fast-changing stars at one time. I'd made some estimates of the RRab type star RR Leonis the first time I'd been out with the scope on January 28th, but tonight I could take a second "crack" at it. The AAVSO Website link had a prediction that this star would peak in brightness around 10:20 PM EST (3:20 UT Feb. 27). Along with this, an Eclipsing Binary Star I'd never observed before, sitting just about 7 degrees away from the first variable, was predicted to be at mid-eclipse around 11:30 PM EST (4:30 UT Feb. 27).


  It was an extremely clear and cool night. At dusk, I went outside to catch a glimpse of the Chinese Space Station Tiangong-1. It had been predicted to pass almost overhead from my location at about 7:21 PM, just as skies were getting dark enough to see a lot of stars. Adrian went out to look for it with me. We saw a satellite pass from west to east and thought this must be Tiangong-1. It seemed to be on the same path as the Station was supposed to be moving along. However, this satellite was only about 2.0 magnitude or dimmer and it was going through the sky about a minute or less before the Station was supposed to appear. Then, before the first satellite vanished into the Earth's shadow, we spotted a brighter object moving along the predicted path, about 1.0 magnitude in brightness (about as bright as the brightest stars we could see but much dimmer than the star Capella nearby). This second object had to be Tiangong-1, but it left us wondering what the first object had been. I'll try to research it soon. 

  I should also write that the Moon was a nice, bright Waxing Crescent high in the western sky at dusk through the start of the night. It was paired with blazing Jupiter, while an even more blazing Venus sat lower in the sky below them. These three solar system objects were a really pretty sight!


  I had the 10" f/4 outside and started observing just before 9:00 PM. I ended the session just after 1:00 AM. During that time I was usually moving the telescope back and forth between the two variable stars in Leo, RR Leonis and Y Leonis, and writing down my magnitude estimates and times for them. I took several breaks because even though this wasn't a super-cold night, it wasn't mild either! The temperature went from about 43F to 39F during that time but the wind chills were near the freezing point. There was a noticeable breeze the whole time I was out there. My fingers felt numb and painful so I kept going back inside to warm them up. 


  To make a long entry shorter, I ended up making 13 estimates for Y Leonis and 14 for RR Leonis during these hours outside. Y Leonis faded to the point where I could barely see it even through the 10" scope, but I was also able to catch it getting brighter again. I figure mid-eclipse must have happened around 11:18 PM (4:18 UT February 27) but this could be off by several minutes. RR Leonis was about an hour behind the predictions, just as it had been during the time I observed it at the end of January. It slowly brightened between 9:00 PM to 11:00 PM, but then it really took off and climbed in brightness between 11:00 and 11:30 PM. I reported these estimates and times to the AAVSO.


  I also had my first glimpse of the area of T Bootis before ending tonight, and estimated it to be less than 12.5 magnitude. I had to settle, as always, for a negative estimate for this star, because it wasn't visible (no one has seen it since Baxendell in 1860!). I also made a negative estimate for the nearby cataclysmic variable UZ Bootis. This star last flared up, I believe, in 2002.

  I've added the light curves observed tonight for both RR Leonis and Y Leonis, generated using the AAVSO Light Curve Generator. Y Leonis is a type EA/SD + DSCT star which dims out once every 1.686102 days (1 day 16 hours 27 minutes 59.2 seconds) as a much dimmer star, in orbit around a brighter one, crosses in front of it along our line of sight. RR Leonis brightens and dims with a fast period once every 0.4523999 days (10 hours 51 minutes 27.3 seconds) as it expands and contracts.