PM Sat. July 16 - Satellite Observing

  I've had a few good observing nights in June and so far in July, and made about 20 more variable star estimates. I haven't posted these to the site yet but may soon. 

  Yesterday evening (Saturday July 16) was clear at sunset but by the end of dusk clouds were starting to move in from the northwest. The clouds and the fact that there would be bright moonlight all night (the Moon was rising and 2 nights since Full Moon) made it not worth setting up the telescope, but I decided to get out the 7X35 binoculars, grab a patio chair, and watch for artificial satellites passing overhead. When I'd spot one by eye I'd follow it through the binoculars, jot down the time and position, and look up which satellite I saw online later when I was back inside. There was a flurry of activity between 10:55 PM - 11:10 PM where I saw 5 satellites, and I think I've identified them all this morning. Here's a summary:

  10:55 PM - Cosmos 2228 (#22286) (1992 - 094A) I spotted this one as a 3.0 magnitude steady object as it passed through the constellation Hercules into Draco, nearly overhead and heading north. The websites I researched gave it an orbit of 602 x 635 kilometers, inclination 82.5 degrees, and an orbital period of 97.07 minutes. It was launched December 26, 1992 by the Russians. 

  10:59 PM - Cosmos 1980 Rocket (#19650) (1988-102B) This was also steady in brightness, about 3.5 magnitude or brighter. I saw it pass through the constellation Lyra heading south to north. It has an orbit of 829 x 852 kilometers, inclination of 71.0 degrees, and a period of about 101.7 minutes. This was launched on November 24, 1988 by the Russians. Whenever I look at spent rockets in orbit I try to see if the magnitude brightens and dims to see if the rocket is tumbling in space, but this one either isn't tumbling or I was seeing it at the wrong angle.

  10:59 PM - Iridium 46 (#24905) (1997-043C) This was passing through Lyra at the same time as the Cosmos 1980 Rocket just mentioned, but it was going the opposite direction; from north to south. It was fainter at a steady 5.5 - 6.0 magnitude and faster, which showed it was in a lower orbit than the brighter satellite. It has an orbit of 776 x 779.4 kilometers, inclination of 86.4 degrees, and a period of about 100.4 minutes. It was launched August 21, 1997 by the USA. These satellites have super-reflective panels on them and are known to catch sunlight and flare up in brightness as seen from the ground below, but this one wasn't at the right angle to show a flare.

  11:06 PM - Thor Agena Rocket (#733) (1964-002A). This was bright and steady at about 2.5 - 3.0 magnitude. I saw it passing nearly overhead from Hercules to Draco heading north. It has an orbit of 762 x 812 kilometers, inclination 99.0 degrees, and a period of about 100.6 minutes. This is a super old rocket body from a launch on January 19, 1964, and it's still in orbit! It's a spent Agena rocket launched by the USA. Apparently it either isn't tumbling in orbit or I was seeing it at the wrong angle. After so many years since launch, if it had rotation in the past it probably stabilized a long time ago. 

  11:09 PM - I spotted a flash of light about 3.0 magnitude near Corona Borealis, high in the Northwest. When I trained the binoculars to that spot, I saw a faint object about 6.0 magnitude speeding off to the north, and while I was looking at it there was another brief flash where it brightened again to 3.0 magnitude. It faded again and disappeared into the trees to my north. I spent a lot of time using Calsky.com to try to find out what this one was, and the best match I have is this - USA 3 / Farrah 5 / KH 9-19 Elint (it seems to have at least 3 names) (#15071) (1984-065C). This is an aging US military satellite launched June 26, 1984. The orbit is 619 x 639 kilometers, inclination 95.9 degrees, period of about 97 minutes. I'm pretty sure this is a match and it's obviously tumbling. I'm going to find other pass predictions for this and try to get another look at it to know for sure if this ID is correct. I found out that this is a regular target for the Belgian Working Group of amateurs; known internationally for observing rotating satellites and rockets to determine how the rate of rotation changes over time. This was another reason I was pretty sure my ID was right.

  That was all the observing done tonight. Altocumulus bands moved in overhead and the moonlight was also an issue. It was also getting hazier as the night went on. Indianapolis is part of the newest big heat wave that's supposed to move in for the next week.