2006-07-13

Just as with yesterday, no marks of any sort were visible on the Sun.

While setting up the 905 to look at Jupiter I noticed a very bright satellite in the same general part of the sky. It was "above" Jupiter and was heading south to north in the western part of the sky. When I first saw it I would have said it was at least as bright as Jupiter but as it headed further north it faded rapidly.

Sadly, as normally happens with these chance observations, I wasn't really in a position to make careful notes of exact location and path.

At the time I suspected that it might be an Iridium flare but, after checking later on Heavens Above, it would appear that there was no predicted flare around that time. I'm left wondering what it was.

Update 2006-07-17: According to stella, a poster on the SPA's BB, what I saw was "classified surveillance satellite, USA 186, 05-42A".

With the 905 and the 6mm eyepiece all four main moons were visible with Ganymede on its own on one side of the planet and Io, Callisto and Europa grouped in a nice, neat triangle on the other side. TYC5575-473-1 was still close by but its position in relation to Jupiter was obviously different from last night.

The image was pretty good from the start. The main northern band stood out very well and had very visible signs of mottling. Interestingly the main southern band didn't stand out anywhere near as much and, at times, it almost appeared to be lighter than the surrounding surface. I've never noticed or seen this before — they've always appeared to be about the same shade to me in the past.

Around 21:47 UT the image started to boil a little and some of the detail was lost. Out of curiosity I decided to try the ND25 filter. I don't know if it was just my mind or my eyes playing tricks on me but, with the reduced brightness, I was sure I could see a hint of brown in the colour of the planet — almost like you see in many pictures of Jupiter.

By 21:57 UT the image was getting really bad so I decided to take a short break and possibly come back to look at something else.

A couple of weeks back, while at the RAF Waddington airshow, I picked up a cheap and unnamed 7x50 binocular. I mostly got them so I could throw them in the car and take them anywhere (and, at the time, mostly because I forgot to take a binocular to the show). Given that the skies were still too light to get any "serious" observing done I decided to try them out at night.

They turned out to be less than brilliant for astronomical work in that, towards the edge of the field, stars would appear slightly out of focus. Towards the middle of the field everything seemed fine. That said, because they're quite small and light they did feel very comfortable for just lying back and sweeping the sky.

I noticed another bright satellite, this time in the western sky, not far "below" The Plough. I saw it brighten a bit and then fade. I wasn't paying a whole lot of attention but I would estimate that it got at least as bright as Alioth.

Checking later on Heavens Above I suspect that it might have been Iridium 81 as that was predicted to flare around 22:18 UT. I'm a little concerned that the times are so far apart (at worst I probably noted the time down as being a couple of minutes late) but the other details given for the flare seem to match.

Update 2006-07-17: According to stella, a poster on the SPA's BB, this wasn't Iridium 81 but was, instead, "Terra, 99-68A".

Sky was still quite light and I really need to be getting off to bed so decided to call it a night.