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All observing logs tagged with Iridium Flare


Location: Billingborough (South Lincolnshire, UK)
From: 2006-07-13 13:00 UT
To: 2006-07-13 13:05 UT
Equipment: Solarscope
Temperature: 24.6°C ...
Dew Point: 7.6°C ...
Humidity: 34% ...
Wind Speed: 0.4mph ...
Wind Dir: North West ...
Pressure: 1025.3hPa ...

Another very clear and warm day. Not a single cloud in the sky. Took the Solarscope out to do a sunspot count.


From: 2006-07-13 13:00 UT
To: 2006-07-13 13:05 UT

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

Location: Billingborough (South Lincolnshire, UK)
From: 2006-07-13 21:25 UT
To: 2006-07-13 22:30 UT
Equipment: Antares 905
7x50 Binoculars
Temperature: 15.4°C ...
Dew Point: 7.7°C ...
Humidity: 60% ...
Wind Speed: 0.8mph ...
Wind Dir: North North East ...
Pressure: 1029.2hPa ...

Nice clear night, less haze than last night. Very slight breeze now and again. Also felt cooler than last night. Decided to get the 905 out to have another look at Jupiter.

Bright satellite

Time: 2006-07-13 21:26 UT

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".


From: 2006-07-13 21:30 UT
To: 2006-07-13 21:57 UT

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.

Test of 7x50 binocular

From: 2006-07-13 22:10 UT
To: 2006-07-13 22:25 UT

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.

Another bright satellite

Time: 2006-07-13 22:27 UT

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".

End of session

Time: 2006-07-13 22:30 UT

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


Location: Billingborough (South Lincolnshire, UK)
From: 2005-08-15 20:24 UT
To: 2005-08-15 22:55 UT
Equipment: Naked Eye
Sky-Watcher Explorer 130M

The main reason for venturing out was to give the 130M a proper "run under the stars" after center spotting the primary mirror on 2005-08-13. Also, before heading out, I use a laser collimator to try and improve the collimation. I didn't plan on doing any star-tests tonight — I just wanted to see how well I got on with the 'scope having actually had the mirror out of it.

Moon was a waxing gibbous quite low in the sky (not visible from my position). There was some thin haze in parts of the sky but no noticeable clouds. Temperature was cool but still warm enough to be out in a t-shirt.

When I started out the sky was still somewhat light.

General testing

From: 2005-08-15 20:24 UT
To: 2005-08-15 21:05 UT

Started out by pointing the 'scope at Mizar. With the 25mm eyepiece there was some obvious "flaring" of the brighter stars in the field. I could also see, from time to time, a faint "rainbow" effect in the flare. At this point I had trouble recalling exactly how bright stars used to look in the 'scope. I've always seen some flaring but — never having really made a point of noting exactly how it appeared — I didn't really have anything to compare. Lesson for the future: make notes about the really obvious things such as how stars look before you do some work on your 'scope.

With the 15mm eyepiece the flare (which, at times, looked like a very tight double image of each bright star) had a noticeable difference in appearance either side of best focus. When unfocused either side there was the impression of an oval effect to the unfocused stars. Either side of focus the orientation of the oval would rotate 90°. As I understand it this is evidence of astigmatism in the primary or secondary mirror! I don't think I've ever noticed this before (not that I've ever really gone looking for it before).

I tried a few things to see if the oval effect would differ: I changed eyes (no difference), changed my orientation at the eyepiece (no difference) and rotated the eyepiece in the focuser (no difference).

I then tested with the 10mm and then 6mm eyepieces and, as best as I could tell, the oval effect wasn't noticeable. Most confusing.

The more I thought about it the more I felt that what I was seeing actually wasn't any worse than the 'scope used to be. Also, there's the fact that I don't generally know what a bright star should look like through a smallish Newtonian Reflector.

I wished that I'd had Jupiter or Saturn around still so that I could compare how things looked with a more "substantial" target.


Time: 2005-08-15 21:01 UT

Saw a reasonably bright meteor pass roughly North to South through Lyra.

Probable Iridium Flare

Time: 2005-08-15 21:10 UT

Saw a very bright Iridium Flare in Ursa Major — just below the "handle" of "The Plough". I got the impression that it was one of the brightest flares I've ever seen. It was a lot brighter than any of the stars in Ursa Major.


From: 2005-08-15 21:25 UT
To: 2005-08-15 21:45 UT

After the slight annoyance and frustration early on in the session I decided to try the 'scope out on a DSO and opted for an easy target: M13. Initial impression with the 25mm eyepiece was that it looked magnificent! While it looked like a cometary-like "blob" (as I'd noted in a previous observing session) there was, this time, the occasional faint hint that it was comprised of lots of stars. It wasn't so much that I could see stars, it was more a case of it looking slightly "grainy" from time to time.

Made a sketch via the 25mm eyepiece:

Sketch of M13

Possible "late" Perseid

Time: 2005-08-15 21:49 UT

Saw a faint meteor pass through Andromeda. Was very quick (less than a second I'd have said) and, given the direction of travel, it looked like it might have been a "late" Perseid.

Satellite between Cygnus and Lyra

Time: 2005-08-15 21:52 UT

Watched a faint satellite go roughly North to South, more or less via the zenith, and pass between Cygnus and Lyra. It seemed to occult a faint (to the naked eye) star somewhere between the two constellations. Unfortunately, at the time, I wasn't in a position to note which one it was.


From: 2005-08-15 21:53 UT
To: 2005-08-15 22:01 UT

Went back to M13, this time with the 15mm eyepiece. Appeared slightly brighter. There was now a hint that it's made of actual stars with the grainy appearance mentioned above being much more pronounced. While doing viewing a thin but obscuring line of cloud (might even have been a contrail) moved into the area and made observing rather hard. Somewhat annoying as I was about to start a sketch of what it looked like with the 15mm eyepiece.

M31 (and possibly M32)

From: 2005-08-15 22:12 UT
To: 2005-08-15 22:55 UT

M31 is now in a position where I can see it with the 'scope. First looked at it with the 25mm eyepiece. M31 itself was obvious but, at the same time, indistinct. There was an obvious brightness difference between what I assume is the central bulge and between the disk. There was no hint of any sort of structure and the whole thing had the appearance of a sort of light-gray "mist". The fact that I was looking in the direction of a street-light and that there was still a very faint haze in the sky probably wasn't helping matters.

After a short while I noticed that a star in the field was actually rather "fuzzy" when compared to all the other stars. Started to wonder if what I was seeing was M32. My initial impression was that it was further away from M31 than I'd imagined it would appear to be but, that said, that impression is formed from the photographs I've seen of M31 (which obviously show a lot more of the galaxy than I'd be seeing through my 'scope).

Checking with a chart I had to hand the fuzzy object did appear to be in about the right location for M32. To be sure I went and checked with my copy of Sky Atlas 2000 and, looking at that, I convinced myself that I wasn't seeing M32 (based on the pattern of stars near it which seemed to be in SA2000 but not in the correct position for M32). Lesson here: be sure of the width of the field of view of the eyepiece so you can make good estimates of separation of objects.

Switched to the 15mm eyepiece. The "fuzzy star" still had a fuzzy appearance and still looked quite different from all other stars in the field.

Switched back to the 25mm eyepiece and made the following sketch:

Sketch of M31

At 22:55 UT I finished the session.

Mars pops up

Time: 2005-08-15 22:55 UT

As I was starting to pack up I noticed that Mars had popped up over the roofs of the houses to the East of me. I did consider setting up the 'scope again to have a look at it but given that it was still low down and given that it was very close to a street-light I decided to save that for another night when conditions were a little more favourable.


Location: Billingborough (South Lincolnshire, UK)
From: 2005-06-18 21:25 UT
To: 2005-06-18 23:00 UT
Equipment: Sky-Watcher Explorer 130M

Very light sky plus Moon just past first quarter. The reason for venturing out so early was that this was the first clear night I'd had for a while and I'd just acquired 6mm and 15mm eyepieces from Scopes'n'Skies and I wanted to give them a try out as soon as possible.

Jupiter & 6mm eyepiece

Time: 2005-06-18 21:25 UT

Tried the 6mm first. Jupiter showed up quite nicely. Based on first impressions and a quick at-the-'scope comparison I found that the 6mm gave a more pleasing image than the SkyWatcher-supplied 10mm with the supplied 2x barlow. Made a sketch of what I saw with the 6mm -- noted that I could see a faint star quite close to Jupiter (it obviously wasn't a Jovian moon as they were obvious and the star itself was in the wrong location for that).

Tried the 6mm with the 2x barlow. It was hard to get good focus with this combination. While the image was obviously bigger I couldn't see any obvious increase in detail on the planet -- but I was fighting a warm 'scope, a light sky and a lack of collimation (I must get round to this).

Jupiter & 15mm eyepiece

Time: 2005-06-18 22:16 UT

Jupiter looked excellent in the 15mm eyepiece. Although I could only see the two main bands (no hint of the mottling that I've seen on previous nights but see above regarding what I was working against) the image was bright, crisp and clear.

The Moon

Time: 2005-06-18 22:31 UT onwards

Finally got round to having a good look around the Moon for the first time since getting the telescope.

The first thing that really stood out was the top of the rim of the crater Reiner being highlighted even though the bulk of the crater itself was behind the terminator. Quite an amazing sight. I spent some time trying to have a go at sketching this but after a couple of false starts gave up. I need to do some more practice and, more to the point, I should probably plan my observing of the Moon ahead of time and make up a template or two of what I want to look at.

Spent some time taking in the ray systems of Copernicus, Kepler and Tycho.

With the 15mm eyepiece I got an excellent view of Aristarchus, Herodotus and Vallis Schröteri. With the 6mm the view was even better. Vallis Schröteri looked very detailed. I could also clearly see what appeared to be two small craters in what looked like higher ground to the North of Aristarchus. I noted that these craters appeared to be shown on my Moon map but they were not named.

Iridium Flare

Time: 2005-06-18 23:00 UT (approximate)

After packing up, while heading back into the house, noticed a rather bright Iridium flare high up and around due South.

Page last modified: 2013-04-09 09:19:19 UT
Dave Pearson <davep@davep.org>
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