Friday 28 May 2010

USA 198 brightness behaviour: a belated 2nd report

A belated report on a second instance of USA 198 (07-060A) flaring.

On May 13th I captured another one of such instances, after first capturing it on May 5th (see report here, 2nd part of that post).

On May 5th I captured it decreasing in brightness froma prominent brightness peak. This time, I captured it increasing in brightness towards a prominent peak near 21:44 UTC, with a hint of the start of a decrease later. Here is a selection of images, all spaced 1 minute apart:

click image to enlarge

The first 11 images in the series yield the curve below (I did not include the rest of the images, as they are all saturated)

click diagram to enlarge

Both this May 13 and the earlier May 5th flaring occurred close to the moment that the sun, observer and satellite lined up, indicating it is probably due to reflection on the solar panels.

Thursday 27 May 2010

An IGS 1B flare, and Geostationary satellites again

Last evening 25-26 May was not the best of evenings: cirrus, and moonlight, plus this time of the year the sky darkens late and in fact remains in twilight all night at 52 N.

In twilight, I observed the KH-12 KeyHole USA 186 (05-042A), IGS 1B (03-009B), and Lacrosse 4 (00-047A). Short after midnight, the still flaring commercial geostationary satellite Galaxy 11 (99-071A) and the classified military geostationary satellite Milstar 5 (02-001A) were the target.

IGS 1B slowly flared to mag. -0.5 at about 21:15:48.5 UTC (May 25), while the camera was open. below photograph shows the brightnes speak, when it was cruising close to the Coma cluster:

click image to enlarge

IGS 1B is a defunct Japanese Radar Reconnaissance satellite. Since it went out of control, it is producing flares occasionally (sometimes up to mag. -3 to -5 peak brightness).

Galaxy 11 was flaring again, but is getting fainter at its peak. If my modelling is right, it might flare again in a new cycle around the 3rd week of July. Below link provides an animated GIF of last night covering 20 minutes with the geosat flaring up. Milstar 5 is in it as well, moving southward.

Link: animated GIF ( 5.5 Mb)

Around 22:10 UTC, Intelsat 802 (97-031A) briefly flares up close to Galaxy 11. It stays faint, but is visible. The single image below might help discern it:

click image to enlarge

Monday 24 May 2010

Geostationary Galaxy 11 flaring to mag +2.5

In my post of yesterday, I reported a bright geostationary satellite flaring to naked eye brightness, observed by several Dutch and Belgian observers.

Below are my images of last night (taken with the EF 50/2.5 Macro). It shows two "stars" "too many" in Ophiuchus: a brighter one (A, vertical arrow) and a fainter one (B, flat arrow). The second image is a more detailed crop of the first, at full pixel level resolution.

click images to enlarge

The glare next to the tree in the wide field image, is due to a street lantern.

The satellite flaring to mag. +2.5 turns out to be Galaxy 11 (99-071A). It peaked near 22:18 UTC (23 May) and was visible with the naked eye at that moment, nothwithstanding it was low in the sky and I was observing from the city center.

The other object is Milstar 5 (02-001A) again. A faint trail of a non-geostationary satellite is visible as well: this turned out to be Globalstar 55 (99-049C).

Link: 2.2 MB animated GIF

Above link opens a 2.2 Mb animated gif with images from 22:10 to 22:19 UTC, which shows Galaxy 11 increasing in brightness. Milstar 5 is slowly drifting south.

A third geosat was captured on the images (not shown here), which is either Thuraya 2 (03-026A) or USA 202 (09-001A); probably the first.

Sunday 23 May 2010

Two naked eye flaring Geosynchronous sats

Dutch meteor observer Peter van Leuteren contacted me this week as he had a strange bright stationary object on images of his photographic all-sky meteor fireball camera, appearing in Ophiuchus at around 22:18 UTC on 3 consecutive nights. The same object was also noted visually, at mag. about +2.5, by BWGS chairman Bram Dorreman. It was evidently a brightly flaring geosynchonous satellite.

After an alert on Dutch and Belgian astronomy mailing lists, several observers noted it as well.

I took images last night (22 May, 22:13 - 22:25 UTC) in hopes of catching it and identifying it from the position. I used the Canon 450D with the EF 50/2.5 Macro for that purpose.

Unfortunately, as it later turned out, "the" mystery geosat (for now) was hidden just behind some tree branches for me. A few degrees west of it, I however captured a second flaring geosat!

That one has now been identified by Bram and me, based on my photographic positions, as Milstar 5 (2001-001A, #27168). I have made a movie out of 13 images (10 second exposures) spaced one minute each. It can be seen here (1.4 Mb animated GIF)

The FOV of the movie is a small crop from the images, at full pixel level. The object is moving southwards at about 55"/minute.

Wednesday 19 May 2010

Volcanic dust effects at last! Bishop's Ring on May 18th

On May 17, a cloud of ash erupted from Iceland's now infamous Eyjafjallajökull volcano reached the North Sea area. It led to another temporary suspension of flights over the (western) Netherlands. And this time, there finally were clear visible effects in the sky as well!

The evening of May 17th stood out by being very hazy. Sunset colors were an unusual ochre (see photographs by Dutch KNMI meteorologist Jacob Kuiper here). But more excitedly, both Jacob and I managed to observe (and in my case, photograph) the rare Bishop's Ring.

Below image was taken by me on the late afternoon of May 18th, when remnants of the ash cloud passage still lingered in the atmosphere.

click image to enlarge

Visible is a diffuse disc of light around the sun (the sun itself is just behind the roof tip). The outer edges are reddish, the inner part is more bluish, as can be seen from this version where I depicted the RGB color values for two parts of the ring in the color spectrum:

click image to enlarge

With "normal" halo's, due to ice particles where refraction is the dispersal mechanism, the blue is on the outside and the red on the inside. Here however, it is the other way around, which confirms it is due to diffraction by dust.

Wednesday 12 May 2010

An unidentified object

While reducing the remainder of my May 9-10 observations, I found what appears to be a UNID (unidentified object) on one of the images, close to eta Uma:

click image to enlarge

It does not identify with any known catalogued object, or classified object known to us. The appearance is HEO-like (very short trail), it is present on only one (out of a series of five) images taken with the EF 100/2.5 Macro USM, and the trail looks to be part of a flare.

Most likely, it is a tumbling rocket stage of some past HEO launch.

Monday 10 May 2010

-5 KeyHole flare! (May 9th observations, Part I)

Yesterday evening (9 May) I observed the most spectacular Keyhole flare I have ever seen. KH-12 USA 186 (05-042A) flared brilliantly to at least mag. -5 in a blue twilight sky, while crossing from Cvn into Uma. It yielded this Iridium-like picture:

click image to enlarge

I cannot provide a brightness profile: for the simple reason that the trail is saturated over the full length. Peak time was about 20:34:29.4 UTC (9 May 2010).

I also observed on the 5th and 6th of May, capturing a.o. USA 186 again, as well as the IGS 5 r/b and the Molniya object USA 198.

USA 198 (07-060A) showed a clear, slow brightness variation over the 1m20s image series of 5 images, taken on May 5th, growing slowly fainter over the series:

click images to enlarge

The data during the first 12 seconds of the diagram above, are close to saturation. Hence, the brightness variation in reality is probably more expontential than the diagram suggests.
The background readings have been taken just to the right of the trails, and are plotted to show that the change in brightness of USA 198 is not due to lens vignetting, but real.