Wednesday, 25 May 2011

Nanosail-D: a spectacular show of bright flashes!

Last night I finally was able to capture Nanosail-D (10-062L), the NASA experimental solar sail. It put on a spectacular show, flashing rapidly, becoming an easy naked-eye object after culmination when it reached magnitude +1.

As it gradually brightened from invisibility to naked-eye brightness while passing at 61 degrees altitude due east, it initially flared rapidly, in an irregular pattern, at a rate of 1 to 3 flashes per second. below is the first image, and two other where the trail runs out of the image frame (in haste, I aimed badly when repositioning the camera):

click images to enlarge

When it descended towards the South-Southeast, it became brighter, reaching mag. +1. The flashing pattern became somewhat more regular and slowed down to about one flash per 1.6 seconds. On the image, the trail is quite saturated and hence the brightness variability on the image below is less apparent than it was visually. Visually, the objet was clearly "winking", very cool to see:

click images to enlarge

Thursday, 12 May 2011

PAN at its new slot at 45.0 E

Below is an image I shot in the evening of May 9, under not too good conditions (moonlight, and some twilight left).

It shows PAN (09-047A) in its new position at 45.0 E, following the relocation from 49.0 E early May.

Image was shot using the Carl Zeiss Jena Sonnar MC 2.8/180 mm.

click image to enlarge

Tuesday, 10 May 2011

ISS over the Sun

Late this afternoon (10 May 2011), at 17:29:25 CEST (15:29:25 UTC), the International Space Station (ISS) passed in front of the Sun disc again as seen from the SatTrackCam station, silhoueting the Space Station on the solar disc.

Like on March 24th, I used my small ETX-70 telescope equiped with a Solar Screen Filter, to photograph the event. This time I used prime focus plus a Kenko 2x converter, instead of eyepiece-projection, effectively yielding a f=700mm F/10 system.

Four images out of the series show the ISS silhouted againts the sun, along with several sunspots. Below is a composite image of the four images (showing the ISS four times), plus a detail. The ISS solar arrays are well visible.

click images to enlarge

Monday, 9 May 2011

UNID-I 3 May 2011 = PAN [UPDATED]

On May 3rd, I found two unidentified geostationary objects close to Galaxy 27 and Intelsat 12 (see report and pictures here).

One, UNID-I, was stable in brightness. The other, UNID-II, was flashing. I imaged UNID-I the next night (May 4th) as well, showing it drifting westwards. I might have imaged UNID-II again too, though misidentifying it at that time as Intelsat 12 (except for the occasionally very bright UNID-II, the objects were, due to worse observing conditions, at the edge of detectability).

At that time (see the link above) there already was some suspicion that UNID-I could be the enigmatic classified geostationary satellite PAN (09-047A), caught in the act of yet another relocation.

That suspicion is now confirmed, following additional imaging by Peter Wakelin from the UK on May 8th. Still drifting when I picked it up on May 3rd, PAN now appears to have settled in a new position at 44.9 E, just west of Galaxy 27 and Intelsat 12. It has moved 2 degrees higher in my local sky, to an altitude of 19 degrees.

The identity of the second, flashing UNID, UNID-II which is still drifting westwards on May 8th, is still uncertain. While it is possibly the Indian communication satellite GSat-2 (03-018A) in the act of relocating, Space-Track still lists that object stable in its usual orbit slot placing it at 48 E. So we have something of a remaining mystery to solve there (although in the end, it will probably turn out to be Gsat-2, with Space-Track for some reason failing yet to recognize it is being moved).

UPDATE 09/05/2011: about an hour after I posted this, Space-Track updated the orbit for Gsat-2, showing that UNID-II is indeed Gsat-2, probably on it's way to the graveyard orbit. So, it appears I beat Space-Track to it by several days!

PAN (09-047A) has a history of frequent relocations, making this already enigmatic satellite the more enigmatic. Previous to this early May 2011 relocation, it relocated in early December 2010, an event that I was the first person to detect as well. So far, it has been located at 33.0 E from late 2009 to May 2010 and then was moved to 38.0 E; then to 49.0 E in December 2010; and now to 44.9 E in May 2011.

Thursday, 5 May 2011

[UPDATED] Two Unidentified Geostationary Objects on May 3 and 4

May 3 was an unusually clear evening, and I decided to target a few classified geostationary satellites, using the Carl Zeiss Jena Sonnar MC 2.8/180mm.

While imaging the region of PAN (09-047A) and Mentor 4 (09-001A), I found two unidentified objects. Yes: two.

The first object, UNID-I, was discovered close to the commercial geosats Galaxy 27 (99-052A) and Intelsat 12 (00-068A). It was present on multiple images, and the astrometry shows it is stable in declination. It was about as bright as the two commercial geosats, and stable in brightness.

The plot thickened, when a second unidentified object, UNID-II, was discovered just east of the first, just north of the commercial geostationary Syracuse 3A (05-041B). This object was irregular in brightness, alternating between faint and very bright (comparable to Mentor 4 at peak brightness, i.e. about mag. +8).

Below image shows UNID-I near Galaxy 27 and Intelsat 12:

click image to enlarge

The two images below show UNID-II near Syracuse 3A, and the clear flaring behaviour of the UNID.

click image to enlarge

On May 4th, the sky quality was poorer. Nevertheless I tried to recover the two objects, with partial success: UNID-II was captured again on several images.

It had drifted westwards, closer to Galaxy 27 and Intelsat 12 towards the position of UNID-I. The latter was not visible on the images, most likely due to the poor sky quality (Galaxy 27 and Intelsat 12 were barely visible either).

The object showed a clear variable brightness behaviour, being invisible in one image and very bright in the next one taken 30s later. Together with the slowly changing declination, this shows that the object is likely UNID-II, not UNID-I.

Below images were taken 30 seconds apart: the object is bright in one, and invisible in the other:

click image to enlarge

In the series of images, it is present in the following images:

from - to (UTC, May 4th)
21:03:02.30 - 21:03:12.35
21:04:02.30 - 21:04:12.35 - very bright
21:05:02.30 - 21:05:12.35
21:07:32.30 - 21:07:42.35
21:08:02.30 - 21:08:12.35
21:08:32.30 - 21:08:42.35 - very bright
21:11:02.30 - 21:11:12.35
21:12:02.30 - 21:12:12.35
21:13:02.30 - 21:13:12.35 - very bright
21:14:02.30 - 21:14:12.35 - very bright

As can be seen, there is a clear semi-1 minute periodicity in this.

I have no idea as to the true identity of these two objects. As I could find no trace of PAN (09-047A) near Yamal 202 on my May 3rd images, it is possible that UNID-I is PAN once again relocating.

The presence of a second, tumbling/spinning object, UNID-II, close to it however suggests that more is going on. Finding two UNID's close together is definitely weird and might suggest a connection between the two objects.

UNID-II has a small but clear inclination to it's orbit and appears to be drifting westwards. UNID-I is stable in declination, indicating an inclination close to zero. It might be drifting as well (only more observations will tell, given that I failed to find it on May 4th).

UPDATE 5-5-2011:
Ted Molczan feels UNID-II (the flashing one) could be the Indian commercial geosat Gsat 2 (03-018A) in the act of relocating. UNID-I could indeed well be, as I suggested in my report on Satobs, the classified geosat PAN (09-047A) relocating, according to Mike McCants. I captured the same satellite relocating in December last year: this enigmatic satellite is frequently on the move.