ROSAT down over the Indian Ocean [RENEWED UPDATE]

ROSAT is no more.....according to a TIP bulletin by SSC issued at 03:41 UTC, it reentered at 1:50 UTC +/- 7 minutes, placing it over the Indian Ocean (and far away from any eyewitnesses, bar maybe some ships and maybe Ceylon, Sumatra and Birma/Malaysia/S-China if it survived into the second half of the given window: and of course the US tracking facility at Diego Garcia).

See update 2 below for latest map version (update 1 below now deprecated)

update 1 - deprecated. 
[Below two map shows the final orbit and (thick red line) the reentry windows according two assessments:
- The first is with the last available TLE (issued over a day before the reentry) propagated with SatEvo.
- The second, is made by adjusting the time (by about 5 minutes) so that the satellite position matches the nominal position for the reentry given by SSC in the TIP bulletin: 7 N, 90 E]

click maps to enlarge

[As can be seen there is some difference between these two. This is the result of there currently being no recent TLE available: the last available TLE dates 24 hours before the reentry. In the 24 hours between that last issued TLE and reentry, the orbit evolved fast. Without the availability of more recent elements, it is difficult to assess where the satellite exactly was along its orbit. That uncertainty is no more than a few minutes in time, but that amounts to over 2000 km in position....]

UPDATE 2: SSC released a new tle, with an epoch dating to two hours before the decay (about 1.5 revolutions). This allows this map to be created, which closely tallies with map 2 above:

click map to enlarge

It shows the difference a new TLE much closer in time to the decay makes, with regard to locating the satellite in its final moments....

(note: thanks to Daniel Fischer for inquiring about the differences between my map and Simone Corbellini's map, and to Simone for communications on the why of the time offset)

ROSAT reentry update (2)

Update to my previous post: Space-Track (SSC) finally released a new elset, 11294.85810509, which is still and "old" elset (almost a day old). And they released a new TIP with a new reentry prediction.

The new TIP gives this prediction:
Space-Track (SSC): 23 Oct, 02:34 UTC +/- 7 hrs

Based on the new TLE, independant analyst Harro Zimmer now provides the following prediction:
Harro Zimmer: 23 Oct, 04:17 UTC +/- 4 hrs

Other independant analysts have not updated yet (see  my previous post for these values). I did a run of SatEvo with the newly released TLE and the current F10.7 cm solar flux, and get, for what it's worth, a projected time of 10:20 UTC (23 Oct) +/- 5 hrs. That seems a bit late compared to the SSC and Zimmer estimates (although the uncertainty windows of course overlap).

ROSAT reentry update

New independent updates on the projected moment of the ROSAT reentry are hampered by the fact that no new orbital elements have been released for 1.5 days now - the last elset released being elset 11294.06213865 (epoch time 21 Oct 01:29:29 UTC) as of this moment (22 Oct 12:10 UTC).

Meanwhile, here is a summary of the latest available predictions at this moment of writing:
Space-Track (SSC): 23 Oct, 01:31 UTC  +/- 14 hrs
Aerospace Corp: 23 Oct, 13:24 UTC +/- 16 hrs
Harro Zimmer: 23 Oct, 05:33 UTC +/- 6 hrs
Ted Molczan (using SatEvo): 23 Oct, 05:00 +/- 10 hrs
T.S. Kelso: 23 Oct, 03:15 UTC (uncertainty not listed)
DLR: 23 Oct, ~3h UTC +/- 9hrs (midtime from window given)

The FAA has realeased a NOTAM warning for the reentry:

!FDC 1/9172 FDC SPECIAL NOTICE .. ..........EFFECTIVE IMMEDIATELY UNTIL 1110252359 UTC. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY OCCUR DUE TO REENTRY OF THE SATELLITE ROSAT INTO THE EARTH'S ATMOSPHERE. THE FEDERAL AVIATION ADMINISTRATION (FAA) IS WORKING WITH THE DEPARTMENT OF DEFENSE (DOD) AND THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA) TO ENSURE THAT THE MOST CURRENT RE-ENTRY INFORMATION IS PROVIDED TO OPERATORS AS QUICKLY AS POSSIBLE. FURTHER NOTAMS WILL BE ISSUED IF SPECIFIC INFORMATION BECOMES AVAILABLE INDICATING A UNITED STATES (US) AIRSPACE IMPACT. IN THE INTEREST OF FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY AND INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. THE DOMESTIC EVENTS NETWORK /DEN/ TELEPHONE 202-493-5107, IS THE FAA COORDINATION FACILITY

Gearing up for ROSAT's re-entry, and an older observation of a Breeze-M tank near M31

Shortly after UARS, another satellite about to reenter is in the news: ROSAT. I last observed and photographed it about a week ago (see here and here) - since then, passes have become unfavourable for the Netherlands.

In an interesting twist, Sky & Telescope's J. Kelly Beatty reports that DLR and ESA sources confirmed to him that they expect the entire telescope mirror array - which weights 1.6 tons! - to survive reentry, impacting intact!

Various modellers now project the reentry to occur on October 23rd. Here is a short list of what various sources currently predict [editted 12:10 UTC, Oct 21, with latest Molczan update):

Space-Track (SSC):  23 Oct, 05:49 UTC (+/- 24 hrs)
Harro Zimmer: 23 Oct, 05:03 UTC (+/- 48 hrs)
Ted Molczan (using SatEvo): 23 Oct, 05:00 UTC (+/- 10 hrs) [editted]
Aerospace Corp.: 23 Oct, 13:24 UTC (+/- 16 hrs)

Since Ted uses the same software I used for my UARS predictions, and hence our results will be similar, I will not put forward my own predictions here but refer to Ted's.


A Breeze-M near M31, the Andromeda nebula

In my post of October 2nd, I featured an image I took on 29 September of a Russian Proton upper stage Breeze-M tank near the trail of USA 129. I wrote that:

These pieces of Russian space debris pop up more often on my images lately. They are the jettisonable torroidal (doughnut-shaped) fuel tanks of a Breeze-M, the upper stage of a Proton M. There are now over 40 of these spent empty tanks in space, often in highly elliptic orbits representative of a geostationary transfer.

Just a few days later, on October 2nd, I took advantage of clear skies to image M31, the Andromeda galaxy. The camera (Canon EOS 450D) with the Samyang 1.4/85mm lens was piggybacked on a Meade ETX-70 in order to use the telescope drive to follow the stars. A long series of 10 second images was taken.

Several satellites showed up on the image series, including a Breeze-M tank again, this time 2006-056B:

click image to enlarge

Here is the final image of M31, a stack of 105 individual 10 second images:

click image to enlarge

Given that this image was taken from a town center with modest equipment, I am quite happy with it! If you compare it to a single frame image (above) it shows the strong improvement in signal-to-noise ratio that comes from stacking images.The two satellite galaxies come out much better, and so does a glimpse of the spiral structure and dust bands in the Andromeda galaxy.

Another ROSAT observation

Yesterday evening was clear, and I again observed the doomed satellite ROSAT (see my previous post), in deep twilight (sun at -6 degrees). It was again bright, magnitude +1, very fast, easy to see even though the sky was still bright blue with only a few stars visible. Like my earlier observation the day before yesterday, it was steady in brightness, with no sign of brightness variations, suggesting it is not tumbling.

Photographically it was a challenge: I had to do some serious image editing tricks to pull the trail out of the bright twilight background on the image below (on the unedited image, the trail is visible but very inconspicuous):

click image to enlarge

These high elevation (near 70 degrees) twilight passes are quickly moving  earlier (and too early) in the evening for me: yesterday's was the last one I could expect to realistically observe. Passes at lower elevation (12-14 degrees) in late twilight will become visible for me after tomorrow and might allow me to observe it for a few more days later this week, until these passes move too early as well.

Using Alan Pickup's SatEvo software and the current 10.7cm solar flux, I get a projected decay at October 23. Harro Zimmer, using another model, gets October 24th. These predictions still have an uncertainty of a few days, so expect them to shift over the coming days, amongst others due to changing solar activity.

Observing another doomed satellite: ROSAT

Shortly after the UARS reentry, which got wide attention, another scientific satellite is about to meet its demise by an uncontrolled plunge into the atmosphere. It is the German X-ray astronomical satellite ROSAT. This satellite is currently predicted to reenter about October 22 to 24.

This evening I watched it pass during twilight (sun at 8 degrees below the horizon, first stars just visible in a blue sky). It was fast, zipping across the sky, and bright: magnitude +1 and an easy naked eye object.

I used the new EF 2.0/35mm lens (a new purchase, first used last weekend during the Draconid meteor outburst, on which I will post in a later post), set to F2.5, making 5 second exposures at 400 ISO. The fast moving objects ran out of the frame of two of the three images. Below is the image thats shows the complete trail. The satellite was moving from left to right, across Cepheus. The streak in top is a streak of cirrus.

click image to enlarge