Observing HEO objects

In wintertime at latitude 51 degrees North, satellites in Low Earth Orbit are mostly invisible except for twilight, as all their passes are completely within the Earth shadow.

This season is therefore the season that I focus on HEO and GEO objects. HEO stands for Highly Elliptical Orbit and is almost synonymous with the more informal name 'Molniya orbit', after a class of Russian communication satellites employed in such orbits.

Military SDS COMSAT USA 198 (SDS 3F5), imaged in Cassiopeia on 4 Jan 2014

Satellites in a Molniya orbit have an orbital period of about 2 revolutions per day, an orbital inclination near 63.4 degrees, perigee at a few hundred kilometers altitude over the southern hemisphere and apogee at altitudes near 36000 km over the Arctic. They spend most of their orbital time near their apogee.The 63.4 degree orbital inclination ensures that perigee keeps at a stable position over the southern hemisphere.

US military payloads and 'unknowns' in Molniya orbit

The advantage of a Molniya orbit is that it allows a good, long duration view of high northern latitudes, including the Arctic region, which are not well visible from a geostationary orbit. This is ideal for communications satellites serving these regions, for SIGINT satellites, and other applications (such as infrared ICBM early warning systems, e.g. SBIRS) that benefit from a long 'stare' and good view of high Northern latitudes.

The US military has several systems in a Molniya orbit (see image above): communication satellites (e.g. two components of the SDS system), several SIGINT satellites (TRUMPET and TRUMPET-FO), and components of the SBIRS system (piggybacked on three TRUMPET-FO SIGINT satellites). Identifiable payloads include:

- TRUMPET 1, 2 and 3 (SIGINT);
- TRUMPET-FO and SBIRS USA 184, 200 and 259 (SIGINT and SBIRS);
- SDS COM satellites USA 179 and 198

There are a couple more which we cannot (yet) tie to a specific launch and function (see note at end of post).

Near their apogee, satellites in Molniya orbit are located high in the sky for my location, and because of their high northern position, they are sun-illuminated and hence visible (typically at magnitudes near +9 to +12) even at midnight and in winter. They move very slowly when near apogee, creating tiny trails on the images.

On December 13, the NRO launched (as NROL-35) a new SIGINT and SBIRS platform into a Molniya orbit: USA 259 (see a previous post). It is currently still actively manoeuvering to attain its final orbit, which makes it an interesting object to track. The image below was taken in late twilight of Jan 4, when the satellite was past its apogee and on its way to perigee. It was 4 minutes early against orbital elements based on observations of only a few days old.

SIGINT/SBIRS satellite USA 259 (NROL-35) imaged in Andromeda in the evening of Jan 4

I image these objects with an old but good Zeiss Sonnar MC f2.8/180 mm telelens (made in the former DDR and sturdy -and heavy- as a tank). This lens has a 67 mm aperture at f 2.8, which means it shows faint objects. As these objects move very slowly, the relatively small FOV is no problem. My observational data from January 4th can be found here and here.

Note: the 'unknowns' in the orbital plot above are objects we track that are not in public orbital catalogues and which we cannot tie to a specific launch. Although some of them certainly are, not all of these need to be payloads: some might be spent rocket stages from launches into HEO.

At last the FIA Radar 1 (NROL-41), and the first images with the new Carl Zeiss Jena Sonnar MC 2.8/180

Last weekend saw my first observation, at last, of the payload of the NROL-41 launch: the FIA Radar 1 (2010-046A). At 4:25 am local time it made a pass in the northern sky over Polaris, and became visible to the naked eye at a brightness of mag +3.5. Below is one of the two pictures, plus a picture of the launch patch of NROL-41.

click images to enlarge

The orbit of the satellite is unusual, as it is retrograde, and in fact resembles a retrograde version of the Lacrosse orbits. There is some speculation as to the why of this.

The object currently is actively manoeuvring: when I captured it, it was 34 seconds late with regard to just one day old elements after one such manoeuvre. The apparent intention is to create a frozen orbit.


A new lens added to the equipment

This weekend saw the first active use of a new piece of optics added to the repertoire: an old, DDR-made, Carl Zeiss Jena Sonnar MC 2.8/180mm lens. The lens itself is renowned, for its sharpness. Originally made for 6x7 cameras, it provides very good sharpness from edge to edge on a DSLR image. Fitted with a P6 to EOS adapter, it works perfectly on my Canon EOS 450D. It yields almost twice the aperture of my EF 100/2.8, and hence will be used to capture faint distant objects such as Molniya orbit objects. The lens is of very heavy build: solid metal and glass with no plastics. It weights 1.5 kg!

Below is an image of the optics I am now using in my observations: a Canon EF 2.5/50 mm Macro used for LEO and some GEO objects; a Canon EF 2.8/100 mm Macro USM used fro MEO and HEO objects; and the Carl Zeiss Jena Sonnar MC 2.8/180 mm for HEO and GEO objects.

click image to enlarge

The advantage of the lens is that it goes deeper in magnitude of the objects it captures. A disadvantage is that it has a smaller FOV (6.8 x 5.0 degrees) which, with the software I use for astrometry (AstroRecord), means I have to carefully select the part of the sky to aim for (it should have enough stars brighter than +8 and at last 3 stars with a Flamsteed number, as the AstroRecord sequence starts with identifying 3 of those after which it starts to auto-identify stars). Especially the requirement of the 3 Flamsteed numbers in such a small FOV is limiting.
Anoher drwaback of this lens is that with 1.5 kg it is heavy! It is at the edge of what my lightweight camera tripod can carry, and hence vulnerable to vibrations.

On October 9 and 10 I used the lens to capture two Molniya-orbit (HEO) objects: USA 184 (06-027A), and USA 198 (07-060A, SDS 3F5). As a stray, it also captured another Molniya, the Russian US-KS Oko IR missile detection platform Kosmos 2393 (02-059A), and an old Russian rocket body in LEO (Kosmos 411 r, 71-041J). The image sequence shows that Kosmos 2393 was flaring at that time (20:14:02 - 20:14:12 UTC, 9 Oct 2010)

Below are two parts (at full pixel resolution) of one image that contained both USA 184 and Kosmos 2393 (the latter close to the edge of the image); and one of the images of USA 198.

click images to enlarge

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.

-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.

Last observations of the year, and 2009 at a glance

December 2009 saw a lot of clouded sky, a few clear frosty skies, and lots of snow (for our country at least). After my December 6th observations (see previous post) I observed on December 13th (under modest conditions) and December 28th (under good conditions).

Targets imaged were the HEO objects USA 179 (04-034A), USA 184 (06-027A) and USA 198 (07-060A), and the STSS Demo objects (09-052A & B); and the LEO objects Lacrosse 2 (91-017A) and Lacrosse 5 (05-016A).

These are probably my last observations for this year, as today is overcast and tonight will see fireworks. So, what did 2009 bring on the observational front?

2009 was a good year. I observed on 77 nights, obtaining a total of 953 positions (8 visually, 945 photographically). They were spread over the year as follows:





These observations concern 32 different classified objects (both payloads and rocket boosters), plus a number of special-interest non-classified objects such as Space Shuttles, GOCE, and the Iridium 33 wreckage:

click image to enlarge list

Just for fun, I have also plotted all obtained positions on an RA/Declination map:

click image to enlarge

The clustering in certain positions is because I tend to select sky areas with easily recognizable bright star patterns. This helps easy aiming of the camrea, and it also speedens initial star identifications during the astrometric reduction of the images.

An unidentified HEO object

Yesterday evening was very clear. I photographed the STSS Demo r/b (09-052C) using the EF 50/2.5 Macro, and then switched to the EF 100/2.8 Macro USM to capture the HEO objects USA 184 (06-027A) and USA 198 (07-060A).

One of the four images capturing the latter, contained an unknown object some 3 degrees south of USA 198. It is a clear trail, similar to that of USA 198 in length and direction. It shows evidence of being the capture of a brief flare. And it doesn't match any known object from the unclassified or classified catalogues.

Below is a detail of the image showing the object (the inset is a 200% blow-up). The trail is about 20 pixels long, or about 3.5'.

click image to enlarge

The past week saw several bright evenings, yielding a rich haul of satellite positions. Observations were done in the evenings of September 16, 17, 20 and 21. Data were obtained on some of "the usual suspects": the KH-12 Keyholes USA 129 and USA 186, the SAR Lacrosse 2, the HEO objects USA 184 and USA 198, and the USA 144 decoy.

Both KH-12 Keyholes USA 129 and 186 slowly flared to -1 at September 16th: 96-072A at about 19:44:27 UTC in the southeast; 05-042A at 21:01:46 UTC in the northwest.

USA 129 showed another bright slow flare peaking about 20:00:51 UTC on 17 Sep, just after the end of an exposure. I captured the rising part of it.

Below are two pictures of last evening (21 Sept), showing the KH-12 Keyhole plus a faint stray near M31, the Andromeda galaxy: and showing the USA 144 decoy passing close to the ELINT USA 184. The first image was made with the EF 50/2.5 macro lens, the second with the EF 100/2.8 macro USM lens.

click images to enlarge

More HTV-1 and Molniya satellites

Yesterday evening 13-14 September was clear again. I had a very fine near-zenith pass of the HTV-1 (09-048A) on it's way to the ISS. It was fast and bright again (mag. 0), and again distinctly orange. It flared to -2 at 19:28:35 UTC (13 Sep). On below image (taken with the Tamron lens this time, at 17 mm) it is rising over the rooftops, with the distinct orange colour visible:

click image to enlarge

I also imaged the high altitude objects USA 184 (06-027A) and USA 198 (07-060A) again later that night, using the EF 100/2.8 Macro USM lens. Below animated GIF is composed of 5 images of 10 seconds exposure, taken at 20 second intervals, and shows USA 198 between 22:04:02 and 22:05:22 UTC. It was cruising at 34300 km altitude at that time, over 56.8N, 11.9 E. The frames are crops of small parts of the original images, shown here at full pixel resolution. One pixel equals 10" (arcseconds):

More observations from last evening

The clouds that threatened last evenings HTV-1 observation (see previous post) moved out somewhat later, allowing me to bag several objects.

I observed both of the evening KH-12 Keyholes, USA 129 (96-072A) and USA 186 (05-042A). USA 129 was very bright (mag. -1) while ascending through Aquila low in the south, yielding some very fine pictures of which this is the first:

click image to enlarge

The other KH-12, USA 186, featured a slow bright flare to mag. -2 around 21:10:35 UTC (12 Sep), alas outside the camera view.

Some high altitude objects were captured again as well: the by now familiar USA 184 ELINT/SBIRS (06-027A), the SDS-3 USA 198 (07-060A) and the USA 144/Misty-2 Decoy (99-028C).

I recently obtained the launch patches of both USA 184 and USA 198:

click images to enlarge

The USA 198 patch (bottom) shows the satellite constellation it is part of: two Molniya orbits and a geostationary orbit. The Latin text roughly translates to "Beware of our Sting".

Molniya orbits and a Keyhole flare again

The evening of September 10 saw more than a nice Space Shuttle pass (see previous post) and the ISS.

In fact, it was a prolific evening which yielded data on the Lacrosse 2 SAR (91-017A), the USA 186 KH-12 Keyhole (05-042A) and two objects in Molniya orbits: the ELINT and SBIRS satellite USA 184 (06-027A) and the SDS-3 communication satellite USA 198 (07-060A).

USA 184 was imaged in two sessions 1h 45m apart. It is interesting to see the effect of it moving towards its apogeum (see below: in these images, which are on the same scale and at full pixel resolution, 1 pixel equals 10" (arcseconds)): while during the first session the satellite still creates a recognizable trail in the 10 second exposures (taken with the EF100/2.8 Macro USM), it appears as an almost static stellar object in the exposures taken 1h 45m later:

click image to enlarge

The Keyhole USA 186 flared brightly to -1 at about 20:25:43 UTC, just before the start of an exposure. I captured the descending branch of the flare. As I had mispointed the camera in haste, the satellite unfortunately runs out of the FOV (the sat is moving from right to left on the image):

click images to enlarge