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A Lunar or Solar transit by low earth orbit satellite is not that unusual...it happens quite often , but rarely is the event seen or indeed , captured on video.

Since June 2003 I have managed to image and document six transits , including two on consecutive orbits.

Listed in chronological order,most recent events appear at the top of the page .

August 29 2003
Location Wirral UK

A low elevation transit with the Sun just 15 degrees above the horizon. ISS is at a range of 1125 km , and having an angular diameter of only 4.1" , this was an experiment to see how useable the results would be.
A total of 33 frames were captured at 15 FPS , 1/1000th sec. The resulting animation has been reduced in size to allow easier loading . ISS can just be seen passing top right to bottom left between sunspots 445 and 442.

CalSky.com data

8h07m09.8s ISS Crosses the disk of Sun. Separation: 0.05d
Angular Velocity: 13.4'/s. Transit duration: 2.33s
Angular diameter: 4.1" cylindrical, 20.0m x 10.0m
Satellite at az: 94.9d E h: 15.5d dist: 1125.2 km
Path direction: 80.3d E ground speed: 11.153 km/s width: 38.3 km max. duration: 2.6 s

First recording of two consecutive orbit transits : August 14 2003

August 14 2003 , the sky over north west UK stayed clear and I embarked on a 120 mile
round trip to see if I could capture ISS on video , crossing the Sun on two consecutive orbits.

This is the first time this has ever been fully documented and caught on video

Advance details were obtained using Tom Fly's ISS alert programme and CalSky
Maps were drawn up pinpointing suitable locations , plus back up sites in
case the primary location was unsuitable .
Aerial photos were also consulted to ensure the locations chosen were not in built up areas.

The first transit was the most northerly and occured at 1449:35 BST to the north of
the resort of Southport, a very flat area on the Lancashire coast scattered with market gardens.

Telescope , laptop and GPS were set up in the parking area of A W Baxter Ltd a Fruit
and Vegetable Wholesale firm. The manager of the company was most helpful . With large transport
vehicles coming in and out of the yard he took great care to ensure I was operating in a safe location.

The transit took place right on the button , and capture confirmed.
Temperature was 25 degs C , thermal activity in the optical tube can be seen as a shimmering effect

Details orbit 27012

14h49m35.1s ISS Crosses the disk of Sun. Separation: 0.10d
Angular Velocity: 47.5'/s. Transit duration: 0.62s
Angular diameter: 8.9" cylindrical, 20.0m x 10.0m
Satellite at az: 213.6d SSW h: 46.8d dist: 517.5 km
Centerline: Lon:357d04m47s Lat: +53d42m21s dist: 1.16 km
az: 5.4d N Path direction: 81.1d E ground speed: 7.547 km/s

With the first one "in the bag" I then had just over ninety minutes to pack up
my equipment , stow it in the car and drive south , ten miles or so to find the second site.

The second transit was scheduled for 1625:05 BST , this time near to the Royal Birkdale Golf Club.
I had chosen a set up point on a piece of wasteland to the east of the course.
By now the temperature had risen to 27 degs C . The telescope had been "cooking " in the
car for over four hours so trying to get a good focus on the sun's disk proved difficult.
Capture was however made , again on time.On this occasion ISS was at a greater range (620 km) and presented
a smaller target.
See angular diameter below

Details orbit 27013
16h25m05.6s ISS Crosses the disk of Sun. Separation: 0.02d
Angular Velocity: 35.3'/s. Transit duration: 0.89s
Angular diameter: 7.4" cylindrical, 20.0m x 10.0m
Satellite at az: 241.3d WSW h: 36.4d dist: 620.5 km
Centerline: Lon:356d58m26s Lat: +53d37m37s dist: 0.39 km
az: 26.6d NNE Path direction: 99.5d E ground speed: 7.830 km/s

Equipment

  • Meade LX90 8 " telescope
  • Eyepiece projection using ToUcam webcam 10 fps at 1/1500th sec
  • Orion full aperture solar filter

Sunspot 431 provided a good reference point , with both tracks passing north of the group.This is producing X class flares at the time of writing.

Thanks to :

A.W.Baxter Ltd

Southport Information Office

Tom Fly

Arnold Barmettler ( CalSky.com)

June 24 2003
Location Wirral UK

An opportunity arose on the 24th June to capture another solar transit by ISS.This time the event would be visible from my home location.
Although I was not on centre line , the transit would last about four tenths of a second. This time I elected to use a higher magnification , webcam at prime focus with focal reducer fitted.This effectivly was the equivalent of an 8mm eyepiece. As a result the field of view was very small. I anticpated getting no more than one good frame at 15 frames per second , 1/1000 shutter speed.

All set up and with 90 seconds to go , the laptop crashed. Panic stations!
After trying to restart the capture programme three times , I eventually managed to get it fired up again , with about 15 seconds to spare. Little time to check the camera settings , consequently the captured file is somewhat underexposed .

The image shows ISS in some detail.The main P6 array can been seen , together with the Zvezda and Zarya solar panels.In addition one of the truss radiators is just visible.

This five frame animation is in real time and demonstrates just how quickly the station passed through the field of view !

Calculations courtesy of CalSky.com....see below for link.

ISS Solar Transit

June 16 2003

Location Crosby . Lancashire .UK

June 16 2003 , just over a week after capturing ISS crossing the Moon I realised that within a couple of days I would have the chance to see the station making a solar transit, from my home location on the Wirral.
However , the weather here in England is closing in , with rain and cloud forecast mid week.
So , checking CalSKY.com I found that today , June 16 , there would be a transit visible 14 km north of me.A quick check on the map and a few calculations later I had the target area confirmed.....right in the middle of the West Lancashire golf course ...... Oh dear !....... FORE!

Fortunately , when I phoned the secretary of the club he was very understanding , although obviously I couldn't trek across the greens and fairways , I was welcome to use the car park , if that was close enough to the centre line . "That'll do for me I thought ".

At the allotted time 1415 gmt , I was all set up , having checked my position in the club car park to GPS co-ordinates. The sky was clear , the only danger being a rogue incoming missile in the form of a golf ball.... or two !
With car park security looking on , ISS made her appearance , crisp and clear ..... straight down the middle....... Hole in One !

In all the round trip was about 40 miles ,on one of the hottest days so far this year , but it was well worth the effort.

Thanks again to Arnold Barmettler's CalSKY programme


CalSKY.com

....... to the crew of ISS for their brilliant pass , and of course to West Lancashire Golf Club , for allowing me to do a bit of target practice in their car park :o)

Now the "techie" bit......

This is how CalsSKY predicted the pass.

Here's how it turned out.

In a couple of frames the shape of the station is quite distinct with the P6 array visible and the main components.In addition in one frame I think you can just make out one of the truss radiators.

The station is in LVLH mode.

Here's the data from CalSKY:

15h15m17.9s ISS Crosses the disk of Sun. Separation:0.14d

Angular Velocity:48.7'/s. Transit duration: 0.54s

Angular diameter: 9.3" cylindrical, 20.0m x 10.0m

Direction towards center line: 1.44km, az: 14.9d NNE az: 229.7d SW h: 52.2 dist: 497.4km mag=12.6m

Equipment check list

Meade LX90 8 inch telescope / 25mm Eyepiece projection.

Philips ToUcam webcam at 1/1000 th sec 10 frames per second

Toshiba satellite laptop

Garmin GPS

See also

BBC i

ISS Lunar Transit and daylight capture

June 8 2003

Location Wirral UK

A Lunar transit by low earth orbit satellite is not that unusual...it happens quite often , but rarely is the event seen or indeed , captured on video. On June 8 2003 I was aware that the International Space Station would transit the Moon , as seen from my location.( red dot on aerial image above ) Using predictions calculated by Arnold Barmettler's CalSKY programme


CalSKY.com

and confirmed by Tom Fly I crossed my fingers for good weather and spent a couple of hours preparing my Meade LX90 telescope , fitted with Philips ToUcam webcam.

There was no margin for error !

The event would take less than a second from start to finish....exposure had to be just right and , of course the clouds had to stay away !

This is how CalSKY.com predicted the path of ISS.It would be visible within a narrow corridor stretching across the UK.

18h41m19.9s ISS Crosses the disk of Moon. Separation:0.01d

Angular Velocity:42.1'/s. Transit duration: 0.76s

Angular diameter: 7.7" cylindrical, 20.0m x 10.0m

Direction towards center line: 0.09km, az:201.9d SSW

az: 170.4d S h: 39.9 dist: 596.0km mag=-0.8m

With my wife Sue giving time checks in the run up , and son Andrew manning a second web camera fitted to a 200mm zoom lens we waited.

At 18h41m gmt we started the cameras.

At 18h41m-19secs gmt this is what appeared !

Not only did we catch ISS transitting the Moon , but also a rare glimpse of the station in daylight , travelling at around 17,000 mph at a range of 600km.

A fantastic sight !

Transit prediction courtesy CalSKY.com , all other images Copyright John Locker

My thanks to Tom Fly and Arnold Barmettler

If you have any questions about how to plan for and capture transits , please feel free to contact me :john@satcom.freeserve.co.uk

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ISS

Solar Transit
1227 GMT: February 8 2004

Location: Wirral.UK

Crosses the disk of Sun. Separation: 0.00d Position Angle: 13.7d Angular Velocity: 28.8'/s. Transit duration: 1.13s Angular diameter: 21.1" size: 73.0m x 44.5m x 27.5m Satellite at az: 180.3d S h: 21.6d dist: 877.1 km Satellite apparently moves to direction 283.6° Centerline, Lon:356d54m24s Lat: +53d23m19s dist: 0.15 km az: 326.4d NNW Path direction: 56.4d ENE ground speed: 7.943 km/s width: 34.9 km max. duration: 1.2 s


ISS Transit email alert