Astrophotography by Anthony Ayiomamitis

Satellite Transit Gallery

I have a particular interest in satellite transits across the solar/lunar surfaces due to the opportunity they present the lucky observer to discern greater physical detail and structure as a result of their silhouette against the bright background of the sun and/or moon; the ability to restrict the satellite's location in the daytime or evening sky to an area measuring 0.5x0.5 with little or no effort; it permits for the bypassing of satellite tracking which itself is a challenge due the very short period transits are visible during a particular overhead pass; and the difficulty in obtaining accurate and timely orbital elements and TLE's. As this "search and identify" project has literally become a DAILY ritual, I expect this web page to be updated constantly with more and more images of the very unique phenomena of satellite transits across the solar and/or lunar disks.

Note: The capture of a solar transit by the International Space Station was an incessant chase for 3-4 years until July 28, 2005 when the ISS (with STS-114) was finally captured transiting against the Sun and which included the space shuttle Discovery. Approximately nine months later, the ISS was also caught transiting the rising moon (click here) albeit at a very low altitude. My best ISS transit capture occurred in 2010 when the ISS was at a range of 432.4 km away. During the same year, I was able to also capture the ISS during the day transiting Jupiter at a range of 439.5 km as well as Mars at a range of 565.9 km.

The transit below involves the latest ISS captured successfully and perhaps the most difficult owing to the fact that the transit was a grazing event in every sense of the word. Such transits have a duration which are best measured in hundredths of a second and, as such, the element of luck plays a major role. The sunspot on the northwest quadrant is AR1176.

Note: Following my successful capture of the ISS with the space shuttle Discovery (STS-114) transiting the sun on late July/2005 and which appeared on NASA's APOD (AstroPhoto of the Day, July 29, 2005), I received many requests for instructions in the identification and observation of similar opportunities and which are now fully documented here.

Note: For a complete set of images involving the International Space Station, click here.

Note: Unfortunately the presence of strong winds and thin clouds adversely impacted the fine resolution which is normally possible otherwise.


Image Details
ISS Transits the Sun
Imaging Details
Satellite(s):
Int Space Station

USSPACECOM Cat No:
25544 (ISS)

Physical Dimensions:
73.0 x 44.5 x 27.5 m

Orbit / Inclination:
351.3 x 355.1 km, 51.6

Range (Image):
481.2 km

Angular Diameter:
38.5 " (ISS)

Pass Details (ISS):
Duration : 0.19 sec
Angular Vel : 52.9 ' / sec
Direction : 32.8
Azimuth : 218.1
Altitude : 46.3

Launch Date (UTC):
Nov   20, 1998   (ISS)
Date:
Mar 23, 2011
14:13:12 UT+3


Location:
Athens, Greece

Equipment:
AP 160 f/7.5 StarFire EDF
AP 2x Convertible Barlow
AP 1200GTO GEM
Canon EOS 5D Mark I
Baader UV/IR-Cut filter
Baader ND-5 (full-aperture)


Exposure:
1 x 1/1600 sec
ISO 800
RAW image format
4368x2912 image size
Continuous Servo Mode
Manual Mode


Software:
Photoshop CS2

Processing:
RAW to TIFF (16-bit conv)
Grayscale
Unsharp Masking
Brightness/Contrast
Levels
Resampling
Cropping
JPG Compression