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 0.5°x0.5° 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.
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):
Launch Date (UTC):
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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 |