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Iridium flares

Discussion in 'Astrophotography' started by CiaranCReilly, Feb 20, 2014.

  1. CiaranCReilly

    CiaranCReilly Mu-43 Veteran

    481
    Oct 18, 2012
    Dublin
    Ciaran Reilly
    Anyone else shoot Iridium flares? Heavens Above is a great source of info, and a smartphone or tablet is almost a necessity to get the timing right, you literally have a 1/(2*focal length) to hit the shutter. (1/focal length shutter speed to keep the stars round, and I've found 30 seconds a good exposure time to catch the flare with some margin).

    Here's one I shot last summer at an ancient monastic settlement and round tower called Taghadoe

    9259521668_60dcfcaf61_b.
    Iridium Flare at Taghadoe by Ciaran C Reilly, on Flickr
     
    • Like Like x 5
  2. JudyM

    JudyM Mu-43 All-Pro

    May 5, 2010
    Westminster, MD
    Thank you for a unique thread! My husband and I have made some attempts at catching the International Space Station:

    12662969035_cb95e4804d_c.
     
    • Like Like x 4
  3. CiaranCReilly

    CiaranCReilly Mu-43 Veteran

    481
    Oct 18, 2012
    Dublin
    Ciaran Reilly
    That's very cool, looks like a meteor shower! Iridium flares are handy in that you predict them to the second, and just leave the shutter open long enough to catch them.
     
  4. JudyM

    JudyM Mu-43 All-Pro

    May 5, 2010
    Westminster, MD
    You can tell I'm a novice at this. So a shorter exposure is actually preferable? We use NASA's Human Spaceflight website to find out when the space station will be flying over, so predicting it isn't a problem. Feel free to laugh at the second one, I won't be offended. Without a reference point on the ground, it's just two streaks on a black background, but I was happy to witness it. The fainter of the two streaks is the space shuttle Discovery on her last flight. The brighter streak trailing behind is the ISS. Obviously, I need a lot of practice at this.:redface:

    12662974825_4d37ccffec_c.

    12663074933_aab118f495_c.
     
  5. CiaranCReilly

    CiaranCReilly Mu-43 Veteran

    481
    Oct 18, 2012
    Dublin
    Ciaran Reilly
    I guess it's personal, but I like to keep stars rounded, which needs a lower shutter speed.

    If you're not using a tracker, I've found that this requires a shutter speed of roughly 1/(focal length), i.e. 1/20 for a 20mm lens. This is a very rough calculation. Ultimately, I've found I need to keep experimenting with shutter speed and ISO to capture something I'm happy with. Shooting not so long after sunset, like my shot above, helps when you've looking for some detail on the horizon too.

    The second picture is cool in that you've captured a unique event in a personal way!
     
    • Like Like x 1
  6. slothead

    slothead Mu-43 All-Pro

    Aug 14, 2012
    Frederick, MD
    Nice shots Claran.

    I don't even know what Iridium flares are (but I will soon find out)! I do know that Iridium (beside being an element) is the program name for Motorola space-borne communications system. In fact we used their solar array on the HST for Servicing Mission 3.

    Judy, you've made a great start. I only wish we could get a few clear comfortable nights here on the east coast of the USA.

    I have used the Langley Research Center's overpass prediction tool ( http://cloudsgate2.larc.nasa.gov/cgi-bin/predict/predict.cgi ).