RE: Many consecutive visible ISS passes

From: Dale Ireland (
Date: Sun Aug 05 2001 - 19:09:53 PDT

  • Next message: Ted Molczan: "USA 129 elements and observations"

    I think the maximum number of passes depends on the dates that the ISS lines
    up with the terminator, the observer's latitude, and how well a particular
    observer can spot a pass in twilight.
    It is 5 or 6 passes when the ISS lines up with the terminator about a month
    or so before or after the solstice and from a latitude about 40-45 ( very
    approximately). This latitude gives the longest night and ISS is still above
    the horizon on every pass and every pass the ISS is just barely illuminated
    (which occurs like this last sequence about 6 or so weeks before or after
    the solstice) which again means the period of darkness is maximized. The
    last parameter just depends on your eyesight.
    Lots of people have seen 5, I can't remember anyone reporting 6.
    > -----Original Message-----
    > From: Edward S Light []
    > Sent: Sunday, August 05, 2001 2:49 PM
    > To:
    > Cc:
    > Subject: Re: Many consecutive visible ISS passes
    > Recently, the question was asked regarding the maximum number of
    > consecutive ISS passes visible in the same night (i.e. sunset to
    > the next sunrise).  It seems to me that for such maxima to occur,
    > it helps if the satellite is in constant sunlight during its entire
    > orbit and I was curious how often this arises.
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