Re: Solar Vs Lunar ISS transits

From: Gerhard HOLTKAMP (
Date: Thu Feb 23 2006 - 15:22:28 EST

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    Anthony wrote:
    >Has anyone studied the issue of solar vs lunar transits and which of the 
    >two has a tendency (if any) to be more frequent?
    I did a quick run with nominal ISS orbit elements for the whole of 2006 and 
    for locations at 50, 40 and 30 deg. latitude. I don't claim that this is in 
    any way representative but I find that you get about twice as many (solar and 
    lunar) transits at 50 deg than at 30 deg latitude. For each latitude you get 
    indeed about as many solar as lunar transits if you allow for lunar transits 
    in the daytime as well as for the nighttime and you also allow for 
    non-illuminated ISS passes in front of the Moon. Nighttime passes in front of 
    the Moon (with the ISS illuminated and non-illuminated) are about half of the 
    daytime passes.
    I have not considered the phase of Moon (whether the ISS passes in front of 
    the illuminated or the dark side). I guess many of the daytime lunar passes 
    will be difficult to observe (has anyone done that?). So I guess in practise 
    you are bound to see only half as many lunar passes than solar passes.
    Gerhard HOLTKAMP
    Darmstadt, Germany
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