Satellites in lunar penumbra - SkyMap

From: Björn Gimle (
Date: Thu Oct 23 2003 - 15:48:35 EDT

  • Next message: Ted Molczan: "TJM obs of 2003 Oct 24 UTC"

    Since version 6.3, SkyMap has an option to find track segments where the
    Sun is partially obscured.
    It uses track colors dark blue and dark purple, but my color vision is so
    poor I can barely tell the difference if I see them side by side.
    Also there is a lot of trial and error, selecting the time and direction
    to look, unless you have some coordinates for the umbra limit (or center
    line) that you can convert to look angles.
    If you produce a HPGL file, you can search for the SP (select pen)
    commands, and compare to one without the flag below, and see which pen
    codes are added (and locate the context, like time and sat name labels -
    and chart location).
    Rob ??
        Added toggle (F8) in Lighting Constraint Menu to instruct
        SkyMap to check if the sun is occulted by the moon as viewed
        from the satellite.  (This toggle should be set "Off" unless
        you know a solar eclipse is occurring.  The added overhead of
        determining the moon's position will noticeably increase run
        When F8 (Check for satellites in lunar umbra) is "On", program
        determines if moon occults any portion of the sun as seen from
        the satellite.  If so, the satellite visual magnitude is adjusted
        to account for the fraction of the sun occulted.
        If the sun is more than 50% occulted, the satellite track color
        is set to dark blue.  (This is a slightly darker blue than the
        blue used for tracks when the earth limb is blocking part of the
        sun.)  If the sun is more than 90% occulted, the satellite track
        color is set to dark purple (a darker purple than that used for
        tracks dimmer than the satellite magnitude limit).
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    This archive was generated by hypermail 2b29 : Thu Oct 23 2003 - 17:28:59 EDT