Superbird A update

From: Matson, Robert (
Date: Tue Jun 05 2001 - 12:04:41 PDT

  • Next message: Matson, Robert: "Superbird A flash report"

    Hi All,
    For those that have been trying to keep up with Superbird A,
    I apologize for not being able to provide predictions over
    the last month.  The Iridium solar array flare problem took
    I've now had some time to update the spin axis and precession
    rate based on observations by David Brierley, Leo Barhorst
    and myself, and particularly the terrific sequence of
    observations by Don Gardner in April and May.
    For those that care about such things, the current spin axis
    is RA 19.8914h, Dec -6.000d, with a cone angle of 89.853 deg
    (epoch June 5.16, 2001).  Best estimate of the precession
    rate is +.0405 deg/day in right ascension.
    I observed Superbird A last night from southern California in
    twilight, and had no trouble spotting the +2 magnitude flashes
    in binoculars.  Because of axis precession, this will be the
    last year that Californians will be able to observe
    Superbird A in the springtime -- next year's cycle will be
    too close to sunset.
    Here are the predicted flash period center times for various
    locations tonite (Tuesday, June 5th local, June 6th UTC).
    All times are UTC on 6 June:
    3:49  Los Angeles
    3:50  San Diego, Las Vegas, Salt Lake City
    3:51  CA/AZ border, central Utah, central Wyoming, north Dakota
    3:52  central Arizona, NW Colorado, SE Wyoming, the Dakotas
    3:53  SE Arizona, NW New Mexico, central Colorado, NW Nebraska,
          central South Dakota, NW Minnesota
    3:54  Albuquerque, SE Colorado, central Nebraska, central Minn.
    3:55  SE New Mexico, Oklahoma panhandle, western Kansas, SE
          Nebraska, NW Iowa, Wisconsin, Michigan upper peninsula
    3:56  Cabo San Lucas, western Texas, Oklahoma, Kansas, Iowa,
          southern Wisconsin
    3:57  western Texas, Oklahoma, Missouri, northern Illinois
          (Chicago), Michigan
    3:58  central Texas (Dallas), SE Oklahoma, NW Arkansas, SE
          Missouri, Illinois, Indiana, NW Ohio, Cleveland, Buffalo,
          Toronto, northern New York, northern Vermont, Maine
    3:59  southern and eastern Texas, Arkansas, Kentucky border
          with Illinois and Indiana, central Ohio, Pennsylvania,
          southern NY, Vermont, New Hampshire
    4:00  Texas Gulf coast (Houston), Louisiana, Mississippi,
          Tennessee, Kentucky, West Virginia, Maryland, northern
          Virginia, D.C., New Jersey, NYC, Long Island.
    4:01  New Orleans, southern Mississippi, central Alabama,
          northern Georgia, North Carolina, southern Virginia,
          Delmarva peninsula
    4:02  Florida panhandle, Georgia, South Carolina, southern
          North Carolina.
    4:03  northern Florida (Jacksonville)
    4:04  central Florida (Tampa, Orlando)
    4:05  southern Florida, northern Bahamas
    4:06  Cuba, Bahamas
    4:07  eastern Cuba
    4:08  Haiti, Puerto Rico, Virgin Islands
    Flash location right ascension is about the same for everyone:
    around RA 10h 55m.  Declination varies with latitude:  around
    Dec +2.4 deg for Los Angeles, +1.4 deg for Washington, D.C.,
    +1.1 deg for Chicago.  Basically the further north you are,
    the lower the declination.
    Flash period is currently 22.85 seconds +/- .015 seconds,
    with flashes also visible on the half-period for several
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