Re: brightness of James Webb Space Telescope

From: Tony Beresford (
Date: Sat Oct 30 2010 - 12:21:46 UTC

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    At 01:27 PM 29/10/2010, Kevin Fetter wrote:
    >On another list, people are talking about the James Webb Space Telescope.
    >Any idea, of how bright it would appear.
    given the size (300 sq.m) and the average distance of an orbit around
    the L2 Earth Sun point i would say mag 16.5
    there are currently 2 European spacecraft at L2, Herschel &  Planck
    There was until recently the US WMAP as well  but its mission has
    All of these objects have been observed by a various
    observing station who report minor planet positions to
    the IAU's Minor planet Centre. They are a nuisance as far as the 
    asteroid astronomists
    are and the MPC are concerned of course. The standard reporting form for these
    objects as privately published by MPC staff has a crude magnitude estimate in a
    variety of pass-bands. An typical magnitude for the Herschel telescope
    is magnitude 20. its somewhat brighter for ESA,s Planck spacecraft
    being magnitude 17.5 to 18. herschel is an IR telescope of 3.5m aperture,
    while planck is looking at the cosmic background with a slightly
    smaller aperture.
    The Minor Planet Centre has a page with a menu offering predictions
    for the objects mentioned and some others, accesable via the menu
    selection of 'distant Artificial satellites' on the left hand
    side of the page at
    further links on that page get you too a list of observations.
    One is banned from jumping to the page I tried a some 12 hours
    ago.  I guess this is simply a security measure.
    Tony Beresford
    Seesat-l mailing list

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