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    SofaJpl page is down
    From: Paul Hirose
    Date: 2019 Apr 8, 13:00 -0700

    On 2019-04-08 10:16, David Shoemaker wrote:
     > I've done several searches for SofaJPL and keep running into dead
    ends - http://home.earthlink.net/~s543t-24dst/SofaJpl_NET/index.html for
    example - page not found - does anybody have a working URL for SofaJPL ?
    
    My site is down, reason unknown. Until I get it working again, contact
    me by private email and I'll deliver the product as an attachment. To
    quote the web page:
    
    SofaJpl is a positional astronomy DLL to assist Windows .NET Framework
    applications with computation of celestial body positions. In my tests,
    the reduction to apparent place examples in The Astronomical Almanac are
    duplicated within one digit in the last place. Because it complies with
    the CLS (Common Language Specification), SofaJpl is equally accessible
    from all .NET Framework languages. SofaJpl was developed primarily for
    my personal use, but anyone may use it for free.
    
    SofaJpl components:
    
    • The International Astronomical Union SOFA Collection (SOFA release of
    2017-04-20), "an accessible and authoritative set of algorithms and
    procedures that implement standard models used in fundamental
    astronomy." These include astrometry, calendars, time scales, Earth
    rotation and sidereal time, ephemerides (medium precision), geocentric /
    geodetic transformations, precession, nutation, polar motion, star space
    motion, and star catalogue conversion.
    
    • Jet Propulsion Laboratory Planetary and Lunar Ephemeris software to
    duplicate the JPL Fortran programs. They convert files from the ASCII
    download format to binary, and cut, splice, read, and test the binary
    ephemerides. The files include the same Chebychev coefficients as the
    standard JPL binary files and produce the same results (verified by
    TESTPO), but the binary format is unique to SofaJpl.
    
    • A bright star subset of the Hipparcos star catalog (re-reduction by
    van Leeuwen, 2007) complete to magnitude 3, searchable by star
    designation, updated to include the names recognized by the IAU as of
    March 2018. The catalog data and designation (name) files are in VOTable
    format (a form of XML) and may be modified by the user.
    
    • A collection of classes, mainly built on the SOFA and JPL routines,
    which implement common data types and operations in positional
    astronomy, such as Julian dates, durations, time scale conversions,
    vectors, rotation matrices, decimal to sexagesimal conversion,
    calculation of geocentric and topocentric apparent place, etc.
    
    NOTE THAT SOFAJPL IS NOT AN APPLICATION AND IS NOT USEFUL UNLESS YOU CAN
    WRITE PROGRAMS. However, I have rudimentary example programs in C++, C#,
    and Visual Basic to get the user started. The free Visual Studio Express
    (or whatever they call it nowadays) development environment from
    Microsoft is a suitable compiler. In fact, SofaJpl was built with VS
    Express 2013.
    
    SofaJpl ships as a 313 k .zip file.
    
    
    The other product I mentioned is Lunar, which is a Windows application,
    i.e., requires no programming. To quote the web page:
    
    Lunar4 is a free celestial almanac and navigational sight reduction
    program for the Windows desktop environment. Its almanac function
    produces barycentric, geocentric, and topocentric coordinates. Its sight
    reduction function produces azimuth, altitude, and intercept for the
    Marcq St. Hilaire position line method. It also solves for time, given
    
    • altitudes of the Moon and another body, plus their separation angle,
    observed from an unknown location (the classic "lunar distance" problem), or
    • the altitude of a body observed from a known location, i.e., a
    navigational time sight, or
    • the separation angle between the Moon and another body observed from a
    known location
    
    The available solar system bodies are the Sun, Moon, and planets,
    including Pluto. Their positions and velocities are obtained from a Jet
    Propulsion Laboratory planetary ephemeris. An internal star catalog (a
    subset of the Hipparcos catalog, second reduction) contains all stars
    down to third magnitude. There's also a manual entry form for stars not
    in the catalog.
    
    The current release is Lunar 4.3, which ships as a 252 k .zip. That
    includes the SofaJpl components that it needs. On request I can ship
    version 4.4, which has some improvements:
    
    • Remembers some parameters from the last run, such as observer
    position, the JPL ephemeris file, and the leap second file.
    • Solar eclipse mode, which adjusts the Moon size and position to match
    the predictions in the Astronomical Almanac.
    • Center of light option for the Moon and planets, instead of the
    default center of mass as the basis of the computations.
    • JPL Horizons compatibility mode to match the output of the JPL online
    facility. (This is accomplished by changing the precession and nutation
    model.)
    
    I have not formally released 4.4, but the program is tested and giving
    complete satisfaction here. Any changes will be small tweaks to the
    appearance. On the down side, the documentation of version 4.4 is pretty
    far along but not complete. Also, this is not any sort of mass market
    product, even by celestial navigation standards. It was written to
    support the things I do, and so in its output you find arcane data such
    as the geocentric position and velocity of the topocenter with respect
    to the ICRS.
    
    To duplicate all four "equinox" times that I gave in an earlier message,
    you need v. 4.4, since 4.3 does not give the geocentric apparent place
    of a body with respect to the ITRS (geodetic) coordinate system. It does
    take polar motion into account in the computation of azimuth and
    altitude, however.
    
    Both SofaJpl and Lunar ship as .zip files which are extracted to any
    desired place in your Documents folder. (By default a new folder is
    created for the product.) Due to the small size and simplicity of both
    products, I don't think an installer is necessary. The problem with an
    installer is that it opens a security hole when it's at work, because it
    has system administrator privileges. Even with virus protection, there's
    an uneasy feeling when installing freeware from "some guy on the net."
    
    Anyone wanting either product should contact me by private email.
    

       
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