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    Re: FWD: Star Finder "2102E" spreadsheet
    From: J Tiffany
    Date: 2009 Feb 19, 14:58 -0800

    Hi Brad,
    
    I've been looking at your 2102-E spreadsheet - this is a great idea!
    This is a potentially
    amazing tool for teaching the use of the starfinder. Thanks for
    sharing it; I'm sure that
    you have a significant amount of effort in it.
    
    I worked with it for quite a while. I have a few comments/suggestions
    if you don't mind my
    input. I hope these comments are useful and help you improve the tool
    (you called it a toy,
    but no, not a toy at all in my view).
    
    1) I think the ability to rotate the star field and also the way you
    show the display of the
    sun position are both wonderful ideas. But I noticed that when you
    rotate the star field,
    the vernal equinox on the sun display does not rotate with them, which
    it should. The VE
    (Aries) should always be at SHA=0 deg.
    
    2) The GHA slider is not aligned correctly with Aries. Try this: Set
    the latitude to 45
    degrees N to deform the blue overlay enough to identify the centerline
    which is 180 degrees
    or due south (this is the blue line that points directly away from the
    north celestial pole
    - on your real 2102-D it has an arrow on it that points at the LHA).
    Next, set "day of year"
    to 79 which is the day of the vernal equinox (March 20), then adjust
    the GHA slider so that
    the 180 degree line of the blue overlay crosses the center of the sun.
    Note that the GHA
    value is shown as 102 degrees, but it should read 0 degrees in this
    case.
    
    3) Again regarding the "GHA Aries" slider, I think this should be
    labelled "LHA Aries", and
    the range of the slider should be 0-360 deg with the blue overlay
    rotating once (currently
    it goes from 0-180-0-180-0 and the blue overlay rotates twice through
    the slider range).
    
    4) The star "Alphard" is misspelled "Alpharad" - (finally, an easy
    fix!)
    
    5) The star field is displayed differently than on a 2102-D - it is
    reversed. The
    spreadsheet display is like a planisphere "facing North" view and
    shows the stars as they
    would appear in the sky - the 2102-D shows what the geographic
    positions (subpoints, if you
    prefer) of the stars would look like if plotted on the (flattened)
    surface of the Earth. Try
    this: Rotate the star field until Archernar is at the top. Notice that
    Ankaa is displayed to
    the lower left of Archernar. Now take out your 2102-D star base (North
    side) and likewise
    turn it so that Archernar is at the top. You'll see that Ankaa is
    displayed to the lower
    RIGHT of Archernar. Compare the other stars and you will see that they
    are all reversed in
    regards to their positions between the spreadsheet and the 2102-D.
    Some people who are
    accustomed to using planispheres think that the 2102-D is "backwards",
    but it just uses a
    different viewpoint, one that is better for celnav.
    
    6) Would be nice if the correct hemisphere (for the stars) could be
    taken from the latitude
    slider rather than the N/S radio buttons, so you don't accidentally
    have the latitude slider
    in the S hemi and acidentally leave the stars in the N hemi
    configuation (yes, this is
    getting picky, sorry).
    
    7) The Blue overlay doesn't seem to work correctly in S hemisphere
    latitudes.
    
    Again, I think you have created something really significant here.
    
    Regards,
    John
    Tokyo, Japan
    
    On Feb 14, 5:23�pm,  wrote:
    > Here is my version of the 2102-D, upgraded to the 2102-E. �
    >
    > Some general directions for use.
    > 1) Just play with the slider bars, don't attempt to type in your desired values, as that has no effect
    > 2) You can adjust the Day of Year, which places the solar disk
    > 3) You can adjust the Latitude (most fun) to see ANY latitude clear overlay
    > 4) You can adjust for Aries
    > 5) You can rotate the stars
    > 6) You can select northern or southern hemisphere.
    >
    > PLEASE DONT USE THIS FOR ACTUAL NAVIGATION. �Its just a toy.
    >
    > Depending upon your settings, you may have to enable content. �
    >
    > For those who want to see how I made it work, you will have to unhide 
    worksheet elements. �There is no password protection, I just hid the sheets 
    so it wouldn't be destroyed immediately by "poking around"!
    >
    > The key to the entire deal is azimuthal equidistant. �The mathematics are published in many places.
    >
    > Enjoy!
    >
    > Best Regards
    > Brad
    >
    > Linked File:https://www.NavList.net/imgx/2102e.xls
    
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