Re: [guide-user] GSC-2.2/SDP4/million galaxies/etc.

Juan Carlos Rosso Jun 23, 2001

Hi,
    I've tested the new GSC2.2 feature in two computers with different Internet connections (dial-up and LAN) without success. When I click on the toolbar button the hard drive shows activity but there's no further data traffic on the Internet connection. Maybe this report can help you make this promising feature go. Bye.
----- Original Message -----
From: Bill J. Gray
To: guide-user@yahoogroups.com
Sent: MiƩrcoles, 20 de Junio de 2001 09:31 a.m.
Subject: [guide-user] GSC-2.2/SDP4/million galaxies/etc.

Hi folks,

   I've just posted an update (for testing purposes) with the function
to grab chunks of GSC-2.2 and display them.  Details are at

http://www.projectpluto.com/gsc22.htm

   At present,  it's not announced in the "usual" update spot,  and won't
be until I hear from a few people telling me that it worked on their PCs.

   Mark Elowitz asked about SDP4 implementation in Guide.  I was about
to reply that the main obstacle to this has been the fact that I found
excellent C source code for SGP4,  but nothing for SDP4.  However,
Mark's post prompted an e-mail from Magnus Backstrom offering me his C
code for SGP4/SDP4.  His code looks _quite_ good;  like me,  he started
with NORAD code,  and went to great lengths to turn it into something
understandable by mere mortals.  However,  I only had SGP4 code,  and
his version should get me past the SDP4 hurdle (at last!)

   This won't happen,  though,  until Guide 8 is out the door.  I am
doing my best to resist making "software-only" changes,  so I can focus
on items that must go on the CD-ROMs.  Software-only improvements can
be made anytime I want,  thanks to the wonders of the Internet.

   For the nonce,  I'd point out that you _can_ use SGP4 to get passable
high-satellite data... but the elements have to be of fairly recent date.
Several people have been tracking geosynchs and Molniyas with Guide by
making use of this fact.

   Regarding display of the million-galaxy catalog(ue):  see

http://www.projectpluto.com/guide8.htm#pgc1m

   Incidentally,  the aforementioned GSC-2.2 does a more impressive job
of showing galaxies (including their orientations and position angles)
than I would have expected.

   Regarding GPS:  ummm... maybe eventually... though the main reason
would be more to let the PC get the (highly accurate) GPS time.  The
lat/lon would be nice,  but you can enter that by hand without great
difficulty.

-- Bill




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