Bill;

Reading your recent post to the Guide user group, "(For those wondering
what UTC vs. UT1 is..." reminded me of one of my pet peves.

How does Guide manage time for people who live 'not exactly' of their
Time Zone line. Say, I live exactly between my Time Zone line and that of
the 'next' Time Zone. Guide8 gives me choices, Standard Time or Daylight
Savings Time, but that is the Time Zone's time, not my actual time some 29
minutes later, or an offset of -5.5hrs. I want an accurate Siderial Time to
the minute. Presently, to my knowledge, I have to use the time which I live
in, not actually of 'where' I live.

To get around that I go to USNO's "Calculate Local Apparent Siderial
Time" page, http://tycho.usno.navy.mil/sidereal.html to get my
actual/apparent time which I manually load it into Guide8.

I'm wondering if you've taken 'Local Apparent Siderial Time" into
account in your programming of Guide8 and I'm causing problems for myself by
doing what I have.

Thkx for your continued and valued support of Guide8, sometimes you
really open my eyes with some of the things you talk about. What a way to
learn...joe :)


"May You Go Among The Imperishable Stars"

Joe Mize: jmize@...
StarFields Observatory http://www.cav-sfo.com
Chiefland, FL 29:24'33.4"N 82:51'37.7"W
Moon Phase: http://tycho.usno.navy.mil/cgi-bin/phase.gif

----- Original Message -----
From: "Bill J Gray" <pluto@...>
To: <guide-user@yahoogroups.com>
Sent: Wednesday, January 19, 2005 9:47 PM
Subject: [guide-user] Satellite mags/UCAC-2 coverage/UTC/WCS


>
> Hi Kevin,
>
> There are some odd things going on with the magnitude data. I asked
> Mike McCants about this not long ago. Seems the magnitude data in the
> 'quicksat' file (the one Guide is now using) is for "full" phase,
> rather than the usual 90% illumination. That's no biggie (the difference
> is pretty negligible anyway).
>
> The second problem is trickier: the 'quicksat' mag is the brightest
> possible (and therefore least likely) magnitude, i.e., the one you'd
> get if the object was ideally oriented. The Molczan magnitude is based
> on a more average orientation. So contrary to what you might expect,
> the Molczan and Quicksat mags don't match.
>
> (In truth, I could see both being useful... i.e., "this object is
> usually about mag 6, but sometimes rises to 4." I may modify Guide
> accordingly.)
>
> About UCAC: the status image you're mentioning shows the portion of
> the sky that the UCAC folks have _imaged_... and, as you say, that now
> includes the whole sky (they got the last of it in May 2004). However,
> the actual data released thus far isn't quite so comprehensive. See
>
> http://ad.usno.navy.mil/ucac/skycov_u2c.gif
>
> About UTC vs UT1: you're right, there is a problem here. EST is
> given as UT1 minus 5 hours, rather than as UTC minus five hours. Hmmm...
> I'll have to get back to you on that one...
>
> (For those wondering what UTC vs. UT1 is: there's a discussion here:
>
> http://www.projectpluto.com/update8.htm#utc
>
> The difference is negligible for some purposes, but not all.)
>
> I now have FITS images with WCS data (such as that inserted by PinPoint
> and a few other programs, including the SkyView server) working in Guide.
> I'll post that in a bit, after I address this UTC issue.
>
> -- Bill
>
>
>
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