[guide-user] Re: filtering of asteroids

Andrea Pelloni Jan 27, 2000

"Bill J. Gray" wrote:
> NEW TEST VERSION OF GUIDE:
> I'm about ready to post yet another update to the software on the Web
> site. Adventurous persons should look here:
>
> http://www.projectpluto.com/new.htm
>
> for information and a beta version.
>
> -- Bill

Dear Bill, as you know i'm very interested in asteroids work, so I
appreciated the possibility to filter asteroids, choosing mainly
only the ones close to opposition, that I asked you some time ago. So
yesterday I loaded the Test update of GUIDE and
checked the example you gave :
ASTFILTER=(y>-20) & (x>350 | x<40)
Everything went ok!
But due to the fact that now the opposition point is at about 8h 30m RA
(128°) I made this change:
ASTFILTER=(y>-20) & (x>108 | x<148)
And now the surprise: ALL the asteroids were shown, except the ones
lower than -20° DEC.
I tried then this one, inverting RA coordinates:
ASTFILTER=(y>-20) & (x>148 | x<108)
Correctly I had ALL the asteroids except the ones in the RA interval
between 7h 25m and 10h00m.
I remember that many many years ago (I was young) at the beginning of my
job in an airline, averaging 2 values of magnetic heading (I'm speaking
of aircraft) I made a mistake, so when crossing from 359° to 1° the
result was 180° and not 360°; I had not added 180° when this was
happening.
May be there happened something of this kind?

About the GUIDE 7 and USNOA.2 on hard drive, everything is OK, with my
total satisfaction: thank you.
By
Andrea