Re: NEAs or NEAs today?

Stefano TREVISAN Mar 31, 2010

Thank you. You've got the point, that is exactly my original question: why there is such a difference?
I ALWAYS use ONLY the NEAm00.dat but I would like to know why the two datasets give different results.
Stefano.

--- In guide-user@yahoogroups.com, "P. Clay Sherrod" <drclay@...> wrote:
>
> Why are you using two files?
> You should be using NEAm00 for the date on which you want to observe. That is the
> estimated position for the exact current epoch. There is no need to use both files.
> There will be a difference (why, I do not know) between NEA and NEAm00 and I recommend
> using ONLY NEAm00, which is the same file as the previously know file as "neatod.dat" on
> the older MPC site.
>
> Dr. Clay
> _____
> Arkansas Sky Observatories
> MPC H45 - Petit Jean Mountain South
> MPC H41 - Petit Jean Mountain
> MPC H43 - Conway West
> http://www.arksky.org/
>
>
>
> ----- Original Message -----
> From: "Stefano TREVISAN" <trvsfn@...>
> To: <guide-user@yahoogroups.com>
> Sent: Wednesday, March 31, 2010 1:08 AM
> Subject: [guide-user] Re: NEAs or NEAs today?
>
>
> > OK experiment, try this:
> > 1) download the two files, NEA and NEAm00 from MPC and rename them both mpcorb.dat, (of
> > course keep them separeted in two different directories)
> > 2) put one of them in Guide,
> > 3) choose one asteroid, let us say 2010 FL48, but enyone else is fine, if it is fast is
> > better,
> > 4) show the asteroid on Guide,
> > 5) keep note of the time and AR and Dec,
> > 6) substitute the first mpcorb.dat file with the second,
> > 7) set the same time as recorded at point 5 and check the coordinates for the same
> > asteroid you choosen at point 3,
> > 8) compare the two mesures as point 5 and point 7 of AR and Dec, are they the same?
> > Best regards, Stefano
> >
> > --- In guide-user@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
> >>
> >> I use the database every night and other than small residuals which should be expected,
> >> the targets are very much where they "should be". I am not sure why you would be
> >> seeing
> >> any offset unless the TIME on your computer or telescope is set incorrectly....I have
> >> noted that Guide is once again "losing an hour" compared to true GMT because of the DST
> >> time change. I had to change one observatory computer TIMEOFFSET = 1 and then reboot
> >> to
> >> have the correct GMT...that very likely could be the source of the offset.
> >>
> >> Dr. Clay
> >> _____
> >> Arkansas Sky Observatories
> >> MPC H45 - Petit Jean Mountain South
> >> MPC H41 - Petit Jean Mountain
> >> MPC H43 - Conway West
> >> http://www.arksky.org/
> >>
> >> ----- Original Message -----
> >> From: "Stefano TREVISAN" <trvsfn@>
> >> To: <guide-user@yahoogroups.com>
> >> Sent: Tuesday, March 30, 2010 11:44 AM
> >> Subject: [guide-user] Re: NEAs or NEAs today?
> >>
> >>
> >> > OK, sorry, please read NEAm00 instaed of NEAtod in all my previous messages, I keep
> >> > using the old name but I mean NEAm00.
> >> >
> >> > Stefano
> >> >
> >> > --- In guide-user@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
> >> >>
> >> >> Where are you getting NEAtod datasets? MPC is no longer putting out that file. It
> >> >> is
> >> >> now
> >> >> only NEAm00. If you are picking up NEAtod.dat files from a mirror site, that is
> >> >> very
> >> >> likely outdated. (probably from Feb. 12 when MPC computers were hacked).
> >> >>
> >> >> Dr. Clay
> >> >> _____
> >> >> Arkansas Sky Observatories
> >> >> MPC H45 - Petit Jean Mountain South
> >> >> MPC H41 - Petit Jean Mountain
> >> >> MPC H43 - Conway West
> >> >> http://www.arksky.org/
> >> >>
> >> >> ----- Original Message -----
> >> >> From: "Stefano TREVISAN" <trvsfn@>
> >> >> To: <guide-user@yahoogroups.com>
> >> >> Sent: Tuesday, March 30, 2010 7:02 AM
> >> >> Subject: [guide-user] Re: NEAs or NEAs today?
> >> >>
> >> >>
> >> >> > Hi Dr. Clay,
> >> >> > that is what I knew and what I do.
> >> >> > Nevertheless I still don't fully understand why I get different results using the
> >> >> > NEA
> >> >> > and the NEAtod datasets.
> >> >> > Many thanks for your replay.
> >> >> > Stefano
> >> >> >
> >> >> > --- In guide-user@yahoogroups.com, "P. Clay Sherrod" <drclay@> wrote:
> >> >> >>
> >> >> >> Hello Stefano....
> >> >> >> You will want to load "NEA Today" (NEAm00):
> >> >> >> http://www.minorplanetcenter.org/iau/MPCORB/NEAm00.txt
> >> >> >> and then change the file name AND extension (.dat) to the
> >> >> >> mpcorb.dat and neatod.dat names.
> >> >> >>
> >> >> >> Having both datasets (identical except for different names) in Guide will allow
> >> >> >> the
> >> >> >> same
> >> >> >> dataset to match in both Guide and Charon.
> >> >> >>
> >> >> >> Dr. Clay
> >> >> >> _____
> >> >> >> Arkansas Sky Observatories
> >> >> >> MPC H45 - Petit Jean Mountain South
> >> >> >> MPC H41 - Petit Jean Mountain
> >> >> >> MPC H43 - Conway West
> >> >> >> http://www.arksky.org/
> >> >> >>
> >> >> >> ----- Original Message -----
> >> >> >> From: "Stefano TREVISAN" <trvsfn@>
> >> >> >> To: <guide-user@yahoogroups.com>
> >> >> >> Sent: Tuesday, March 30, 2010 5:28 AM
> >> >> >> Subject: [guide-user] NEAs or NEAs today?
> >> >> >>
> >> >> >>
> >> >> >> > Hi all,
> >> >> >> > I downloaded the two files from the MPC mirror, saved both as mpcorb.dat and I
> >> >> >> > used
> >> >> >> > them
> >> >> >> > on Guide.
> >> >> >> > Same asteroid, same time, same...all but the positions shown on Guide are
> >> >> >> > slightly
> >> >> >> > different.
> >> >> >> > I know I have to use NEAtod.dat but I do not understand the difference between
> >> >> >> > the
> >> >> >> > two
> >> >> >> > datasets, or better, I don't understand why two different results.
> >> >> >> > Probably this issue was already discussed in this forum in the past but I
> >> >> >> > didn't
> >> >> >> > find
> >> >> >> > it, sorry.
> >> >> >> > Any help is really appreciated.
> >> >> >> > Best regards
> >> >> >> > Stefano TREVISAN
> >> >> >> > B38
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> > ------------------------------------
> >> >> >> >
> >> >> >> > To unsubscribe from this group, send an empty email to:
> >> >> >> > guide-user-unsubscribe@! Groups Links
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >> >
> >> >> >>
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> > ------------------------------------
> >> >> >
> >> >> > To unsubscribe from this group, send an empty email to:
> >> >> > guide-user-unsubscribe@! Groups Links
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >>
> >> >
> >> >
> >> >
> >> >
> >> > ------------------------------------
> >> >
> >> > To unsubscribe from this group, send an empty email to:
> >> > guide-user-unsubscribe@! Groups Links
> >> >
> >> >
> >> >
> >> >
> >>
> >
> >
> >
> >
> > ------------------------------------
> >
> > To unsubscribe from this group, send an empty email to:
> > guide-user-unsubscribe@...! Groups Links
> >
> >
> >
> >
> >
>