[meteorite-list] Re: Look At That Asteroid (2002 NY40)

From: birger.andresen_at_fesil.no <birger.andresen_at_meteoritecentral.com>
Date: Thu Apr 22 10:00:12 2004
Message-ID: <C1256C06.005B21C3.00_at_mailgw.fesil.no>

It could be worth mentioning that the map in the Nasa web article should be used
with care. This asteroid is, as the article expalins, only 1.3 times farther
away than the moon at the closest point the night between Aug. 17th and 18th.
That means that the trajectory against the stars is strictly correct only for
the one location it is calculated for. This is the same thing as you see solar
eclipses only from a narrow 'line' and that lunars occultations of stars are
seen only from some areas and at different times depending on where you observe
from.

Hence, you should definitely use the ephemeris program link(s) to calculate how
the trajectory looks like from your site. It is difficult to locate a 9-10 mag.
object if it is a moon diameter or so away from where you look for it.

And you better do the calculations close to the night you observe because I will
bet the orbit elements will be much more precise then that they are now. This is
a close encounter, so a small error now may translate to a large error in 2-3
weeks time if you do the calculations now. And only a small error in position at
close encounter will give a considerable deplacement on the sky. I say that
without having checked how accurate the data actually is at this time, but the
advise is general (but for fun, I have calculated this for one location now and
I will compare it with a similar calculation on August 17th to see how much the
error is).

    Birger Andresen
Received on Tue 30 Jul 2002 12:35:23 PM PDT