S&T 2004XP14 Charts off by 10 mins?

My sons and I compared the S&T 2004XP14 charts from the website to those
produced by Cartes du Ciel, and we think that the 6:00 UT mark is actually
6:10 UT, and that the track labels are correspondingly all 10 mins off. I
just talked with a fellow astro club member who uses different software, and
he too shows a 10 min discrepancy. If you have difficulty using the S&T
charts try adjusting them by 10 mins.

Dennis

Dennis Woos wrote:
My sons and I compared the S&T 2004XP14 charts from the website to those
produced by Cartes du Ciel, and we think that the 6:00 UT mark is actually
6:10 UT, and that the track labels are correspondingly all 10 mins off. I
just talked with a fellow astro club member who uses different software, and
he too shows a 10 min discrepancy. If you have difficulty using the S&T
charts try adjusting them by 10 mins.

As noted in another thread in this group, because 2004XP14 is passing
so close to the Earth, its apparent position varies greatly with your
topocentric position. It is unlikely that any one North American wide
chart will be accurate. Rather using your planetarium program with
updated orbital parameters for this asteriod, generate a finder chart
for your location.

For Cartes du Ciel and the Asteriod catalogue dialogue, use the update
button. There is a new download program fix at the Cartes du Ciel site
dated May 2006 that updates the "externes.ini" file for a change in the
download path for the asteriod data file at the Minor Planet Center.
See further info at:
http://www.stargazing.net/astropc/download.html

Comets and Asteriod Update 5/26/2006
http://www.stargazing.net/astropc/prog/extres.ini

"CfA web site change is base url from cfa-www to www.cfa. As the
program do not follow the url redirection the download failed. Replace
this file in the Ciel directory to use the new url."

- Canopus56

Kurt wrote:
As noted in another thread in this group, because 2004XP14 is passing
so close to the Earth, its apparent position varies greatly with your
topocentric position. It is unlikely that any one North American wide
chart will be accurate. Rather using your planetarium program with
updated orbital parameters for this asteriod, generate a finder chart
for your location.

The chart provided by Sky and Telescope has multiple tracks, one for
each of five different locations: Miami, Boston, Seattle, Los Angeles,
and Hawaii. Interpolation is possible, although non-trivial.

Over much of the tracks, the asteroid moves an apparent 1 to 1.5 degrees
per 10 minutes. At these times, the distance of the asteroid (something
over 430,000 km) implies that a separation of about 7,500 km is needed
to change the apparent position of the asteroid by even 1 degree. So
variations in observing site are unlikely to account for a 10-minute
error in track.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

Dennis Woos wrote:
My sons and I compared the S&T 2004XP14 charts from the website to those
produced by Cartes du Ciel, and we think that the 6:00 UT mark is actually
6:10 UT, and that the track labels are correspondingly all 10 mins off. I
just talked with a fellow astro club member who uses different software, and
he too shows a 10 min discrepancy. If you have difficulty using the S&T
charts try adjusting them by 10 mins.

The Minor Planet Ephemerides site agrees with the Sky and Telescope map;
for instance, at 7:00 UT in Los Angeles, it shows the declination of
2004 XP14 to be 54 degrees, 55 minutes, 12 seconds. Obviously, the map
doesn't allow visual determination of that kind of precision, but the
position clearly isn't 10 minutes off; that would require an error in
declination of about a degree or so.

To be safe, you might as well scan along that track. Assuming you're
able to see the asteroid at all, its motion should be unmistakable; at
that time of night, the asteroid will be moving an arcminute about every
8 seconds or so. If you use 60x, that gives an apparent motion of a
degree every 8 seconds.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

I (Brian Tung) wrote:
To be safe, you might as well scan along that track. Assuming you're
able to see the asteroid at all, its motion should be unmistakable; at
that time of night, the asteroid will be moving an arcminute about every
8 seconds or so. If you use 60x, that gives an apparent motion of a
degree every 8 seconds.

Incidentally, at its closest, 2004 XP14 should subtend anywhere from
0.2 to 0.4 arcseconds. (Perigee occurs at about 4:25 UT.) That means
that folks with large scopes might be able to discern the difference in
size between the asteroid's image and the Airy disc of stars of similar
brightness. I think the difference might be hard to image, but perhaps
someone clever will do that, too, with amateur equipment.

--
Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.html

Brian Tung wrote:
[V]ariations in observing site are unlikely to account for a 10-minute
error in track.

Thanks for the correction. - C