Confirm my estimate of speed for Vesta

I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

On 8/4/11 10:38 AM, W. eWatson wrote:
I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

Vesta is at opposition on August 5th. Here's a chart from S&T
http://media.skyandtelescope.com/doc...Vesta-2011.pdf

On 8/4/11 10:38 AM, W. eWatson wrote:
I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?


Roughly 15 arc minutes per day from this chart
http://media.skyandtelescope.com/doc...Vesta-2011.pdf

In article ,
W. eWatson wrote:
I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

That's probably the speed that it's moving in alt-az coordinates -
Earth's rotating at fifteen arc-minutes per minute (360 degrees per
day), so the 'fixed stars' move at 15*cos(declination) arc-minutes per
minute, and Vesta currently has declination -23 degrees so cos(23
degrees) * 15 = 13.8.

Tom

"W. eWatson" wrote in message
...
I used The Sky 6 to figure out how fast Vesta is moving and found it to be
13 arcmin/minute. That seems very fast. Can someone confirm it?

I used SkyTools 3 to show me 'ticks' for Vesta @ 5 days apart, then used its
Measuring Tool to show that the distance between the 8/4/11 and 8/9/11 ticks
to be very close to 1.25 degrees for the 5 days.

1.25 degrees per 5 days = 75 arcmin/ 5 days = 15 arcmin/day = 900 arcsec/day
= 37.5 arcsec/hr = .625 arcsec/minute.

So, my calcs indicate that 15 arcmin/day is a lot slower than your calc of
13 arcmin/min... unless I have made an error... but I did check it twice.

\Paul A

On 2011-08-04, W. eWatson wrote:

I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

You are way off. How did you arrive at this figure? It is suspiciously
close to the apparent motion caused by the rotation of the Earth and not
the motion of Vesta against the background of the stars.

Bud

On 8/4/2011 9:17 AM, Paul A. wrote:
"W. wrote in message
...
I used The Sky 6 to figure out how fast Vesta is moving and found it to be
13 arcmin/minute. That seems very fast. Can someone confirm it?

I used SkyTools 3 to show me 'ticks' for Vesta @ 5 days apart, then used its
Measuring Tool to show that the distance between the 8/4/11 and 8/9/11 ticks
to be very close to 1.25 degrees for the 5 days.

1.25 degrees per 5 days = 75 arcmin/ 5 days = 15 arcmin/day = 900 arcsec/day
= 37.5 arcsec/hr = .625 arcsec/minute.

So, my calcs indicate that 15 arcmin/day is a lot slower than your calc of
13 arcmin/min... unless I have made an error... but I did check it twice.

\Paul A


I think you are a lot closer than I am, and probably right. It just
seemed too fast. I've never tried this in TS6 before. I'll go back and
see what the problem might be.

On 8/4/2011 9:13 AM, Thomas Womack wrote:
In ,
W. wrote:
I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

That's probably the speed that it's moving in alt-az coordinates -
Earth's rotating at fifteen arc-minutes per minute (360 degrees per
day), so the 'fixed stars' move at 15*cos(declination) arc-minutes per
minute, and Vesta currently has declination -23 degrees so cos(23
degrees) * 15 = 13.8.

Tom

Very interesting. That's quite close, but incorrectly computed via TS6.
I used the arc distance tool between two points, which now sounds
suspiciously wrong.

On 8/4/2011 9:51 AM, wrote:
On 2011-08-04, W. wrote:

I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. Can someone confirm it?

You are way off. How did you arrive at this figure? It is suspiciously
close to the apparent motion caused by the rotation of the Earth and not
the motion of Vesta against the background of the stars.

Bud
See above responses by me. Yes, it's way off.

On Aug 4, 10:32*am, "W. eWatson" wrote:
On 8/4/2011 9:51 AM, wrote: On 2011-08-04, W. *wrote:

I used The Sky 6 to figure out how fast Vesta is moving and found it to
be 13 arcmin/minute. That seems very fast. *Can someone confirm it?

You are way off. *How did you arrive at this figure? *It is suspiciously
close to the apparent motion caused by the rotation of the Earth and not
the motion of Vesta against the background of the stars.

Bud

See above responses by me. Yes, it's way off.

Harvard MPC says 61.6 arcsec/sec.
http://scully.cfa.harvard.edu/cgi-bin/mpeph2.cgi