Finding solar position and velocity vectors for a JD

On 9/27/2011 8:43 PM, W. eWatson wrote:
I'd like to find the six pieces of data in Subject for JD 435400.82885.
I think there are tables for these elements. Are they available on the
web or use some computation to find them?

As it happens, I had another question about the vectors and used Google.
One of the first hits was this thread I started back in late Sept.
Here's the answer to the weird date. It's actually CE 1955 October 20
07:53:32.6 UT.

What happened was that I was looking at an old source that listed the
first 7 digits of the JD. Currently, the JD starts with a 2, and current
JDs are 2 million plus. The reason why the 2 was not needed is because
back in 1955 many computers could not handle 8 digit precision in the
integer portion. Further, the JD was differenced with another JD, so an
8 digit integer portion didn't really matter in this case. Apparently,
it was common to ignore the leading 2 back then.

On 11/27/2011 3:18 PM, W. eWatson wrote:
On 9/27/2011 8:43 PM, W. eWatson wrote:
I'd like to find the six pieces of data in Subject for JD 435400.82885.
I think there are tables for these elements. Are they available on the
web or use some computation to find them?

As it happens, I had another question about the vectors and used Google.
One of the first hits was this thread I started back in late Sept.
Here's the answer to the weird date. It's actually CE 1955 October 20
07:53:32.6 UT.

What happened was that I was looking at an old source that listed the
first 7 digits of the JD. Currently, the JD starts with a 2, and current
JDs are 2 million plus. The reason why the 2 was not needed is because
back in 1955 many computers could not handle 8 digit precision in the
integer portion. Further, the JD was differenced with another JD, so an
8 digit integer portion didn't really matter in this case. Apparently,
it was common to ignore the leading 2 back then.
If anyone knows how to get the two vectors for three days before the
date and three days after the date using Horizon or some of the other
tools mentioned, I'd appreciate it.

I did send a msg to the USNO early last week about it, and have not yet
gotten an answer.

"W. eWatson" wrote in news:jauhkl$2qh$1@dont-
email.me:

On 11/27/2011 3:18 PM, W. eWatson wrote:
On 9/27/2011 8:43 PM, W. eWatson wrote:
I'd like to find the six pieces of data in Subject for JD 435400.82885.
I think there are tables for these elements. Are they available on the
web or use some computation to find them?

As it happens, I had another question about the vectors and used Google.
One of the first hits was this thread I started back in late Sept.
Here's the answer to the weird date. It's actually CE 1955 October 20
07:53:32.6 UT.

What happened was that I was looking at an old source that listed the
first 7 digits of the JD. Currently, the JD starts with a 2, and current
JDs are 2 million plus. The reason why the 2 was not needed is because
back in 1955 many computers could not handle 8 digit precision in the
integer portion. Further, the JD was differenced with another JD, so an
8 digit integer portion didn't really matter in this case. Apparently,
it was common to ignore the leading 2 back then.
If anyone knows how to get the two vectors for three days before the
date and three days after the date using Horizon or some of the other
tools mentioned, I'd appreciate it.

I did send a msg to the USNO early last week about it, and have not yet
gotten an answer.



Try asking sci.astro.research.

....
If anyone knows how to get the two vectors for three days before the
date and three days after the date using Horizon or some of the other
tools mentioned, I'd appreciate it.

I did send a msg to the USNO early last week about it, and have not yet
gotten an answer.



Try asking sci.astro.research.

Very good. I'll try it. Didn't know the NG existed.

On 27/11/2011 23:37, W. eWatson wrote:
On 11/27/2011 3:18 PM, W. eWatson wrote:
On 9/27/2011 8:43 PM, W. eWatson wrote:
I'd like to find the six pieces of data in Subject for JD 435400.82885.
I think there are tables for these elements. Are they available on the
web or use some computation to find them?

As it happens, I had another question about the vectors and used Google.
One of the first hits was this thread I started back in late Sept.
Here's the answer to the weird date. It's actually CE 1955 October 20
07:53:32.6 UT.

What happened was that I was looking at an old source that listed the
first 7 digits of the JD. Currently, the JD starts with a 2, and current
JDs are 2 million plus. The reason why the 2 was not needed is because
back in 1955 many computers could not handle 8 digit precision in the
integer portion. Further, the JD was differenced with another JD, so an
8 digit integer portion didn't really matter in this case. Apparently,
it was common to ignore the leading 2 back then.
If anyone knows how to get the two vectors for three days before the
date and three days after the date using Horizon or some of the other
tools mentioned, I'd appreciate it.

I did send a msg to the USNO early last week about it, and have not yet
gotten an answer.

It is kind of basic stuff. Either you look it up or work it out using
one of the many ephemeris programs available these days or you write a
program to do it based on the published algorithms.

See for example Ch 26 "Rectangular Coordinates of the Sun" in Meeus's
Astronomical Algorithms. I presume you are are trying to use Gauss's
method to determine the orbit of a comet from the observations?

Regards,
Martin Brown