[AZ-Observing] Re: Rigorous Precession
- From: "AJ Crayon" <acrayon@xxxxxxx>
- To: <az-observing@xxxxxxxxxxxxx>
- Date: Sat, 22 May 2010 10:48:47 -0700
Stan and Ken, I am just now in the middle of working on a program to take an
objects position and determine its constellation. In the process the
coordinates are precessed back to 1875, which is the date constellation
boundaries were agreed upon.
That said I have a program, from Project Pluto, that precess coordinates
from one epoch to another. During my research I did check out Sky Catalog
2000.0. The only, seemingly difference, seems to be amongst the constants
in use. So it appears those constants change from time to time and I don't
know how to find the most current ones, but I would believe the ones from
Project Pluto to be more current than 1970 or 2000.
Any idea how to determine to most current constants?
AJ Crayon
Phoenix, AZ
----- Original Message -----
From: "Ken Sikes" <kengsikes@xxxxxxx>
To: <az-observing@xxxxxxxxxxxxx>
Sent: Saturday, May 22, 2010 10:28 AM
Subject: [AZ-Observing] Re: Rigorous Precession
Stan, I am quite familar with what you are talking about in rigourus
precession methods. Back in the 1970's I wrote a reduction for Richard Lines
to reduce his photoelectric readings. To precess to epoc of date I needed to
precess from Jan 0 1900 to current date using Simon Newcombs constants. Bill
Andersen and I went to Lowell and got Art Hoag's permission to us e the
library to research Newcomb's constants even farther.
I also have an excellant book "Astronomical Algorithms" by Jean Meeus
published by Willmann-Bell that has the constants for both the last and
current centries.
Ken Sikes
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