NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

HOME

Re: Aldebaran occultation
From: Paul Hirose
Date: 2017 Mar 7, 11:05 -0800

On 2017-03-07 9:13, Brad Morris wrote: > Alex notes his time of occultation at 3h56m48s. > > Paul, using up to the minute tools, makes that "4 seconds earlier" at > 3h56m44s. Actually my Lunar4 program was not designed for serious occultation computations. For simplicity it assumes the Moon's limb is a perfect circle. That's why I gave results to only .01′ precision, and I'm not confident about the last digit. However, I've never tested the program against the IOTA predictions, which I assume include all the refinements. At IOTA's nominal Indianapolis site the Aldebaran lunar distance errors from Lunar4 are +.014′ (begin) and +.012′ (end), but those are only two points on the limb. I want to try more points, and more than one occultation to get some variation in libration angles. Don't expect a lunar limb model in Lunar4. I don't think it's worth the bother. But the next release may include a small change in Moon radius. Currently I use the IAU value, 1737.4 km. Based on private correspondence with another enthusiast, I believe 1738.0 km is a better fit to the mean limb visible from Earth. That would eliminate about half the error in the values above.

What is NavList?

NavList is a community devoted to the preservation and practice of celestial navigation and other methods of traditional position-finding. We're a group of navigators, navigation enthusiasts and hobbyists, mathematicians and physicists, and historians interested in all aspects of navigation but primarily those techniques which are non-electronic.

To post a message, if you are already signed up as a NavList member, start a new discussion or reply to any posted message and use your posting code (this is a simple low-security password assigned when you join). You may also join by posting. Your first on-topic messsage automatically makes you a member, and a posting code will be assigned and emailed to you for future posts.

Uniquely, the NavList message boards also permit full interaction entirely by email. You can optionally receive individual posts or daily digests by email, and any member can post messages by email (bypassing the web site) by sending to our posting address which is "NavList@NavList.net". This functionality is similar to a traditional Internet mailing list: post by email, read by email, reply by email. Most members will prefer the web interface here for posting and replying to messages.

NavList is more than an online community... more about that another day.

© Copyright notice: please note that the rights to all messages and posts in this discussion group are held by their respective authors. No messages or text or images extracted from messages may be reproduced without the explicit consent of the message author. Email me, Frank Reed, if you have any questions.

Subject:
Author:
Start date:	(yyyymm dd)
End date:	(yyyymm dd)

NavList:

A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

Compose Your Message

NavList

What is NavList?

Join / Get NavList ID Code

Retrieve a NavList ID Code

Email Settings

Custom Index

Add Images & Files
Name or NavList Code:	Email:

Name:
	(please, no nicknames or handles)
Email:

NavList ID Code: