Welcome to the NavList Message Boards.

NavList:

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

Compose Your Message

Message:αβγ
Message:abc
Add Images & Files
    Name or NavList Code:
    Email:
       
    Reply
    Re: Obscure Nautical Almanac star
    From: Frank Reed
    Date: 2021 Jan 2, 07:41 -0800

    Robin,

    Thank you. Wikipedia has some good article on constellations and asterisms, but some of the asterisms are local lore, and "local" may be as small as one astronomy club somewhere! Coincidentally (there's a lot of that going around!), NASA's apod for yesterday, 1 Jan 2021, is a deeply exposed (over-exposed??) very wide-angle photo of the southern sky about 60° tall from north of the Southern Cross --and including the Eta Carinae nebula-- through that so-called "Diamond Cross" and across the barren south celestial pole area to the Magellanic clouds. And you know the exposure is deep when globular cluster 47 Tuc looks ten times brighter than beta Hydri

    There's a comment in the caption for the photo that may be a little joke. It offers advice to find the SCP: "Just look for south pole star Sigma Octantis. Analog to Polaris the north pole star, Sigma Octantis is little over one degree fom the the South Celestial pole." Yeah, couldn't be easier! 

    Speaking of beta Hydri... Stellarium users, have a look at the data for this star. It looks to me as if the proper motion data is incorrect. It's not really "close" but then again it's "in the same ballpark" as what I believe would be the correct numbers. Any thoughts? I encountered this by running the position of the star back to 1500 AD for some testing. It was shifted from where I expected to see it by a substantial fraction of a degree, which strikes me as quite an unusual error, if that's what it is, given that this is an exceptionally well-studied nearby star (24 lightyears distance) and an astrometric standard star.

    Note: the attached image (below) is only a screen cap of a portion of the original. Here's the complete apod entry: https://apod.nasa.gov/apod/ap210101.html.

    Frank Reed

    File:


       
    Reply
    Browse Files

    Drop Files

    NavList

    What is NavList?

    Get a NavList ID Code

    Name:
    (please, no nicknames or handles)
    Email:
    Do you want to receive all group messages by email?
    Yes No

    A NavList ID Code guarantees your identity in NavList posts and allows faster posting of messages.

    Retrieve a NavList ID Code

    Enter the email address associated with your NavList messages. Your NavList code will be emailed to you immediately.
    Email:

    Email Settings

    NavList ID Code:

    Custom Index

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

    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site
    Visit this site