View Single Post
  #24  
Old 11-10-2012, 02:20 AM
glenc's Avatar
glenc (Glen)
star-hopper

glenc is offline
 
Join Date: Jun 2005
Location: Terranora
Posts: 4,161
Magnitude Limits

How faint were the galaxies that the Herschels saw?
How good was their speculum reflector compared to the refractors used by others?

The answers are in the attached table.
Columns
Observers that found more than 50 NGC and IC galaxies
Number of galaxies found, visual not photographic
Sorted by aperture in inches, speculum reflectors in yellow
5% of galaxies are brighter than magnitude
25% of galaxies are brighter than magnitude
50% of galaxies are brighter than magnitude
75% of galaxies are brighter than magnitude
95% of galaxies are brighter than magnitude
Faintest galaxy seen ?? The faintest galaxy magnitudes may not be reliable.

95% of the galaxies found by William Herschel were brighter than magnitude 13.9.
95% of the galaxies found by John Herschel were brighter than magnitude 14.1.


Speculum only reflects 65% of the light.
William Herschel used the front view with no secondary after 13 Oct 1786.

Bigourdan did an amazing job with a 12.4" refractor!
Attached Files
File Type: pdf Gxy vis mags.pdf (21.6 KB, 24 views)
Reply With Quote