After a few quick calculations, Albers said that the limiting magnitude
at that altitude in daylight should be about 4th magnitude.
The brightness of the faintest star that can be seen on a given night, is the limiting magnitude
It is readily visible when the limiting magnitude
Figure 2 shows how the limiting magnitude
changes with focal ratio for a given focal length.
Koos observed up to 3/hr under limiting magnitude
(LM) = 5.
A total of 132 limiting magnitude
observations recorded on clear nights were compiled and plotted on maps of the tri-county area using Geographic Information Systems software.
The limiting magnitude
for supernovas would be somewhere between 24.
You can see it as a soft little hazy patch of light on the west side of the Keystone asterism in Hercules -under skies with a limiting magnitude
of about 6.
The star chart below can be used for checking the limiting magnitude
around the south celestial pole with the naked eye.
Observers are reminded to carefully record the observing conditions and the stellar limiting magnitude
, and should also bear in mind the nightly eastwards 'drift' of the Perseid radiant due to Earth's orbital motion.
It was a perfectly clear night with excellent seeing conditions and exceptional transparency with a limiting magnitude
A limiting magnitude
was obtained from each observation.