[AZ-Observing] Re: How deep can you see?
- From: Russell Chmela~ <rchmela@xxxxxxxxxxxxxxxxxxx>
- To: az-observing@xxxxxxxxxxxxx
- Date: Fri, 13 Dec 2002 08:31:00 -0700
Steve:
I'll pass on that project also. On some DS objects that I find near the
limits of view, I'll note these and look them up with a field guide later.
Most of what I find for results is expected, few surprises given the scope
and magnifications in use. I tend to find out more about the actual brightness
of the object when I look up such info.
The limiting magnitude is a complex cocktail of so many factors. To your
list you could add eyepiece type, collimation and clean percentage of the
optics, and how many faint contrails and how much haze from the valley or
smog from there or LA has drifted over the site. Its all splitting of hairs
and varies on timescales of minutes and not worth it (IMHO) to know.
The one from your list that is interesting is the one about flashlight
color. Years ago, if you bought from a surplus store one of Uncle Sam's
angle neck milspec green flashlights, it came with a red filter and a white
and a clear diffuser to insert over the lamp. This same light started to
include a blue-green filter about year 1988. Supposedly this color was
better for navigation and reading than the red. I tried it once or twice
and found it just as good as red if I put in the clear diffuser also. Did
not do much beyond that as I drew lots of comments from observers about a
non-standard color light on the site. and most of this came from the astro
photographers.
At this point with the weather we have had, I'll take any night we can
get, twilight, midnight, aurora, tired, wired, just give us some!
RC
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
A variety of questions to answer here:
What is the magnitude difference at a site close to the city versus a dark sky
site?
What is the magnitude difference right at the end of twilight versus at
midnight?
How much does getting tired effect these limits?
Does caffeine or chocolate help?
Is red light better than dim green light for reading charts?
How long after reading a chart does it take to return to 100% capability?
Can an observer spend so much time determining magnitude limits that no deep
sky observing gets done?
An interesting study, I am not certain that I wish to take it on, but I would
like to see someone else's results.
Clear Skies;
Steve
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