Hi:
When I was out at the Sentinel-Schwaar Stargaze a few weeks ago, my friend Steve Coe found an object that would be a good test of light loss for a big SCT with a binoviewer.
The object is NGC3165 in Sextans. I've had my copy of The Sky filtered at the limit of the NS11, mag 14.7. The Sky lists this barred spiral galaxy as mag 15, although Guide has it at 14.5. Therefore, I had never even looked for this object before.
With a single eyepiece, this was an averted vision object in the NS11, visible maybe 20% of the time.
So, check the limiting magnitude of your scope, and see if you can find this object with a binoviewer. I'll try next trip out to a dark site.
Careful, NGC3166 and NGC3169 are close by.
NGC3165 Summary
Clear skies,
Jim
A limiting magnitude test
Started by
Guest_**DONOTDELETE**_*
, May 08 2003 01:52 PM
1 reply to this topic
#2
Tom T
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A Father, A Teacher, A Pioneer
Posted 08 May 2003 - 02:22 PM
Jim,
Is it a cause for concern if I can't see this object in my binoviewed pronto?
Seriously tho, testing your "speed limits" is a neat thing to do. Brian Skiff did an indepth photometric treatment of the M57 area that is another great way to do it. This is a nice way to determine just how deep you can go, and M57 will shortly be placed very advantageously (if you are a late night/morning person, it already is). This test should be pretty good for scopes 4" and up. Check out:
http://c3po.cochise....o/deepsky02.htm
And be sure to take a look at his link to the "JPEG from POSS print", cause that's where the REAL meat is:
http://c3po.cochise..../M57!dss2_3.jpg
Remember this is also a test of transparency, (and the observer
) as well as light loss, and you may want to repeat the test on a couple of different nights. Of course the usual warnings apply: Give yourself time to dark adapt, stay away from nicotine and alchol, etc...
Jim, I remember a globular region that had a similar treatment, but I can't seem to find the link - anyone have this? I think it was maybe the m13 area?? Nearly any region that has had a somewhat detailed photometric treatment would work, although some would probably be better than others.
Great idea Jim - thanks for bringing it up!
Tom T.
Is it a cause for concern if I can't see this object in my binoviewed pronto?
Seriously tho, testing your "speed limits" is a neat thing to do. Brian Skiff did an indepth photometric treatment of the M57 area that is another great way to do it. This is a nice way to determine just how deep you can go, and M57 will shortly be placed very advantageously (if you are a late night/morning person, it already is). This test should be pretty good for scopes 4" and up. Check out:
http://c3po.cochise....o/deepsky02.htm
And be sure to take a look at his link to the "JPEG from POSS print", cause that's where the REAL meat is:
http://c3po.cochise..../M57!dss2_3.jpg
Remember this is also a test of transparency, (and the observer
) as well as light loss, and you may want to repeat the test on a couple of different nights. Of course the usual warnings apply: Give yourself time to dark adapt, stay away from nicotine and alchol, etc...Jim, I remember a globular region that had a similar treatment, but I can't seem to find the link - anyone have this? I think it was maybe the m13 area?? Nearly any region that has had a somewhat detailed photometric treatment would work, although some would probably be better than others.
Great idea Jim - thanks for bringing it up!
Tom T.
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