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Bortle 4 sky, 8 inch dob... and a full Moon!

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#1 kurtenstein

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Posted 23 February 2021 - 08:57 AM

Hi! We rented a cabin under dark(er) skies (Bortle 4) this weekend and I can't wait to try the 8 inch dob I got for Christmas outside of town... Problem is it'll be the full Moon, as you know.

 

Apart from open clusters, wich types of deep sky objects are worth looking at under a full Moon? (I'm not yet a double-star fan...)

 

 

Thanks!



#2 aeajr

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Posted 23 February 2021 - 09:07 AM

With a full Moon, you are no longer under Bortle 4 conditions.   Consider yourself under Bortle 7 or 8.  In this article, guidance is provide as to which targets are best under these conditions. 

 

Light Pollution
https://telescopicwa...ight-pollution/

 

Most of these will work

 

Messier with Binoculars
https://www.astrolea...s/binomesa.html

 

Messier Telrad Charts
http://avila.star-sh...ssierTelrad.htm
http://www.custerobs...cs/messier2.pdf

 

Depending on how washed out the sky appears, star hopping may be a challenge for the dimmer objects.  You may consider the AltAz method to help you. 

 

Using an angle gauge to help find targets – AltAz coordinates
https://www.cloudyni...y/#entry8120838

 

 

Things I would not spend time on would be galaxies and most nebula. 


Edited by aeajr, 23 February 2021 - 09:08 AM.

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#3 Linked-In-The-Stars

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Posted 23 February 2021 - 09:39 AM

Well, I was going to say orion, or pleaides if you can get your eyes on it depending where you will be anyhow. Seems as by (me) the moon will be up earlier, so if you can stay up a little later, it may not affect your viewing as much. Just a thought, but it would call for a late night. Again, depends on where you will be located. I would suggest getting an app on your phone to help, something like stellarium maybe? CS..



#4 chrysalis

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Posted 23 February 2021 - 10:12 AM

Aside from open clusters, globular clusters are good, but except for M79, you'd need to wait for past midnight for many to rise.

 

Then double stars, which you ruled out. But anyway:

 

Attached File  200 Most Beautiful Double Stars.xls   76.5KB   11 downloads

 

Attached File  DoubleStars Colorful.xls   43KB   5 downloads

 

Attached File  Double Stars Color Contrast.pdf   60KB   6 downloads

 

Attached File  Double Star List.doc   73KB   4 downloads

 

Attached File  Double Star List2.pdf   25.5KB   4 downloads



#5 DSOGabe

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Posted 23 February 2021 - 10:36 AM

You can still enjoy globular clusters and planetary nebulae. Some of them are small or kind of dim, but there are others that are within your scope reach under such skies



#6 LIVE LONG

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Posted 23 February 2021 - 01:55 PM

   I wish you would try observing some double star's. Beta Monoceros, & Castor in Gemini are spectacular !

 

   There are many more, but try these two and I am sure you will change your mind about observing doubles!smile.gif


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#7 coopman

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Posted 23 February 2021 - 05:13 PM

So if my skies w/o the moon are Bortle 8, then they must be Bortle 12 with the full moon!  



#8 radiofm74

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Posted 23 February 2021 - 05:28 PM

I just realized this week, being out almost every night at various locations, how much the Moon impacts astronomical observation. Under a decently dark sky, there was a massive difference between one night and three nights later. Back in town, under severe light pollution and Moon nearing full, my limiting magnitude must be around 2: I see Polaris, barely. Normally it's much better even here and on a good night I can glimpse Beta Mon.

 

So I decided to spend an hour with … the Moon! Armed with my good friend the variable polarizing filter, I enjoyed a walk among craters, rilles, seas and oceans.

 

I guess it will be much the same in coming nights, but I'll take a good look at Ed's list of "any sky" objects!

 

PS: some doubles are worth a moment of your time and yes, Beta Monocerotis and Castor are among my favorites. I'd also mention Herschel 3945 (Winter Albireo) and Sigma Orionis. Just in case you want to give some doubles a try! 



#9 kurtenstein

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Posted 23 February 2021 - 08:44 PM

With a full Moon, you are no longer under Bortle 4 conditions.   Consider yourself under Bortle 7 or 8.  In this article, guidance is provide as to which targets are best under these conditions. 

 

Light Pollution
https://telescopicwa...ight-pollution/

 

Most of these will work

 

Messier with Binoculars
https://www.astrolea...s/binomesa.html

 

Messier Telrad Charts
http://avila.star-sh...ssierTelrad.htm
http://www.custerobs...cs/messier2.pdf

 

Depending on how washed out the sky appears, star hopping may be a challenge for the dimmer objects.  You may consider the AltAz method to help you. 

 

Using an angle gauge to help find targets – AltAz coordinates
https://www.cloudyni...y/#entry8120838

 

 

Things I would not spend time on would be galaxies and most nebula. 

Thanks for those lists! I'll use them for sure... I like the one where objects are listed depending on their "easyness"...


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#10 kurtenstein

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Posted 23 February 2021 - 08:45 PM

Well, I was going to say orion, or pleaides if you can get your eyes on it depending where you will be anyhow. Seems as by (me) the moon will be up earlier, so if you can stay up a little later, it may not affect your viewing as much. Just a thought, but it would call for a late night. Again, depends on where you will be located. I would suggest getting an app on your phone to help, something like stellarium maybe? CS..

Well, I'm so tired these days... Thanks for the tip!



#11 kurtenstein

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Posted 23 February 2021 - 08:46 PM

I just realized this week, being out almost every night at various locations, how much the Moon impacts astronomical observation. Under a decently dark sky, there was a massive difference between one night and three nights later. Back in town, under severe light pollution and Moon nearing full, my limiting magnitude must be around 2: I see Polaris, barely. Normally it's much better even here and on a good night I can glimpse Beta Mon.

 

So I decided to spend an hour with … the Moon! Armed with my good friend the variable polarizing filter, I enjoyed a walk among craters, rilles, seas and oceans.

 

I guess it will be much the same in coming nights, but I'll take a good look at Ed's list of "any sky" objects!

 

PS: some doubles are worth a moment of your time and yes, Beta Monocerotis and Castor are among my favorites. I'd also mention Herschel 3945 (Winter Albireo) and Sigma Orionis. Just in case you want to give some doubles a try! 

I'll try those one day for sure!


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#12 kurtenstein

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Posted 23 February 2021 - 08:47 PM

You know what? It'll be cloudy for thre or four nights in a row anyway...

 

But thanks for your tips, lists and hint!



#13 Tony Flanders

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Posted 24 February 2021 - 08:16 AM

So if my skies w/o the moon are Bortle 8, then they must be Bortle 12 with the full moon!  

It doesn't work like that. The full Moon might change an otherwise Bortle-8 sky to Bortle 9 -- or not.

 

At a site with little or no artificial light pollution, even a thin Moon alters the sky greatly. At a site with lots of directly visible streetlights overhead, the full Moon is just another streetlight.


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#14 aeajr

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Posted 24 February 2021 - 08:44 AM

Thanks for those lists! I'll use them for sure... I like the one where objects are listed depending on their "easyness"...

That would be the Messier with Binoculars list.   That is part of an Astronomical Society Observing program. These are guided programs to help you organize and learn about the sky.

https://www.astrolea...s/binomess.html

 

I like to suggest this to beginners because these are the brightest of the Messier objects.   If you can find them with binoculars you should be able to find and observe them in more detail in a telescope.

 

 

Astronomical League

https://www.astrolea.../observing.html

 

You don't have to be a member to use the programs.  But if you complete a program and want to received the certificate you have to join the League. I am a member through my astronomy club.

 

I am currently working on the globular cluster program.

https://www.astrolea.../globular1.html

 

In addition to giving me things to find I am learning about globular clusters, my favorite deep sky objects. 

 

I encourage you to take a look.   They have several lunar observing programs, double stars, open clusters and more.  As you work the programs you learn about the sky and what can be seen.  


Edited by aeajr, 24 February 2021 - 08:57 AM.

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#15 radiofm74

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Posted 24 February 2021 - 08:45 AM

It doesn't work like that. The full Moon might change an otherwise Bortle-8 sky to Bortle 9 -- or not.

 

At a site with little or no artificial light pollution, even a thin Moon alters the sky greatly. At a site with lots of directly visible streetlights overhead, the full Moon is just another streetlight.

Hi Tony, as always I read your posts with great interest. I must say that even though I am in what has been evaluated as a Bortle 8 zone (Milano, town center… shows grayish-white on a map) the full moon yesterday made a very big difference. As said, I can usually see the major constellations without any trouble, and if I strain a little on a good night I can see Beta Mon naked eye. Yesterday night I could see clearly Capella, Sirius… barely Polaris. My guesses from reading your post:

 

1. Bortle ratings are always very "rule of thumb", and in fact, from my 5th floor balcony above the street lights, my situation is better than one would surmise on moonless nights – so when the Moon is out, there's more difference. I'm actually pretty convinced of this.

2. MeteoBlue gave the night as entirely cloudless, but there was in fact some humidity or haze in the air. I did not seem to notice while observing the Moon with my telescope, but looking up naked eye the sky was unusually "milky" (not in an attractive way!) and the Moon cast quite a halo around its disk. 

 

I suspect both are true. 

 

(Apologies to OP for piggy-backing on this very interesting discussion!)


Edited by radiofm74, 24 February 2021 - 08:47 AM.



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