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What's your home's Bortle/MPSAS number?

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#101 CrazyPanda

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Posted 15 May 2021 - 10:03 AM

I'm curious to find out what the average amateur astronomer's (on this forum) light pollution level at home is.  I'm guessing that most people are like me and the majority of the time they are observing/imaging from their home.

 

My Bortle number is 3.6

 

My MPSAS number is 21

 

Thanks! 

Mine is listed as class 4, and I've measured my MPSAS at between 20.9 and 21.3, though typically it seems to fall around 21.15


Edited by CrazyPanda, 15 May 2021 - 10:03 AM.


#102 PEterW

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Posted 15 May 2021 - 11:58 AM

Mine is around sqm19, but local direct lights. One recent paper to bear in mind is that SQM may age…. Should check old ones against new ones…. https://arxiv.org/pdf/2012.04042.pdf

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#103 Nick Dangerr

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Posted 15 May 2021 - 12:50 PM

According to Clear Dark Sky's map - home is between Bortle 7 and 8. My club's dark site is about Bortle 4. I have no way to actually measure these values.



#104 Bill Geertsen

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Posted 22 May 2021 - 09:42 AM

Bortle 6-7, N.Ft.Myers, FL, backyard.

 

B.R.O. (Banana Republic Observatory)

 

BG



#105 AstroRBA

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Posted 23 May 2021 - 01:25 PM

18.19 - absolutely horrible. But on the bright side (pun intended), I can read a manual at midnight right beside the scope if necessary!
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#106 Dave Mitsky

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Posted 23 May 2021 - 03:18 PM

According to the Clear Sky Chart, my home lies in a Bortle 7 area with SQM readings of 18.38 to 18.95.



#107 eits

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Posted 23 May 2021 - 03:45 PM

I observe from a "roof-less" shelter in my backyard that blocks most human originated light EXCEPT one streetlight about 190 yards distant. According to https://www.lightpollutionmap.info using Overlay VIIRS 2020, Feature SQM and Basemap HYBRID I have an SQM of 20.4 to 20.9 and according to https://en.wikipedia...ki/Bortle_scale I have Bortle 4 (Rural/Suburban transition), NELM 6.1 to 6.5 and SQM 20.49 to 21.69 ... I have just this month started actual measurements with an SQM-L.



#108 Dave Mitsky

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Posted 23 May 2021 - 09:55 PM

The sky where my home is located is described at the following sites as:

 

1) Bortle 7 with a SQM reading of 18.38 to 18.95 according to the Clear Sky Chart at https://www.cleardarksky.com/

 

2) the second brightest color level - https://darksitefind...-scale-meaning/ -  according to the Dark Site Finder at https://darksitefinder.com/

 

3) a radiance value of 6.48 (2020)

 

Zenith sky brightness info (2015)
Coordinates
SQM 19.18 mag./arc sec2
Brightness 2.31 mcd/m2
Artif. bright. 2130 μcd/m2
Ratio 12.5
Bortle class 6
 

(The 2015 data is definitely out of date.)

 

according to the light pollution map at https://www.lightpollutionmap.info/

 

During the past year, more and more of my neighbors have switched to using glaringly bright LED bulbs in their unshielded carriage style outdoor lights.



#109 osbourne one-nil

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Posted 24 May 2021 - 01:28 AM

The last time I checked under a moonless sky, back in April, it was 20.75. I suppose that's better than many but when you consider I'm in one of the most rural bits of England, it's also a little bit depressing.

 

I did take the reading using an app on my phone so perhaps it should be taken with a pinch of salt?



#110 darkskychaser

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Posted 03 June 2021 - 05:12 PM

My former primary location used to be 6 but now more like 8/9.

 

My secondary, which became my primary is border of 2 and 3. Supposedly SQM 21.87. Southern sky is 2, west and east is 2/3, north is 3 to 4 (small town lights).

 

It is high altitude at 8,800 feet (2,682 meters), which is a plus and usually very dry, another plus. Minus is that my neighbor installed extra lights on the garage of his rental place, which is a minus. This almost negates the previous two plusses mentioned.

 

My tertiary location, but not recently, is a true Bortle 1 (Big Bend National Park, supposedly SQM 22).

 

Clear and dark skies everyone.


Edited by darkskychaser, 03 June 2021 - 05:17 PM.


#111 jcastarz

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Posted 04 June 2021 - 06:00 PM

From:  https://www.lightpollutionmap.info/

 

My Home:  Bortle 5, SQM 20.40

 

Skyline Drive:  Bortle 3, SQM 21.70  (upper Hawksbill parking lot)

 

To my eyes the SQM 20.4 at my home seems a bit too good to be true, but that's a map for you; I have no meter myself.



#112 Napp

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Posted 04 June 2021 - 08:04 PM

My home sky is Bortle 7 based on my own estimate and the light pollution map.  I just recently got a SQM-L meter.  My first night's reading was 18.44 which is consistent with Bortle 7.  Complicating this is an unshielded LED streetlight across the street and a couple more within 100 feet either way and carriage lights on each side of almost every garage door.  There is a Super Target about 500 feet away with a well lit parking lot that introduces a glow to the northwest and west.  I set up in my house's courtyard or behind my pickup parked diagonally across my driveway to block as much direct light as possible.  The backyard is treed and slopes down to a retention pond so is unusable for observing.  I have access to two two remote sites - Bortle 3 and 4.  I haven't had an opportunity to check the MPSAS at either yet.



#113 angle4cor

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Posted 10 June 2021 - 07:55 PM

19.7 to 20.1 on the best dry nights with no Moon, measured with Unihedron Sky Quality Meter model "L" - SQM-L. So it would be Bortle 5. I am living in Belgium, which is one of the most light polluted countries in the world and in general, western Europe is glowing. That being said, there are nights where the sky looks really beautiful and I can see a lot more stars than usual. There are 1-3 nights a year, when really washed out structures of the Milky Way in the swan are visible. Thats when our galaxy is in the zenith. Ive never seen M31 or 33 wih naked eye here.

 

There are no Bortle 3 skies in this country. The best is Bortle 4, which can be found in the area called Ardennen. My go-to place is 200km away with the sky of 21.3 (according to the maps, havent measered it there yet myself). 

 

The closest Bortle 3 is in France, near the town Chatel Chehery with 21.7. 


Edited by angle4cor, 10 June 2021 - 07:57 PM.


#114 Tony Flanders

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Posted 11 June 2021 - 04:10 AM

19.7 to 20.1 on the best dry nights with no Moon, measured with Unihedron Sky Quality Meter model "L" - SQM-L.
 
....
 
There are 1-3 nights a year, when really washed out structures of the Milky Way in the swan are visible. Thats when our galaxy is in the zenith. Ive never seen M31 or 33 wih naked eye here.


I wouldn't expect you to see M33 under such skies, but I'm very surprised that you can't see M31. When M31 is high in the sky and the transparency is good, I can generally spot M31 any night when my SQM-L reads 18.0 or darker -- though at SQM-L = 18.0 it's only visible if you know exactly what to look for.
 
When my SQM-L reads 19.0 I find both M31 and the Cygnus Star Cloud to be obvious.

When my SQM-L reads 20.1 I can see many deep-sky objects without optical aid, including M44, M8, and M47. The Milky Way is completely visible from Cygnus through northern Sagittarius, and the Great Rift is obvious.

 

Of course Belgium lies 1,000 km north of my home in Massachusetts, US, so M8, M47, and the Sagittarius Milky Way would be buried much deeper in the skyglow haze. I wouldn't expect you to be able to see them until SQM-L=21.0, at which point the Milky Way starts to take on some semblance of its true appearance.



#115 jwaldo

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Posted 12 June 2021 - 07:46 AM

Bortle 7-8, according to light pollution maps. Five years ago I used to be able to catch a glimpse of the summer Milky Way, but not anymore. 



#116 Delta608

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Posted 12 June 2021 - 09:07 AM

Bortle 4-5 according to the light pollution maps as well....



#117 earlyriser

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Posted 04 July 2021 - 08:20 AM

Finally broke down and bought an SQM-L. I measured 18.30 from my back yard a few nights ago. NLM was around 4.3, but I didn’t put a lot of effort into determining that. 



#118 Neytiri

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Posted 05 July 2021 - 07:21 PM

I'm happy with our dark sky!

 

Bortle 2

SQM 21.9

 




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