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General Astronomy >> Light Pollution

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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: obin robinson]
      #6138101 - 10/14/13 11:39 PM

Well last night I looked up and I couldn't see any. So there Of course it was cloudy...

Seriously though what time was this? I have to do a test when the weather clears out, but I suspect with the moon out around 8/9 pm I might get similar results. 11pm is when things start getting a lot better.


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obin robinson
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6138361 - 10/15/13 06:15 AM

This was at about 9:30PM local time. It is cloudy now and the mornings are better because many lights which stay on until midnight are finally off. In the morning I estimate that I can see a hundred or so stars with the naked eye.

obin


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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6138561 - 10/15/13 08:53 AM

Quote:

http://stellarium.org/img/screenshots/0.10-bortle.jpg

your darkness conditions, and what can you see?




It's a little hard to say. I don't find that Stellarium site helpful at all. But going by John Bortle's original criteria, I would have to classify the skies of my local urban park in Cambridge, MA, as Class 8 on a typical night of good transparency -- which is fairly common here in New England except in the summer.

It correlates pretty well: My limiting magnitude is a bit better than 4.5; I can see M31 and M44 naked-eye, but only with considerable effort, and many of the stars making up the traditional constellations are missing, especially low in the sky.

However, all of the Messier objects are detectable through my 7-inch scope, which is certainly modest by modern standards. And many of them are quite pleasing -- though that's bound to be a subjective judgment.

By the way, this is 4.5 miles from the center of Boston, a metropolis of several million people.

My country home (halfway between Albany, NY and Pittsfield, MA) is harder to classify. It meets most of the criteria for Bortle Class 4. But the zodiacal light is pretty hard to detect, because it just happens that Albany is to the west and Pittsfield is to the east, and those are the directions where the zodiacal light is strongest.

If the dominant light sources were north and south rather than east and west, but the level of light pollution overall was the same, then the zodiacal light would be easy to see, but the southern Milky Way would be much harder to see. On the whole, I think I have the better deal!

The worst location where I have done much time stargazing is Manhattan, which is a good match for Class 9 in most ways. Limiting magnitude just about 4.0, only the Pleiades readily visible naked-eye. (This assumes being on a balcony or in a park where there are few or no lights shining in my eyes.)

However, most of the Messier objects are still visible through modest-sized telescopes, and several of them aside from open clusters are quite attractive. That list is headed by, but not restricted to, the Orion Nebula.

Judging by posts on Cloudy Nights, the biggest problem for most American stargazers is direct glare from nearby lights rather than skyglow. The Bortle Scale is really couched in terms of skyglow, so it's not necessarily applicable in a typical suburban backyard.


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: Tony Flanders]
      #6138626 - 10/15/13 09:36 AM

Obin, I think our conditions are similar. I think I'm going to look at living in a white zone as a challenge rather than focus on the negative side too much.

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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: obin robinson]
      #6138652 - 10/15/13 09:45 AM

Quote:

This was at about 9:30PM local time. It is cloudy now and the mornings are better because many lights which stay on until midnight are finally off. In the morning I estimate that I can see a hundred or so stars with the naked eye.




It's also because of the sky itself. During evenings in autumn, the southern sky is filled with faint constellations; the only really bright stars are Fomalhaut and Deneb Kaitos.

Before dawn you're seeing the winter sky, which is by far the brightest sector, including the brightest constellation (Orion) and the brightest star besides the Sun (Sirius).

What fraction of the sky can you see, and do you have lights shining directly into your backyard? Those are more likely to limit the number of visible stars than skyglow is.


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6138663 - 10/15/13 09:47 AM

Tony, I know the new england area quite well. I grew up outside of Providence which is supposedly a red zone on the map, but is definitely not significantly better than my current white zone. Hale-Bopp was an incredible dissapointment just looked like a star and couldn't make out a tail at all. I later lived in the Berkshires on the NY line, and my interest in astronomy had kind of fallen off at that point, but there was not an impressive amount of stars in the night sky and I never saw the Milky Way there. The main difference with my former red zone was there were more stars closer to the horizon but Albany and Pittsfield's light domes didn't make it all that impressive.

A somewhat impressive location I spent some time at was central Vermont. I'd guess it was a green zone, didn't see the Milky Way either but there were at around a couple thousand stars visible on a good night I'd say and quite a lot near the horizon as well. The best skies I ever saw where in Eastern Kentucky in the mountains and I can't find the small town on the light map, but I bet it was a blue zone easily. I still didn't see the Milky Way, but that may have just been my lack of experience in having seen it before. An unbelievable amount probably 5,000 stars and tons near the horizon too. Would love to live in an area like that.

Anyhow, I've been a bit of gypsy, I also lived in Brookline for a short time, so what you wrote is encouraging to me as I should be able to approach your results with experience. I'm looking to purchase some books are there any particular ones you recommend for white zone people?


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obin robinson
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Reged: 10/25/12

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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6138722 - 10/15/13 10:21 AM

Quote:

Obin, I think our conditions are similar. I think I'm going to look at living in a white zone as a challenge rather than focus on the negative side too much.




That is the way I look at it as well. You have seen the pictures that I can do with basic gear in a heavily polluted suburban yard. The tough part is finding the deep sky objects to photograph. Goto is a necessity for some of them. I only found the whirlpool galaxy using astrophotography. Even through my 10 inch telescope it was pretty much invisible.

I find the greatest challenge in suburban observing to be hunting geostationary satellites. They are extremely dim but finding one is like locating a needle in a hay stack. It is satisfying and lots of fun just to search for the "star" that is not moving.

obin


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: obin robinson]
      #6138820 - 10/15/13 11:19 AM

Yeah that's why I think I'm going sct. If I was in a dark zone I think I'd try the dobsonian. It would be fun to locate objects on my own, but here I think I'd eventually lose interest. Never thought about looking for sattelites or the space station or things like that, but that would be a pretty neat find.

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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6138872 - 10/15/13 11:52 AM

Quote:

I grew up outside of Providence which is supposedly a red zone on the map, but is definitely not significantly better than my current white zone. Hale-Bopp was an incredible dissapointment just looked like a star and couldn't make out a tail at all.




That surprises me greatly. Hale-Bopp was quite prominent, with a beautiful tail, from here in Cambridge.

Quote:

I later lived in the Berkshires on the NY line ... there was not an impressive amount of stars in the night sky and I never saw the Milky Way there.




That surprises me even more. Did you have bright lights around?

I know every road that crosses the MA/NY line, and from every one of them, from Connecticut to Vermont, the Milky Way should be instantly obvious at the state line, as soon as you turn off your headlights. (Obviously, on I90, you would also have to wait for a break in the traffic.)

Sure, there's ample light pollution all around. But the summer Milky Way is ultrabright, shining easily even through pretty heavy suburban light pollution. And nowhere on the MA/NY line could reasonably be called suburban by any normal definition.

Quote:

I'm looking to purchase some books are there any particular ones you recommend for white zone people?




Rod Mollise's Urban Astronomer's Guide is the classic.


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: Tony Flanders]
      #6139809 - 10/15/13 08:59 PM

I think I was a bad observer in VT because there was a ton of stars there, but didn't see the milky way. I wasn't far from Pittsfield so maybe that's why the Berkshires weren't good? Not exactly a big city so dunno. Yeah Hale-Bopp ticked me off because I was reading the papers about all these great observations and didn't see all that much from where I was. Oh well, maybe Ison will be better for me.

Thanks for the suggestion, I'll have to get that book off ebay.


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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6140322 - 10/16/13 06:12 AM

Quote:

I think I was a bad observer in VT because there was a ton of stars there, but didn't see the milky way.




Yes, I can't make any sense of that. All I can imagine is that you saw the Milky Way and didn't recognize it. Or perhaps you were never away from light long enough to become dark adapted.

Some of the houses near my country home have "security" lights on all the time. Very likely the people who live there have never seen the Milky Way -- though they easily could at the flick of a switch.

If you were only there for a few months, it might have to do with the time of year. The summer Milky Way is unmistakable, but the winter Milky Way is much subtler. I can easily imagine somebody overlooking it if they didn't know what to expect. And in spring, the Milky Way lies close to the horizon and is quite hard to see -- especially if the horizon is blocked by trees.

Yet another possibility is that your night vision is severely defective. Have you asked your eye doctor about this?

Quote:

Yeah Hale-Bopp ticked me off because I was reading the papers about all these great observations and didn't see all that much from where I was.




Again this baffles me, because my wife and mother-in-law, both of whom have quite poor vision, found Hale-Bopp quite impressive from heavily light-polluted surroundings.

Quote:

Oh well, maybe Ison will be better for me.




Extremely unlikely. We'll be lucky if ISON ever becomes visible at all to the unaided eye.

Edited by Tony Flanders (10/16/13 07:38 AM)


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: Tony Flanders]
      #6140520 - 10/16/13 09:41 AM

I don't know about my night vision I don't tend to trip over things when I'm out and about in the dark, I wasn't even aware there was a specific test for it. One possible explanation for the aforementioned mysteries was perhaps I needed glasses a lot earlier than I got them? After getting married in my mid twenties my wife suggested I get my eyes checked, I forget why, and the doctor said my eyes were somewhat weak. I don't have thick glasses, but they're a few levels up from the weakest that are sold.

If you don't mind I have a couple of observation questions somewhat related to this: I hate my glasses so as usual I was being stubborn and observing without them. My wife suggested I try them and see what the difference would be. I can't quite say how many more stars began popping into vision, but I had definitely been missing some. Around 11pm at roughly zenith at 37.5 north I found this beautiful yellow star with glasses on. When I took my glasses back off I couldn't see anything there at all. I'm guessing this star is between Mag 5-6, although it could be as low as 4.5 I'm still learning this stuff. Anyways I'd love to know the name.

As for VT I was well adapted I was hanging out some nights with my girlfriend at the time to watch the August meteor showers, which were a site I hadn't seen before. I doubt my vision was anywhere near as bad as it is now, but it likely wasn't 20/20, but from pics I don't get the impression it is hard to see.

Edited by AcesDJD (10/16/13 09:43 AM)


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6140572 - 10/16/13 10:14 AM

Obin, I went out at 10pm your time to do a count under an almost full moon. Without the full moon, I'd say the weather would be ideal. I just did a count of the bright stars that I can see sans glasses rather than take a long time getting dark adapted and all that. I counted a 102 stars. Not great, but not awful considering it's still early here. I can only barely see delphinus tonight and probably wouldn't have recognized it at all if I hadn't known where to look for it. I also found I think another one which looks either like a W or an M and is getting close to zenith. It's a pretty big one, much bigger than delphinus.

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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6140577 - 10/16/13 10:18 AM

Quote:

One possible explanation for the aforementioned mysteries was perhaps I needed glasses a lot earlier than I got them?




No, that wouldn't explain it. Glasses make a huge difference for the visibility of stars, which are point sources. But I'm pretty myopic, and I can see the Milky Way equally well with or without glasses. It's huge and fuzzy either way.

Quote:

Around 11pm at roughly zenith at 37.5 north I found this beautiful yellow star with glasses on. When I took my glasses back off I couldn't see anything there at all. I'm guessing this star is between Mag 5-6, although it could be as low as 4.5 I'm still learning this stuff.




Impossible to guess. The star -- or whatever it was -- was surely brighter than mag 4.5, otherwise it wouldn't have stimulated color vision. (Mag 5 and 6 are fainter than mag 4.5.) But there are so many reasonably bright yellowish stars that I wouldn't even venture to guess.

Quite likely it was something ephemeral -- an airplane or satellite, or possibly even a head-on meteor.

Quote:

As for VT I was well adapted I was hanging out some nights with my girlfriend at the time to watch the August meteor showers.




OK, now I'm really baffled! How you can fail to see the Milky Way when you're observing the Perseids from a dark site is a mystery to me. No doubt you saw it but didn't notice it.


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: Tony Flanders]
      #6140638 - 10/16/13 10:42 AM

Maybe my mind was on other beauties.....:)

The yellow/orange star I'm seeing is definitely a star I've seen it multiple times with glasses now, same location. I can rule out Betelgeuse and mars, but that's about it, I need to get some of these books soon.


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Tony Flanders
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6140887 - 10/16/13 01:04 PM

Quote:

The yellow/orange star I'm seeing is definitely a star I've seen it multiple times with glasses now, same location. I can rule out Betelgeuse and mars, but that's about it.




Okay, I was thrown off by your talk of magnitudes. Mag 5 and 6 are very faint, and mag 4.5 is barely visible in a typical suburb. If it's a star that could be mentioned in the same sentence with Betelgeuse -- and appear yellow -- it must be much, much brighter, around magnitude 1 or even 0.

I'm going to take a wild guess and say that the star was actually Capella, even though that's less than halfway up the sky at 11 p.m.


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obin robinson
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Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6142383 - 10/17/13 07:41 AM Attachment (7 downloads)

Quote:

Obin, I went out at 10pm your time to do a count under an almost full moon. Without the full moon, I'd say the weather would be ideal. I just did a count of the bright stars that I can see sans glasses rather than take a long time getting dark adapted and all that. I counted a 102 stars. Not great, but not awful considering it's still early here. I can only barely see delphinus tonight and probably wouldn't have recognized it at all if I hadn't known where to look for it. I also found I think another one which looks either like a W or an M and is getting close to zenith. It's a pretty big one, much bigger than delphinus.




You might actually have better skies than I do! This morning it is cloudy so I took a photo at 6AM (about an hour before sunrise) of the sky to give you an idea of the sky glow and light pollution.

This is a 1/2 second photo taken with my point-and-shoot camera. These are lights which are about 1km away reflecting off the clouds. These lights are on from before sunset until after sunrise every day of the year. This is the kind of excessive light pollution I have to deal with here.

obin


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: obin robinson]
      #6142469 - 10/17/13 08:58 AM

Yuck, that's what we deal with here to about 30 degrees up the horizon I'd guesttimate and at times its even worse. I'd say the first 30 degrees are washed out of all but magnitude 1 maybe 2 if I'm being generous, basically the heavy hitters like sirius, betelgeuse and the like are the only ones that really cut through.

Wonder if you could help me with something...I'm looking at two telescopes currently one is an 8" celestron SE with no accesories and the cheap stand (I understand it isn't great anyways) and the other is the 9.25 xlt with a strong tripod and several different lenses, laser collimator the basic accesories essentially. I can get the 8se for 1400 shipped or the 9.25 xlt for 2100 shipped. I've decided I'm not going to factor in weight, hopefully a heavy telescope will bulk me up. Neither would be a grab and go.

I'll take a look at the sky here later if you're interested at all, I think it may have clouded over though.


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AcesDJD
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Reged: 10/06/13

Re: Which number on the scale best correlates with new [Re: Tony Flanders]
      #6142476 - 10/17/13 09:04 AM

Tony,

I located Capella at about exactly where you described it, so it definitely wasn't the one I was referring to. It's not a standout star like Capella or Betelgeuse at all, it's actually hard to see (from here anyway) but it's got this beautiful yellow color to it. I can see several reddish stars but this is the only yellow one. Wish I had a more unobstructed view here and could see more constellations and unfortunately I have a piece of garbage chromebook which won't let me download stellarium.

Edited by AcesDJD (10/17/13 09:08 AM)


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obin robinson
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Reged: 10/25/12

Loc: League City, TX
Re: Which number on the scale best correlates with new [Re: AcesDJD]
      #6142515 - 10/17/13 09:29 AM

Quote:

Wonder if you could help me with something...I'm looking at two telescopes currently one is an 8" celestron SE with no accesories and the cheap stand (I understand it isn't great anyways) and the other is the 9.25 xlt with a strong tripod and several different lenses, laser collimator the basic accesories essentially. I can get the 8se for 1400 shipped or the 9.25 xlt for 2100 shipped. I've decided I'm not going to factor in weight, hopefully a heavy telescope will bulk me up. Neither would be a grab and go.

I'll take a look at the sky here later if you're interested at all, I think it may have clouded over though.




The cost difference between those two I am not sure justifies the increase in aperture. If it was my money I would go for the 8" and then get the DIY skills working to make a better tripod. Tripods are very easy to make and if you want a cheap but strong pier get a bench grinder mount from a home improvement store. Here is a link to one:

http://www.tooltopia.com/sunex-tools-5003.aspx?utm_source=pricegrabber&ut...

You can make some longer legs for it or just bolt it into the ground if you want a permanent pier. In my washed out skies I have found that more aperture helps with astrophotography. With visual all it does it make the sky go from dark blue to medium grey and some of the stars that were invisible are now visible in the medium grey. I could get a 24" telescope but it would be wasted in skies like this.

obin


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