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dag123

Light pollution filter suggestions to improve view of M82 Supernova

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Hello,

I had clear skies last night and so ventured outside to try and spot the supernova that has been seen in M82.

I was able to find M82 without too much trouble with a 32mm EP but the light pollution made both very faint againt the background glow.

When I switched to a 10mm EP I would like to think I managed to spot the supernova with averted vision.

Anyway, to my question, I don't have any light pollution filters and so I was wondering if they might help.

My road has has orange streetlamps but a more whitish glow seems to be coming up into the sky from the direction of the local shops.

Any ideas?

Thanks
dag123

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For galaxies the only real solution is to get away from the lighting. Try and find a darker spot where you observe or take the scope somewhere darker and away from as much light pollution as possible. 

UHC and O-III type filters help improve the contrast of some nebulae but even those are much more effective under dark skies.

I have similar issues here and tend to wait for my target objects to get high in the sky before observing them. My overhead skies seem to be somewhat darker than they are closer to the horizon - unless the moon is around of course !

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That's very true. If it is just orange light then you can get filters to cut out that specific frequency, but if, as it sounds, it is white light giving you the problem then I agree that the only answer is to get away from the lights!<br />

<br />

Stu

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Thanks for the replies so far.

Unfortunately, going somewhere darker is not so easy if you have little ones asleep in the house to watch over.

I was looking at the follow filters on the FLO website

http://www.firstlightoptics.com/light-pollution-reduction/baader-neodymium-filter.html

http://www.firstlightoptics.com/light-pollution-reduction/skywatcher-light-pollution-filter.html

The latter at less than £20 is perhaps worth a try, but I am not sure it is worth going for the more expensive option if there is little to gain.

dag123

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Thanks for the replies so far.

Unfortunately, going somewhere darker is not so easy if you have little ones asleep in the house to watch over.

I was looking at the follow filters on the FLO website

http://www.firstlightoptics.com/light-pollution-reduction/baader-neodymium-filter.html

http://www.firstlightoptics.com/light-pollution-reduction/skywatcher-light-pollution-filter.html

The latter at less than £20 is perhaps worth a try, but I am not sure it is worth going for the more expensive option if there is little to gain.

dag123

I must say I have the latter of the two options (the bog standard Skywatcher) and I have never seen any benefit from it. Every time I've tried it, I have failed to see any big difference (if anything it was worse with the filter).

Then again, I am a newbie so maybe I'm doing it wrong (goodness knows how). Also, I'm in Brixton which is pretty much central London, so maybe the LP here is just beyond help.

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All filters reduce the total amount of light, whilst boosting the contrast. To get the best benefit you still need to try to get your eyes dark adapted as best you can, otherwise the image may dim too much. This is obviously challenging when the LP is bad.....a blanket over the head maybe? :-)<br />

<br />

Stu

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if the galaxy is small in extent and faint in your scope, you may have seen the SN and not realised.

this was the view through my 12" dob last night at about 130x.

post-5119-0-14441600-1390515671_thumb.jp

look for the three stars in a line pointing approx at the SN and you may get it. I have heard it is set to increase in brightness shortly so might get easier.

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In fact I did use a sketch to double check, although compared to Moonshane, mine was just a scribble. - even with my light polution it was far to dark to be able to see the pencil marks on my bit of paper as I did my best to draw my EP view.

From the view in my EP, I noted a group of four stars in a kind of cross shape below M82 and there were what looked like four stars starting to the left of M82 and going accross it heading to the right.

When I went inside and compared with what Stelarium showed, once I had matched the correct rotation with the cross shape of stars as a reference, I had an extra star on my scribble overlayed on where M82 would be. I am hoping this extra star is the supernova.

I too understand that the supernova should increase in brightness and so will hopefully confirm what I saw.

Certainly when I viewed the SN in M101 a year or so ago I was able to watch it fade to nothing over a few weeks, confirming it was the supernova and not a star.

dag123

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Have you fitted a dew shield to your scope as this will help to block out stray light entering the tube?

Also try and relax your eye and employ averted vision

And as above aim to become fully dark adapted, wait until M82 has reached a high point and screen off any unwanted light from your observing area if you can.

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Get the best you can ,light pollution filters are like cheap instant coffee buy the 99 pence jar or the 4.99 jar ,they both coffee one tastes better than the other the sky watcher I found was useless I gave it away in the end get the best one you pocket can aford

Pat

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Have you fitted a dew shield to your scope as this will help to block out stray light entering the tube?

Also try and relax your eye and employ averted vision

And as above aim to become fully dark adapted, wait until M82 has reached a high point and screen off any unwanted light from your observing area if you can.

This is a valid point if you look down at the blunt end of your scope and can see any form of stray light or light and dark shadows then so can your scope.

I have had this problem and have even cosidered cutting a hole out of the bottom of a large black dustbin to act as a shield but i would need a second tripod to mount it on.

Alan

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Certainly when I viewed the SN in M101 a year or so ago I was able to watch it fade to nothing over a few weeks, confirming it was the supernova and not a star.

dag123

M82 is much easier to spot than M101 I reckon. I saw that SN as well but sometimes I could hardly make out M101 at all !

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Regarding the dew shield, I have already wrapped my scope with sections cut out of a camping mat. This includes a tube about 30cm long, painted matt black which acts as a light shield.

dag123

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As far as a filter is concerned, I use a 2" Orion Ultra Block, which I consider works well both in light pollution and at a dark site, in enhancing the image / increasing the contrast whilst observing nebula. I do not know whether or not it will assist with detecting the supernova in M82 though, as apart from a select few bright galaxies, observing them requires a dark sky as a filter will not help.

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Problem with galaxies and filters is that galaxies/stars are wide band targets. You really cant block anything except the sodium light bands or you will be blocking light from the target itself. Best cure is to have something between you and the lights and make sure you have a dew/straylight shield on the scope. 

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It sounds to me that you might have spotted it. After the bright 10 mag star there was no other closer star visible than the supernova within the galaxy in my small telescope. It was better seen with averted vision also. Hope you can confirm it soon. The star is inside the haze as shown in sketch. andrew

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if the galaxy is small in extent and faint in your scope, you may have seen the SN and not realised.

this was the view through my 12" dob last night at about 130x.

post-5119-0-14441600-1390515671_thumb.jp

look for the three stars in a line pointing approx at the SN and you may get it. I have heard it is set to increase in brightness shortly so might get easier.

Hi,

getting off the subject a bit but I could see the three stars in line just before it got misty overhead. Now I know exactly where to look!

Back to the original post, I fully sympathise with the kids in bed bit...I'm, a single parent and have exactly the same problem! Could you take them on an exciting camping trip? It would get around the light pollution problem and they may even enjoy it, depending on their ages. My daughter was dancing around the table in the living room after seeing the Ganymede transit last night. She's nine, though.

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Hi,

getting off the subject a bit but I could see the three stars in line just before it got misty overhead. Now I know exactly where to look!

Back to the original post, I fully sympathise with the kids in bed bit...I'm, a single parent and have exactly the same problem! Could you take them on an exciting camping trip? It would get around the light pollution problem and they may even enjoy it, depending on their ages. My daughter was dancing around the table in the living room after seeing the Ganymede transit last night. She's nine, though.

Thanks for all the replies so far. I don't think I have heard enough positive comments to get a light pollution filter for now.

I am sure when older camping and staying up late will be something to look forward too.

dag123

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