Imaging galaxies from LP

[DaveS]

OK, this is for those of you labouring under the curse of LP.

What galaxies do you find you can image? And what is (Roughly) your NELM

With the end of winter and NB targets we'll shortly be entering "Galaxy season" again so I'll be switching to my 130P-DS and an Astronomik CLS filter, going LRGB.

So what do you reckon? M101 possibly, M51, maybe M81 / 82. Unfortunately for the main Coma / Virgo galaxies and the Leo Triplet I'm looking through the worst of the LP kicked up by a big retail park.

[pipnina]

You can get decent images under LP when targeting galaxies. You just need to do gradient removal.

I can never seem to get the colour right with those...

I got the first under mag 5~ skies (yet unconfirmed) the second under about mag 4.3ish. You can see the Flame, Horse head & IC-434. Even little hints of a certain witch head. And a giant orange cloud, obviously...

This was all done with a Nikon D3200 with a standard lens without much exposure time. With a proper setup you could make much better. I had another image i thought went really well but it's gone...

 

    ~pip

[DaveS]

Thanks Pip. OK, for reference, here are the two that I was working on last year before the nights got too short.

The first is of the Leo Triplet, 1 1/2 hours worth of 5 min subs, with flats, darks, and bias frames.

 

The second is of M101, a 2 hour stack of 5 min subs again.

 

My skies are barely mag 4.25, worse looking south over the Victoria Road Retail Park, a bit better looking north-ish. Both are Luminance only taken with my 130P-DS, Trius 694 and Astronomik CLS filter.

Edit: Also taken before I had my Trius serviced, so only getting about -10 or so degree cooling.

[Daniel-K]

id they say they pretty good given your location and short exposure time.

[kirkster501]

A good LP removal filter helps a lot.  Not cheap though, my 2" IDAS one was over #150 I recall.

[DaveS]

I would say vital, given our LP.

I have the Hutech IDAS P2, Baader UHC-S, and Astronomik CLS. Of those I find the Astronomik gives the best results with my LP, YMMV.

How things will change with the creeping arrival of LEDs I don't know. On the one hand they will make LP filters useless, but on the other, if they're well designed may improve the LP anyway. The ones in neighboring Harrow look to be quite good.

[pyrasanth]

Light pollution is a real pain. I have 5 sodium lights over looking my garden where the telescope lives. I always have the Hutech IDAS LP filter in the imaging train & I believe it helps a bit but not able to really quantify how much as I have never imaged LRGB without it.

It really is worth the minimal investment if you have Photoshop to use GradientXterminator as it usually does a superb job. I even think in some instances it does a better job than PixInsights DBE which takes a lot of fine tweaking to get the best result.

I also favour NB imaging but as I explained before it is not a substitute for dark skies to Use NB but that flavour of imaging (if the moon is away) really helps to improve the SN which it is all about. I really envy dark skies but I guess we all have to adapt to where we live. Filters certainly help but again there is no substitute for dark skies.

[MartinB]

There are a lot of variables, not least the atmosphere.  On a good night my naked eye limiting magnitude gets up to around 5 but if there is a bit of haze (ironically, good conditions for seeing) the orange glow goes right up to the zenith.  The other problem is that your retail park is probably illuminated by white light so bang goes any LP filtration.

This is probably my best effort from my home location.  Taken in conditions of good transparency and poor seeing 

Scope Tak FSQ106 with 0.73 reducer - F3.7  Camera: QHY8  16x10min subs  with an IDAS filter

 

 

[DaveS]

I'll have to run a check on the retail park, but I think they're still HP sodium. I also have a lot of glow from the local main road which is a bus route, so with big street lights.

Like you Martin, sky conditions can make a *huge* difference to the LP, on occasions taking me down to a NELM of 2-2.5, while pushing up to 4.35 on a very good night.

I think my next targets will be to get RGB on M101, and possibly have another look at M81 / 82. The Leo Triplet is a bit of a pain.

[ollypenrice]

There are some galaxies which, though small, have high surface brightness and that's what you need in LP. The Blackeye surprised me, but we had the focal length for it at the time.

What do you feel to be wrong with your Triplet and 101? For modest exposure times they are very good, I'd have thought. You'll see plenty of 20 hour efforts on these, after all.

Olly

[DaveS]

Thanks Olly. TBH, looking at them now they look be better than I remember at the time. Part of my question was along the lines of "What else is there?", considering that my longest FL is only 650mm, and unless I buy a SCT anything longer will be a bit iffy on my HEQ5.

Ah, well I reckon they'll be quite enough to keep me occupied over the spring.

[ollypenrice]

For more modest FLs try M33, of course, and then groups and pairs such as your Triplet. You could get a widefield M51 very nicely. Wait till it's high in the sky. (That really is a big deal with galaxies.)

Olly

[DaveS]

Why did I forget M33, dur....? Actually I'll put that on the to-do list for Autumn. A wide field image of M51 might be interesting as will M81 / 82 as a nice pair.

Probably will add some H-alpha to the mix as well. Hmm... maybe some H-beta for the hell of it as I have a filter kicking around somewhere.

[MartinB]

M81 and 82, also galaxy clusters esp Markarian chain

[DaveS]

I think I will give Makarian's Chain a go if I can remember where it is. I've seen plenty of images of it but had writen it off for me.