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My First Nebula - M27


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Hi

Took this last night with the qhy8l, in spite of the moon :). Unfortunately it's only 4 x 360s which I realise is nowhere near enough but was all I could get. If it stays clear tonight might be able to get some more. Still, it's the first nebula I've tried, having only imaged star clusters before. It was stacked with flats and darks using dss. Processed in StarTools to remove lp and stretch etc. Reduced to 50pc of original size to upload.

post-33532-0-84319700-1397473825_thumb.j

Cheers

Louise

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well done, long exposures considering your location & conditons
so did you finally sort out the problems with the lamp glow ??
weather says maybe a chance tonight so hopefully I can get back out and conditions are better,
 

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Hi

Took this last night with the qhy8l, in spite of the moon :). Unfortunately it's only 4 x 360s which I realise is nowhere near enough but was all I could get. If it stays clear tonight might be able to get some more. Still, it's the first nebula I've tried, having only imaged star clusters before. It was stacked with flats and darks using dss. Processed in StarTools to remove lp and stretch etc. Reduced to 50pc of original size to upload.

attachicon.gifM27_ST_2_50pc.jpg

Cheers

Louise

Well done louise, what time did you capture the M27?  From my location it does not rise above the LP zone till nearly 4am at the moment. Incidentally I reprocessed my only capture of M27 from July last year as the clouds and the Moon put an end to my imaging plans last night again. Here is a link if u wish to have a look. http://www.astrobin.com/90275/

Regards,

A.G

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Well done louise, what time did you capture the M27?  From my location it does not rise above the LP zone till nearly 4am at the moment. Incidentally I reprocessed my only capture of M27 from July last year as the clouds and the Moon put an end to my imaging plans last night again. Here is a link if u wish to have a look. http://www.astrobin.com/90275/

Regards,

A.G

Hi

I took the subs between 02:42 and 03:02. Unfortunately, because of my window I can't image above about 32 deg of altitude :( So all my images are below that... Similarly, I only have between about 80 and 92 deg of azimuth - I obviously have to allow space for the finder guider. I'm thinking about whether I might be able to fit the finder without using the usual mount which makes it stick out. I've been thinking about getting a pedestal mount (possibly one from Orion Optics UK) which would let me lower the scope and allow me to get nearer the window than the tripod does. That way I ought to be able to image things higher in the sky.

Yours is a lot better than mine (of course!).

Cheers

Louise

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well done, long exposures considering your location & conditons

so did you finally sort out the problems with the lamp glow ??

weather says maybe a chance tonight so hopefully I can get back out and conditions are better,

Hi

Yeah they released a v3.2 ascom driver. This cured the amp glow problem which was introduced with v3.1. But now it seems to have gone back to the v3.0 problem of overscanning the chip! That means I have to crop out the chip imaging area manually which is a bit annoying - I mean, you spend £1000 on a camera and...

I hope there will be more opportunities again tonight!

Cheers

Louise

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Hi

I took the subs between 02:42 and 03:02. Unfortunately, because of my window I can't image above about 32 deg of altitude :( So all my images are below that... Similarly, I only have between about 80 and 92 deg of azimuth - I obviously have to allow space for the finder guider. I'm thinking about whether I might be able to fit the finder without using the usual mount which makes it stick out. I've been thinking about getting a pedestal mount (possibly one from Orion Optics UK) which would let me lower the scope and allow me to get nearer the window than the tripod does. That way I ought to be able to image things higher in the sky.

Yours is a lot better than mine (of course!).

Cheers

Louise

I my take hat to you Loise, so difficult a to image from and yet you do produce great images.

A.G

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I my take hat to you Loise, so difficult a to image from and yet you do produce great images.

A.G

Hi

Thanks! I'm still a beginner - I stand in awe at the superb images produced by the experienced imagers here.

I managed to get 6 more subs of M27 last night so hope they all came out ok. Then I'll be able to improve the current version - of course I'll post the updated version. Could always do with more integration time!

Thanks to everyone's positive comments :)

Louise

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Hi all so here is my updated version - now 10 x 360s:

post-33532-0-63786000-1397566762_thumb.j

Actually, I'm not too impressed! I hoped it would be better... Maybe I did something wrong, or maybe it just needs a lot more integration time?

Oh well, I'll keep it as a work in progress for now.

Thanks again for everyone's responses.

Louise

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putting yourself down a bit

remember its a learning process, If you got it right first time every time life would be boring

Hi

Well I was just thinking out loud that maybe I could have done something in the stacking/processing to bring the nebula out more without spoiling the stars. Having looked at other peoples' images, 60min isn't that long, I suppose.  I'll have to do some more research and educate myself about processing nebulas!

Cheers

Louise

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Hi

Well I was just thinking out loud that maybe I could have done something in the stacking/processing to bring the nebula out more without spoiling the stars. Having looked at other peoples' images, 60min isn't that long, I suppose.  I'll have to do some more research and educate myself about processing nebulas!

Cheers

Louise

You were imaging at very altitude, as M27 is very low at this time of the year, so there is a lot more of the light polluted turbulant atmosphere for the photons to get to the sensor and this will cause star bloat. You could use the Magic Module in ST to reduce the size of the stars to some degree. Atleast your scope is producing round stars, my 150 PDS is defying all logical attempts to get it collimated at the moment.

Regards,

A.G

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You were imaging at very altitude, as M27 is very low at this time of the year, so there is a lot more of the light polluted turbulant atmosphere for the photons to get to the sensor and this will cause star bloat. You could use the Magic Module in ST to reduce the size of the stars to some degree. Atleast your scope is producing round stars, my 150 PDS is defying all logical attempts to get it collimated at the moment.

Regards,

A.G

Hi A.G.

Oh ok, though I think I've probably bloated the stars even more in processing... Mind you, from a purely aesthetic point of view, I quite like stars to be different sizes even though I know that, technically, they should all be point sources. I sit and watch PHD2 doing it's thing and I've noticed how turbulence and poor (city?) conditions both affect guiding - oh for some adaptive optics! I had problems with guiding before so I switched back to a finder guider after struggling with my ST-80. I had problems with the finder too - couldn't quite see what the real problem was. My mount happily tracks for 60s without guiding but switch the guiding on and it was going astray very quickly.  I think I've fixed the problem simply by tweaking PHD2 settings. I've reduced the aggressiveness to 50 and increased hysteresis to 50 - those changes seem to have smoothed things out quite a bit. Then reduced the max RA duration to 300ms, DEC duration to 150ms. I seem to tend to get twice the rms error in DEC, not sure if that's partly due to inaccurate PA but the DEC error is definitely periodic. One day I might have a go at PEC. Minimum move is set to 0.05 for both. Things seem to be working ok generally. I do often struggle to find/select suitable guide stars - no doubt that's caused by a combination of things.

Funnily enough, I've never collimated my scope! I checked it when I got it and it seemed fine so decided to leave well alone! I expect I'll need to bite the bullet and have a go one day but for now it's happy.

Hope you can sort yours out. Imaging time is dwindling with the longer days. I could have imaged for another hour or so last night but there was nothing of interest in the east at that time.

Cheers

Louise

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Hi A.G.

Oh ok, though I think I've probably bloated the stars even more in processing... Mind you, from a purely aesthetic point of view, I quite like stars to be different sizes even though I know that, technically, they should all be point sources. I sit and watch PHD2 doing it's thing and I've noticed how turbulence and poor (city?) conditions both affect guiding - oh for some adaptive optics! I had problems with guiding before so I switched back to a finder guider after struggling with my ST-80. I had problems with the finder too - couldn't quite see what the real problem was. My mount happily tracks for 60s without guiding but switch the guiding on and it was going astray very quickly.  I think I've fixed the problem simply by tweaking PHD2 settings. I've reduced the aggressiveness to 50 and increased hysteresis to 50 - those changes seem to have smoothed things out quite a bit. Then reduced the max RA duration to 300ms, DEC duration to 150ms. I seem to tend to get twice the rms error in DEC, not sure if that's partly due to inaccurate PA but the DEC error is definitely periodic. One day I might have a go at PEC. Minimum move is set to 0.05 for both. Things seem to be working ok generally. I do often struggle to find/select suitable guide stars - no doubt that's caused by a combination of things.

Funnily enough, I've never collimated my scope! I checked it when I got it and it seemed fine so decided to leave well alone! I expect I'll need to bite the bullet and have a go one day but for now it's happy.

Hope you can sort yours out. Imaging time is dwindling with the longer days. I could have imaged for another hour or so last night but there was nothing of interest in the east at that time.

Cheers

Louise

Thanks Louise, this is a very detailed reply and I think that as with regards to the PHD settings you have got it sorted, the only point to consider is the Min motion value may have been set too low for a 50mm finder. I have mine set at 1.5 but if the valuof 0.5 is working for you then it is correct for your set up. If you have good PA which by what you have described it is good and the balance is spot on, you could always lower the aggressiveness lower and see if you get a smoother guiding. As with collimation, you  are right mine was way out once i got it and if you remember we had a little chat about the focuser shaft being loose and rattling on mine when I got it. I have since discovered that the locking bolts for the main mirror are bent. With  hindsight I should have returned the scope but I guess is too late now after having everything but the main mirror out several times. Lets hope we get a clear night tonight but there is always the Moon so I may collect some Ha data for M106 or something else.

Regards,

A.G

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Thanks Louise, this is a very detailed reply and I think that as with regards to the PHD settings you have got it sorted, the only point to consider is the Min motion value may have been set too low for a 50mm finder. I have mine set at 1.5 but if the valuof 0.5 is working for you then it is correct for your set up. If you have good PA which by what you have described it is good and the balance is spot on, you could always lower the aggressiveness lower and see if you get a smoother guiding. As with collimation, you  are right mine was way out once i got it and if you remember we had a little chat about the focuser shaft being loose and rattling on mine when I got it. I have since discovered that the locking bolts for the main mirror are bent. With  hindsight I should have returned the scope but I guess is too late now after having everything but the main mirror out several times. Lets hope we get a clear night tonight but there is always the Moon so I may collect some Ha data for M106 or something else.

Regards,

A.G

Yeah, I'm at a theoretical 4.55"/pixel for the finder so the min motion need not be so small. I'll try some bigger values next time :). Sorry, I'd forgotten about your scope history. That's very annoying about the mirror bolts :( It might still be worth complaining. Some manufacturers in the astro business seem to get away with more poor quality issues than in any other spheres that I know...

Probably no imaging for me tonight - I may have Jury service tomorrow! Will find out later. In any case, I don't think the forecast is so good as the last two nights :(.

All the best

Louise

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Nice work Louise! You starting to get the hang of the CCD camera! :)

Hi Guillermo :)

Getting better now the guiding is working better :) There are still issues with the qhy8l ascom driver, sigh. But at least it's useable.

I could do with some constructive criticism. Also some advice - how to get sufficient exposure for the nebula without blowing out the stars? Or maybe just lots more subs?

Cheers

Louise

ps note to self: don't write on forums whilst sitting on couch and eating dinner as this can result in entire meal spilling onto couch creating clean-up nightmare. :(

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You might think about trying a Ha filter to add as an extra luminance layer.

There are People that do this with their OSC cameras to improve the overall image.

Tho, they usually use a mono camera alongside their OSC, there are plenty of people doing it with just an OSC camera. Especially since your QHY8L has 50% QE in red. ;)

It won´t increase the resolution, as you only capture with 25% of the pixels on the OSC sensor.

But as the Ha filter will guarantee block all Light Polution, you can take very long exposures with it (only Limited by your PA and guiding) and so definitely collect more data. :)

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