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Fireworks Galaxy (NGC6946)


alan4908

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For my first attempt at the Fireworks Galaxy, I decided to go for an LRGB image with an Ha blend in both the Red and Lum channels. Since the galaxy is not particularly bright, I found that the Ha blended into the Lum channel gave the image a significant signal boost.   

Despite the weather and lack of long nights, I somehow managed to capture just over 15 hours. I can only conclude that my recent move to unguided imaging is improving my capture efficiency....  

Alan

5995af9caac0c_15.NGC4946Jpeg.thumb.jpg.4871f9e0a5a9c561ba9bf59ce22d9ef2.jpg

LIGHTS: L:11, R:9, G: 15, B: 9 x 600s; Ha:16 x 1800s. DARKS:30; BIAS:100; FLATS:40. Captured with an Esprit 150.

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Very nice image Alan. I've not tried this target yet.

1 hour ago, alan4908 said:

 Despite the weather and lack of long nights, I somehow managed to capture just over 15 hours. I can only conclude that my recent move to unguided imaging is improving my capture efficiency....  

LIGHTS: L:11, R:9, G: 15, B: 9 x 600s; Ha:16 x 1800s. DARKS:30; BIAS:100; FLATS:40. Captured with an Esprit 150.

Can I ask why you decided to go 'unguided'? My NEQ6 would certainly not manage that with 1800s exposures - not sure it would cope with 600s either.

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36 minutes ago, Adreneline said:

Can I ask why you decided to go 'unguided'? My NEQ6 would certainly not manage that with 1800s exposures - not sure it would cope with 600s either.

I think you'll find that's exactly why he's got a GM1000HPS mount from 10 Micron!

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3 hours ago, alan4908 said:

For my first attempt at the Fireworks Galaxy, I decided to go for an LRGB image with an Ha blend in both the Red and Lum channels. Since the galaxy is not particularly bright, I found that the Ha blended into the Lum channel gave the image a significant signal boost.   

Despite the weather and lack of long nights, I somehow managed to capture just over 15 hours. I can only conclude that my recent move to unguided imaging is improving my capture efficiency....  

Alan

5995af9caac0c_15.NGC4946Jpeg.thumb.jpg.4871f9e0a5a9c561ba9bf59ce22d9ef2.jpg

LIGHTS: L:11, R:9, G: 15, B: 9 x 600s; Ha:16 x 1800s. DARKS:30; BIAS:100; FLATS:40. Captured with an Esprit 150.

Great image! There's even more dust hiding in the background. Another 15 hours, perhaps? :icon_biggrin:

1 hour ago, AKB said:

I think you'll find that's exactly why he's got a GM1000HPS mount from 10 Micron!

That certainly explains it.

But, what camera was used? (can't see the signatures from my phone)

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2 hours ago, Adreneline said:

Very nice image Alan. I've not tried this target yet.

4 hours ago, alan4908 said:

 Despite the weather and lack of long nights, I somehow managed to capture just over 15 hours. I can only conclude that my recent move to unguided imaging is improving my capture efficiency....  

LIGHTS: L:11, R:9, G: 15, B: 9 x 600s; Ha:16 x 1800s. DARKS:30; BIAS:100; FLATS:40. Captured with an Esprit 150.

Can I ask why you decided to go 'unguided'? My NEQ6 would certainly not manage that with 1800s exposures - not sure it would cope with 600s either.

Thanks for the comment Adrian. :happy11:

My decision to go unguided was simply an attempt to improve my imaging efficiency due to the poor UK weather !

To explain: when I analysed my ACP logs when guiding with my NEQ6, I found that guiding was introducing several inefficiencies:  the time waiting for the guider to acquire a guide star, the guider/mount settle time and losing the guide star due to intermittent cloud.  With my NEQ6 imaging at 1.4 arc seconds/pixel I could only manage about 2 - 3 minutes unguided before the imaged stars resulted in unacceptable aspect ratios, so I realized this required a new mount. After a bit of research, I decided to go down the 10micron route, mainly because of the very positive user reports.

 

1 hour ago, wimvb said:

Great image! There's even more dust hiding in the background. Another 15 hours, perhaps? :icon_biggrin:

2 hours ago, AKB said:

I think you'll find that's exactly why he's got a GM1000HPS mount from 10 Micron!

That certainly explains it.

But, what camera was used? (can't see the signatures from my phone)

Thanks wim ! :hello2: - strangely, dust always seems to be lurking in the background irrespective of your chosen imaging time.  :happy11:

The image was taken with a SX Trius 814, giving me an imaging scale of 0.7 arc seconds/pixel.

Alan

 

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Thank you for your response to my question - as a relative newbie I'm afraid I did not appreciate the significance of the 10 Micron mount.

I have to say PHD guiding can be a mixed blessing. Life was simpler when I first started with a Canon 70D imaging nice bright things like M31 and M42 with relatively short exposure times. I too have experienced frustration with PHD now I've moved into the realms of long exposure imaging.

I've decided astrophotography is really an object lesson in managing multiple frustrations - it seems everything in your favour is constantly against you.

Thank you again for sharing an inspiring image.

Adrian

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Clearly the '10 Micron' mounts are very good mounts, but may I ask what the 10 micron on these mounts refers to?

It 'sounds' impressive but my 3D printer works happily with 60 micron layers and 10 microns is a realistic limit for 'hobby machining' with an ordinary lathe.

But if it's the accuracy of the worm wheels I will be impressed...

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26 minutes ago, ollypenrice said:

What a fine result!

I have imaged this twice and found it very tricky both times. Partly it's the density of the starfield which tries to overwhelm tha galaxy. Great stuff.

Olly

Thanks Olly :happy11: - yes, I know what you mean about the star field - it took me a few processing attempts before I was happy with the result !

4 minutes ago, Stub Mandrel said:

Clearly the '10 Micron' mounts are very good mounts, but may I ask what the 10 micron on these mounts refers to?

It 'sounds' impressive but my 3D printer works happily with 60 micron layers and 10 microns is a realistic limit for 'hobby machining' with an ordinary lathe.

But if it's the accuracy of the worm wheels I will be impressed...

Neil, that is an interesting question - as far as I know it is simply the company's name, rather than the precision of any of the components. So, to me it is just marketing branding, presumably with the aim of conveying precision.  However, I may be wrong :happy8:

Alan 

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11 minutes ago, alan4908 said:

Neil, that is an interesting question - as far as I know it is simply the company's name, rather than the precision of any of the components. So, to me it is just marketing branding, presumably with the aim of conveying precision.  However, I may be wrong :happy8:

Having looked at the website I imagine it is, I suspect they could claim better... I had always assumed that a '10 micron' mount was one that met a certain accuracy required for unguided imaging, rather than being a brand!

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7 minutes ago, astro mick said:

Very nice indeed Alan,amazing and colourful detail you have here.

Think my effort now belongs in the bin.(LOL)

Mick.

Thanks for the comment Mike - yes, I'm happy with the detail, I've found that my imaging set up of 0.7 arc seconds/pixel seems excellent for my site.  Although I image from an (almost) dark site, I also found that the addition of the Ha blended into the Lum really helped boost the image brightness.  

Alan

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Love the colour, especially the stars and the Ha regions.  Looks like a pretty challenging target given it's small size. 

Out of interest, have you tried binning with this set up?  I don't want to start a binning debate, just curious to know whether you have and if so how you found the results.

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22 minutes ago, MartinB said:

Love the colour, especially the stars and the Ha regions.  Looks like a pretty challenging target given it's small size. 

Out of interest, have you tried binning with this set up?  I don't want to start a binning debate, just curious to know whether you have and if so how you found the results.

Martin

Thanks for the comment.  :hello: In terms of challenge, I actually found the star field, rather than the galaxy to be the most challenging aspect of this target - since I had blended quite a lot of Ha into my Lum for the galaxy - I found this gave a non optimal appearance for the starfield, so this consists of mainly an RGB starfield with only a small amount of blended Lum.  

Although my camera (SX Trius 814) can happily bin either 2 x 2 or 4 x 4, I've never tried it during DSO captures - mainly because I've always though I should image at the highest possible resolution, even in the colour space.  The only time I tend to bin is when ACP automatically selects my bin mode when performing an autofocus or I'm creating a skymodel for my mount (which I generally do in twilight conditions to avoid eating into valuable imaging time).  Anyway, I suppose I really should try it and compare the results to the unbinned version to see if my theory is actually correct (or not).

Alan

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7 hours ago, astro mick said:

Very nice indeed Alan,amazing and colourful detail you have here.

Think my effort now belongs in the bin.(LOL)

Mick.

The comparison isn't a fair one, as Alan's data has longer exposures (x3) with a larger aperture, and a different pixel scale. All this on a rock solid mount. Add to that the very important aspect of location, and you're really comparing apples and ... (well, anything good but fruit).

Edit: somehow I assume that Alan is at a dark location, but rereading, I can't see where I got that from.

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1 hour ago, wimvb said:

somehow I assume that Alan is at a dark location, but rereading, I can't see where I got that from.

Hi Wim

I think you probably got that information from my response (above) - I image from an (almost) dark site which as you say, makes an significant difference to LRGB image quality. 

Alan

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Alan,

I think you may have caught a supernova in your image!

For fun I compared it to an RGB image of this galaxy that I processed from Liverpool Telescope (LT) data (data from 2014-08-26 to 2016-10-01) and your image contains a very bright "star" that is not present in the LT data. I now also checked Ha data from LT (taken 2013-06-10 to 2013-07-10) and that "star" is not there, so it does not come from you including Ha data. I have marked it in you image and enclose the LT RGB image as well as a very crudely processed LT Ha image (just run through "Equalize" in PS).

When did you do your exposures? Wonder if it is still there.....

Very exciting I think!

Alan4908 NGC6946arrows.jpg

LT NGC6946 RGB PS12sign.jpg

LT NGC6946HaEqualized.jpg

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1 hour ago, gorann said:

Alan,

I think you may have caught a supernova in your image!

For fun I compared it to an RGB image of this galaxy that I processed from Liverpool Telescope (LT) data (data from 2014-08-26 to 2016-10-01) and your image contains a very bright "star" that is not present in the LT data. I now also checked Ha data from LT (taken 2013-06-10 to 2013-07-10) and that "star" is not there, so it does not come from you including Ha data. I have marked it in you image and enclose the LT RGB image as well as a very crudely processed LT Ha image (just run through "Equalize" in PS).

When did you do your exposures? Wonder if it is still there.....

Very exciting I think!

Gorann - thanks for the info - the images were captured July to August 2017 - so I presume it is still there ! 

Alan

31 minutes ago, gorann said:

It is a 2017 supernova!

But "unfortunately" it has already been discovered. I just googled supernova ngc6946 and found it. See this link:

http://www.rochesterastronomy.org/sn2017/sn2017eaw.html

Never mind - my claim to fame will have to wait then. :happy11:

10 minutes ago, Stub Mandrel said:

Yep, already well known, even i managed to get it although my image is bit flat compared to yours, Alan!

 Thanks Neil 

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Nice image... I seem to recal reading somewhere that the Fireworks is fairly prolific for SN's.

Also, another ACP user I see. I couldn't do without it now to grab those gaps during my sleeping hours. Even though we've still only a short period of darkness up here, checking my logs I see the obsy fired up 3 times last night to grab a few subs ?

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Alan,

got so excited by the supernova that I forgot to tell you that your image is fantastic, with detail comparable with that of the Liverpool Telescope - a 2 m RC scope on the top of a mountain. And you accomplished this with a 150 mm refractor! The cost difference must be many magnitudes.

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