M109

[alan4908]

My first attempt at M109, a galaxy located in Ursa Major which is about 55 million light years distant. In the image below you can also see quite a few other background galaxies - the ones marked PGC37553, PGC37700 and PGC37621 have recession velocities very similar to M109 and are classified as dwarf companion galaxies.  

The LRGB image below represents 16.5 hours integration and was taken with my Esprit 150.

Alan

M109

M109 (annotated)

LIGHTS:  L:37, R:21, G:23, B:18 x 600s. DARKS: 30, BIAS:100, FLATS: 40 all at -20C.

[MarkAR]

Lovely image especially as you've picked up the disc formations of the tiddlers.

[Whirlwind]

It's a lovely image.

Can I ask though what's happened with the blue element of the processing? It seems to make the image look a bit 'spotty' and there are areas that have a very blue tint (e.g. PGC37700 / PGC37621)

[geoflewis]

An excellent image

[alan4908]

13 hours ago, MarkAR said:

Lovely image especially as you've picked up the disc formations of the tiddlers.

Thanks for the comment.   Yes, I was quite happy with the amount of detail that I managed to acquire.

11 hours ago, Whirlwind said:

It's a lovely image.

Can I ask though what's happened with the blue element of the processing? It seems to make the image look a bit 'spotty' and there are areas that have a very blue tint (e.g. PGC37700 / PGC37621)

Thanks for the comment. 

On your blue processing point, I believe the blues are an accurate representation.  For instance, take a look at these images from three accomplished astrophotographers:

Adam Block - http://www.caelumobservatory.com/obs/m109.html 

Robert Gendler - http://www.robgendlerastropics.com/M109.html

On the small blue stars and the blue tint of the small background galaxies, these also appear accurate - for instance,  have a look at this APOD from Bob Franke:   http://www.star.ucl.ac.uk/~apod/apod/ap130523.html 

 

6 hours ago, geoflewis said:

An excellent image

Thanks Geoff !

Alan

[alan potts]

Really lovely image there.

Alan

[Whirlwind]

11 hours ago, alan4908 said:

On your blue processing point, I believe the blues are an accurate representation.  For instance, take a look at these images from three accomplished astrophotographers:

Adam Block - http://www.caelumobservatory.com/obs/m109.html 

Robert Gendler - http://www.robgendlerastropics.com/M109.html

On the small blue stars and the blue tint of the small background galaxies, these also appear accurate - for instance,  have a look at this APOD from Bob Franke:   http://www.star.ucl.ac.uk/~apod/apod/ap130523.html 

Hmm I think they should be more pink in the main galaxy.  From the larger images they appear to be star forming regions and hence you'd have some red from the emission nebula as well as the hotter stars.  The very intense blue would be representative of very hot stars and relatively they are rare.  As for the Franke image I'd have the same argument.  The smaller galaxies are too blue.  The cores of galaxies are generally old and hence cooler.  Such intense blue is generally only seen in galaxies that are interacting (at least nearby anyway) and still in the tidal tails rather than the core.  The core of them would be more akin to M109 pinky blue at the edges and cooler towards the centre (and if it is an elliptical then cool all the way).  I've included a basic photoshop image of the areas.

Of course it is artistic licence and still an excellent picture but I just find the intense blue areas 'distracting'.

[MarkAR]

I think the only difference between Alans' and Block/Gendler is very slightly more colour saturation.  Nothing to worry about at all.

 

[alan4908]

On 05/05/2020 at 09:41, alan potts said:

Really lovely image there.

Alan

Thanks Alan 

14 hours ago, Whirlwind said:

Hmm I think they should be more pink in the main galaxy.  From the larger images they appear to be star forming regions and hence you'd have some red from the emission nebula as well as the hotter stars.  The very intense blue would be representative of very hot stars and relatively they are rare.  As for the Franke image I'd have the same argument.  The smaller galaxies are too blue.  The cores of galaxies are generally old and hence cooler.  Such intense blue is generally only seen in galaxies that are interacting (at least nearby anyway) and still in the tidal tails rather than the core.  The core of them would be more akin to M109 pinky blue at the edges and cooler towards the centre (and if it is an elliptical then cool all the way).  I've included a basic photoshop image of the areas.

Of course it is artistic licence and still an excellent picture but I just find the intense blue areas 'distracting'.

Thanks for your detailed comments.

In acquiring the image, I did wonder if I could detect some star forming regions, so in acquiring the image, I also decided to try to capture some emission data via my 3nm Astrodon Ha filter. Unfortunately, even after 7.5 hours (15 x 1800s), the resultant stacked Ha image just looked like a grainy version of the stacked red channel. So, unfortunately, no more detail, only noise was revealed. I therefore decided not to use the Ha data.  I should point out that I'm not implying that there aren't any star forming regions in M109 - it is just that I didn't detect any  

On a general point, it is quite interesting trying to compare my image with others, high resolution M109 images seem to be in short supply. 

10 hours ago, MarkAR said:

I think the only difference between Alans' and Block/Gendler is very slightly more colour saturation.  Nothing to worry about at all.

 

Thanks for the comment !

Alan