A rarely imaged galaxy - best one so far?

[gorann]

More RGB data processed from the Liverpool Telescope (a 2 m RC scope on the Canary Islands).

This time of what appears to be a rarely imaged galaxy NGC691 and this is possibly the best image of it so far. Tell me if I am wrong, but I have not been able to find any good images on the net that I could use as reference while processing it, and this is probably the first object I have processed that I cannot read about on Wikipedia

Filters and exposures:
sdss-r 20 x 90 s
Bessell B 13 x 90 s (blue channel)
Bessell V 15 x 90 s (green channel)

So, 72 min of data which is OK when it comes from such a big scope

Comments most welcome

[The-MathMog]

Sorry if I missed it, but what galaxy is it exactly? Quite a beautiful one with its almost flower-like structure.

[gorann]

18 minutes ago, The-MathMog said:

Sorry if I missed it, but what galaxy is it exactly? Quite a beautiful one with its almost flower-like structure.

Thanks and good point! I put in the galaxy name in the tag-line but obviously it should also be in the text. Fixed it now.

Cheers

[Mr niall]

Wow that's lovely, I think we all agree it should be called Nialliopia. Definitely!

[ollypenrice]

I looked at the picture before reading the text. (Rather a childish thing to do!! .) My first thought was that it was very attractive but short on the reds. Is the core really so blue? Then I read the capture and it made sense. None the less this is a fine galaxy and an appealing image.

Olly

[gorann]

2 hours ago, Mr niall said:

Wow that's lovely, I think we all agree it should be called Nialliopia. Definitely!

Thanks Niall. Happy journey to Nialliopia!

[gorann]

1 hour ago, ollypenrice said:

I looked at the picture before reading the text. (Rather a childish thing to do!! .) My first thought was that it was very attractive but short on the reds. Is the core really so blue? Then I read the capture and it made sense. None the less this is a fine galaxy and an appealing image.

Olly

Thanks Olly!

Hard to know what the colours should be like when getting data from these sdss and Bessell filters that does not really match our ordinary RGB filters. And there was no usable Ha for this one. That is why I try to find reference images - but for this one there were essentially none.

Cheers

[gorann]

3 hours ago, Mr niall said:

Wow that's lovely, I think we all agree it should be called Nialliopia. Definitely!

Olly,

a slight touch on the red channel curve (and suppressing some apparent gradients)....

 

 

 

[wimvb]

Nice image, Göran. As for the colour: if the surrounding stars have a natural colour variation, this is usually a sign that the colour can't be too far off. I think you got it about as ok as possible.

The image bears the tell-tale sign of the LT telescope: mirror reflections in the blue channel.

[gorann]

7 hours ago, wimvb said:

Nice image, Göran. As for the colour: if the surrounding stars have a natural colour variation, this is usually a sign that the colour can't be too far off. I think you got it about as ok as possible.

The image bears the tell-tale sign of the LT telescope: mirror reflections in the blue channel.

Thanks Wim!

Yes, I was also hoping the stars would guide me (sounds biblical). You are right about the blue reflections affecting bright LT stars. Possibly something with the filter. In this case it was at least rather symmetrical and maybe even rather nice. The big blue asymmetric rings we sometimes get from LT I am inclined to clone stamp away. I have also noticed that the Bessell B images are often rather noisy, at least more noisy that the sdss-r.

[wimvb]

I rather like those reflections, so I tend to leave them there. Maybe it's the low signal in blue that is the cause that they show up in that colour (more stretch needed). I've never looked for them in the other channels.

[gorann]

Noticed some gradients and thought it could also benefit from a crop, so here is a revised version. Wonder how they manage to get gradients with a professional set up on a dark mountain top...

[wimvb]

Maybe someone forgot to turn off the lights. 

If you can read all of the FITS header, it will show the distance (degrees) to the moon and the moon fraction. I have data from NGC 891 that was captured with a 0.288 (29%) moon at 154 degrees. I don't know how much of a gradient that would cause, since the fov is quite small. On the other hand, I believe I read somewhere that they do take flats and darks.