NGC 1964 - collaboration on a rarely imaged galaxy in Lepus

[gorann]

NGC 1964 is a barred spiral galaxy 65 million light years away from Earth.

This is a collaboration between Wim van Berlo @wimvb and me - two Swedes right now enjoying near midnight sun and no chance of doing our own astrophotography. So when being left with nothing else to do we have started processing free data from the Liverpool Telescope archive, and yesterday we came up with two different version of NGC1964 that each had some good qualities. This is a mix of the best of the two versions.

As far as we can tell, this is the best image of this rarely image galaxy so far. The Liverpool Telescope is a 2 metre f/10 RC scope on the top of the mountain on La Palma, Canary Islands.

Filters and exposures used.
sdss-r 16 x 90 s (red channel)
Bessell V 9 x 90 s (green channel)
Bessell B + sdss-g 20 x 90 s (blue channel)

Comments most welcome

[celestron8g8]

Goran this is a really good capture with excellent detail . However your PP work puts the image right at the edge of clipping your BP . If you take this final image into PS and raise the exposure slightly and drop the gama back slightly you will back off of clipping your BP and you will reveal lots of dust lanes visible in your image and it will look a lot better . One thing about clipping the BP is you cover up a lot of data in an image . I checked it in PS and did so but I wont post cause I don't have your permission but you can do this yourself and post the picture back in this thread for comparison .

[wimvb]

23 minutes ago, gorann said:

NGC 1964 is a barred spiral galaxy 65 million light years away from Earth.

This is a collaboration between Wim van Berlo @wimvb and me - two Swedes right now enjoying near midnight sun and no chance of doing our own astrophotography. So when being left with nothing else to do than processing free data from the Liverpool Telescope archive, we came up with two slightly different versions that each had some good qualities. This is a mix of the best of the two versions.

As far as we can tell, this is the best image of this rarely image galaxy so far. The Liverpool Telescope is a 2 metre f/10 RC scope on the top of the mountain on La Palme, Canary Islands.

 

Comments most welcome

 

Well, a bit of nitpicking here: one Swede and a Dutchman (I'm like Sting, a legal alien, just not in New York) 

The weather gods are mocking us. Now that it's too bright to do any AP, we enjoy cloudless nights. I believe this to be a new fundamental force: water vapour (cloud) is attracted by darkness, and repelled by light. Why else do we have clear weather when there's a midnight sun or a full moon?

Thank you very much, UK tax payers. 

[wimvb]

2 minutes ago, celestron8g8 said:

Goran this is a really good capture with excellent detail . However your PP work puts the image right at the edge of clipping your BP . If you take this final image into PS and raise the exposure slightly and drop the gama back slightly you will back off of clipping your BP and you will reveal lots of dust lanes visible in your image and it will look a lot better . One thing about clipping the BP is you cover up a lot of data in an image . I checked it in PS and did so but I wont post cause I don't have your permission but you can do this yourself and post the picture back in this thread for comparison .

I believe that what is left in the background, is residual light from reflections and perhaps a bit of remaining gradient. See my version of this image for a definitely non-clipped background.

[celestron8g8]

Well here is slight adjustments I've made and i'm seeing a lot of BG dust lanes . Doesn't look like residual light reflections to me .

 

[gorann]

17 minutes ago, celestron8g8 said:

Goran this is a really good capture with excellent detail . However your PP work puts the image right at the edge of clipping your BP . If you take this final image into PS and raise the exposure slightly and drop the gama back slightly you will back off of clipping your BP and you will reveal lots of dust lanes visible in your image and it will look a lot better . One thing about clipping the BP is you cover up a lot of data in an image . I checked it in PS and did so but I wont post cause I don't have your permission but you can do this yourself and post the picture back in this thread for comparison .

Point taken but,

actually the background in Wims original version (posted just above) and my mixed one is exactly the same (I largely used his background), so I did nothing to the black point. Wim had the background down to around 10. I usually stay at 20 - 25 (Olly school), but then I have seen that many take galaxy images down towards 10. In any case, like Wim I suspect that what you found when bringing up the background is remains of our fight againt terrible reflections on the big stars and gradients.

[wimvb]

To clarify: everything within the circled area in the image is due to reflections or gradients. I have checked the original masters, and can't detect any hint of dust. In the masters, as in my version of the image, there are in fact three reflections for each star. Two are very bright and smaller, and the third is very weak and big.

Otoh, there is some very faint detail to the upper right of the galaxy, between the galaxy and the three, evenly spaced bright stars. (Not in the fov of this crop)

In my original image, I left the reflections so as not to destroy all the faint fuzzies in the background. Göran removed the reflections, but couldn't save the faint fuzzies in the process. In our joint effort, we tried to keep the best of both images.

[celestron8g8]

5 minutes ago, gorann said:

Point taken but,

actually the background in Wims original version (posted just above) and my mixed one is exactly the same (I largely used his background), so I did nothing to the black point. Wim had the background down to around 10. I usually stay at 20 - 25 (Olly school), but then I have seen that many take galaxy images down towards 10. In any case, like Wim I suspect that what you found when bringing up the background is remains of our fight againt terrible reflections on the big stars and gradients.

Well you maybe right , but it sure fooled me this time . This image of NGC1313 by Robert Gendler has outer dust like I was referring to . Only not as evident as in Robert Gendlers image .

http://robgendlerastropics.com/NGC1313.html

[wimvb]

13 minutes ago, celestron8g8 said:

Well you maybe right , but it sure fooled me this time . This image of NGC1313 by Robert Gendler has outer dust like I was referring to . Only not as evident as in Robert Gendlers image .

http://robgendlerastropics.com/NGC1313.html

Yes, that's an excellent example of dust near a galaxy. If you look at images from R. Jay GaBany (http://ccd.cosmotography.com/), there are lots of galaxies which have faint dust surrounding them. I don't know if ngc 1964 is among them, but the Liverpool telescope data doesn't show it.

[gorann]

14 minutes ago, celestron8g8 said:

Well you maybe right , but it sure fooled me this time . This image of NGC1313 by Robert Gendler has outer dust like I was referring to . Only not as evident as in Robert Gendlers image .

http://robgendlerastropics.com/NGC1313.html

That is a striking image but I expect that few galaxies are as dusty as NGC1313, and when processing I do so with a rather bright background (around 35) and always look for dust and do my best to bring it out before taking down the background to a comfortable level at the end.

[gorann]

Here is a new version where I tried to take away the last remains of those reflection artifacts around the brightest stars (a problem apparently inherent to the Liverpool Telescope), so they do not get confused with dust. I also darkened the core a bit to reveal more detail.