M83 from light polluted Perth

[alocky]

We've finally had a few clear days in Perth, so I thought I'd get my new QSI camera out for the second time in three months. I haven't got the focuser on my Starfinder 10" motorised yet, so this is hand focused. I took 20x 2min L, and 8x5min R,G and B. I also took some 15 min H-alpha, but they're not in this mix yet. Apart from the slight yellow cast, I'm reasonably pleased with the colours in this, especially the red in the star forming regions in the arms.
comments and constructive advice welcomed!
slightly higher res version at http://www.astrobin.com/43784/
cheers,
Andrew.

[johnnyt123]

Great capture Andrew.
I had trouble just fingding M83.

Looks good but as you said the colour is just not right.
Maybe you need some more blue Data, or play around with the Hue settings...

What equipment did you use to get such magnification??

My last attempt resulted in a galaxy a quarter that size....Wasnt even worth keeping the data saved on disk!!!

John

[Larryp]

Nice image, Andrew!

[alpal]

Looks good but you have some tracking problems shown by elongated stars.
How were you guiding it? - not an OAG?

[alocky]

Yep OAG using PHD with a reported error of 0.5 RMS. I think the elongated stars are a result of sloppy focus and poor collimation. To be addressed in the next week or so!
Still not sure on the best way of getting the colour balance right. Definitely lacking blue.
cheers,
Andrew.

[alocky]

Hi John - thanks,
The scope is a 10" f 4.5 Meade starfinder, the camera is a QSI 683 wsg, and the mount a G11, so focal length slightly over 1100mm.
Not sure why the colour is so far out, but there seems to be something unusual about the blue channel.
cheers,
Andrew.

[alpal]

Hi Andrew,
OK - I use a laser collimator for my Newt. but I'm not sure how you'd do yours.
The colors should come out right if you make the histogram
even for all RGB. ( in Photoshop )
You have a lot of detail in the photo - there is great potential in your system.

cheers
Allan

[alocky]

I'm a complete numpty - I'd forgotten how to do the LRGB in pixinsight. It's worth going through the tutorials again every now and then!

[alpal]

Now you're talking - that's great.

[cybereye]

Andrew,

Now that's a nice image and the colours look pretty spot-on! :thumbsup:

Cheers,
Mario

[alocky]

Thanks guys - all I need to do now is get the robofocus motor fitted, and collimate the thing and I can go nuts from my backyard now.
Cheers,
Andrew.

[Draco]

Nice job Andrew. well done

[LewisM]

Great job, but can we still call you Numbty? ;)

[alocky]

Sure - go ahead! I've been called worse :-)

[Arthur Coombs]

Hi Andrew, from one imager in light polluted Melbourne to another in Perth, I think you have done very well with capturing M 83. You have done a great job in your overall processing, including the very centre of the barred galaxy. I found it difficult not to burn out this area. Re the overall colour, you may possibly need to look at the filter factors when initially combining the RGB images. These factors take into account your complete system:- telescope optics, filters and the characteristics of the camera chip. As Alan suggests, a final tune up can be carried out in Photoshop.
Overall, well done :thumbsup:
All the best, Arthur.

[alocky]

Thanks Arthur - I was going to image a few standard colour stars and work out what the filter coefficients should be next. The second version in this thread uses background neutralisation and the Pixinsight colour balance tool setting the central region of M83 to white. The step I'd goofed on was doing the LRGB combination in linear space, not after stretching the data. I quite like the colour now!
cheers,
Andrew.

[Ross G]

Very nice looking galaxy photo Andrew.

I love the detail.

Ross.