Hi All,
I imaged this while finishing off other targets in the earlier hours. Thought the scene would be interesting given the object pairing of a globular and spiral galaxy. Looks like two coins as opposed to the single Silver Coin galaxy. Ironically, the Silver Coin galaxy doesn't look that silver either, more like corroded copper coin...
Two Silver Coins
Located in the constellation Sculptor, the Globular cluster NGC288 (top left) and at 1.8 degrees south-east the spiral galaxy NGC253 (aka Silver Coin galaxy) appear to interact. However, they are in fact extremely far away from each other. NGC253 was discovered by Caroline Herschel in 1793 and is one of the brightest galaxies beyond our local group. Both objects are near the South Galactic Pole, a point on the celestial sphere that is not obscured by stars and gas as it is at right angles to the Milky Way. Due to this a rich field of galaxies both bright and dim are visible across the presented scene. NGC288 is approximately 30,000 light years away, while NGC253 is 10 million light years away hence there is no interaction between them.
Well, being a single frame image, I though I'd try process this image entirely in PixInsight. eeekkkk! Way out of the knowledge zone. Overall I think its a reasonable job. Not certain what happened to the star alignment function as it looks like far edges of the frame aren't aligned - perhaps the data was the cause. I will be honest, I don't like the data rejection routines in PI. They work, don't get me wrong but there's a lot of fuzzing around getting the right balance. I'm sure I would become more proficient at it, but CCDStack still feels superior. I love the ability to see what you are rejecting as opposed to throwing your subs into an outlier rejection algorithm and repeating the result again and again until you are satisfied all you are throwing out is outliers as opposed to important data. DBE on the other hand - it rocks on simple scenes like this! Was quite impressed. I intentionally stretched the data hard to bring out the full shell of NGC253. The shell itself extends further than I expected and with an interesting lobe. Plentiful background galaxies both bright and dim are present. I experimented with DDP to get the stellar profiles right but it took two hours to understand how to integrated them again with masks. All part of the learning curve I guess. I don't think I'll be doing that again! HDR Wavelet Transform processing is still to be discovered. One step at a time but I'm enjoying it. I'm keen to see how well PI handles Ha+R combines and the like. In all seriousness, I can see myself swapping data in and out of various tools. I have more data to process so will try the hybrid approach when I get a chance. PI seems to mangle the FITS data when bring it back into CCDStack. Seems there are differences in 32 bit float point formats - more to learn.
Anyway, thanks for checking it out.
Cheers