My first Pacman

[DaveS]

Nothing special, a simple Ha / [OIII] / [OII] RGB synthesis, in the absence of any meaningful [sII]

1 hour each of Ha and [OIII] is 6 x 10 min subs. Baader NB filters, Megrez 90 / 0.8x WO AFR IV / Trius 684 binned 2x2. Stacking Sigma, Histogram Stretch and Trichromy in AA5

Still getting some odd green and red stars.

[astro mick]

That's not a bad image Dave,its all there,obviously more Data would benefit greatly,but still very good.

Your green and red stars may be Hot Pixels,are you taking Dark Frames?

Mick.

[DaveS]

They may be hot pixels, though I do a hot pixel removal during stacking, and again after the final combination.

I was going to do some Darks, but re-reading the Trius 694 manual, SX said darks could cause worse images, so I'm not sure. I did another stack and combination after taking a set of 20 Bias frames of 1/1000 sec, but again I'm not sure how much difference it's made. I think I should do some Flats, but again not sure, as I've made changes to the light path since, and don't know if I could put everything back as it was.

Something that's been worrying me, I've had an Astronomic CLS filter in the image train (Not the CCD version) and I'm wondering if it's attenuating any [sII] that might be there.

[astro mick]

Hi Dave.

I would suggest Dark Frames first,take at least 25/30,and load into DSS if that's what you use.I do know it has a hot pixel remover,but it does,nt catch them all.

You could also use the clone stamp in Photo-Shop to remove the worst offenders.

A Bias Frame is,nt necessary if you use Darks,as that will contain the Bias also.

Remember to take the Darks at the same time and Temperature as the lights.

One other thing is that the Black Point has been clipped,so you are losing Data,keep an eye on this.

Cant help with the CLS Filter unfortunately.

Mick.

[DaveS]

Well, just for the fun of it and because it's too rubbish for imaging, I'm getting a sequence of 12 x 10 min Darks to go with my Pacman images. The first ones coming in show a nice array of hot pixels.

Given the short windows of imaging that we get here I'm loath to give up imaging time for Flats and Darks.  

[Epicycle]

There should be some sii there. Why binning? Your set up should allow a nice resolution for those pillars in the nebula and the Bok globule in the center. Anyhow, good attempt,

E.

[DaveS]

The [sII] subs I took (only 2 x 10 min) show a *very* faint image, not enough to use. Possibly the CLS filter I was using blocked it out, though I thought the pass-band extended to [sII]. The binning was to increase sensitivity as I was concerned about getting any kind of image at all.

I think the next run I do I'll push the subs to 900 sec, if the guiding will allow, bin 1 x 1 and take dark and flat frames.

[Scott]

Well, just for the fun of it and because it's too rubbish for imaging, I'm getting a sequence of 12 x 10 min Darks to go with my Pacman images. The first ones coming in show a nice array of hot pixels.

Given the short windows of imaging that we get here I'm loath to give up imaging time for Flats and Darks.  

I get that you don't want to take darks when the sky is clear but 5-10 mins at the end of a run  for flats and bias is well worth it darks can be done while you're tucked up in bed

[DaveS]

That's a point, though I'd have to bring the 'scope and laptop in to my unheated conservatory overnight as the chances are it would chuck it down if I left them out. Either that or they'd get nicked.

[DaveS]

Well, I've been having another play, using the Dark and Bias frames I did today. I also did a background normalisation after histogram stretch and before RGB synthesis and a max entropy deconvolution afterwards.

I think it's slightly better, but not much. I did try a Hubble Palette using the [sII] frames but as expected there wasn't enough data to give much of a red signal.

Edit; did a gradient removal and second stretch on the PNG after I saw what my post looked like.