NGC281 in HA, OIII and SII...

[fatwoul]

I hope this doesn't look like spamming, but rather than ditching these in my Pacman HA thread I thought it'd be nice to just show the three narrowband images I got this week of NGC281, together with the different ways I have used those images.

I was using my MN190 with my shiny new Atik 314L+. Exposures were all kept at 480 seconds for comparison, and each of these images was made up of around 10-15 seperate exposures, stacked using DSS:

That's H-Alpha, OIII and SII respectively.

Here is an image made up using H-Alpha as the red channel, and OIII as both the green and blue channels:

Here is the image created using all three filters, red as H-Alpha, green as SII and blue as OIII, which I think looks the most natural/believable:

And here are the same three images with the red and green channels switched over (red as SII and green as HA) and tweaked a little to give a Hubble Palette image:

If any other newbies want to take the three NB at the top of this post and try shoving them into photoshop channels themselves, please feel free. I've left them unaligned so you can practice the alignment bit as well, which is what I found most tricky.

Anyway, I hope you find this as interesting as I did, particularly the SII channel and the effect it has when you add it to an existing HA/OIII image.

[AndyUK]

Well these are all VERY nice... One more version and you'd have a Hockney painting!

I guess as with all these types of things, it comes down to personal preference at the end of the day - I always find that there's something about hubble pallette images... and there's something very subtle about the HOO as well. It's also very interesting seeing the raw Ha/OIII/SII frames as well (as you say, there appears to be no SII there at all, but it must be doing something!)

[fatwoul]

You're right, Andy. The HOO in particular is growing on me. Subtly is the right word, I think.

The biggest bug in the system for me right now is no filter wheel (hence the alignment hassle). I can't afford a "proper" one for another few weeks, but in the meantime I was considering one of the Astro Engineering ones. It only holds 5 filters, but at the moment I've only got my narrowbands and moonfilter anyway, so it would keep things light. I remember reading Merlin advising you add washers to the wheel to us it with Baader filters, but that's no biggy.

[AndyUK]

I must admit, I wouldn't be without my filter wheel... I did consider one of the bigger 8/9 slot wheels to effectively store the whole lot, but as it was noted that I wouldn't use LRGB with narrowband, I took the view that reducing the weight by "only" using a 5 slot wheel was probably better and easier for me, and even though most filters of the same make are quoted as being parfocal, I don't fully trust it, so the idea of spending the extra on a USB wheel would have been wasted on me!

Admittedly I was lucky - I bought my Atik manual wheel off Anna (who was upgrading to USB), but at the moment I'm very happy with it - I'm tending to "store" LRGB in the wheel and the 5th slot has a narrowband. My feeling is that if I'm doing a narrowband run, I'm probably going to want to spend the whole session on the one filter anyway so having any more is probably going to be overkill. I then use the L filter for framing and then flip to the narrowband. When I want to do RGB, the filters are already there and if I want to use a different narrowband for the next session, I open it up remove slot 5 filter and replace it...

(Again, I know it's a personal thing and many like the idea of safe storage and hands free use, but I just thought I'd add my reasoning just in case it's of any interest )

[Uranium235]

The HOO and second HST pallete versions definitely get my vote!

I have both the AE and Brightstar filter wheels which are roughly the same price, and if you want my honest opinion - get the Brightstar from Modern Astronomy - its a lot better than the AE wheel becuase it lets in a lot less stray light.

The AE wheel has quite an open bottom and NO numbers on the wheel so I had to use coloured stickers to mark which filter was where. In the end I had to build a cover for the wheel, which put an end to the gradient issues i was getting.

But, with both wheels some adjustments need to be made when you get it out of the box becuase to turn the wheel it can be quite stiff so I just lowered the tension using a hex key.

PS: just had a little tinker with the sharpening to bring out those blobs, hope you dont mind

[Tim]

Coming along nicely

If I can make a suggestion, the easiest method I have found of putting together a NB image is to use a program called Registar. It is a little dated, but does the job admirably, and makes it SOOOO easy to assign colour channels to the correct nb channel, aligns everything too, even stuff taken at different focal lenghts and with different cameras.

Cheers

Tim

[RobH]

Nice work, and thanks for showing the different combinations.

For me, the HOO gets it

Cheers

Rob

[dc509]

Nicely done, and great results.

d

[rich_t]

Very nice, good to see the different palettes of the same image, I like the HaOO image best too.

Regarding the tricky alignment that you mention, if you're using DSS to stack the images you can get it to do the alignment for you, the resulting stacked channels are then already aligned when they come out of DSS.

Before you stack the Ha, you select one of the subs to be the alignment reference frame (select sub, right click, use as reference frame), ideally use your best Ha sub as the reference. When you stack the Ha, the resulting image will be aligned to the selected sub.

When you stack the O3 and S2, you include this Ha sub in the list of light frames, again select it as the reference frame, but leave the sub unticked so that its data is not included in the O3, S2 stacks. The resulting O3 and S2 stacked images will now be aligned to the Ha image:)

Cheers,

Rich.

[mag10]

"If any other newbies want to take the three NB at the top of this post and try shoving them into photoshop channels themselves, please feel free. I've left them unaligned so you can practice the alignment bit as well, which is what I found most tricky".

Hello Fatwoul,

Very considerate of you to provide "trainings pictures" for us newbs.

I'm fairly adept at handling Photoshop in the traditional (non-astro) way, but I tried a few things with your pictures (like assigning a colour layer to each image) but when I combine the three images, it still comes out gray.

Is there a tutorial where I could learn how to process such images?

Thanks.

[Cloudwatcher]

you can practice the alignment bit as well, which is what I found most tricky.

You and me both!

In the end I cheated and cropped the combination image to the best of the aligned section.

Anyhow, this is the best I could come up with,over done as usual, bloated stars et al.

[fatwoul]

Wow sorry to everyone who replied who I didn't respond to. That was very bad-mannered of me.

mag10 - If there is, I don't know about it. To be honest, I was just aligning the channels visually, trial-and-error style. Now I'm aligning them with DSS as per rich-t's suggestion. I've not got a copy of Registar yet, but once the co-op stuff starts to take off, I think it will be a must-have (Thanks, TJ).

Thanks also to uranium and cloudwatcher for taking the time to fiddle about with the image.

Pacman is still in a good part of the sky for me, so I'm still firing away at it as a test target.