don4l

Thanks, Wim. I've downloaded it and I'll have a play tonight.

I said that I would have another go - and I almost wish that I hadn't! I've reprocessed the image, but I don't think that it is any better. I've added in some of last year's SII data to the green channel, using layer masks to keep the halos at bay. I need to do some research on star removal, and replacement.

Thank you. You are absolutely right about the stars. The image was almost nothing but stars when I did the first colour combine. So, your comment about aggressive star reduction makes complete sense. I used two different methods at different stages, which won't have helped. I didn't notice the issue until I did some final touch ups. I'll have another go at this tonight to see if I can improve things.

The Sharpless catalogue is full of slightly unusual Ha objects. I get the feeling that these are ignored because people used to think that Ha imaging was a bit difficult. For whatever reason (Light pollution, optics, camera????) I find Ha much easier than RGB, so these objects are much easier for me than Galaxies. The Sharpless catalogue is part of the "LBN" catalogue on this page :- https://www.ap-i.net/skychart/en/documentation/installation_of_extra_catalogs Deal Salman maintains a very good website, which is a very good reference for the Sharpless imager:- http://www.sharplesscatalog.com/sharpless.aspx

This is SH2-119 in Cygnus. It sits just under the North American Nebula. I tried to image this last year, but I couldn't get a result that was at all acceptable. I was using old Astronomik filters which had appalling halos. This was taken with Chroma Ha and OIII filters. Unfortunately, there is very little OIII in this, (but there is loads of SII). Hopefully, I will have a decent SII filter next year, and I will come back to this. The Blue data was almost identical to the OIII as far as I can see, and only takes a fraction of the time. Camera STL6303, OTA FSQ106 @ F3.6, Mount: EQ6. 120m Ha, 110m OIII, 12m Green, 12m Blue. CCDCiel, CCDStack, Gimp. Any advice would be very welcome.

Lovely image. Should it be in the "Getting started" forum?

This is a simple 2 panel mosaic of a part of Cygnus. There are three Sharpless objects in the left hand pane, and these would be very suitable targets for a longer focal length than I have used. SH2-112 has plenty of OIII, so could make a very nice target. It is also fairly bright. The field of view is about 7 x 2.75 degrees. Each pane is 60m mins Ha - Chroma 3nm filter. Moravian G3-16200 MKII, Tak FSQ106 (F3.6) on EQ6.

I wouldn't worry about rebalancing at this stage. My EQ6 isn't half as sensitive to balance as many other mounts. If you are happy doing the alignment using an eyepiece, then do it that way first. The first problem with the camera will be finding focus. To get the camera into focus you will probably need to move inwards from where the eyepiece was. However, if you are removing a diagonal to fit the camera, then you will probably have already moved in too far. The first time that I tried to find focus, I was so far off that I had no idea if there were any stars in the field at all. For me, the thing that helped was to make absolutely certain that I could trust the finder scope. Before putting the camera on, I would align the finder so that I could use it to put a bright star in the centre of a high powered eyepiece. Once you know where the focus is, then aligning with the camera is likely to be more accurate.

Excellent idea. I've started a spreadsheet. 10 "man points" for using a 20 year old copy of Corel Draw.

I'll never be able to look at the Soul Nebula again without that image coming to mind.

I think that most people are not very familiar with this object. I've just revisited my own version, and I agree that I was not able to supress the background noise. However, I have that problem with all of my images (a combination of over stretching and a very noisy camera).

I'd also assume that it was temperature. I often have to refocus every 30 minutes.

Thanks. I found this in the Baader link that you provided :- " All cell-mounted filters are already oriented in a way that the most appropriate filter face is facing the sky when the filter would be mounted directly onto the front end of the nosepiece of a camera. " That actually sounds very sensible to me. I'll check to see if the Moravian filter wheel will accept the screw in filters from the sky side - it is possible. The Moravian manual doesn't give a definitive answer. The unmounted filters definitely go in from the CCD side. I need a new set of filters anyway, so I guess that I will have to get unmounted.

I wonder if I have read your post correctly. The filters on my SBIG and Moravian cameras both screw in from the sensor side, so the threaded side faces away from the sensor.

I've done the exact opposite. I have an image "M24.tif" that I took in 2009 but only managed to identify a few months ago. It is M25. The whole area is full of fantastic stuff.

That's really quite beautiful.

I haven't read the whole thread, but I agree with you completely. I never realised how addictive that AP would become (or how expensive). And yet, my best images are just in my memory. I can clearly remember my first views of Saturn and Jupiter (and moons!!!) My best memory is the view of the Perseus double cluster. One of them struck me as a diamond ring. I've never seen an image that had anywhere the colour and vibrancy that I thought that I saw.

This is a 6 pane mosaic with 60 min per pane. It has been combined by hand in the Gimp. I know that the joins are visible, but I sort of enjoy seeing if I can put one of these together. In the past, I've struggled with mosaics because I cannot really get my head around the rotation issues involved - and once I start rotating panes in the Gimp, the stars become visibly different from one pane to the next. During this image I tried a completely new (to me anyway) method of aligning frames. Each image was platesolved and put into Cartes du Ciel as a background image. For the next frame I platesolved, and used CCDCiel's "Send frame to Planetarium" option. This immediately showed if the camera need rotating or re-centering. This sounds much more complicated than it is in practice. Anyway, the result is that none of the panels needed to be rotated. They aren't perfect, but they are close. FSQ106ED at F3.6 G2-16200 MKII camera, EQ6 EQ6 Acquired with CCDCiel, Calibrated and stacked in CCDStack, patched together in the Gimp. Comments, suggestions and advice very welcome.

I think that you need to be a mathematical genius to get a proper answer to your question. I've read that doubling your exposure time improves your signal to noise ratio by 1.4(ish). If I combine 2 subs and compare the result to a stack of 4 subs, I can usually see what this difference looks like. However, I recently had a go at the Squid in SH2-129, which is a notoriously weak OIII target. After 2 hours of data I had a result which looked promising. I then got another 6 hours of data before having another at processing. I was horrified to see that the 8 hours showed absolutely no improvment at all over the 2 hours. The subs in the extra 6 hours all looked to be of similar quality to the first two hours. I don't understand what the problem is. I think that it is either related to read noise, or sky background or something else. I have just received a new camera which is much more sensitive to OIII and it has lower read noise. If you see a post from me in the next few weeks about SH2-129, then have a look, because I will definitely comment on this issue.

Yes. If you can look at one of the images as it came out of the camera, then you will have a better idea. Perhaps deepskystacker allows you to look at the images before you process them??? If they are in Raw, then it should be possible to convert one to a jpg. Depending on the settings in your camera, you might have the jpegs already. If the moon caused the problem, then you should be able to see it in a single image. To be honest, the moon was quite bright two nights ago, so you wouldn't have been able to get anything great without narrowband filters.

How do the individual frames look before you calibrate them?

I spent last year playing with all this stuff. I can image with a 3nm Ha filter almost anytime. If the moon is too bright, I keep away from it. Tonight I am imaging around the Crescent, and I cannot see any effect. However, if I was a much better imager, then I might notice that the dimmer areas were not as good as they might be. Maybe next year I won't bother on a night like tonight. When I was using a 7nm filter, the moon had a much greater effect. Even then, I could do stuff binned 2x2. OIII is affected much more by the moonlight, even at 3nm. At 12nm, I found the OIII almost unusable if there was any moonlight at all. I think that is partly due to the fact that most OIII targets are much weaker than the Ha targets, so if there is any background light, then it will have a bigger impact. I found that practising gave me a feel for what I can do. I wouldn't bother imaging without narrowband tonight.

That is an excellent result for just an hour's worth of data. It is very satisfying to be able to produce an image in an evening.

Superb! I looked at it in full resolution. If you split that image into 9 panels, then 6 of them would make brilliant images in their own right.

I would never have noticed it if you hadn't pointed it out.