Archive for the “Writing” Category

Last night, for the first time since I put it together, I have been able to use the 2 x Canon 200mm lenses (and M26C Trius cameras) as intended.

The whole idea with this rig was to get two horizontal frames for a very large FOV mosaic, so that the overall frame would be almost square.  The other reason for going for 2-framers with the 200mm lenses is that time-wise I would be able to do the equivalent of a single (200mm) frame with a 4-framer using the Sky 90s, and as there are 3 Sky 90s then it would almost take the same time as well – so pointless doing a single frame with a single camera on the 200mm lens.  Not so pointless with 2 lenses, but I didn’t have 2 when I was working this all out months ago.

Carrying on.  I had 3 hours of imaging time from 11:00 p.m. until 2:00 a.m. when the Crescent would transit so I managed to grab 10 x 15-minute subs on the left hand frame and 12 x 15-minute subs on the right hand frame.  A single frame measures 398 x 267 arc minutes.  Not enough time spent on this for a high quality image but at least it shows that the general principle works as expected.  Now all I need is some longer nights, some clear Moonless skies – and this kit will ROCK :)

 

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I have just assembled this DNA model that comes from Cochrane’s of Oxford.  It is extremely well thought out and the instructions for assembly are quite excellent given the complexity of the thing being put together.  When I first saw this kit I thought that it was a little expensive for what was being offered – I now think it is very good value for money indeed!

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You too can make your own full-colour, high-resolution, deep-space images, just like the Tulip nebula mega-mosaic below – and you don’t even need to own a telescope.

However, you do need a copy of Photoshop and a copy of Noel Carboni’s Astronomy Actions for Photoshop.

The first thing you need to do is get your hands on the data which you will process into a full-colour image – I have described this process in an earlier Astronomy Now article – so if you are an Astronomy Now subscriber, look the process up there.

You will grab the data from the SkyView Query Form site.  Put in the co-ordinates of the object you want a picture of (or the object name) in the box at the top.  Go down to where it says what datasets are available and click on DSS2 red AND blue data.  Where it asks for image quality data put in 6000 pixels and leave the rest unchecked – this will give you a 6000 x 6000 pixel image at the highest spatial resolution on offer.  Send off the query and it will download the images to your monitor.  Go to the bottom of each image and click download the FITS files.  You will now have the red and blue channel data for your chosen object.  Now we need to process the data.

Open up Photoshop – and in Noel’s actions click on “Construct RGB image from channel files”.  This process expects you to supply red, green and blue channel data – but as you only have red and blue channel data you need to put the blue channel data into the green channel when the program asks you for it.  Go through the construct RGB process and at the end you will have a colour image of your object – but in the wrong colours as you didn’t provide any green channel data – fear not – Noel’s actions will come to the rescue!  Now click on “Synthesise Green Channel from Red and Blue” and Noel’s Actions will create an artificial green channel for your image giving something that looks a bit closer to “real” colour.

Now all you need to do is tweak the image in Photoshop to get something closer to what you are looking for.  I actually take the image into Paint Shop Pro at this point as it has a couple of very powerful “one click” processes.  I use the contrast enhancement tool on Darker/Normal/Normal and the saturation enhancement tool on More Colour/Normal – to get the image looking more how I want it – I then take it back into Photoshop for further cleaning up and to put on any (Noel Carboni) star spikes if I feel they are appropriate.

And that’s it.  You can produce deep-sky images of a quality far better than you can grab from your back garden with mega-expensive kit, and do it in far less time than it would take you to get just the data.  Makes you wonder why we actually bother to do it the hard way!

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I have been putting together a full-colour mega-mosaic of the Tulip nebula region in Cygnus using the wonderful DSS2 data.

As this is a pretty huge mosaic you can imagine the dataset was getting a bit unwieldy – and in fact my computer was starting to fall over – it couldn’t handle all the data.

So for now, until I get my hands on a Quantum Computer – this is it.  Won’t be adding any more to this one.

Printing out right now at A1-size on the HP Deskjet 130 6-colour printer.

Enjoy :)

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Clear Moonless night last night and good seeing – BUT – only 3 days before the summer solstice meant that the sky never really got dark and it was perhaps a bit stupid to image a nebula rather than a star field.  Never mind – live and learn – I have never taken an image this close to summer solstice before so didn’t realise it was a bit of a pointless exercise with an OSC.  Using both Canon 200mm lenses and both M26C OSC CCDs I managed to grab 20 x 15-minute subs on this one, so if the sky had only been dark this would have turned out pretty nice – 5-hours worth of 15-minute subs is nothing to be sniffed at.  So I will wait for darker nights before having another go at this one, but looking at this result, it’s got to be worth another try under better conditions.  In the meantime – if I get any more clear Moonless nights I think I will continue with the Lyra 4-framer, of which I currently have one frame.

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Just a reminder that you can see most of my Astronomical images on Flickr.

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A couple of nights ago with a full Moon I took some Arcturus data with the 3 x Sky 90s.

I combined the recent data with some taken a while back and came up with this result :)

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Here is a CCDInspector result from one of the 200mm lenses with an M26C Trius OSC CCD from last night:

 

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Last night I used the two Canon 200mm lenses and M26C Trius OSC CCDs to image the left hand half of Corona Borealis – the idea eventually to make a 2-frame mosaic showing the whole of the constellation.  When I processed the image this morning I was very surprised to see that R Coronae Borealis was blazing away (relatively speaking) at magnitude 8.  Why was this such a surprise?  Because when I imaged the same star in August 2013 with the 3 x Sky 90s for quite some time I was really disappointed to find that I could hardly see the thing.  Looking it up on Wikipedia I saw that it was not only at its minimum, but it had also been down there for the longest period in its (recorded) history.  So at that point I forgot all about R Coronae Borealis – until this morning :)

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It was a beautiful clear Moonless night last night (we don’t get very many of those in a year) and instead of imaging I was setting up :(  These things unfortunately need to be done, shame it was under almost perfect conditions though.  Never mind.  So I was working on the two Canon 200mm lenses and their Trius M26C cameras last night.  Both lenses are now aligned with the Sky 90s so everything on the megawasp array is pointing to exactly the same point in space – great.  Next was focus training.  Tom How not only built a second autofocuser unit for the second 200mm lens, he also swapped out the original stepper motor I had for one with much finer steps.  The result is that I now get great V-curves from both lenses and I only now need to click on “Focus” in FocusMax for both lenses to come to a very good focus.  Excellent!!  So the last job to do is to flatten the new Trius M26C to the optical train using CCDInspector.  It’s now 12:30 a.m.  CCDInspector running, camera downloading images for inspection – yes it is a little bit out (the other 200mm lens and M26C is almost perfectly flattened) so I just need the Allen keys to adjust the second camera.  I can’t see them.  They aren’t where I usually leave them.  There’s been a big tidy up in the observatory especially as there is now yet another computer in there (making 5 in all) and I know I put them somewhere safe and obvious – but I can’t see them.  O.K. it’s 1:00 a.m. now and I’m just going to break something if I carry on, so I shut down for the night and come indoors.  Brushing my teeth before bed, of course, I remember where the Allen keys are – I put them in a clear plastic bag and stuck them to the side of the pier where they would be obvious!!  Go out this morning and check – yep of course that’s where they are.  Very annoying I didn’t get EVERYTHING set up and ready to go for the next rare, clear, night – but that’s the nature of this game.  Pure frustration and annoyance for 360 nights of the year for the joy of 5 nights of great imaging.

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