Archive for the “mini-WASP Array” Category

The creation and use of the New Forest Observatory mini-WASP array

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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Here is the latest state of play on the array now known as the “megawasp” array :)

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Looking through this year’s captures I found one I hadn’t put up for viewing.  This is Carbon star X Cancri taken on 15th February 2015.

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A “Little Planet” shot taken this afternoon with the Canon 5D MkII and a 15mm Canon fish-eye lens.

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Nice way to start off a new month.  After 4 days of drilling, cutting, taping and wiring – the upgrade converting the mini-WASP array to the mega-WASP array is now complete.

Additions to the top plate are another Canon 200mm lens with M26C Trius OSC CCD and an Altair finder scope with web cam (a Lodestar can be swapped for the web cam if necessary).  A fifth computer was installed in the north dome ready for the new goodies and I am sharing the monitor between camera 3 and camera 5 (since both won’t be used at the same time) so only 4 monitors in there instead of 5.  Got to admit it looks a lot like a car wiring loom in there now, but I’ve done a LOT of tidying up of cables while I had to make the changes so it is a lot less messy looking now (though it is still pretty messy looking).

So that’s it for the parallel array imaging system – no more places to fit any new stuff – time to send along the good weather so I can put this thing through its paces.

Still plenty of setting up to do though before it can be let loose in anger.  Both 200mm lenses need to be aligned to the rest of the system.  Need to get good V-curves for both lenses and check that the autofocuser works o.k.  Need to move the array all over the sky and check that the Megrez 80 guider can also point through the aperture with the 2 x Canon 200mm lenses.  If it can’t then the web cam comes off the Altair finder and a Lodestar goes on for guiding – a bit of a pain, but not too bad.  With the web cam on the Altair finder I will need to get good polar alignment again as all this weight change will definitely have thrown it out a bit.  Probably a dozen more things will need sorting as I go along – but that’s the “fun” of this hobby isn’t it?

 

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After 3 days I have now finished all the metalwork, drilling and tapping, and reconfiguring the top plate of the mini-WASP array.

The top plate will now accommodate 2 x Canon 200mm prime lenses, each with a Starlight Xpress M26C Trius OSC CCD + an Altair finder scope with a Philips web cam attached.

I’ve said it before but this time I think that’s really it as I simply cannot bolt anything else onto the frame.

With this final incarnation I think a name change is also in order – so what was the mini-WASP array is now officially titled the mega-WASP array.

The array can be run as two separate imaging systems (the limitation of the dome aperture means I cannot run all cameras at the same time, which is a great shame).

System 1:  The very wide field imager.  This is the 2 Canon lenses with M26C Trius cameras.  Both lenses/cameras image the SAME object, so I am getting data down at a rate that is 2x the actual imaging time.  The FOV of the system is 4.46 x 6.64 degrees with a sampling of 6 arcseconds per pixel.  The M26C Trius cameras are 10-megapixel resolution.  The Canon lenses are run with their apertures wide open and I use a 52mm UV/IR cut filter on the front which doubles as both a filter and an aperture giving f#3.8 operation and good quality stars across the whole of the M26C chip.  The bonus of aperturing the lens in this way is that you don’t get the 8-spiked star spikes which I personally find pretty unattractive.  You get no spikes at all with the Canon lenses used in this way, just as with a refractor.

System 2:  The Sky 90 array.  This system comprises 3 x Sky 90 imaging refractors each with an M26C (non-Trius) OSC CCD.  Two of the three refractors have a filter-wheel attached with IDAS, H-alpha, H-Beta, OIII and SII filters.  Again, each imager images the same object which gives me a data rate of 3x the actual imaging time.  The FOV of a Sky 90/M26C is 3.33 x 2.22 degrees at a sampling of 3 arcseconds per pixel.  All three Sky 90s have the Takahashi reducer/corrector fitted so the f# of a Sky 90 is f4.5.  The fourth slot in the main frame houses the Megrez 80mm William Optics guide scope with a Starlight Xpress guide camera (driven from one of the M26C cameras).  This guider also acts as a guider for the 2 Canon lenses on the top plate.

O.K. so we are never going to get enough clear Moonless skies to justify all this lot – but at least for those short opportunities, when they finally do come along, I can make the best of the time given to me by the weather Gods.

Pics will follow when everything has been set up. tuned in, and running :) :)

 

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I composited some 4-hours of Hyperstar III data and some 6-hours of Sky 90 data to give the following deep image of NGC281 – the Pac Man nebula.

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A clear Moonless night last night so I put the mini-WASP array on Polaris.

A total of 36 x 5-minute subs gave the result below which I’m pretty pleased with.

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