Here is the Crab Nebula, taken under dodgy conditions, and nowhere near enough exposure.
We've been off-air due to technical problems with the dome roof opener. The H-bridge limit switch input (an innocent looking 8015 quad AND gate) was possibly fried after a vicious thunderstorm - we've had some impressive jump-out-of-your-skin thunder. Replaced the chip and we're now operational but yet to see how robust everything is, or whether there is other damage.
Apart from Bildan, everyone else on IIS is wisely leaving the far north alone, perhaps because the seeing has been so appalling. Last night we had and FWHM of 10 pixels, and we lost two subs to intermittent cloud, but we've been waiting for ages and ages, so here's half a crab.
Six hrs of H-alpha mapped to R+G, and only 3hrs of OIII mapped to blue, then palette rotated -15 degrees to give a quarter nod to natural colour. (To recover individual channels, rotate palette +15.)
What can we see that nobody else has mentioned? There is a small and very faint slightly streaky tongue of light (about 90 pixels = 50 sec arc high) heading off toward 9 o'clock, almost to the left hand edge of field, seen in both H-alpha and OIII, that isn't obvious in say the Hubble image or any other that we're aware of.
Question: We've read that the blue glow of the Crab is Cerenkov radiation - electrons spiralling in a powerful magnetic field. Presumably only some proportion of that would go through our 3nM OIII filter. Would we in fact do better with a wideband blue filter? Ordinarily we'd just give it a try, and all would be revealed, but what with Christmas, Cloud, and Crispy Electronics, it's been a struggle.
Field is cropped to only 9.3 min arc. Total exposure 9 hrs in 1hr subs. Aspen CGC16M on 20" PlaneWave.
That's lovely MnT! It was an object that I've wanted to image until I saw just how damned small it is!
It is one of my favourite objects simply because it is one of the few objects in the sky younger than human history
Nice image there Mike and Trish,I have never seen that streak before either.
On checking The "images" on google, there are a few pics with the streak on them.
One pic even has two.
Link here. http://www.cosmotography.com/images/small_new_m1.html
Cheers
Nice image there Mike and Trish,I have never seen that streak before either.
On checking The "images" on google, there are a few pics with the streak on them.
One pic even has two.
Link here. http://www.cosmotography.com/images/small_new_m1.html
Cheers
Thanks hugely, Ron. That's the most beautiful image. It at least in part answers our question - one of the very few emission nebulae seemingly worth a go in natural colour, especially if we can move the observatory a few feet further north.
Great capture guys! Such a cool object, hard to take from 33deg S too, nicely done Yes that extension is well seen in several other images, I wonder what caused it? Looks like some sort of expanding bubble breakthrough ...maybe the Millennium Falcon escaping an Imperial Starship
The Gold Coast Bulletin has a pic of a crab with one white claw and a likeness of Michael Jackson on its carapace, but yours is a lot more impressive M&T! Shame about the weather and technical difficulties, but still a good result.
The extension is very cool too. I must have a dig around for one of those "time lapse" images of the crab and see if there's anything interesting detectable in that region.
Well done M&T, I love the gold and silver colour scheme with the blue glow around the edges. Not sure how you got 3 distinct colours from bi-colour data, must something to do with your palette rotation.
Great capture guys! Such a cool object, hard to take from 33deg S too, nicely done Yes that extension is well seen in several other images, I wonder what caused it? Looks like some sort of expanding bubble breakthrough ...maybe the Millennium Falcon escaping an Imperial Starship
Mike
Thanks Mike! The Starship theory is very attractive, but the burst bubble explanation has the advantage that it's been observed in other SNR's.
Quote:
Originally Posted by RickS
The Gold Coast Bulletin has a pic of a crab with one white claw and a likeness of Michael Jackson on its carapace, but yours is a lot more impressive M&T! Shame about the weather and technical difficulties, but still a good result.
The extension is very cool too. I must have a dig around for one of those "time lapse" images of the crab and see if there's anything interesting detectable in that region.
Cheers,
Rick.
Cheers, Rick. Glad we can't see Mr Jackson in our image.
Quote:
Originally Posted by billdan
Well done M&T, I love the gold and silver colour scheme with the blue glow around the edges. Not sure how you got 3 distinct colours from bi-colour data, must something to do with your palette rotation.
Cheers
Bill
Thanks Bill. Wild guess about the colours: With any two complementary colours (opposites on the colour wheel), say red and cyan, or yellow and blue, or green and magenta, mixing them 50-50 will produce white, and other ratios will produce various pastel shades that we could give names to.
A very detailed image M&T! I only got a smudge of light last time I shooted it.
Must be deep to get that side appendage.
Thanks, Kevin. Weather might have been even worse for you. There are a few SNR's in the far north that are either low (like the Veil) or that we just can't do at all from here. But we have the Vela SNR.
Quote:
Originally Posted by Andy01
That's cool, looks like a metal brooch - nice colour scheme too
Aha! Delighted that you like the colour, Andy. We think we might make that "Ha to R+G, OIII to Blue, then rotate -15 deg to add a hint of naturalness" our standard Placidus Palette for bicolour.
They are called Supernova Remnant Breakouts, read about our two recently imaged little buggers N11 and N86 that show such breakouts HERE
Mike
Ta. One thinks of an explosion inside a house, and stuff flying out the windows.
Quote:
Originally Posted by Ryderscope
A tiny but significant object that tracks modern human history and provides for an informative discussion as well. Thanks for posting.
Cheers, Rodney.
Quote:
Originally Posted by multiweb
Very nice Mike. Pity about the seeing and as Mike pointed out pretty low.
Thanks, Marc. Last time we had seeing that bad, it was looking over a tiled roof in a suburban summer heat-wave. I actually had to edit our automatic focussing software, because the FWHM was off the graph. That lost half an hour. But as Rodney and Colin mentioned, it's such a juicy target. One has to have a go.
Here is the Crab Nebula, taken under dodgy conditions, and nowhere near enough exposure.
Question: We've read that the blue glow of the Crab is Cerenkov radiation - electrons spiralling in a powerful magnetic field. Presumably only some proportion of that would go through our 3nM OIII filter. Would we in fact do better with a wideband blue filter? Ordinarily we'd just give it a try, and all would be revealed, but what with Christmas, Cloud, and Crispy Electronics, it's been a struggle.
Hello Mike and Trish,
The correct terminology is synchrotron radiation.
Cherenkov radiation occurs when gamma ray photons from the Crab are converted into high velocity electron/positron showers when interacting with atoms and molecules in our atmosphere.
These showers which carry a charge can further interact with atoms and molecules causing then to be polarized by the shower.
As the shower passes, the atoms and molecules return to their non polarized state and produce Cherenkov radiation in the process.
Our atmosphere is the source for Cherenkov radiation not the Crab.
Since synchrotron radiation is basically a continuous spectrum you will do better with a wideband blue filter.
Synchrotron radiation is highly polarized and using a polarisation filter at different angles combined with luminance data, leads to some very interesting details not ordinarily seen as revealed in the attachment.
There are not too many amateur images of a polarized Crab and it might make an interesting challenge.
...maybe the Millennium Falcon escaping an Imperial Starship 
