Abell370 two? gravitational arcs

[Shiraz]

Hi
finally finished processing this one! Abell370 has a vast gravitational arc that is visible even though the primary galaxy cluster is about 4 billion light years away. The galaxies that feed light into the arc are about twice that far away (ie these photons started travelling this way well before the sun existed). Australian seeing is not too flash for this sort of work, so an early image from the 8.2m VLT is included for comparison and identification of features.

http://www.astrobin.com/full/246996/None/?real=&mod=

In addition to the main arc, I think that I can just make out a second one (it is directly below the main arc and near the bottom of the frame in the ESO image). Although the second arc is right down in the noise, there seems to be a weak linear feature in the right location.


thanks for looking. regards Ray

[rustigsmed]

wow!
impressive work Ray! and a good mind bender when you start considering the distance and age!

Russ

[Peter Ward]

While not a pretty picture....it certainly is sub-zero on the coolness scale.

Nice one :thumbsup:

[Atmos]

That's a seriously good effort Ray! With more luminance do you think you'd be able to bring that second arc above noise? Or is it buried behind sky glow do you think?

[RickS]

Well done, Ray!

[peter_4059]

Great stuff Ray.

[el_draco]

Considering what amateurs were capable of a couple of decades ago, pretty damn mind bending, (he,he sorry about the pun), result I reckon. :thumbsup:

[Shiraz]

yep, it is mind bending Russ - the idea that the fabric of the universe is twisted out of shape by the gravity is also confronting.


Thanks very much Peter! Agreed, it is not very pretty.


Thanks Colin. Am sure that the second arc is definitely within reach with more data - it already shows up quite well in the inverted luminance as attached


thanks a lot Rick.


Thank you Peter.


Thanks Rom. Couldn't agree more - modern technology is amazing.

regards Ray

[multiweb]

+1 Very cool. :thumbsup::thumbsup::thumbsup:

[Atmos]

That's fantastic Ray, personally, I think it's worth the extra time to see if you can get a stronger signal on that last little bit :)

[astronobob]

Someone would need to 'bend' my arm plus some to have a go @ this !
Very interesting gravitational lensing effect captured there Ray - Well Done on having that show up as well as you have done :thumbsup: :thumbsup:

Cant fathom how light can still shine after traversing the universe for billions of years :eyepop: :thumbsup:

[gregbradley]

What an unusual image. Normally we think of these types of images as only in the realm of the multi million dollar mountain pro observatories or Hubble.

Nice push out of the amateur boundaries there Ray.

Greg.

[Placidus]

All hail Ray! That is truly impressive.

We reckon you have the second arc there.

What is your exposure to date? The technical card didn't seem to mention it. If it's not an impossible amount of work, it would be very tempting to try for say 4 times the exposure to try to bring that second arc out more.

Best,
M & T

[Shiraz]

thanks Marc!


I think that it really needs at least double the exposure to date on lum and the colour needs even more than that. I also have run into some fixed pattern noise, so will need to improve dither if I want to get this far down in the weeds. next year, will add to it - only had about 6 hours luminance for this version so doubling will not be too hard.


This stuff is real fun - where else can you see some of the wierd predictions of Einstein's theories laid out in such a way. Thankfully photons do not have a use-by date - a few of those coming off my screen as I type are escaping through the window and flying off out into the universe - and they will keep on travelling out there for the rest of time. That is a cool thought. It is also cool that each arc photon that my system detected, popped into being in a star that was over half way across the universe and it happened 8 billion years ago - and then each photon travelled all that way to get here, passing galaxies, stars and dust clouds. While the photons were on their journeys, the sun and earth formed, life started up and humans evolved - eventually one of those humans had a telescope pointed in just the right direction at just the right time and a few of those tiny photons passed down the 10 inch aperture of my scope and then finally gave up their energy and information in my tiny CCD.


thanks Greg. This image is nowhere near the resolution of those from the pro scopes, but it is good enough to show the arc(s) and the huge collection of galaxies out there.


Thanks M&T. Thanks for the encouragement. Luminance is currently only about 6 hours, so further data will not be too onerous. I had been concentrating on a couple of other targets and only used this as a fall back when the main ones were not well placed - next time it will be a primary target.

I only realised that a second arc might be visible while I was looking at the ESO image and the inverted image just prior to posting - the second arc isn't in the field of view of the Hubble image that I was using as a reference.

Gosh it would be nice to find somewhere with better seeing.

regards Ray

[Ryderscope]

That's a great technical journey Ray, very interesting. Thanks for posting.

[strongmanmike]

Really enjoyed this image Ray and what it shows (I recon you have the other arc there too), fantastic capture :thumbsup:

Once again, you demonstrate there are certainly brilliant and interesting things that can be done without days worth of exposure :)

Mike

[Paul Haese]

That is an interesting image Ray. A real look back in time. I wonder what those galaxies look like in real time now. That is the real mind bending thing about these sort of images.

[graham.hobart]

Very impressive Ray. Have been reading about these recently so good to see an amateur image. :thumbsup:
Graham

[Shiraz]

Thanks very much Rodney!


thanks Mike - I was very pleased with what actually showed up in a ffairly short time - even though the noise is pretty severe.


Thanks Paul. I really enjoy doing this sort of imaging - kinda puts the odd minor problem into context


Thanks very much Graham - appreciated.

regards Ray

[PRejto]

That is really really impressive. Great effort! LP and all....

Peter

[andyc]

Very impressive indeed - something special from the backyard!

[RobF]

Wow. Kudos Ray for such an original and inspiring image! :thumbsup:

[rmuhlack]

Impressive Ray ! I wonder to what extent a lucky imaging approach would help (if at all) in addressing the loss of resolution due to seeing? (using one of these new CMOS cameras with sub 1e read noise that we have discussed in other threads)...:question:

[Shiraz]

thanks you Peter!


thanks Andy - there sure is some interesting stuff in the back yard:)


hi Rob - thanks very much.


Thanks Richard. Yes, I hope that one of the new cameras will provide better resolution by using short subs. Bit of an issue with such dim targets though - there will still be a need for moderately long subs to keep even 1 electron read noise under control. I am going to do some experiments soon to see just what resolution advantage is available from short and very short subs.

regards Ray

[Atmos]

I suppose the advantage is largely going to be seen in poorer seeing conditions. At 1e- read noise you may be able to image at about 15s subs and still be RN limited. This will not technically help over a longer sub purely from seeing conditions but it will help against the small accumulation of over/under corrections from the guider.

[Shiraz]

I think that it will help with the seeing as well Colin. Have found that seeing can sometimes vary quite a bit over short periods. If you are imaging with long subs, that poor data has to be included with the good and you cannot remove it. If you are imaging with 15 second subs, the poor subs can be discarded, which gets rid of data from the bursts of poor seeing. I hope to do an experiment soon to determine how-much/if improvement there can be.

[Atmos]

That is a good point :thumbsup:

[rmuhlack]

Ray, what camera/sensor do you plan to test with...?

[Shiraz]

Hi Richard. The 250Newtonian and icx694. Will use a star field, so can test down to very short exposures. The system samples at 0.91 arcsec/pix and hopefully resolves to much better than that, so can produce usable FWHM measurements down to below 1.8arcsec (and I would be overjoyed to get anything that good)

[astronobob]

Wowsers Ray, your a real light-hearted fan :eyepop:
I imagined a cricketer outfielding, the ball is struck, high and far it flies, meanwhile the legs of a human fires up and scramms across millions of blades of grass, :lol:
But Hey, - You Win !!! :rofl:

[Stevec35]

Once again extremely impressive Ray! I'm running out of superlatives for your images. The second arc is definitely there I think.

Cheers

Steve

[Shiraz]

Haha..Though you might enjoy a bit poetry..:rofl:


Hi Steve. that is very generous and appreciated. Would be nice to get a bit more data on the second arc.

regards Ray