A tip of the hat to Mike S for his photo-essay in this months AS&T, it was however a comment in the essay that has me thinking...was this "the deepest colour Cent-A shot taken" ?
While I can't claim the same heroic total exposure time effort as Mike, a quick back of the envelope calculation shows 5 hours with a 14 inch easily gathers more flux than 19.5 hours with a 6 inch telescope....begging the question are there even deeper examples out there?
A tip of the hat to Mike S for his photo-essay in this months AS&T, it was however a comment in the essay that has me thinking...was this "the deepest colour Cent-A shot taken" ?
While I can't claim the same heroic total exposure time effort as Mike, a quick back of the envelope calculation shows 5 hours with a 14 inch easily gathers more flux than 19.5 hours with a 6 inch telescope....begging the question are there even deeper examples out there?
Can of worms really. Exposure time is just one of the variables. Transparency, filtering, chip sensitivity, optics quality (transmission), processing....
But depth is depth - surely it's how 'deep' you can see in the finished product, full stop. And Mike's looked pretty deep!
Humm let's see, 150 inch AAT, flux collecting area about 67,000 sq inches.
6 inch APO 113 sq inches....so everything else being equal about 592x more flux being gathered by the AAT in the same time.
Or to put it another way 19.5 hours of 6" data in under 2 minutes. Cool.
Humm let's see, 150 inch AAT, flux collecting area about 67,000 sq inches.
6 inch APO 113 sq inches....so everything else being equal about 592x more flux being gathered by the AAT in the same time.
Or to put it another way 19.5 hours of 6" data in under 2 minutes. Cool.
In ball park-terms, for sheer sensitivity, a 6" scope loaded with a CCD camera can rival a 36" scope loaded with photographic film camera ....which is why so many amateur deep sky images these days rival professional imagery of a generation ago.
Humm let's see, 150 inch AAT, flux collecting area about 67,000 sq inches.
6 inch APO 113 sq inches....so everything else being equal about 592x more flux being gathered by the AAT in the same time.
Firstly congratulations to Mike upon his image and its publication which was well deserved -- it is superb.
Take a look at the attached image -- it is a David Malin ultra-deep image of NGC 5128 in negative format. I think it is a result of stacking of many UK schmidt plates and shows an incredible amount of the galactic cirrus near NGC 5128.
A tip of the hat to Mike S for his photo-essay in this months AS&T, it was however a comment in the essay that has me thinking...was this "the deepest colour Cent-A shot taken" ?
While I can't claim the same heroic total exposure time effort as Mike, a quick back of the envelope calculation shows 5 hours with a 14 inch easily gathers more flux than 19.5 hours with a 6 inch telescope....begging the question are there even deeper examples out there?
Peter Is that the October edition? of AS&T as there is nothing in my September copy of the magazine
Ron
A tip of the hat to Mike S for his photo-essay in this months AS&T, it was however a comment in the essay that has me thinking...was this "the deepest colour Cent-A shot taken" ?
While I can't claim the same heroic total exposure time effort as Mike, a quick back of the envelope calculation shows 5 hours with a 14 inch easily gathers more flux than 19.5 hours with a 6 inch telescope....begging the question are there even deeper examples out there?
Actually Peter I didn't say that at all, if you re-read my article I said "...we have what I BELIEVE is the deepest COLOUR image ever taken of this galaxy and its SURROUNDING FIELD"
An exhaustive web search and discussions with both David Malin and Harvey butcher (director of ANU Research School of Astronomy and Astrophysics) showed up nothing..?
Sooooo all your impressive mathematical analysis aside (ie possible in theory yes but has it been done??? )...if you would be so kind as to please show us all a deeper version I for one would love to see it. That doesn't mean there isn't one out there but it sure is hard to find.... hence my "belief"
I do hope one day to manage a 10 - 20hr total exposure image... Then I'll have awesome images ala, this cent A... Untill then, my 15min images will suffice!
I must say 20hrs exposure to one image shows dedication without a doubt... but then to think of the processing time on the other end of that 20hrs... man... Dedication doesn't even come close to describing that...
First of all I think I've seen every Cen A image on the web and I think I may never image Cen A again
Gary, I saw Yohannes excellent Cen A in my extensive web surfing and for sure his large 50% size colour image is also quite deep, although as presented on his web site it is clearly not as deep as either my 50% size "Deep Field" here:
Yohannes's roll over enhancement is great but in Luminance only so not a true full "colour" image and it is displayed rather small so hard to analyse properly. I have a deep luminance only image at my site too, just not with the scroll over (and a larger image size so the noise is more obvious):
Les, that deep UK Schmidt plate was just a single 70min exposure then photographically enhanced using image amplification by David Malin, amazing huh? The UK Schmidt is a 1.2m aperture F2.5 astrograph that takes 14" square plates . It is sure to have gone somewhat deeper than my effort but it is of course not in colour though . I actually have that image cropped to match mine and displayed at my web site with all the other versions of my Cen A done with the same data set.....
Greg, yes all 19.5 hrs (over 20hrs including a few subframe discards) were taken from Wiruna, which has very dark skies and at over 1000m ASL, with good seeing, clear and transparent for three nights in a row, not to mention a flawlessly operating portable rig, sheesh... I think I got lucky ...oh and I've got a long way to go to be in the Gendler marathon league, that guy is a machine
...... I said "...we have what I BELIEVE is the deepest COLOUR image ever taken of this galaxy and its SURROUNDING FIELD"
Ah...quite true, it was not clear whether to me you were referring to the galaxy part, surrounding field or both.
That said, there are a good number of colour images of the galaxy that are considerably "deeper" (ESO has a data 90 minute data set with their 8 metre...that makes us all look like, well, amateurs).
The point of my post was however to make obvious something occasionally lost....for "deep" sky imagery, aperture (particularly buckets of it) can and is used to to plumb the depths, without having to stay there for hours on end.
Nice pic and write-up just the same.
Last edited by Peter Ward; 20-09-2008 at 07:22 PM.
Reason: typo
And Mike's looked pretty deep!
So my maths is crap.
)...if you would be so kind as to please show us all a deeper version I for one would love to see it. That doesn't mean there isn't one out there but it sure is hard to find....
and I think I may never image Cen A again 
. It is sure to have gone somewhat deeper than my effort but it is of course not in colour though 
