I continued imaging while the Moon steadily increased its influence during last week... I had to limit myself to fairly bright targets so I stuck to globulars. The following image was taken under an unforgiving 94% illuminated Moon and I had to battle with some strong gradients but the end result proved much better than I could hope for, so here is the third brightest globular, NGC 6752 in Pavo:
This image is a crop of about 80% of the full frame, there was a nasty reflection from the Moon near the top so a slight crop was called for. I also did a thorough collimation prior to taking this image and think I have eliminated most of the coma now. The FWHM was hovering around 2.0"-2.5" which is a bit less than in my previous images so that was promising.
Despite the moonlight there are even a handful of faint background galaxies showing, see if you can spot them
BTW I actually really enjoy the refractor like views that the wire spider provides - look at that, not a diffraction spike in sight! Only an ever so slight hint of them on the 7th magnitude star HD 177999 near the centre
Hope you enjoy this view of one of the more overlooked of the bright globulars (click image link above for best quality version). Comments and critique is most welcome .
Nice image Rolf all the normal parts are spot on, the only thing that isn't really to my flavour is the electric blue stars and the deep orange. Flavour is what one makes it though!
Q. When giving the length of exposures (24:8:8:8) ... is that the total of the stacks or a length of each single image? Just trying to work out how long to expose for...
Very nice, Rolf, colors are very saturated and add lots of beauty to the picture IMHO!
Quote:
Originally Posted by SkyViking
Hi All,
here is the third brightest globular, NGC 6752 in Pavo:
? I didn't know it, what is the ranking? I supposed it was Omega/47 tuc/M13..
Another question: I don't usually image with LRGB if the moon is up, apart from gradients do you find a big difference comparing to RGBs you get on moonless nights?
? I didn't know it, what is the ranking? I supposed it was Omega/47 tuc/M13..
Marco
Ah huh!
We have 7 of the top 10 brightest Globulars well down in the southern hemisphere incuding the three brightest!
1) Omega centauri in Centaurus Mag 3.9 Dec -47
2) 47 Tuc in Tucana Mag 4.91 Dec -72
3) NGC 6752 in Pavo Mag 5.4 Dec -59
4) M13 in Hercules Mag 5.8 Dec +36
5) NGC 6397 in Ara Mag 5.9 Dec -53
6) M22 in Sagittarius Mag 6.17 Dec -24
7) NGC 2808 in Carina Mag 6.2 Dec -65
8) M3 in Canes Venatici Mag 6.2 Dec +28
9) M15 in Pegasus Mag 6.2 Dec +12
10) M55 in Sagittarius Mag 6.3 Dec -31
NB. Of these 10, only really M13 is not well placed for viewing from mid southern latitudes (although still a good view when crossing the meridian from most of Australia) all the others are easy pickings!
So see?.. this is yet another reason why you located your APO down under
Not only is N6752 the third brightest globular, it is also one of the nearest! According to the Globular Cluster Catalog of W.E. Harris, it is at 4 kiloparsecs, in other words.....13,000 light years.
This relatively small (for a globular!) distance is one reason why this is one of the few globulars in which stars can easily be seen when visually observing with a 3 inch telescope.
But M22 is even nearer (3.2 kiloparsecs).....that's why it is so gigantic, in angular diameter.
Ah huh!
1) Omega centauri in Centaurus Mag 3.9 Dec -47
2) 47 Tuc in Tucana Mag 4.91 Dec -72
3) NGC 6752 in Pavo Mag 5.4 Dec -59
4) M13 in Hercules Mag 5.8 Dec +36
5) NGC 6397 in Ara Mag 5.9 Dec -53
6) M22 in Sagittarius Mag 6.17 Dec -24
7) NGC 2808 in Carina Mag 6.2 Dec -65
8) M3 in Canes Venatici Mag 6.2 Dec +28
9) M15 in Pegasus Mag 6.2 Dec +12
10) M55 in Sagittarius Mag 6.3 Dec -31
Thanks Mike! Well, I never end to learn new things, this is one of the great points of this passion
Quote:
Originally Posted by strongmanmike
So see?.. this is yet another reason why you located your APO down under
Mike
Haha, indeed, now I have another good argument supporting my observatory down under, next time my wife is complaining about the cost
Here is The Catalog of Milky Way Globular clusters, by Bill Harris (W.E. Harris). It should be about as up to date as any catalog of globulars can be, because Harris has spent his entire life researching globular star clusters.
There are some very exciting & gripping & interesting numbers here. This catalog reads like a thriller!!
(("Notepad" in Windows, mucks up the formatting of this text file, but any of the millions of text file readers available on the internet will display this file properly.
"WordPad" will probably work. ))
