M 104

[Shiraz]

Hi

Got some luminance in 2.5 arc sec seeing and some colour in rather poorer seeing. There is not enough data to extract detail and still control the noise, but it is OK for now. I have a fair bit more lum data taken under worse seeing, but it doesn't add to the image - now waiting on really good conditions :).

Colour was a bit red/brown overall from extinction, so the blue (and to a lesser extent green) was enhanced to compensate (hopefully). It was nice to see a little bit of detail on the disk.

The negative version of the luminance shows many of the large number of globular clusters around this galaxy, as identified by Rolf in his post at http://www.iceinspace.com.au/forum/showthread.php?t=92183

thanks for looking. Ray

250f4, RCC1, H694, EQ6
lum 1.75 hrs @ 2min subs, RGB ~45 mins each at 2x2 binning, 1 min subs.

[rat156]

Really nice Ray.

Cheers
Stuart

[strongmanmike]

That's excellent Ray..I think you have extracted plenty of detail :shrug: The seeing really makes no difference to RGB collection - a good aspect of LRGB image ie as long as your Lum is detailed, then all good :thumbsup:

Mike

[alpal]

Hi Ray,
That's an excellent shot - I know how hard this galaxy is to image.
Nice detail in the dust lanes & a view of the disc.

well done.

cheers
Allan

[tilbrook@rbe.ne]

Superb with the colour Ray!:thumbsup:

I'd be over the moon with that detail, but your chasing more! :scared2:
Take my hat off to you.

I'm having a go at M 104 at the moment, needless to say don't expect anything as good as yours.

Cheers,

Justin.

[Ross G]

An excellent galaxy photo Ray.

Ross.

[nandopg]

WOW Ray, a killer image. The difficult to get dust line in M-104 stands out perfectly. The galactic light spreading out for both hemispheres is beautiful and is an indication of a super-B processing. One of the best images I've seen of the Sombrero.
Another thing: your Newt 12" f/4 is spot on !!

Congratulations for this great outcome,

Fernando

PS: Ray, remember that you helped me to put my Newt 12" f/4 to work ? With your hints, the scope tuned up just great. However, I just can not use it because of my disability. When I tried anyway, I fell down the stairs (to access the focuser) ending up in the hospital. Since then, I quit using the scope definitively.

[gregbradley]

That is really a superb M104 Ray. Its definitely worth the effort to add to it. Its way better than a normal image of M104. I agree you do need good seeing for luminance in galaxies. Lovely round stars. 2 and 1 minute subs - wow. Short subs because of tracking or for other reasons? The usual logic is its better to go longer but those stars look great and probably would deteriorate with longer subs.

Greg.

[Shiraz]

thanks very much Stuart.


Thanks Mike. I couldn't get at the detail without "enhancing" the noise, so decided to go for the detail and leave the noise as is. noise reduction did not work since I wanted to keep the faint globs - in any case, almost all noise reduction techniques can give an artificial plastic look to things or turn "fuzzy" into "splotchy". Just need a couple more hours of high res luminance data.


Thanks Allan - it was exciting to see the detail just starting to show on the disk.


Thanks Justin. Don't get me wrong - am pleased with the image. I just think that there might be a little bit more within reach of the scope......:lol:



thanks very much Ross


Thanks very much Fernando. Yes, I remember your efforts to tame the scope - wondered what had happened. Really sorry to hear of the accident - that is a serious problem with bigger scopes - they can put you in physical danger. You are doing well with the refractor though :thumbsup:.



Hi Greg - thanks for your very generous comments.
I used short subs for 3 reasons:
1. the sky was fairly bright and 2 minutes was all that was needed to bury the read noise under the shot noise (ie, it was the optimum sub length for the conditions).
2. the galaxy has a very hot core and I wanted to keep that from saturating.
3. the wind was gusting to 25kts and I wanted to maximise the number of usable subs.
As a general comment, on this fast scope and with the low read noise of the camera, the maximum broadband sub length needed under dark sky is only about 8 minutes. Longer is possible, but that doesn't help the SNR - it just saturates more of the stars.

Regards Ray

[Paul Haese]

Nice image Ray. Great detail and colours is very pleasing. Some noise in the background though and more integration would be of benefit.

Did you use Decon and selective sharpening to the Lum master?

It is on my list to address this year. Maybe after I have finished with the meat hook.

[RickS]

Great work, Ray! Nothing to say that hasn't already been said :)

[strongmanmike]

Agree with all of that, much prefer to see slight noise than slight plastic :thumbsup:



The need for very long subs seems to be rather missunderstood and driven by much follow the leader, hear-say and anecdotes :shrug:

As you correctly point out, there are indeed many good reasons not to do them :thumbsup:

Mike

[Shiraz]

thanks Paul - yep, needs a bit more. Used both decon and sharpening, but very sparingly due to small amount of data.


thanks Rick


Agree. short subs make a lot of sense with low read noise cameras - they do not make sense with high read noise chips though. Optimum sub length scales with the square of the read noise, so one of the older Kodak CCDs with 15 electrons read noise would require 9x the sub length of an icx694 with 5 electrons read noise. I guess that is where the idea that "long subs are always better" has come from - with past generations of chips that was true, but not with some of the current crop. Of course long subs are always better for NB. Here ends the sermon :).

regards Ray

[strongmanmike]

Yeah that is my understanding too :)

Mike

[Mighty_oz]

Spectacular image, going to be great to see the finished product. Hat's off to u.

[multiweb]

Terrific shot Ray. Amazing resolution. :thumbsup::thumbsup::thumbsup:

[Rod771]

Fantastic image Ray! Awesome detail, well done :thumbsup:

[Shiraz]

thanks Marcus - hoping for some more data this evening - need to get the noise down a bit


Hi Marc. the new scope seems to be able to image at the seeing limit - thankfully.


Thanks very much Rod

Regards ray

[DrWho]

Ray, thanks for Sunday sermon,

BTW. Beautiful M104, well done. :thumbsup: :thumbsup:

[alistairsam]

Nice one Ray, by noise do you mean the slight graininess?

is this cropped or full frame?
since the 694 has a smaller surface area than the 8300, it would look bigger in the 694 with the same 10inchF4, is this correct

Cheers
Alistair

[marco]

Excellent Ray! A truly beautiful image of the Sombrero!

Regards
Marco

[Shiraz]

thanks :)


the noise mainly shows up as graininess in the background

it is cropped to roughly 1/4 of the image I think. To put in perspective, the attached image is a full sub, scaled down by 0.5 to fit - it shows how big M104 is re the full field.

M104 will be bigger in the 694 image because the 694 has smaller pixels. The difference in scale will be about 1.2 linear or about 1.4 in area.


Thanks very much Marco.

regards Ray

[allan gould]

Excellent image, Ray. Not over processed and shows excellent detail.
Allan