Ngc3621

gregbradley · #1 26-02-2009, 05:38 PM

From my galaxy imaging weekend last week.

Another one, that is a lot fainter. Usually images of this galaxy only show the bright inner spiral but don't show the outer spiral arms. In this galaxy these arms are quite extensive.

The Baader clear filter lets in a bit more light than the usual luminance filter at the expense perhaps of slightly bloated stars. Its a good tradeoff I think for galaxies as I'd rather have the outer spiral arms showing.

This one could easily be a 12 hour job but practicalities enter into it.
This one is ripe for imaging now and is in a good position.

ClearRGB 160 50 60 60 for a total of 5 hours 30 minutes.

http://upload.pbase.com/image/109598263

Greg.

TJD (Trevor) · #2 26-02-2009, 06:31 PM

amazing !!!!!!!!!!!!!!

Tilt (Michael) · #3 26-02-2009, 08:36 PM

Faint arms but you've got them here. Nice work.

Michael

RobF (Rob) · #4 26-02-2009, 10:11 PM

Mmmmm, galaxy, yummmm!
Good enough to eat Greg - beautiful depth for such a faint object.

strongmanmike (Michael) · #5 26-02-2009, 10:19 PM

Now look Mr Bradley

If I get any more insanely jealous of the amount of imaging you are doing... I will explode

Nicely framed and pretty deep work here Greg and yes you have showed the outer arms nicely, an interesting galaxy.

Psst...I have just finished inserting my new Ha OIII SII Astronomiks set, giving me LRGB & HaOIIISII in the filterwheel now, all ready for Friday night

...hopfully?

Mike

Hagar (Doug) · #6 26-02-2009, 10:44 PM

Very nice galaxy Greg. Looks like you caught a bit of Mikes Galactic Cirrus as well.
Please no 100 repro's

gregbradley · #7 26-02-2009, 10:47 PM

Quote:

Originally Posted by TJD

amazing !!!!!!!!!!!!!!

Thank you! It was pretty hard to process for some reason. Also it was this image I noticed how much seeing affected the images as it was taken over a couple of nights.

Quote:

Originally Posted by Tilt

Faint arms but you've got them here. Nice work.

I also used Mike's approach of sum combine. It brought out the dim stuff a tad better than using median combine (which is nice because it gets rid of all the little defects like cosmic rays, satellites and meteors).

Michael

Quote:

Originally Posted by RobF

Mmmmm, galaxy, yummmm!
Good enough to eat Greg - beautiful depth for such a faint object.

Yes its NGC3621 pie with ice cream.

Quote:

Originally Posted by strongmanmike

Now look Mr Bradley

If I get any more insanely jealous of the amount of imaging you are doing... I will explode

Nicely framed and pretty deep work here Greg and yes you have showed the outer arms nicely, an interesting galaxy.

Psst...I have just finished inserting my new Ha OIII SII Astronomiks set, giving me LRGB & HaOIIISII in the filterwheel now, all ready for Friday night

...hopfully?

Mike

Yes I've had a good run. My dark site weather has returned to its default pattern of clear at night about 80% of the time. The formula I reckon is being in the foothills of the western side of the Great Dividing Range. Its probably true almost anywhere on the East Coast on the ranges. The wet air from the coast doesn't make it over the ranges that easily and the weather mainly comes from the west and next stop is Perth via desert inland Australia! On the eastern side of the ranges you get more cloud as the western air which is warmer hits the cooler high humidity coastal air.

Does this mean you'll be able to image from your backyard?
Don't forget to go longer subs with the S11 filter and perhaps the O111 filter although I find my O111 filter is similar in light throughput as my Ha or at least close to it but S11 is pretty dim.

Greg.

strongmanmike (Michael) · #8 27-02-2009, 12:09 AM

Quote:

Yes I've had a good run.

Sheesh ya not kidding!

Quote:

Does this mean you'll be able to image from your backyard?

No, unfortunattely too many tress and a busy road with large road lights that shine down the scope tube, not even narrow band would negate

so it will be out at my nearly dark site 45min west of Newcastle.

Quote:

Don't forget to go longer subs with the S11 filter and perhaps the O111 filter although I find my O111 filter is similar in light throughput as my Ha or at least close to it but S11 is pretty dim.

After installing the filters I did a library of darks = 1min, 2min, 5min, 10min and 15min, all at -35C, so I'm ready for the bright bits and dim bits - they are 13nm filters so hopefully 15min will be long enough for the SII? I got the H-Beta filter too but I only have 7 locations (LRGBHaOIIISII) in the wheel, but I will try Ha OIII Hbeta = RGB somtime.

Mike

gregbradley · #9 27-02-2009, 12:17 AM

I look forward to seeing your images using them.

Have fun.

Greg.

kinetic (Steve) · #10 27-02-2009, 06:53 AM

Wow Greg that is deep isn't it! Beautiful capture.

I compared your shot to one I got a week or two back with
a 12" and DSI II and you have a whole 2nd set of spiral arms
showing!....

http://www.iceinspace.com.au/forum/s...ad.php?t=41268

Mine only shows the bright inner set, no sign at all of the outer ones!

Wow again.....As you say , the stars don't look too bloated without the
IR filter either.

Steve

Ric · #11 27-02-2009, 07:22 AM

Lovely work Greg, you have brought out the best in that galaxy. The spiral arms are a real treat.

Cheers

gregbradley · #12 27-02-2009, 08:30 AM

Quote:

Originally Posted by kinetic

Wow Greg that is deep isn't it! Beautiful capture.

I compared your shot to one I got a week or two back with
a 12" and DSI II and you have a whole 2nd set of spiral arms
showing!....

http://www.iceinspace.com.au/forum/s...ad.php?t=41268

Mine only shows the bright inner set, no sign at all of the outer ones!

Wow again.....As you say , the stars don't look too bloated without the
IR filter either.

Steve

Here is a quote from Roland Christen of AstrPhysics where he explains why
a refractor can extract deep data more easily. He disagrees about the fluorite and he may well be right as Mike Sidonio's Centaurus A shows a non fluorite triplet will also do this.

"Lenses in general, and oil spaced triplets in particular, have very high light transmission efficiency. Refractor tubes can be ideally baffled to prevent stray light. If the figuring is good, then you can get very good focused energy into the image, which allows you to stretch it to extract ectremely faint detail. It has zero to do with the fluorite, but everything to do with the way the scope is built.

Tony Hallas discovered this himself when he was experimenting with various refractors at his deep sky site. He found that he could go far deeper with a refractor than he could with his 14.5" Cass before background light intruded into the image. Example is his latest M81/82 image, among others, which shows extensive faint extra-galactic dust around those galaxies. His scope is a 206mm F8 triplet apo, non-fluorite: http://www.astrophoto.com/M81M82.htm
I also have a preliminary Rosette which he has not published yet, but which he will show at NEAF. It has faint detail in the core that I have not seen in any amateur photo. No fluorite was needed, just a well baffled oil spaced triplet refractor.

Rolando "

Quote:

Originally Posted by Ric

Lovely work Greg, you have brought out the best in that galaxy. The spiral arms are a real treat.

Cheers

RB (Andrew) · #13 27-02-2009, 09:35 AM

Yet another wonderful image Greg.
Well done.
Thanks also for the info on the weather patterns, I wish I could just pick up my property and move west.

gregbradley · #14 27-02-2009, 02:49 PM

Quote:

Originally Posted by RB

Yet another wonderful image Greg.
Well done.
Thanks also for the info on the weather patterns, I wish I could just pick up my property and move west.

Thanks Andrew. Yes the weather pattern is usually good for imaging there although last year there was about an 8 month period when the weather pattern reversed and it was cloudy there when Sydney was clear.

Greg.

atalas · #15 27-02-2009, 04:39 PM

Looks great Greg ! looking at those faint extended arms It wouldn't of been too easy to process without damaging the inner parts of the galaxy and still keep It looking natural....extremely well done.

Paul Haese · #16 27-02-2009, 05:06 PM

Very nice image Greg, faint blue stars near the core seen.

gregbradley · #17 27-02-2009, 05:11 PM

Quote:

Originally Posted by atalas

Looks great Greg ! looking at those faint extended arms It wouldn't of been too easy to process without damaging the inner parts of the galaxy and still keep It looking natural....extremely well done.

That's right.

I used sum combine for one thing.
Careful use of curves and levels.
Shadows/highlights
A bit of use of the burn tool.

I think also FITs plug in and doing RGB combine in CCDstack and processing luminance separately and layering it in in Photoshop may've helped as well.
I think there can be a slight loss when CCDstack output is saved and transported across to Photoshop as a TIFF.

Greg.

Bassnut (Fred) · #18 27-02-2009, 07:52 PM

Nice pic Greg, smoothe.

Quote:

Originally Posted by strongmanmike

After installing the filters I did a library of darks = 1min, 2min, 5min, 10min and 15min, all at -35C, so I'm ready for the bright bits and dim bits
Mike

Gaud, your kidding, right

Sheesh, you have a painfull learning curve ahead of you in NB Mike, the fun starts at 20min with a ABG cam

. .......Oh, and with a measly refractor, 30 mins

gregbradley · #19 27-02-2009, 09:13 PM

Quote:

Originally Posted by Paul Haese

Very nice image Greg, faint blue stars near the core seen.

Thanks Paul.

Quote:

Originally Posted by Bassnut

Nice pic Greg, smoothe.

Cheers Fred.

Gaud, your kidding, right

Sheesh, you have a painfull learning curve ahead of you in NB Mike, the fun starts at 20min with a ABG cam

. .......Oh, and with a measly refractor, 30 mins

True. The 1, 2, 5 minute dark libraries probably won't be used much. Maybe on M42. I did 7:15 of the Horsehead accidentally in S11 and it was still dimmish and noisy. I should post that for a laugh.

Greg.

strongmanmike (Michael) · #20 28-02-2009, 09:40 AM

Quote:

Originally Posted by Bassnut

Nice pic Greg, smoothe.

Gaud, your kidding, right

Sheesh, you have a painfull learning curve ahead of you in NB Mike, the fun starts at 20min with a ABG cam

. .......Oh, and with a measly refractor, 30 mins

Nice to hear from you Fred....even if it is just to laugh at me

I only did the short exposures for stuff like the very brighteste bits of Eta and the lagoon etc I am using Astronomiks and they are 13nm, 10min is plenty in Ha for most things so I thought 15min might be better?

Oh well