What do you need to snap the Helix?

[g__day]

I am finding this one really challenging from light drenched North Ryde and am wondering if light pollution versus my Canon DSLR is a forget it proposition.

The signal from this nebulae is so faint that shots from 600 - 1200 seconds on my C9 -> OAG -> Hutech LPAS filter -> Canon 400D simply can't distinguish signal from sky glow.

Is this a target that can really only be snapped from dark skies or with more expensive, sensitive astro cameras?

Thanks guys!

[gregbradley]

In short - yes.

It is really a dark site object or CCD object from the suburbs preferably with an Ha filter.

Here is a Canon 20D shot from my dark site a few years ago its about 90 minutes or so from memory and ISO 3200:

http://www.pbase.com/gregbradley/image/70953889

Here is a 10 hour image from the same site with an Sbig STL11 camera and LRGB plus Ha:

http://www.pbase.com/gregbradley/image/98189694

It is a dim object with not many guide stars nearby also.

Greg.

[Peter Ward]

Tough call. I tend to agree with Greg. The problem you will find with DSLR's and any low surface brightness object imaged from the 'burbs is that the skyglow and camera noise increases way faster than that of the object's signal.

The Helix is however pretty easy in narrowband from city skies.
http://www.atscope.com.au/ap155edf/helixhasdp.jpg

This was about 60 mins through a 10nm H-Alpha from southern Sydney...full moon to boot.

A modded DSLR, fast scope and H-Alpha filter might work...and is certainly worth a try.

[Bassnut]

Funny you should mention that. Ive tried Helix in Ha from North Ryde again lately. Even with an 80% + QE cam and 20 min subs, with Ha its woefull, really hard. I gave up (well, with 3nm Ha anyway)

[Peter Ward]

3nm at F10 would be hard. F7 10nm much easer

[Bassnut]

Interesting you say thet Peter, its still just Ha isnt it?. I have much less signal from the Helix than any other neb, whys that?. A prevoius attempt at 15nm was far more sucessefull, Im puzzled.

[Peter Ward]

The ionized nitrogen line is also pretty close to the H-Alpha, and this would be transmitted by a broader filter.

Also with the Helix in urban skies, you are chasing a signal to noise ratio optimum. It's very low surface brightness is easily affected by skyglow and transparency. Any thin cloud would make it a very difficult target.

[Bassnut]

Intersesting,Thanks Peter.

[g__day]

Imaging at a near full moon didn't help matters, and the DSI isn't really sensitive enough to find very dim stars. I had to use PHD with the DSI have 10 seconds of light before it just managed to grab a very faint star.

If Fred can't do it I think I have little hope (still love to see you gear and how you set up an image acquisition and processing session one day Fred!).

Peter and Greg thanks for your comments - they were particularily insightful!

Matthew

[Bassnut]

Any clear night Matt, it would be a pleasure, PM me.

[Terry B]

I think that the light pollution will be a big problem but from a dark site it picks up with my 40D. I have very dark skies and took this image at the beginning of August with my 40D. It is 17 x 5 mins only. Needs more data but you get the idea.

[gerry aarts]

Hi Terry
There is a lot more data in your image then you may think.
Unfortunately the image appears to be clipped.

Anyway I just applied some levels and curves in photoshop to bring out more detail.

Hope you don't mind??

My initiial RGB image of the Helix aslo looks like that but again processing brings out the data. see above (on the left) 20x30 seconds RGB image, Celestron GPS11, Meade DSIc and f1.8 Hyperstar Lens.

I agree with the other comments, Dark skies are important but then imaging at, f5, f3.3 or as in my case f1.8 is helpful as is narow band imaging.

Regards
Gerry

[avandonk]

Have a look here.
http://www.iceinspace.com.au/forum/showthread.php?t=23971

If you want I will put up the hi res image. Below is a crop.

It is very dim. I hope to get better data once the clouds go away.

Bert

[bluescope]

Patience and preferably a Dedicated Astro CCD ....... here's my latest effort from 1-07-08 with a SBIG ST2000XCM on F4.7 10" Newt. Also heavily light polluted skies :( dark skies would be great .... working on it !

:thumbsup:

[g__day]

All great shots guys - I'll try it when there is no moon and a guide star available. If the darkest skies around here is too bright - its a target for the day I get a better camera.