suitable unguided DSO imaging targets?

[rocketandroll]

Hi all

I've kinda asked this before, but maybe in the wrong place... I'm running my scopes unguided on a HEQ5 Pro at the moment so I'm limited to 2min subs max.

Other than M42, what other DSO targets are there that could be captured on 2min subs on say ISO 1600 or so?

I am guessing all galaxies are out as they are too feint?

Are there any other nebulae that are viable on those sort of settings with an f7.5 scope?

Cheers for the advice all!

Ben

[Dave Smith]

M31, M45, ngc7000 (N. America Neb), M57, M27, region around Sadr in Cygnus, M33, and probably many more.

Dave

[riklaunim]

If you stack many short exposures you can get nice images even of the darker objects. Planetary style DS imaging

[Demonperformer]

Star clusters are plentiful and definitely suitable

You can get galaxies and (if your camera is modded) nebulae. My alt-az mount limits me to 20s/30s exposures and I can get some surprising results by stacking loads and a bit of post-processing (still learning!)

[rocketandroll]

Cheers all for the thoughts so far!

I was assuming that 100 X 60 sec exposures wouldn't get you the same data as 10 X 600 sec exposures because the really feint objects wouldn't put enough photons on the CCD in such a short time for anything to show up at all?

ie: if there's nothing there, no matter how many nothings you add up, it still won't show anything :-)

Will have a stab at some of those... better start finding my way around where everything is I think :-)

Ben

[jgs001]

Ben, M81 and M82 can come out quite nicely... I used 2 and 3 minute unguided subs on those and the Leo triplet.

I even got the bubble nebula with an unmodded camera with 168x40 second. Stacking took longer than the capture time mind you...

[Demonperformer]

ie: if there's nothing there, no matter how many nothings you add up, it still won't show anything :-)

This is something I have looked at from both sides and whatever position I have tried to adopt seem to be shot down by other SGL members putting the opposing view.

But it seems that if you have an object dropping one photon on the ccd every ten images, if you stack enough of them the software can work out that it is more than background noise.

[takes cover and dons hard hat to prepare for an attack of the "oh no it can't"s:p]

[jsigone]

I'd say about 80% of the object that are up, u can shoot w/ 2min subs. Don't limit yourself until you try, you might be surprised. You'll need a min of 90mins on the object to come away w/ some decent data. You'll find that dusty objects like Iris are no go. I spent 4hrs of data on it and can barely get any of the outside dust. But I still got some data w/ it, but was hard.

[dph1nm]

I was assuming that 100 X 60 sec exposures wouldn't get you the same data as 10 X 600 sec exposures because the really feint objects wouldn't put enough photons on the CCD in such a short time for anything to show up at all?

Not true - you get the same number of photons from the object in 100x60 or 10x600. Makes no difference.

The short answer to your question is that you can image anything you like with 2 mins subs. Just take lots of them.

NigelM

[riklaunim]

Here are some of my old images with f/5 6" Newtonian and DMK21. 1-2 sec exposures, few hundred of frames:

[jsigone]

here's one of my old images from the summer 2.5min x 24 for 60min total

NGC6960 Veil Nebula, 60min total by jsigone, on Flickr

check out my flickr for other unguided images ranging from 30s to 2.5min.