Five galaxies

Folks, for those interested, here are five galaxies I imaged over the weekend. The usual setup (C8 plus DSI and 6.3 reducer) but exposure times varied from 30 to 120 seconds.

Cheers

Dave

www.astroshack.net/gallery/AOP/NGC%202655.jpg
www.astroshack.net/gallery/AOP/NGC%202715.jpg
www.astroshack.net/gallery/AOP/NGC%202732.jpg
www.astroshack.net/gallery/AOP/NGC%202748.jpg
www.astroshack.net/gallery/AOP/NGC%202985.jpg

Dave ,those are interesting images,

the first looks like its peripherals are faint,
the second had some fine detail, yet noisy
the third pair are small enough
the 4th is bright and has some nice detail.
The last has very faint arm structure around the core, a fine contender.

Just a question WRT all of those images, why do you use such short exposures, I would have thought you'd be pushing 5 minutes+ on galaxies such as those.

I thought had he increased the exposure on those images any more he would have seriously washed out any more potential detail!

Maybe on the first and third images cores, but I would have thought 2 and 5 would benifit significantly, its the arms you want. Or how about 2 images of each object 1 long and 1 short and using photoshop to merge them, just ideas.

I used short exposures just to see how it went. In reality, I'll need to refine the exposure times. But in theory, these exposure lengths would be OK since a supernova would show up reasonably well (they tend to outshine the host galaxy).

The third image was interesting - the larger of the two is the galaxyof interest. The little s-shaped one is just a nice bonus

The second image was a bit odd. Its a 12 mag galaxy but it clearly has a low surface brightness - and its big! This one could do with 3 or 4 minutes worth or even more to squeeze out more detail.

Seanie - as it happens, longer exposures will improve the images. They are intrinsically 'dim' compared to the moon, mars etc (which would wash out on longer expsoures) and so the longer the exposure, the better your signal/noise ratio. The limiting factor is typically sky brightness - your maximum exposure duration is reached when the sky brightness starts to creep in (e.g light pollution) and then you'll get no more benefit of even longer exposures. SOme of the folks on the boards would image similar galaxies to these and shoot 10 or 20 HOURS worth... :shock:

Cheers
Dave

Maybe on the first and third images cores, but I would have thought 2 and 5 would benifit significantly, its the arms you want. Or how about 2 images of each object 1 long and 1 short and using photoshop to merge them, just ideas.

That's interesting. I guess I was thinking about just longer single expsoures. But combinations of short/long could work... Or lots of stacked mediums... Food for thought.

As it happens, these images are the first shots in preparation for a SN search project. As such, they're not taken for the 'pretty picture' effect. As long as subsequent images (at the ideal to-be-determined exposure duration) can identify a supernova, then the goal has been achieved.

Thanks for the feedback lads

Dave