Five galaxies

ok, you're just "testing the water", I would need to take significantly longer exposure times with the canon, I'm in 2 minds about using a focal reducer, I would nearly prefer the grief of a longer exposure if you saw the arms as bigger, especially in the smaller galaxies, more chance of seeing anything unusual maybe? but like yourself, its going require a fair amount of experimenting to get it down to a T.

Good images BTW.

dmcdona wrote:

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

after thinking about it again, are we more likely to see SNs in the arms, if so who cares if the core is over-exposed, but could you imagine missing a SN if one was near the core and some other group got it.

That would be a bummer - missing something near the core. But presumably, pretty much everyone would miss it. The only safeguard would be to iamge bright-core galaxies at more than one expsoure length - significantly increasing the number of images. Puckett does 1500 a night...

As an example though, SN2005ep seems not to be a part of the host galaxy - presumably the arms are just not visible - but the SN being very bright certainly is:

www.astroshack.net/gallery/SN2005ep.php

So, the exposure length chosen is not chosen to show spiral arms etc. Its chosen so a possible SN can be imaged - and that would look a lot like the images above - no spiral arms or fancy detail, but a definite new star
Whilst this sounds like it might take a lot of trail/error, I don;t think it would in reality. All you need to do is image to a certain magnitude range - say 10 to 16 (or more if you have the kit) - its not really about capturing galaxy detail, just a really bright SN.

Even in the case of the M51 SN in the summer, if you remember the pics (I think Dave Grennan posted one) the new star was clearly obvious even at very short exposures that didn't do M51 justice in the 'pretty' sense of the word...

Oh, don't forget, a focal reducer, whilst reducing the image size (magnification) it will reduce your exposure duration which could be a handy trade-off. Its not important to fill the frame with the target galaxy, just get the SN somewhere in the frame

Cheers

Dave

Dave i like your images. As you said, you are after supernovae so pretty shouldnt even come into it. These are good master images and a bright new SN would stand out well. Thats the name of the game after all. After you find a new SN then you could go for a 'pretty' image

A couple of questions Dave..

1) Are you using these as master images to use for comparison with future galaxy shots?

2) Is that 2 knots within the spiral arms of the 2nd image?

Good luck with your SN hunt Dave. I honestly believe that if you can get this hunt active then you will find a new SN sooner or later

Best of luck and keep us informed

Thanks Martin - watch this space for more 'masters'... !

I thought the same about the second image. I was surprised how large the galaxy was and there's a definite knotiness thing going on... I'd like to reshoot it asap.

Cheers

Dave

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

I see your point! I just thought that images 1 and 5 looked like they were almost overexposued, as there's no detail apart from a blob! :oops:

Why is the second image very grainy?