M101 and SN

[Astrosurf]

Hi all, I managed to image M101 last night before the clouds rolled in, but I could only take 30 sec snaps as the light pollution here is quite bad. I've never imaged this galaxy before and am still a newbie so didn't know really what to do! Well, I only got the core with just the faintest hint (I mean faint!) of the arms) and I don't think stacking and processing's going to do any good. I don't think I've caught the SN!

I had the camera on ISO 800 and the usual setting, Raw + large file etc.

What could I have done to improve the situation?

Alexxx

[Zakalwe]

M101 is very very faint. An hour on an astro CCD barely touches it. I reckon 4 hours is required.

[Astrosurf]

Blimey! Lesson learnt! Many thanks.

[ollypenrice]

You could easily take 12 hours on this one.

Olly

[rocketandroll]

Yeah, unfortunately M101 has exceptionally low surface brightness.... even hours of 30sec subs probably won't show much, you need 5min+ exposures really to show anything... unless you're working at f3.2 or lower.

I bet you do have the SN though, IIRC it's brighter than the core of the galaxy now.

Ben

[661-pete]

You ought to be able to get something photographically - M101 is marginally visible in 10x50 bins in a very dark sky - but I agree it's difficult as a visual target. What kind of lens or 'scope were you using? And what is your assessment of the LP (e.g. limiting magnitude)?

Perhaps you should post the data on here and let the processing wizards get to work....

It would be a shame if your contribution to this rare and exciting event came to nothing....

[Astrosurf]

Thanks guys. I was using a SW 200P scope with a Canon EOS 40D at prime focus. I was hoping I'd caught the SN but I haven't yet had a chance to look closely and try processing. I'll have a look when I get home.

I have no idea of limiting mag! I'm too much of a newbie. Maybe you could enlighten me?

I may well post the stacked images here for the wizards! But I really don't think there's enough detail for them to work with.

[JohnnyD333]

You should post the image, although you recieved a lot of great advice you will get even more. I have to agree with Ben, you will need to go at least 5 minute exposures to get detail. What kind of mount are you using, can it autoguide?

[661-pete]

I have no idea of limiting mag! I'm too much of a newbie. Maybe you could enlighten me?

I meant simply, the faintest stars you can see with the naked eye. E.g. if it's a really dark site (which you said it's not! ) you'd be able to see magnitude 6. If it's really bad, about 3 to 4. You can get the magnitudes of the stars you're looking at from Stellarium or similar.

[Astrosurf]

Thanks guys. It's an HEQ5 Pro mount. I've got a thread about autoguiding, so you don't need to comment! You can leave this thread now. Many thanks!

[Shibby]

How many subs did you take? You might be surprised the difference stacking makes... Not saying 30s will give lots of detail, but the SN might at least make an appearance.

[Astrosurf]

Well, that's interesting actually. I took a few more the next evening and decided to stack all the RAW images rather than the JPEGs. The image was excitingly good in Deep Sky Stacker after stacking, compared to the first one I did (although still faint), but when I saved the image (as a TIF file), it went black! I'll have to post a thread about that. I still haven't got to grips with image processing in Photoshop so will need lessons first!

[Ant]

This is an image that I took a few weeks ago (the night of full moon in September).

25 x 2 minutes with an ED80 at F7 - ok it was a CCD not a dSLR, but show's it doesn't need massive exposures to get something.

I bet you'll have a lot more in the stacked image.

DSS does tend (on my pc) to preview a very bright stacked tif, when I open it in PS is is always MUCH darker.

So [in PS] look at the Levels, move the left had slider over to the first steep curve and you should start to see some details coming out.

Play with levels and curves till you are happier with the image - I bet you have something there.

Ant

[Astrosurf]

Great, thanks Ant!