Ha filter for M82 cigar galaxy

[Tommohawk]

Hi all. Quick query re Ha filter for M82.

I'm currently playing with a second hand Quattro 10s which I recently acquired - I'm just checking I can get it collimated nicely before splashing out on an F4 coma corrector. Its also way over capacity for my HEQ5, though I'm currently using that to test it - I've left off the ADM dual mount and guidescope which makes it just doable unguided.

Anyhow I'm using M82 as a test subject - because its relatively near the pole so not too horrendous unguided - with the ASI1600mm doing 30s subs at unity gain. I've actually got a passable result in LRGB, but thought I'd add in some Ha. Pushing my luck here of course, but attempting 120s subs with high gain - so far about half are usable. Trouble is the results are pretty poor in Ha - I'm not seeing the spurty Ha emission at all.

It may be that 120s is just too short - in the past I've used 300s - but surprised I'm not seeing anything. Only managed to get 7 subs before had to pack up yesterday but hopefully more tonight/tomorrow.

Does anyone happen to have an Ha only M82 they could post as an example please? Or any thoughts on this?

One possibility is that when I switched my filters from a 5 posn to an 8 posn wheel recently, I maybe muddled the Ha with either OIII or SII !!! But how do I tell then apart? Any ideas please?

Maybe I'll just shoot some using the other filters just to see what happens, but really want to make the mos of this clear sky!

 

[tooth_dr]

The Oiii looks blue/green through it so that would be obvious, not sure how you would determine if Siii or Ha as Siii is also red!

[Tommohawk]

Ok, well when I switch to Ha the filter is definitely green! Either I put the filters in wrong or edited the Ascom set-up wrong - I know I did it in a rush, but Jeez!

So the bad news is I wasted an hour of sleep last night doing OIII - but the good news is I should be able to get something in Ha after all. Just got to figure out which is which!

If I shot an emission target it would be obvious. But my view to the south is pretty restricted. And my view to the east is non-existent.

Anyone know a nice emission neb to the north or northwest?

[tooth_dr]

2 hours ago, Tommohawk said:

Ok, well when I switch to Ha the filter is definitely green! Either I put the filters in wrong or edited the Ascom set-up wrong - I know I did it in a rush, but Jeez!

So the bad news is I wasted an hour of sleep last night doing OIII - but the good news is I should be able to get something in Ha after all. Just got to figure out which is which!

If I shot an emission target it would be obvious. But my view to the south is pretty restricted. And my view to the east is non-existent.

Anyone know a nice emission neb to the north or northwest?

NGC7822?

[Xiga]

Adam beat me to it. NGC 7822 is a great NB target right now, situated towards the North. If only the nights were a bit longer up here though...

As for M82 in Ha, i tried my hand at this a couple of months ago. I was only using an 80mm Refractor and a DSLR, but here's what a raw stack of 7 x 1200s looked like (with no processing, other than a DDP stretch and Levels adjustment). As you can see, you can still make out the Ha jets, so i would say you probably have just used the wrong filter:

 

[Tommohawk]

Hey guys sorry for the uber slow response - a million things on the go!

I think I sorted it using the heart nebula which I did a test image in Ha previously and knew what to expect - but the previous go was with a  300mm lens and it all looks a bit different with 1000mm FL. Just not so obvious somehow. Also when using the 300mm lens I'm at F4, where withe the PDS200 I'm at F5.

Anyhow it looks like I swapped the OIII and the Ha - though its almost impossible to tell the Si and the Ha apart by looking at them. Whilst doing this I tried to double check they are the right way round too - and thats really tricky. ZWO advise looking at the reflections but thats not at all easy. TBH the 31mm filters are a right royal pain!! 

Anyhow, I shot a load of Ha (probably!) 60 subs guided at 300s but TBH the result wasnt great - see below (no calibration files). Theres something there but detail pretty poor. When I've done the image best I can probably in just LRGB I'll post that in a new thread and see what folk have to say about how to incorparate Ha. I've seen a couple of fabulous renditions of M82 and was trying to emulate them - but maybe my skills and/or my kit aren't up to it!