Rasa 8 as a Galaxy scope? - M95, 96 & 105

[SamAndrew]

I was pleasantly surprised at how these have come out, 1h 52 mins of data from Bortle 7 SW London. QHY 294M in unlocked mode, 1.1" per pixel. Optolong L filter.

This combo gives great resolution and field of view for bagging all the small NGC and UGC galaxies. 

Top pic is a crop, middle is the full field and then an annotaed version as well.

I believe there is a combo of tilt and collimation that still needs to be sorted out, but RC astro BlurXT works wonders on bad stars  Still waiting to complete the RGB data.

 

 

[ollypenrice]

When we started using the RASA 8 I did not expect it to be all that good on fine detail in galaxies but did expect it to be a great hoover of the faint stuff. In fact it does both.  It doesn't give great star shapes straight from camera but this is not indicative of poor resolution of non-stellar detail. With modern post-processing tools the stars can be made to behave!

Olly

[tomato]

And here was me thinking the RASA was only good for imaging galaxies like M31, M33 and Markarian's Chain but after seeing your image and the wonderful Arp 94 image posted by @ollypenrice maybe I should think again. I'm not ready to give up on the Esprit 150/ASI 178 combination, but next galaxy season I might just take one of the refractors off the mount and put the RASA8/268 alongside it. At least I would get some side by side results to help me make up my mind, and scope alignment would be a breeze!

But I'm off to a holiday location soon with a good Southern horizon, with the specific aim of imaging Arp 244. I might get two nights with a 2 hr window on each. Should I pack the Esprit 150 or the RASA8?

[ollypenrice]

2 hours ago, tomato said:

And here was me thinking the RASA was only good for imaging galaxies like M31, M33 and Markarian's Chain but after seeing your image and the wonderful Arp 94 image posted by @ollypenrice maybe I should think again. I'm not ready to give up on the Esprit 150/ASI 178 combination, but next galaxy season I might just take one of the refractors off the mount and put the RASA8/268 alongside it. At least I would get some side by side results to help me make up my mind, and scope alignment would be a breeze!

But I'm off to a holiday location soon with a good Southern horizon, with the specific aim of imaging Arp 244. I might get two nights with a 2 hr window on each. Should I pack the Esprit 150 or the RASA8?

I'd pack the RASA 8. The Arp catalogue is all about the faint stuff.

I'm beginning to think that, with a RASA 11, I could do every kind of target in the book. A bit more resolution on the small stuff and no great loss of FOV on the wide. But beware of anything I say because I'm on fire with the zeal of the convert! 

Olly

[tomato]

1 hour ago, ollypenrice said:

I'd pack the RASA 8. The Arp catalogue is all about the faint stuff.

I'm beginning to think that, with a RASA 11, I could do every kind of target in the book. A bit more resolution on the small stuff and no great loss of FOV on the wide. But beware of anything I say because I'm on fire with the zeal of the convert! 

Olly

Thanks for making my mind up Olly. With the usual vagaries of the UK weather I might only get a couple of hours, at least with the RASA8/OSC combination, I should get something.

Hmm, a RASA11/ASI678 for small galaxies, it's about time I purchased another scope...😉

[SamAndrew]

Yes a Rasa 11 is on the wish list, I think it would be the sweet spot, do everything scope.

A few more samples from the Rasa 8, only an hour of data for each; simply looking to see what's there and if there's anything worth investing time on

 

 

Edited April 16, 2023 by SamAndrew

[clarkpm4242]

Opened my eyes!

What length subs are you using?  On the M95/6 image...

Thank you, Paul.

Edited April 17, 2023 by clarkpm4242

[SamAndrew]

1 hour ago, clarkpm4242 said:

Opened my eyes!

What length subs are you using?  On the M95/6 image...

Thank you, Paul.

I've been using 2minutes for luminance; can't remember the gain setting, but fairly low. That's the same for all these images here.

[Paul M]

I'm pretty much blown away with what you RASA guys are achieving!

Just about every RASA image I see is impressive.

I thought about a RASA when I was choosing a new scope late last year. But I thought they were just super wide field and super fast. So not suitable for the tiny things I like to find. 

Not that I'm now doubting my choice of the RC10. I'd only ruin the reputation of RASA's if I got one😇

In the second image in the OP, the trio including M105 is shown nicely.

I imaged that myself at the start of the year with my then brand new RC10 and it didn't go nearly so well. OK, I was having some teething issues and colimation was out, but it demonstrates very nicely that f/l is not necessarily, or not even your friend in Deep Sky imaging! Plus, I'm dog rough!

 

[gorann]

Great galaxy images! In fact you can even image PNs with a RASA, in this case M97 and RASA 8 with IDAS NBZ filter a few nights ago. The faint outer ring was of course no problem for the RASA.

[ollypenrice]

3 hours ago, gorann said:

Great galaxy images! In fact you can even image PNs with a RASA, in this case M97 and RASA 8 with IDAS NBZ filter a few nights ago. 

 

Agreed. This is a WIP but three hours on Jones Emberson 1 in one shot colour, no filters.

Olly

[tomato]

It feels strange radically cropping a widefield image as a way of imaging small galaxies, but then other time honoured imaging methods (like taking long subs) have recently gone by the wayside so its just a case of embracing the change.

I’m looking forward to hopefully collecting enough data before the season ends to compare the approach to the traditional method.

[ollypenrice]

1 hour ago, tomato said:

It feels strange radically cropping a widefield image as a way of imaging small galaxies, but then other time honoured imaging methods (like taking long subs) have recently gone by the wayside so its just a case of embracing the change.

I’m looking forward to hopefully collecting enough data before the season ends to compare the approach to the traditional method.

I'm completely relaxed about 'cropping' and never give it a thought. Digital astro-imaging began on tiny chips. Now they're much bigger, which is nice if you want what's captured. If you don't, crop. Of course, there is no hiding place if you are working at full size: you have to have enough data to look clean at 100% but, if you do, all is good.

Olly

Edited April 18, 2023 by ollypenrice
False click

[tomato]

50 minutes ago, ollypenrice said:

I'm completely relaxed about 'cropping' and never give it a thought. Digital astro-imaging began on tiny chips. Now they're much bigger, which is nice if you want what's captured. If you don't, crop. Of course, there is no hiding place if you are working at full size: you have to have enough data to look clean at 100% but, if you do, all is good.

Olly

I can’t argue with any of the above it’s just getting my head around that this set up:

can produce small galaxy images comparable to this set up:

The latter costing well over 3 times the RASA rig, took the best part of a year to trouble shoot and optimise, whereas the RASA can be set up on the lawn in half an hour, and takes widefield images to boot.

There, I’ve just torpedoed any hope of selling some of the refractor rig.☺️