NGC6188 imaging Tips

[AstroTom]

Hi All,

This is a first post for me on the main Deep Sky Section of this forum. I'm going to be heading out to the dark skies again this coming weekend and I'm thinking of imaging NGC6188 emission nebula.

I'm wondering whether I'm going top have any success with the equipment below or whether this needs to be captured using narrowband filters and CCD. The equipment is:

ED120 Black Diamond Refractor
AZEQ6 mount
Orion ST80 Guidescope
Synguider Autoguider
Canon 600D modded camera

My big question mark is whether the DSLR would capture any of this nebula if I shoot with 5-6 minute long subs over 2-3 hours. I may go to 10 mins if required. If this is not going to yield much as the nebula is very faint then I may look at imaging somthing else.

Anyway any tops and advice on the above would be great. I tried looking on the internet about this nebula but most of the images are taken with CCD cameras.

Regards,

Tom

[Placidus]

Hi, Tom,

I started out with a Canon EOS 20DA on an 8" scope, although sometimes I used it on a 3" or 6" refractor.

You will unquestionably get something pleasing using the gear you have, and the exposures you suggest. It will effortlessly pick up the stars, and their colours. It will easily pick up the cyan coloured OIII nebulosity and the blue hydrogen beta, and (more so on other objects) it will easily pick up any reflection nebulosity. But it may struggle a bit with the cherry red H-alpha because the infrared cut-off filter will tend to exclude reject perhaps 50-70% of it, making it fainter and grittier.

As you probably already know, your gear will work fine with the brighter galaxies, with just about any globular or open clusters, and with the very brightest dozen or so emission nebulas. NGC 6188 is in the intermediate category - within reach.

Using narrowband filters, you would still have that limitation, but the stars, air glow, light pollution, and any reflection nebulosity will be greatly attenuated, making the nebulosity (that you would have picked up even without the filters) much more obvious.

Going to a cooled CCD is a huge step forward. For the same exposure, the background grit snow and fog is enormously reduced. Hydrogen alpha nebulosity will be detected at - bit of a guess here - two or three times the efficiency. And, if you are at a dark site, and guiding and tracking will allow it, you can take hugely longer exposures.

Bit of personal prejudice: Natural colour is great, spectacular, beautiful, for open clusters, globulars, and most importantly galaxies. But for me (others will disagree vigorously) nebulas in natural colour tend to look like a piece of raw cryo-vac meat: a nasty purple. (We've seen some skilled examples recently where people have avoided that butcher-shop look.) On the other hand, nebulas really call out for narrowband imaging. And it can be done when there's a bit of moon about, and from the outer suburbs.

The attached thumbnails show my early attempts at 6188 using a DSLR and natural colour, and then using a ccd and narrowband filters, both from suburbia, but using an 11" scope. Details lost to history. (our current best attempt, a few years old, is here (www.photos.smugmug.com/Category/Star-Forming-Regions/i-49Fcwf2/0/O/Ara%20Shoreline.jpg)).

Summary: You'll certainly get pleasing results on the Ara nebula using the gear you have and the exposures you suggest, but should a CCD camera and narrowband filters fall into your hands ...

Very best,
Mike

[rustigsmed]

hi tom,

it will be pretty faint if your 600d isn't astro modified as mike has mentioned above (actually it is pretty faint even in long narrowband exposures).

here is a pic Justin did quite some time ago with his non modified canon http://www.iceinspace.com.au/forum/showthread.php?t=90097
the second pic is processed very hard to try and bring some more of the neb out.

all the best

Rusty

[Rod771]

Hi Tom

If you're heading out to a dark site you should be able to get a pleasing result on NGC 6188. I imaged it last year with my Canon 60Da through the C11 @F7 form north west Sydney (orange/red zone.)

You might not have to go as long as you think re exposure. I found 4 minutes was prefect for my camera in respect to the LP I have here. 10 minutes will probably be too long for the DSLR. Take some short subs, 4 to 6 sec just for the star cores then combine these with the longer subs during processing. This helps retain the star colours. Make sure your subs are dithered, take accurate darks and flats and you'll get a nice result. :thumbsup:

Here's a link to my pic for reference NGC6188 (http://astrob.in/182722/None/)

All the best

Rod

[DJT]

Hi Tom

I have tried this a couple of times with an unmodified Canon 30d and a skywatcher ED102 with a HEQ5 mount, as well as a TAK FS60


1st Attempt
These were 5 * 15 minutes subs from North Sydney, RGB.
Nebula NGC6188 and Cluster NGC6193 (http://astrob.in/12497/None/)

2nd attempt
Again, from North Sydney though this time a lot more data, 61 subs of 6 minutes and with a Tak FS60. Issue here was field curvature but it shows NGC6164/5 (just)
NGC6188 and 6193 (http://astrob.in/42620/None/)

Its doable but darker skies would be better and processing skills need a bit of work:)

[AstroTom]

Hi All,

Thanks for the advice and comments. I definetly think this is something I'll attempt. It just looks such an amazing area with lots of interesting nebulosity, which I'm keen to have a go at.

I'll post a photo on the forum (if it comes out OK) after I've tried it.

Thanks for the help and advice.

Regards,

Tom