IC4628 (work in progress)

[Octane]

Yep, another one!

Here is 1.5 hours worth of 7 nm hydrogen alpha, taken in 30-minute sub-exposures.

Just a quickie put together in MaxIm DL with a DPP/log stretch, and saved to JPG in Photoshop CC.

I had a couple of sub-exposures before the crack in my sensor appeared. So, tonight's 30 minute offering didn't contribute too much to the crack.

I had a massive win tonight with my guiding. I turned the aggressiveness right down to 1 for both X and Y in MaxIm DL and I was getting a pretty much perfectly smooth guiding graph with 6.8 second guide exposures (CCD Commander automatic guiding enabled). I previously used to have it at 8, then, tried 4, and 3. Even 2 was too much. The two prior exposures had very slight trailing, but, I included them in my stack, anyway, just to see what would happen. Tonight's 30 minute addition had absolutely perfect round stars. I'm so stoked. :)

SBIG STL-11000M, Takahashi FSQ-106N, Losmandy G-11 G
3 x 1800s f/5.0 530.0mm at -20 degrees Celsius

Larger version available here (http://scratch.hqphotography.com.au/ic4628.html).

H

[RickS]

That's a really nice FOV, H. Should be a cracker of an image.

[Octane]

Thanks, matey!

I paid a lot of attention to my composition. I think the offset with the open cluster and bright stars to the right and the anchoring with the nebula on the left gives the composition some balance.

I'm still chuffed with round stars after 30 minutes with such long guide exposures; it was self-guided, too, at bin 3x3, and not 2x2 that I do normally!

H

[multiweb]

Cool target. On my list to REDO too with the FSQ. Can't access your highres. :question:

[Rod771]

Yeah nicely framed H! Congrats on the guiding too :thumbsup:

[gregbradley]

That's a beauty H.

Greg.

[Paul Haese]

Looks good H. I like the composition and it is a pretty wide field of view.

Most nights I guide around 4 secs but every now and then I get a guide star that can be as much as 10 seconds. I found that if PA is good and Protrack is working well 10 seconds produces very flat graphs. Your mount is clearly well aligned and you must not have any other defect causing aberrations that would cause your guide star to wander around. Keep up the long subs, your ADU will be huge and you signal high.

[Octane]

Thanks, all!

Marc, it should be working -- I've tried it on 3 different connections, and, it's coming up each time...

Paul, yes, I spent quite a while trying to get good polar alignment (well, for the region of sky I was pointing at: near meridian and zenith, and a star 30 degrees above the western horizon; as I know perfect polar alignment is not possible). Having said that, I got it down to below 30 arcseconds in both altitude and azimuth. I think that's perfectly acceptable for guided images. The 30 minute exposures yielded an ADU of just below 3,000. I'd love to go longer, but, that would mean I'd have to redo my dark library. :P

My gotos are pretty accurate. At the moment, I have a 0.3 arcminute pointing error. This is a humble G-11! Can't complain too much with that. :)

I've also done away with the finder scope on the FSQ-106N. I never use it, anyway. This has helped with declination balancing considerably, too.

I tried adding more this image last night, however, 20-minutes through an exposure, the clouds came to join the party. Grr! The forecast is rubbish all through Sunday, so, looks like I might build a new dark library instead. :P

H