Couple of H-alpha quickies

[codemonkey]

Just 1hr on M16 at 1"/px F9; had the gear running for 2hrs but dodgy USB gear dropped out halfway through. Not sure if it's the port on my macbook (which was repaired once), or the USB hub.

M8 is 7x800 at about 2"/px.

[Atmos]

Looking really nice :) I am just so jealous of your clear skies! There is a lot that can be squeezed out of those little 100ED's :)

[codemonkey]

Cheers mate :-)

Yeah, it's nice to be finally getting some clear skies. There was about 6 months where we only had a handful of clear nights and they almost all coincided with something I couldn't get out of.

The ED100 really is a good scope. The apparent slowness is offset by the camera I'm using which has about 65% QE at H-alpha, low noise and low dark signal.

Still, 600s exposures are pretty short for narrowband and I'm getting pretty good results for such short subs and low quantities of them.

The lagoon was captured with the GT-81.

[multiweb]

They both look very good. Excellent contrast and details. :thumbsup::thumbsup::thumbsup:

[RobF]

Definitely - you've nailed the light and contrast on those Lee - not so easy to get right for Ha sometimes.

Congrats on a worthwhile outing!

Can feel your pain re USB - so much time seems to go down the gurgler sometimes - especially on the dark clear nights :mad2: :lol:

[codemonkey]

Thanks guys! :-)

I think I've isolated that particular USB issue, although fixing that one presents another, but the latter is less likely to be a problem.

I managed to get another 1.5hrs on M16 last night, but the seeing (and thus guiding) was terrible. RMS was frequently around 1"/px, same as the sampling rate. Interestingly enough, stacking those subs in didn't visually decrease sharpness.

I decided after imaging for 1.5hrs to try and gather some PE data, so I let that run for an hour only to realise I hadn't increased the PHD search area enough and it lost the star after less than one full worm cycle.

I think I'll try another night on M16 with some longer subs tonight and then move on to OIII.

[rustigsmed]

very nice Lee!
looking fwd to the colour variations!

[RobF]

Hey Lee, if you're pulseguiding through a recent EQMOD you should be able to leave PHD tracking with no dither or other interuptions and just record up to 5 worm cycles in EQMOD.

[codemonkey]

Cheers Russ! I was hoping to finish up with the Ha on M16 tonight, but alas a 3.5hr trip home put an end to that. Fingers crossed it's clear tomorrow.



Cheers Rob! I have done that in the past without great results, in fact it seemed to make guiding worse. Is there a way to get the output into PECPrep or something to tweak the curve manually?

[RobF]

Hmmm. Not sure must confess. Agree you'd have to leave PHD not correcting to save a file for PECPrep. I'd be interested myself is someone knows if EQMOD saves the raw data for each worm pass somewhere....

[codemonkey]

That would be handy, because then we could do it while imaging and tweak it after the fact with (hopefully) better results. I'll dig into it a bit more and see if there's a way...

[codemonkey]

And 5 secs in their docs answers our questions ;-)

Once capture is complete the periodic error data is written out to a text file with the suffix _EQMOD. This can then be further analysed using PECPrep. A PEC file is automatically produced using the PE data and saved to disk

Just a matter of where the files are actually saved, but a quick file search should turn them up. Might try this tonight!

[RobF]

OMG Lee. I didn't think things we so bad we should read the instructions!! :lol:
Ta - will have to check it out - I get some funny spikes from the auto routine sometimes too.

[codemonkey]

I know, who does that?! ;-)

I got clouded out tonight. Clear as a bell when I got home, but by the time I dragged 35kg worth of batteries a couple of hundred metres up the back paddock then got everything in focus my view got obscured by clouds, then I looked up and saw lightening on the horizon. So much for another clear night!

The EQMOD PEC dialog shows the path to the PE files btw, but that's as far as I got.

I think I read somewhere that there's a newer version which allows you to record more cycles, but my one only allows 5. Kinda hesitant to upgrade, astro stuff tends to be error-prone.

[codemonkey]

Since I had nothing better to do tonight, I did a reduced star version of M16. I'm likin' it!

[Atmos]

Really love some of those starless versions, they look so unnatural but nice :)

[codemonkey]

Thanks Colin :-) I wasn't a huge fan of them at first, but they're growing on me recently and since circumstances keep getting in the way of my imaging, I may do more of them just for something to do.

[Regulus]

These are excellent Lee, a real pleasure to look at.

Trev

[codemonkey]

Thanks Trev!

[Rex]

Beautiful images Lee. Awesome detail in both images. Which process did you use to remove the stars in your M16? I know there is a couple of options but I can't ever seem to get it to work very well.

[jase]

Sweet images for quickies Lee. Enjoyed the contrast you presented on M16. That is certainly my pick of the two. Good work.

[codemonkey]

Thanks Rex!

I basically used David Ault's process (http://trappedphotons.com/blog/?p=731) with minor arbitrary tweaks to the masks as I went along.

I did try this on another image recently which had more noise and the results weren't as good due to the use of MT; I ended up with smooth spots where the stars were. I'm sure I could have tweaked it to get better results but I didn't put the effort in.



Thanks Jase! :)

[Rex]

Thanks very much Lee, That technique is very helpful. Will try it out next time I need it.

[RickS]

Nice images, Lee!