M8, M16, M20 and M83 - ST9 + RC

[AlexN]

Last night was amazingly clear and dew free here in brisbane. I took advantage of this situation and invited Robin (Tandum) over for a night of imaging...

I managed to get these four images which are a damn sight better than last weeks efforts with this scope.. Collimation looks a lot better, as does the focus.. I definitely think there is more in it however!

M8 - 60x1min @ 13nm Ha
M16 - 80x1min @ 13nm Ha
M20 - 40x1min
M83 - 33x1min

The M83 image looks a little strange, It was the first image for the night and it was after this image that I pulled my desicant cap out and stuck it in the oven, and replaced it with my refillable unit from PWT. After this the resulting images were a lot sharper...

One thing is for sure, I need a bahtinov mask for my RC.. After using Robin's one I realised that my initial focus was always out by a whisker or two.. So I think fixing that is the way to go!!

Thanks for looking... Oh, the other pics are shots of our setups all ready for the night...

[jjjnettie]

Great pics Alex.
Here's hoping the weather stays good for next weekend. I'd love to see the new scope.

[AlexN]

Thanks JJJ,

Yep my fingers are crossed! I cant wait to give it a fly under darker skies!
Alex.

[Paul Haese]

Much better images Alex. The eagle looks pretty good for focus.

[spacezebra]

Hi Alex

Excellent images, an amazing amount of detail.

Cheers Petra d.

[sjastro]

They look fine to me Alex.

With regards to focusing if you are using a ST-9, I assume you have CCDops software. Try using planet mode on a roughly focused star between 200-250 counts.

I find this far more accurate than any form of diffraction focusing.

Regards

Steven

[AlexN]

Thanks for the comments! I really enjoyed taking the shots, so Im glad people are getting some enjoyment looking at them! :)

Steven - Im using CCDSoft v5 for capture, however I do have CCDOps.. Might have to give that method try... Thanks for the tip!

[vash]

Almost there on some of them, I'd agree that eagle has the best focus a lot sharper and tighter stars than the others.

I too am hoping for dark skies, but judging by the out look, it's not that good this week.

[AlexN]

Oh, I forgot to mention..

Auto-Darks used.
15x Bias frames.
No flats... Didnt really see the need..

[dpastern]

Looking good Alex - agree about the focus, but still, very nice. I'd love to see what this setup can do under dark skies and with perfect focus and really long exposures and lots of subs.

Where abouts in Brissie are you? Wouldn't mind catching up one day.

Dave

[trick]

Great shots Alex, I am with you on the bahtinov mask, mine is in the post from England. With it and more care on setting up my mount I hope to improve my images.

[peter_4059]

Great start with the new gear Alex - its been a long time coming but I agree the conditions last night were the best for a while. The setup looks nice and neat - what's in the box below the mount?

Peter

[dpastern]

Is there any reason for buying the bahtinov mask, when it's possible to make one? Excuse my silly question ;-)

Dave

[AlexN]

Peter - the box below the mount houses 240v AC to 13.8v DC transformer for powering the mount, dew control gear etc. sitting atop the box is the power box for the SBIG and the SBIG guiding relay..

David - Yeah, Laziness is the reason for buying one when you can make them yourself :D

[bloodhound31]

Good shots Alex. The stars could use slight tightening I think. It looks just oof to me..

The use of such numerous short exposures has delivered very smooth graduations though, excellent work.

I noticed your power cable is running parallel to your signal cable on your CCD camera. Has this ever posed a problem for you and created artifacts in your subs? I found that sometimes mine came out with diagonal banding and all-sorts until I separated the two and put an end to that problem.

I like your images mate, keep 'em comin'.

Baz.

[trick]

Dave I find the older I get the less petience I have for fiddly things and sharp objects. For $21.75 free worldwide postage. Why not :shrug:

[AlexN]

Thanks Baz, I've never had a problem with the DC power lead running parallel with the signal lead on either this camera, nor my old QHY8.. I have read before that some people have those sorts of problems, however I guess I've just been lucky..

I'll have a go at reprocessing these shots with fresh eyes in a couple of days to see what I can do with regards to tightening the stars a little.. Although I do think its more an affect of poor focus than processing downfall... Time will tell..

Alex.

[multiweb]

Cool series of pics. I like M16 best. Your camera sticks out a fair bit out at the back. Do you get flexure problems on your focuser?

[AlexN]

My focuser flexture problems are less than most people with this scope.. Mostly due to the fact that my focuser is only racked out 14mm to reach focus.. Also, the effect of the focuser slop is lessened by the fairly small sensor in my ST9E... Yes, it does droop a little bit, although I've found having the focuser positioned upside down as seen in the pics with the locking screw tightly secured, it can be minimised to a useable level... A feathertouch motorised focuser is on its way from the states to rectify the problem completely...

Thanks for your comment Marc, I agree, M16 is the best of the bunch, Although I do really think the M8 image has potential to with some time spent reprocessing it..

Cheers.
Alex.

[dpastern]

Just was curious. I'm probably lazy enough to buy it as well lol.

Dave

[bloodhound31]

I agree, it looks like focus. The first step in correcting a fault is correct fault diagnosis.

Baz.

[AlexN]

don't i know it baz. Don't i know it. :)

[RobF]

Glad to see you both had fun!
Picked a great night for it too.

[troypiggo]

Awesome shots. Friday and Saturday were quite good for us here.

[Peter Ward]

Alex,

Your subs are way too short for your sky background. That's what is causing the fixed pattern noise (herringbone like pattern) in the data. Try at least 10 minutes.

[Peter Ward]

Just to clarify my last post....

To be correct, fixed pattern noise is the wrong term. I simply used it as it best described what the noise "looks" like.

In Alex's case we are getting shot noise, (which reduces with exposure time) on top of less than perfect calibration data. When you stack images that are drifting in a uniform direction the end result is a herringbone pattern in the stacked data.

This pattern disappears with nil drift plus applying a random dither to the guide star tracking.

[kinetic]

You are certainly getting there Alex,
can't wait for some LRGB!



Peter,

I don't doubt your knowledge of the subject at all, but I have also noticed
this pattern on a few of my DS stacks with a drive artifact similar.
I can totally remove it with a better corrected dark frame (bad pxel
mapping in Nebulosity). Sorry for the OT post Alex!

Steve

[AlexN]

all is good guys.. I agree, I shouldnt be using auto-darks, its just that its so convenient.. :D

Peter, You're right, longer subs would be the key... I'm just not too adept at processing out star blooms yet, so I try to avoid stars blooming by keeping the subs short.. Any ideas on processing the blooms out would be appreciated... I also don't know how to dither guiding yet... I've read about it, and would like to be doing it, just unsure how..

Cheers for the comments and constructive criticism everyone... I will endeavour to produce more, better (hopefully colour) images soon! :)