M 16 The Eagle Nebula

[roundycat]

I spent three quarters of an hour on this back in May and another 150m last Tuesday night. The most recent attempt suffered from a misty sky so was not actually an improvement. After 22 consecutive days without so much as a star in the sky I had to do something.

TMB 152 and ST10 with an Astronomik 13nm filter. Guided via Atik/FSQ on an AP1200.

Pre processing in Maxim and post processing in PS. All the usual suspects, levels, curves, some fine high pass, neat image and clone repairs.

Dennis

[Beyond_Vision]

Thats a superb eagle Dennis despite the less than perfect skies

Regards

Kevin

[ncjunk]

It is an interesting image, a fair bit of detail in that.

Neil

[RobH]

Very nice image of a tricky object from our latitudes Dennis

What sub length was used?

Cheers

Rob

[roundycat]

Hi Rob, I started with 500s, a 'normal' exposure length for me unless I go to 10 or 15 minutes. This time I was getting some blooming on the brighter stars so dropped the exposure to 450s. That did the trick. The background was still around 5400adu with the brighter part of the nebula coming in at about 6400adu.

Dennis

[johnh]

Captured great detail and contrast in this low altitude gem, dust columns are pretty sharp. John.

[Psychobilly]

Yep the Eagle certainly leaps out form the background nebulously

Peter...

[steppenwolf]

Excellent detailed and contrasty image, Dennis - this is a really difficult object for me as my garden is at the foot of the South Downs!! The only way I can capture it is with a 30 minute slot as it passes through a small gap between two trees on the top of the Downs.

Always good to see other people's rendition of this wonderful object.

[Tim]

Very nice Dennis. Out of interest, how do you find guiding at these low levels in the sky? I find that the stars get bloated because of the guidestar going back and forward etc in the atmosphere, any solutions ?

Thanks

Tim

[roundycat]

Tim, I think you may be confusing the bloating with a general lack of quality seeing when imaging low down. I had a regular peep at the tracking error graph whilst doing this and it showed quite small errors, typically 0.2-0.3 pix at 6.6"/pix. With a guide star of about 20,000 adu but more to the point, an SNR of around 100-140 guiding would have been quite tight. No problem finding the centroid with those figures. My guide exposure was 4 seconds and it is this that can give rise to 'chasing the seeing' if your guide exposure is too short. I generally use guide exposures in the 4-6s range and when taking very quick focus shots it seems to me that a 4s guide exposure is taking a sensible average of the seeing variation.

I usually focus with a one second exposure and a sub frame of about 40 pixels square. In four or so focus exposures I see quite a variation in the FWHM but this is smoothed out by the guide exposure.

Dennis

[Taff]

H dennis' very nice capture with you nice and clear.Mark

[George]

Great image Dennis, Im glad someone is getting dark enough sky's to image at this time of the year

[RichieJarvis]

Very very nice Dennis - its too low for me - bad obsy design means I'd be shooting through the wall!

Ah well.... One for the August Star Party methinks

[SteveL]

Incredible detail in that, very well done!

[daz]

Yes, a great image.

Thinking the same as Richie.....

[roundycat]

thanks guys, I am lucky (made my own luck, actually) with my southern horizon as I have an unobstructed view of the North sea. Nothing in between except farmer's fields. The obs was designed to give me a view of the sea horizon so my real limit is the amount of crud in the atmosphere low down. I never realised it would be so bad, should have bought a house up a mountain. Attached is the view from roughly due East to SW.

Dennis