Friday, February 13, 2015

Using Deep Sky Stacker Live software on the Great Orion Nebula

The clouds were gone! For the first time in ages (ok, maybe three weeks, at least since I did some truly deep sky imaging) I was able to get out into the observatory and do some astrophotography. The seeing wasn't great but at least I didn't have to play "footsie" with the clouds or fog.

I had just downloaded Deep Sky Stacker which includes it's companion software Deep Sky Stacker Live. The later software is awesome because it takes images "on the fly" as you are photographing "live" and complies (stacks) the "subs" (exposures that are far less than needed for a good bright image). So as one is taking images, Deep Sky Stacker Live is at work at the same time, saving lots of time after the observing session is over.

Here is what a "sub" image of the Great Orion Nebula, also known as M42 (in the constellation Orion) looked like:

Taken with a modified Canon xsi body, ISO 1600, 10 second exposure, daylight setting, through an orange Celestron C8 (8 inch) SCT telescope. with a Celestron Focal Reducer (to f/6.3) like this one.

Here is the same subject AFTER Deep Sky Stacker Live did it's thing after stacking about 110 "subs" resulting in an image worth about 18 minutes of continuous exposure with the same setup:

Lots more detail for sure but the color balance needs some work as well as contrast.

So I opened up the GIMP program and did some "levels" work and here is the result:

What is amazing is the the "sub' if pushed to this same level of brightness would look like this:
Obviously this image is unacceptable...but add 110 together and it minimizes the grain and adds details!

You may be asking, "Why not just take one long exposure of 18 minutes instead of going through all the trouble of 110 subs?"

Well, the answer may surprise you, even perplex you.
When you take a long exposure the possibilities for telescope tracking errors are many: the scope can be jostled by a short breeze, the motor in the scope can have periodic errors due to manufacturing, the motor can be affected by someone turning on an electric heater in the house or a minor "brown out" by the power company, the scope can be accidentally bumped by it's operator, the scope can be jiggled by a large passing semi-truck's vibration in the ground, the ISO needed to produce a bright image is very grainy (see above photo as an example), the telescope may not be accurately aligned with the North Celestial Pole (no, the "North Star" is NOT the North Celestial Pole), ...shall I go on?

As you see, the possibilities of ruining 18 minutes of work can be ruined irreparably by any ONE of these variable factors, not to mention that you then have to take 18 more minutes to produce a "dark" frame (covering the telescope and opening up the camera sensor for the same amount of time that it was open in the first place). The purpose is to uncover "hot pixels" that are in every image that also ruin the overall image.

So we do "subs" and use programs like Deep Sky Stacker Live to produce high grade quality images of deep sky objects like the Great Orion Nebula.

In conclusion, this is my FIRST effort at using Deep Sky Stacker Live. I believe it will be possible to get even more detailed images as I learn its various setting and work under better seeing conditions!

Here is one more post-processed image of the Great Orion Nebula from this session in the La Pine Observatory (in my back yard):

God bless you with His wisdom and may you appreciate His glorious handiwork!

Psalm 19:1
"The heavens declare the glory of God;
the skies proclaim the work of his hands!"

Monday, February 2, 2015

The Moon nearly full

It started out to be a good opportunity to do some astrophotography last Saturday evening so I rushed what I thought was all I needed out to the observatory. Wrong. I forgot this. Then I forgot that. Then I forgot the other thing. By the time I opened the roof and got set up, the clouds rushed in.
Such is life when you can't get out often enough... you forget a whole lot!
Anyway, here is a compilation of about 15 photographs taken with a Canon t3i, with an 18mm eyepiece projecting the image on the ccd (camera lens was removed). The seeing was fair, not great and so the detail had to be brought out in post-processing using GIMP.
Full size view here