Tuesday, November 26, 2019

Coffee First and a Nap Later

There is a nap in my future, I'm sure.

Three cups of coffee for the morning, but that will not be sufficient to make it through the day.

Love this mug!
It was a really good astronomy session last night.  The sky transparency was merely average, but the evil clouds stayed away, and the moon had already set.  A couple of the objects that I wanted to see were mired in the light dome of the nearby city, but I was able to use SharpCap and my ZWO ASI294MC imager to tease out some details!

The Horsehead Nebula

Also known as Barnard 33, is notoriously difficult to see with the naked eye.  I have a good hydrogen alpha filter for use in viewing it, but have never managed to get my eyes dark adapted enough to eke it out.  Probably need to go to a really dark site to have a better chance of seeing it, but nevertheless, I always take a peek in the neighborhood of Orion whenever I'm out.

Last night, I'm glad that I did.

Barnard 33, 25 Frames Stacked, 200s Integrated
This is my best image of the Horsehead to date.  Other than manipulating the controls of SharpCap live view while the frames were stacking, I did no processing of the image.  If you look closely, you can even see some the hot pixel artifacts from the imager.

The Eskimo Nebula

Also known as the Clownface Nebula, or Caldwell 39, is a planetary nebula with double shells of gas.  It sort of looks like a person's head surrounded by a parka.

I love planetary nebula.  They are unusual and often difficult to see.  Naked eye, the Eskimo Nebula looks like a little blue dot.  If you dial up the magnification, you'll need to use averted vision to see it's details.

Here is what I was able to capture using the full field of my imager.  The nebula was only 20 degrees above the city, making things difficult.  It also is pretty bright, which poses another set of challenges.  I'd like to reduce the gain or the frame exposure time so the details won't be over exposed, but that would reduce the amount of stars visible, but I need the stars so the software can align the frames for stacking.

Caldwell 39, 20 Frames Stacked, 80s Integrated
I recently discovered that I can choose a region of interest with SharpCap's live view.  If I don't get too severe, sometimes I can tease out some detail in tiny, bright objects like this nebula.

Calwell 39, ROI 1280x1024, 23 Frames, 47s Integrated
Click on the image to make it bigger!  See the little parka shrouded face peering at you?

NGC 7139

This object has no "also known as." I suppose that I could make one up, but it probably wouldn't catch on...

This is a really dim object.  It is a planetary nebula that appears to occupy the same amount of sky as Jupiter.  Naked eye, I can only detect it with averted vision as a somewhat dark circle in an otherwise crowded field of stars.  Or maybe not.  That is the difficulty with using averted vision to see objects.  Sometimes, you are not really sure if you are seeing something or perhaps engaging in wishful thinking.

But, with electronically assisted astronomy, i.e., my ZWO ASI294MC imager and SharpCap, this is what I see.

NGC7139, 25 Frames, 200s Integrated
The object is just left and above the center of the image.  Click to make bigger.  It's a "bubble" or "ring" shaped object.  These type of objects are really fun!  I like to try to see if I can find any stars inside them.

Here is what I captured with the region of interest reduced to 1280x1024.

NGC7139, ROI 1280x1024, 82 Frames, 656s Integrated

Yep, I can see stars in the object!

I spent a lot of time with these objects last night so I didn't make it through my list.  I'll keep the list for next time!




  1. I'm glad you had a good viewing night! Why do we have to avert our eyes to see some things better?

    p.s. Lovin' the winter coffee mug!

    1. It's a matter of what the rods and cones of the eye are designed to do. The cones, which occupy the center of the eye, are better for seeing bright and colorful light. The rods, which become more prevalent outside of 20 degrees off center, aren't good for color but are sensitive to lower levels of light. The fun part is that everyone's eye are different and have different regions that are more sensitive to low light than other.👀

  2. That image of the Horsehead Nebula is great, C. You should just go ahead and name NGC 7139 - maybe it will catch on and you'll be famous.

    1. Thanks! This is the time of year when some of my more favorite objects are in the sky. The Peiades, the Great Orion Nebula, and the Ring Nebula. NGC 7139 is sort of like the Ring Nebula and I was really happy to find it!

  3. Love the Horsehead Nebula, looks straight out of a science fiction or Marvel movie. And of course, three cups of coffee is never enough.


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