Johnathanmdavis

Monday, August 24, 2015

H-alpha imaging with a 110 mm APO

On 8/22/15 Alann and I made our way to Sierra Vista to visit family and hopefully do some astronomy. It seems like every weekend has been cloudy since the monsoon season started. Dean Ketelsen ( http://theketelsens.blogspot.com ) let me borrow his 110 mm APO refractor and I have been itching to try it out with the "new" CCD camera. Getting the equipment ready after a long hiatus was interesting. I found a big black widow right by the DEC motor where I put my hand to disengage the drive. Fortunately I noticed it before I put my hand there! Because it had just rained the day before, the air and ground were thick with moisture, which made it a wonderful environment for mosquitos. After struggling to get everything bolted together and fired up, I finally had everything working. Only problem was that it was still cloudy : (

From 8pm to 11:30pm the clouds were relatively heavy, with only a few patches of semi-clear sky. Just enough to get the telescope focused and ready in case the skies cleared up.

Around midnight the skies magically opened up, just as the moon was setting. It was time to get down to business and get some shots!

Dean's 110 mm attached to my equatorial mount. This is a beautiful scope!

First object of the night, the moon in H-alpha. This image was shot through hazy clouds

Above is a periodic error plot showing the tracking performance of the mount, using a starshoot auto guider. I'm not convinced its this good, I suspect that the angular resolution of the auto guider system is not sufficient to detect sub-arcsecond perturbations. Although, the mount can track unguided for 10-15 minute exposures with very round stars.

M27, Most of the exposure time was in H-alpha (approximately 20 minutes)

The Pacman nebula, again mostly in H-alpha (approximately 20 minutes). I don't think the focus was quite right for this shot. But overall it turned out well

As I was packing up this giant spider decided to pay me a farewell visit. He was a good 2-3 inches in diameter. I was also visited by kangaroo rats, a jack rabbit and the sound of coyotes howling in the distance.

Saturday, April 18, 2015

Saturday, April 11, 2015

Imaging M51 with a CCD camera

Compare the 2 following images (captured April 10th):

M51, single 5minute exposure, binned 2x2. This is an unguided image, and shows how well the mount was tracking.

Second M51 image is being re-processed.

Overall, you can see that the 5minute single exposure has about the same amount of detail as the stacked 25min exposure. This is primarily due to the fact that the CCD was binned to 2x2, and CCD pixel noise averages out nicely with a cooled CCD. Also the SNR for a single 5minute exposure is much higher than a single 150 second exposure.

Chris Summitt, a friend, fellow optical engineer and photographer, joined in the fun and took some landscape astro-photos. You can find more of Chris's work at his website:

http://chrissummitt.com

Sunday, March 22, 2015

Testing the equatorial mount on the new pier in Sierra Vista

The Equatorial mount bolted to the new pier. Kevin, Lanna and Grandma Thompson. Circe and Lucky in the foreground. Grandma Thompson looks like she's from the "old country", it was really windy out, hence the scarf.

305mm F/4 newtonian with the 80mm Orion short tube refractor on top. The concrete pier consists of 1600 pounds of concrete and rebar. The steel part of the pier is a 8" steel box beam.

Great spot for an observatory!

Lanna and Grandma Thompson

New R.A motor and mechanical modifications. This is a zero-backlash drive. All of the reductions are accomplished with precision timing pulleys and a 11:1 friction roller drive.

Orion Nebula. Using the 80mm short tube refractor, ATIK 428EX ccd imager and H-alpha filter. Total integration time was around 10minutes. I was surprised at the decent imaging quality that came out of a small inexpensive refractor. Imaging in narrowband with the H-alpha filter eliminated chromatic aberration effects.

M51 with the 305mm Newtonian + Paracorr 2. Canon 1000D DSLR, approximately 10 minute integration time. It's amazing what you can accomplish with a cheap consumer grade DSLR, you can pick this same camera up on amazon for $200.

M42 with the 305mm Newtonian + Paracorr 2. Canon 1000D DSLR, approximately 10 minute integration time.

Thursday, January 1, 2015

Our Bisbee wedding

We are working on a narrative for our wedding that took place on November 15th 2014. Stay tuned!

In the meantime, here are some of the beautiful photos that our good friend and photographer, Chris Summitt, took during the event.

Monday, October 27, 2014

Astrophotography by the Desert Museum

Lanna and I decided to do an astronomy event with some friends and family(Brek Thompson, Sean Bottai, America, Trevor Clark, Sam Hameroff, Michael Clark) on October 25th by the Desert museum.

The weather, sunset and company were beautiful. Unfortunately the multitude of cars driving on Kinney road, on their way to and from Nightfall, presented some challenges for deep space astrophotography. Our setup was within 500feet of the road which lead to us receiving a great deal of unwanted light from passing cars and their high beams.

Despite the challenges of passing cars and some early scattered clouds we managed to get some pictures of a few objects. At first I was having technical difficulties with the Equatorial mount. Mostly balancing issues. Eventually we got the mount aligned properly and were taking pictures with Trevor Clark's camera piggybacked on the mount and my camera looking through the main scope.