Observing with Street Lights

Observing with Street Lights
Dark sky sites not always necessary to see the Milky Way (This image was taken ouside of a B&B in Julian, CA)

Friday, April 17, 2015

American Physical Society Meeting in Baltimore, met Dr Gary, fellow traveller on the physicist wannabe path, and success with 2X Barlow to fix solar scope focusing issue

Greetings from Palmia Observatory

Well, I'm finally back to the observatory after a wild week of indulging in physics lectures at the American Physical Society general meeting in Baltimore.  It was neat being surrounded by over 1000 physicists where we had presentations and discussions on astrophysics, dark matter, dark energy, inflation, cosmology and the 100th anniversary of Einstein's general relativity.

Although a lot of the topics were way beyond my current understanding, there were many that were right on.  I summarized the presentations that I attended and forwarded my comments back to the other members of "science squad" of retirees pursuing advanced physics.  I won't repeat that list of comments here, but wanted to comment on two topics that may be of general interest to the amateur astronomers that follow this email posting.

First, I was lucky and fortunate to meet up with Gary L. We bumped into each other while I was ordering my martini after lunch and found out that we shared a similar transition from one career to another involving more physics.  Gary was (is) an MD, who is starting a second career in physics.  We found we had travelled down similar paths of struggling to learn and understand a lot of new physics and required mathematics.  While I am still struggling, Gary has successfully earned a data analyst position with the LIGO team, which hopes to make the first detection of gravity waves from distant merging black holes, neutron stars or supernovae.  Wow, way to go Gary!  Likewise, each of us has our own unique history and journey in our continuing development of our interest in astronomy.

 Secondly, remember, several months back, I asked where you were going to be during the total solar eclipse of August 21, 2017?  Well the new question this time is "where will you seven years from now, when it is been predicted that two large black holes will collide and merge together?  I guess the first part of the answer is "I don't want know where I'll be exactly, but hopefully a long way away from the merging black holes."  Anyway, this announcement at the meeting that observational capability has come far enough to measure orbiting binary black holes is quite new and it caught my interest.  The observed object, understood to be two black holes in a deadly in spiral and eventual collision, was spotted by the Panstarrs telescope observatory in Hawaii and published to the world in March 6, 2015, as PSO J334.2048+01.4075 (J2000).

(Oh, oh, I hope nobody asks what the nomenclature means because I haven't yet figured out how to decipher it myself).  I'm glad the presenter explained that the merger was predicted to be in 7 years, because when I try to read and understand the original publication, I still have a difficult time reading my way all the way through to where I can even see how the merger is mentioned.  If you care to try this for yourself, the original publication can be found on the archive website: http://arxiv.org/pdf/1503.02083.pdf

But now it's time to get back to our current reality.  When I flew back to the observatory, the 2X Barlow lens ordered to solve the camera focus problem with the hydrogen alpha telescope, had been received by Peggy and Danny,  so my first imaging job was to see if it would work or not.  The 2X Barlow lens normally provides two times image enlargement by changing the effective focal length of the other lenses in the telescope.  My hope and assumption was that the Barlow would give just enough increase in focal length so that the whole system could be focused.  Hooray, when I put the whole system together and looked in the camera LCD screen, I could achieve for the first time a good focus with the hydrogen alpha system.

The first image is shown below.  I was so excited about finally getting the system to focus that I forgot to do any review of the camera images with different exposure settings, etc.  So it was only after I had brought the scope back inside and downloading the images to Photoshop, did I find that not all was right.  Yes, the focus was better, but there now seemed to be some overexposure.  The histogram of the image showed unsaturated levels for the green and blue pixels, but some of the red pixels were saturated.  This was going to be a problem.  First, remember that the hydrogen alpha filter only lets through a very narrow wavelength of red light.  Why were the camera green and blue pixels lighting up as well as the red pixels?  Well, the camera color filters are not as sharp wavelength cutoff as the hydrogen alpha filter, so they will receive some light even though all of the incoming light was red, not blue or green.  This is why I didn't notice, I was overexposing the red.  The histogram looked fine based on the other colors and I didn't notice the red was overexposed.  So what to do?  Next time I need to shorten the exposure so as not to saturate reds, even when the other colors look fine.  In the meantime, I just tried to minimize the effects of overexposure and used Photoshop to tweak up the image.

The good news is at least now that the focus problem has finally been solved, fixing the exposure problem is going to be easy.  After all notice how some sunspots are visible in the current image.  Next time, I will also try adjusting the filter bandwidth to bring the solar prominences and other features into view too.  As a bonus the 2X Barlow, makes the photo image twice as large.


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