We have discussed taking long exposure images of dim extended objects during previous blog posts using non-tracking mounts. This time we want to describe the addition of a piggyback adapter to mount a wide-angle camera on the tracking telescope. This post will also describe some email feedback from our Julian visit and review some new books covering physics, gravitation and philosophy of science.
We should first look at upcoming astronomy events like the American Astronomical Society 231st annual meeting held in Washington, DC on January 7-12, 2018. This year I notice that they offer a special discount for amateur astronomers so the conference fee is only $50, instead of the price I used to pay like over $600. I also signed up for the tutorial on Bayesian modeling of cosmic population. Umm good! The meeting is now really affordable, but, of course you still have to get to DC and get a hotel room. I so appreciated the discount that I had to pay it forward and chose to donate $100 to the AAS student travel fund so that other grad students and post docs could travel and attend the conference. Anyway, hope to see you there! Oh, and by the way, my donation was for real grad students, so none of our local gravity study group need apply, even though some of you technically could be listed as "senior" grad students or post docs!
In previous attempts at imaging dim extended objects, we could see the need for a tracking mount to reduce star trails and at the same time the need for wider angle views than are normally available with a telescope due to the large size of the extended objects. This is where the benefits of the piggyback mounted camera stand out. Check out the final assembly of the camera and piggyback mount below.
The photo shows the 80mm refractor telescope with red dot finder mounted on the left side and the wide angle camera mounted on the piggyback adapter. The adapter consists of the additional clam shell ring installed around the telescope tube and the TeleVue camera adapter mounted on the ring. A second mounting position on the clam shell is also available for another accessory, such as a guide camera. The whole setup was easy to install, once the correct tools and lengths of bolts and washers were found. First of all the clam shell rings use metric cap screws and a 4mm hex head wrench is necessary to install the ring. Then the TeleVue adapter mounts on the ring with two 1/4-20 thread cap screws, which required 3/16 inch hex (Allen) wrench. I had some spare 1/2 inch cap screws and as these were just a bit too long, I had to find a couple of 1/4 inch washers to take up the slack.
My only worry now is if something vibrates loose during transit and if I have to assemble the system in the field in the dark and remember to bring all of the required tools.
|Added piggyback adapter for tracking wide-angle, long exposure images (Source: Palmia Observatory)|
This side view shows more clearly the washer kludge setup needed to allow clearance between the v-rail and the 2nd clam shell. The cap screws used here are 1/4-20 and 3/4 inch long. This kludge worries me a bit in that it is a source of additional misalignment between the scope optical axis and the right ascension motor drive axis.
|Side view of piggyback adapter washer kludge to allow 2nd clam shell and v-rail clearance (Source: Palmia Observatory)|
We received an interesting email from the two gentlemen, now identified as Julianites, Dale and Dennis, we met in the Julian Café during our recent observing trip there as described in the blog posting of November 2, 2017. Check out that visit on the main page of the blog and how I was intrigued by their copy of the book, "The Day we found the Universe", by Marcia Bartusiak. I now have that book which describes the early interaction between Hubble and Einstein and the Mt. Wilson observations and final recognition that the universe is expanding.
Anyway, Julianite, Dale asked questions about an article by Caleb Scharf dealing with the 63 orders of magnitude of size between the largest structures in the universe and the smallest structures in physics based on the Planck length. Well, I had not heard of Caleb before, but, wow, am I really appreciated the recommendation. He is a well respected astrobiologist at Columbia U and has several published books (which I will probably pick up very shortly) and various YouTube lectures. Two that I saw and enjoyed are referenced below. The first one deals with the feedback effects from galactic black holes and how that feedback limits and constrains the star formation rate in the galaxy and thereby the size of the galaxy itself. Pretty neat stuff! Thank you for that recommendation, Dale and Dennis!
|Feedback from black holes constrain size of galaxies (Source: https://www.youtube.com/watch?v=yueTFyH0pLw#action=share)|
Finally for all of our physicist wannabe readers we should report on some new 2017 editions of classic textbooks. As you might know from your own studies of general relativity, a good background, often more than many of us got in our undergraduate years, in classical field theory and Lagrangian mechanics, etc., in order to make sense of the more advanced topics. This 2017 edition, although I think the earlier edition was maybe only available on the internet, has all of these important topics covered in much more detail than in the first of our introductory university physics texts. Of special interest to me, other than a handy reference containing other topics, was the last chapters, 24-28, which covered the transition from special relativity to general relativity and gravitational waves and cosmology. It is hard to find a better text or for that matter a less expensive text, on a per page basis, than this text, which goes for 7.65 cents per page on Amazon.
|At 1552 pages and 7.3 lbs. this 2017 excellent text has multiple chapters on gravitational waves|
It seems that Kip Thorne has not been busy enough, what with writing a book for the Interstellar movie and also winning the Nobel prize, and still has time to update his classic gravity textbook. That classic textbook on gravity (Gravitation, by Misner, Thorne and Wheeler) has been released as a 2017 edition. I guess now that Kip Thorne has won the Nobel prize it is time for a new edition. I remember buying the first 1972 edition back in about 1975 from B. Dalton Booksellers at the Montclair Mall. The booksellers are gone for sure and I don't know if the mall is there anymore or not.
I still have my original copy, now over 40 years old, and I'm still trying to understand the subject. I found the text very difficult and much of the discussion assumed that I could work out some of the details myself. Wrong! I needed a little more handholding and examples than the Caltech students who first used this textbook. I don't think I'll get the new released version which, just like the first edition, weighs in at 6.2 lbs. and 1336 pages, because I'm still working on the original edition. I find that after all of my study, I finally can go back and read and understand some of the chapters in this classic text. My other general relativity texts in include those by Weinberg and Carroll, and easier texts by Collier and Moore, but I suppose my favorites, mostly because I find them a little bit easier to understand, are those by Schutz and the great gravity book by Hartle.
|This classic Gravity textbook, first out in 1972, is now available in this 2017 edition|
Well, since we have been discussion great physics books, and while we wait to try our new piggyback adapter on the 80 mm telescope for some tracked long exposure imaging, we should make a few comments regarding some cosmology books that go way beyond cosmology, as a science, and consider how what we are learning about cosmology comes right back and leads to changes in how we think of ourselves as humans in this universe.
In the November 2, 2017 blog post, I mentioned how after hearing Professor Joel Primack, UCSC, who is a world class particle physicist and cosmologist, speak at on the topic of "The Galaxy-Halo Connection", at the UCI physics colloquia, that I was impressed enough to buy his book, "The View from the Center of the Universe." Well it turns out he has another interesting cosmology book out, again coauthored with his wife, Nancy Ellen Abrams.
Abrams in this other book, "A God that could be Real", presents an interesting, even if philosophical argument, regarding the nature of God, where there is little agreement, even among the various sets of believers, about what characteristics apply and which do not. This is normally not the type of book that I read or comment on, although I do like the philosophy of science and how we come to know anything at all, but given the book's author and philosophical nature I actually enjoyed the first couple of chapters that I had time to read.
Abrams central argument begins with the middle ages where little was known of the cosmos and any contradictions with science did not come up. There was much discussion at that time about the characteristics of God and these discussions consolidated around what we know now are false claims about the universe. The Gods of Greece and Rome and other civilizations were often directly connected to nature, but during the middle ages this connection was severed. She argues that for instance the fight between Galileo and the church authorities resulted in further division between the scientific study of nature and belief. But she goes on to explain that this division was not necessary and that God and nature and scientific study don't have to disagree, and the characteristics that we give up to get agreement with physics, are characteristics that don't matter much when it comes to fostering the relationship with God that most people say they seek.
Abrams says that to our modern minds, physics comes first, and since that is all we can know that is tested and relies on evidence, then God must be consistent with those laws and our beliefs can be understood to be made compatible with what we now know and understand. After all the study of physics and other sciences were evidence is used in support of ideas is the most accurate approach to understanding our nature and many of the ideas that are being rejected about God are just those old erroneous, not needed assumptions and arguments that arose in the middle ages before the advent of the scientific method.
Yes, it seems to make sense that we should replace cosmological ideas formed in the middle ages with scientific concepts of the cosmos that are based on evidence and pass the observational tests now part of the scientific method. It is our choice she says that our understanding of God evolves and expands just as we know the universe expands and changes. Ok, ok, that is a lot of philosophical words, but something like that is the argument in the book. If your astronomical interest also flows into philosophy be sure to check out this book. She sees getting rid of some of the erroneous middle ages thinking as a way go getting more concurrence with out current knowledge of the cosmos without really impacting what folks seek by their search for something greater than themselves.
One of the illustrations taken from Abrams book is this one of the Uroboros, the snake swallowing its own tail. It sums up the unique position that we as humans occupy, almost halfway, in the size dimension between the very large and the very small. Modern physics talks about 63 orders of magnitude between the very large and the very small, associated with the Plank length. I still think this symbol which shows how we are located about half way between the very small and the very large of what is currently available, is pretty interesting in that we are pretty well situated to investigate the large and the small. At the same time, there is still plenty of mystery in the universe in that over 95% of the energy density of the currently known universe is made of some unknown stuff. Pretty neat, we will have to keep an open mind and keep studying!
|Humans are located about half way between the very small and the very large (Source: Nancy Ellen Abrams)|
Until next time,