Solar Observing

2 05 2015
Believe it or not, on cold days, I can observe the sun through my living room window.

The solar filter covers the business end of the optical tube. Small bit of foam attached to the inside of the aluminum casing guarantee a snug fit. Photo: JR


Before my last trip to India, I wasn’t much interested in solar observing. I enjoyed observing the Transit of Venus, considered getting a white-light solar filter my scope or investing in an h-alpha system, but never got around to doing either one. But being immersed in the history and ephemera of astrophysics and solar science at the Indian Institute of Astrophysics shifted something inside me. One of the first things I did after I returned to the U.S. was order an inexpensive filter for my small scope (130-mm reflector). I briefly considered ordering mylar sheets and building my own, but decided that I didn’t feel crafty enough to get the job done. I’m happy about that decision — the aluminum outer cell on my ready-made filter is much better (sturdier) than anything I could’ve put together myself.

It should go without saying, but never look through your telescope without a properly installed filter. The first thing I do when I go out, even before putting the optical tube on the tripod, is mount the solar filter. And I’ve made it a habit to double check the filter fit before I take my first look through an eyepiece in solar sessions.

Here, the optical tube is casting a nice, circular shadow. This tells me that my scope is lined up well with the Sun.

Here, the optical tube and spotting tool are casting nice, circular shadows. This tells me that my scope is lined up well with the Sun. Photo: JR

I was pretty excited to get out there the day the filter arrived, but spent the first ten minutes in frustration. You’d think that it would be super easy to spot the Sun in a telescope. It’s a huge star, how hard could be it be? The answer to that question is: pretty hard. Don’t waste time chasing around the sky looking for the Sun. Look for its shadow instead. Use your controller or your hands to line your scope up with the Sun in such a way that it casts a perfect circle shadow. The sharper the circle, the closer the Sun will to the center of your field of view.

I eventually attached a spotting tool to my optical tube with velcro. It’s kind of handy, and helps me double-check my shadow circle. Now that it’s aligned properly (it came with alignment tools), I can just glance at it to check my alignment. Because looking at my shadow takes too much work, apparently.

The other thing that’s a must for starting your solar session is an eyepiece with a wide field of view and low magnification — the widest and lowest you’ve got. When you look at the sky through a solar filter, all you see is black. The Sun isn’t surrounded with a blazing light, so you can’t just scan until you see a glow (thus, initial alignment matters). It really helps to start with a wide field of view, just in case your alignment is a bit off. You can catch a corner of the Sun and move your scope gently to center it (and then adjust your spotting tool for next time).

I start out using a 32-mm plössl with a 52° apparent field of view (2.6° true field of view). This gives me a nice black field with a yellow orb near the center. Once I have the Sun completely centered, I work my way up through my eyepieces. I find with a 130-mm reflector, the best view of sunspots comes when I finally reach my 8-mm plössl (52° APOV,  1.2° TFOV). But I usually spend time with the 13-mm and 9-mm eyepieces as well.

The front circle of the Sol Search casts a shadow on the back. When my telescope is properly aligned with the Sun, the bright light dot (the Sun shining through a hold in the front panel) will be centered on the white circle on the back panel.

The front panel of the Sol Search casts a shadow on the back. When my telescope is aligned with the Sun, the bright dot (the Sun shining through a hole in the front panel) is centered on the white circle on the back panel. Photo: JR

I can’t tell you what the best filter solution is for you, since it depends on what you want to see. My white-light system works well for me because I’m most interested in sunspots right now. But if you’re after limb activity and flares, you’re going to have to cough up some serious money for an h-alpha set up. At any rate, follow the manufacturer’s instructions for installing your filter/setting up your scope, lest you blind yourself. Don’t ever use a filter that goes on an eyepiece instead of the end of the optical tube. The tube filter prevents heat buildup — who knows what all that direct sunlight is doing to an eyepiece filter?

Even though most of the Sun is screened from your scope, setting up in full sunlight can lead to a miserable day. If you can find a partly shaded spot, you’ll thank yourself later. I also throw a dark shirt over my head to block the daylight from the eyepiece. Yeah, I look silly (I observe next to my house, which is next to a parking lot for a very busy convenience store, and you know everyone is talking about the idiot with a shirt over her head), but it really improves the view. Hooded observing shirts are available commercially, but they’re generally designed for cooler temperatures, not the bright of day.

If you get serious about observing sunspots, you should consider keeping an observing log. You can write down as much or as little detail as you want. I like to record my eyepieces and the number of sunspots I see.

Consider keeping an observing log. You can write down as much or as little detail as you want. I like to record my eyepieces and the number of sunspots I see. I find that just a few notes help me remember the session. Photo: JR

If you get serious about observing sunspots, consider joining the Astronomical League’s Sun Spotter’s Program. The AL is a beginner friendly organization, and with its guidance, you’ll soon be recording sunspots like a pro. If you’re more interested in prominences, flares, and other limb activity, check out the Astronomical League’s Hydrogen Alpha Solar Observing Program. Either way, feel free to contact me if you have any questions about getting started in solar observing.

Building the Moon

25 11 2014
Black and white photo of jagged landscape features

Unidentified, possibly an early model of supposed lunar surface, c. 1900-25. Image courtesy: State Library of Victoria

I discovered this intriguing photograph while doing an image search for work. According to the catalogue entry at the State Library of Victoria, this may an imagined view of the Moon’s surface. Believable, with those craters and craggy mountains. But for what purpose? The image comes from a lantern slide, making me think that it’s likely a photograph of a stage or movie set. Does anyone recognize the scene?

New England Fall Astronomy Festival

1 10 2014
NH Observatory Manager Ian Cohen safely shows a young observer the Sun through the Observatory’s main telescope, a 14-inch reflector. Credit: Loni Anderson/NEFAF

NH Observatory Manager Ian Cohen safely shows a young observer the Sun through the Observatory’s main telescope, a 14-inch reflector. Credit: Loni Anderson/NEFAF

Here’s hoping clear skies will come our way this month. First, there’s the total lunar eclipse to watch in the early a.m. hours of October 8 (evening hours of October 8 if you’re reading this from Australia). That’s super exciting, so it’s probably destined to coincide with cloudy weather.

But I’m also looking forward to the New England Fall Astronomy Festival later this month. Events will take place on the west end of the University of New Hampshire Campus (Durham) at the UNH Observatory. The weekend kicks off on Friday, October 17, with a 6 p.m. lecture by Carolyn Porco, Imaging Science Team Leader for the Cassini-Huygens Mission to Saturn. After the lecture and a Q&A session, clear skies will bring a chance to look through some great telescopes and listen to some star talks. The festival continues on Saturday (10 a.m. to midnight), with more observing sessions, activities for the kids (model rockets rumored!), talks, and clinics. I admit I’m pretty excited by the idea of a weather balloon launch.

Here’s a write up about a previous year’s NEFAF, in case you’re wondering what an “astronomy festival” looks like. Full disclosure: John Gianforte and I work together at S&T. Therefore, I know that it’s going to be a top-notch event.

Hope to see you there!

Wallpaper Wednesday: SDO and Sunspots

16 07 2014
"Sweeping Arches and Loops", solar magnetic activity viewed in the ultraviolet, June 30, 2014.

“Sweeping Arches and Loops”, solar magnetic activity viewed in the ultraviolet, June 30, 2014.

Looking at some of the photos returned by NASA’s Solar Dynamics Observatory (SDO), you’d think contemporary solar observing had little in common with what was being done at Kodaikanal c. 1900-1910. But in addition to the dramatic images of solar loops like the one shown above, SDO also sends back sunspot records that closely resemble the photos and charts produced by C. Michie Smith, John Evershed, and company.

"Spots Galore," July 8, 2014. Image credit: Solar Dynamics Observatory/NASA

“Spots Galore,” July 8, 2014. Image credit: Solar Dynamics Observatory/NASA

According to SDO/NASA:

“The Sun sported a whole slew of substantial sunspots over the past 11 days (July 1-10, 2014). This movie and still show the Sun in filtered white light speckled with more and larger sunspots than we have seen in quite some time. Sunspots are darker, cooler regions on the Sun created by intense magnetic fields poking through the surface. The Sun may have passed its peak level of activity, but it will still be producing many more sunspots and solar storms during the rest of this solar cycle. The still image was taken on July 8 at 22:24 UT.”

Looks familiar!

Visit the NASA/SDO gallery to see more images of solar activity. Like the two above images, most are stills excerpted from videos. Click through each image to reach the links to .mov and .mp4 files.

Sunspots, 1903

14 07 2014
paper disc with handwritten notations of sunspots

Sunspot observation record, April 30-May 1, 1903. Image courtesy of Indian Institute of Astrophysics/JR

I was fortunate enough to spend some time studying the historic instruments and library collection at Kodaikanal Observatory in Tamil Nadu this past week. Run by the Indian Institute of Astrophysics, the observatory was founded in 1899 to facilitate solar observing. In 1907, John Evershed arrived on the scene to (quite famously) bring his “auto-collimating spectroheliograph” online. You can imagine my excitement when Mr. Selvendran, Senior In-Charge at KO, opened the door to the spectroheliograph room and slid open the shed roof to expose the instrument’s mirror. So cool.

But I’m getting ahead of myself. I spent my first day poking around KO’s fascinating library. Journals, books, catalogues, and ephemera stacked literally from floor to ceiling. So much stuff that I scarcely knew where to begin. But when I saw a stack of paper circles tucked into a corner shelf, I knew how I would spend the afternoon. I had only just read about these circles in one of C. Michie Smith’s (KO’s first director) annual reports.

Excerpt from Kodaikanal and Madras Observatories report for the year 1904.

Excerpt from Kodaikanal and Madras Observatories report for the year 1904.

Each of these 8-inch paper discs contains a record of 3-7 days of sunspot observations. Each spot was marked in pencil and assigned a letter (A, B, etc.). Every day, the observer recorded the new position and appearance of the lettered spots as they traversed the solar “surface”, i.e., the photosphere. For instance, in the following plates, sunspots A and B are shown moving from NNE to W between March 18 and 29, 1903.

Sunspot Observations, March 18-29, 1903. Image courtesy Indian Institute of Astrophysics.

Sunspot Observations, March 18-29, 1903. Image courtesy Indian Institute of Astrophysics/JR.

Sunspot Observations, March 18-29, 1903, detail. Image courtesy Indian Institute of Astrophysics.

Sunspot Observations, March 18-29, 1903, detail. Image courtesy Indian Institute of Astrophysics/JR.

The next image shows that those same spots continued westward between March 30 and April 2, 1903, breaking up as they went. You can also see a second line of spots traveling roughly parallel to the solar equator. They started out as indistinct patches at the eastern edge of the disc on the March 27-28. The March 30-April 2 disc shows how long it took for them to move half way across the Sun.


Sunspot Observations, March 30-April 2, 1903. Image courtesy Indian Institute of Astrophysics/JR.

According to C. Michie Smith, observers hand-recorded sunspots on 343 out of 365 days in 1904. What dedication, and this at a time when they didn’t really know what sunspots were. Observers just put in the hours and trusted that their efforts would one day lead to enlightenment.

On Learning (and Un-Learning) the History of Astronomy

4 07 2014
Black and White drawing of Comet Biela soon after it broke into two pieces.

Comet Biela, February 1846. From E. Weiß: “Bilderatlas der Sternenwelt”, 1888.

One of the challenges of working on the history of science is that I’m constantly having to forget things that I only just memorized or figured out. This need to learn/un-learn has been particularly acute since my arrival in Bangalore. I’ve been buried in the ephemera of the founding days of astrophysics—correspondence, observational data, eclipse photographs, equipment—and on Wednesday, I’ll be going up to Kodaikanal Observatory to study the historical instruments in situ. I’ve spent a lot of time puzzling through C. Michie Smith’s thoughts on the D line in the solar spectrum, and reading along as John Evershed’s thoughts on sunspots evolved over the course of a few decades.

It’s fascinating, watching a scientific argument grow, falter, and grow again.

The Indian Institute pf Astrophysics has a small collection of Evershed’s letters to and from William Huggins, F.R.S. Although friendly, the two men (and presumably Margaret Huggins and Mary Evershed, who remain in the background as “wives” even though they had a great deal to do with the science successes of both men) were quite cagey in their correspondence. They shared data and floated ideas without ever committing to a particular theory or revealing everything they knew. Reading the letters against their published papers shows that both astronomers left out more than than they included in their personal discussions; Evershed saw Huggins as a competitor as much as a mentor and friend.

Interesting stuff. But what I’ve really had to focus on this past couple of weeks, as I dig more deeply into the history of solar physics, is the art of comprehension without retention. That is, I need to understand Evershed’s early theories, but also need to forget about them as they were eventually proved incorrect. For example, yesterday I found myself drawing a line through my notes on Hervé Faye’s claim that the sunspots were caused by an upflow of material too hot to radiate properly, just to remind myself that later Evershed demonstrated that the upflow was cooler than the surrounding area. Sometimes I can see a problem with a theory based on my own knowledge; sometimes I have to wait until I’ve read three more Monthly Notices of the Royal Astronomical Society before I realize I need to forget a few more things.

The first article I picked up this morning started this cycle up again.

I’ve been looking at Norman Pogson’s original observation logs and comparing them with his published papers and catalogues. This morning, I found an interesting notice of his observations of Comet Biela in December 1872 (click  on the image to download the entire notice):

Norman R. Pogson, "Madras Observations of Biela's Comet," Astronomische Nachrichten, Vol. 84, (August 1874), pp. 183 - 186.

Norman R. Pogson, “Madras Observations of Biela’s Comet,” Astronomische Nachrichten, Vol. 84, (August 1874), pp. 183 – 186.

Kind of cool. But a quick Internet search tells me that Comet Biela was last sighted in 1852—fourteen years before Pogson’s viewing. I know Pogson was an under-appreciated astronomer, but is it possible we’ve completely forgotten about his observations?

As it turns out, Pogson’s claim that he had spotted Biela was challenged as early as January 1873. Pogson may have been misled in his identification by another astronomer, Klinkerfues, who told him to search for Biela near Theta Centauri. Or he may have been encouraged to identify the moving object as Biela since it was roughly coincident with what would later be identified as a Bielan meteor shower, created by the comet’s disintegration. However the confusion arose, by 1892, it was accepted fully that Pogson’s comet, now known as X 1872 X1, was not Biela at all, but some other object in motion. Pogson was able to record only two locations for his comet, so it is impossible to determine X 1872 X1’s orbit or period. Today, we may know X 1872 X1 by a second name, or Pogson may have made the comet’s only sighting before it broke up like Biela.

W. H. S. Monck, "Pogson's Comet and the Bielan Meteors," Publications of the Astronomical Society of the Pacific, Vol. 4, No. 21 (1892), p.19.

W. H. S. Monck, “Pogson’s Comet and the Bielan Meteors,” Publications of the Astronomical Society of the Pacific, Vol. 4, No. 21 (1892), p.19.

So, this morning, I learned that Norman Pogson observed Comet Biela from the Madras Observatory in December 1872. Approximately ten minutes later, I began the process of unlearning this bit of information and replacing it with conclusions drawn in the last two decades of the nineteenth century. After lunch, I may need to unlearn those bits as well and absorb instead analyses of X 1872 X made in the twentieth—or even better—twenty-first century.

India Calling

30 05 2014
John Evershed and Assistant, Kodaikanal Solar Observatory. Image courtesy IIA Archives.

John Evershed and Assistant, Kodaikanal Solar Observatory. Image courtesy IIA Archives.

I took my first dose of live typhoid vaccine this morning, so I guess it’s official: I’m on my way back to India for the summer. One of the benefits of the ACLS NFF is the research budget—large enough to cover the cost of two conferences and a trip to India in the same academic year. So, in two weeks, I’ll be rolling into the library at the Indian Institute of Astrophysics in Bangalore to complete “step two” of a new research project. Last summer was “step one,” exploratory research in the Lick Observatory archives at UC-Santa Cruz. No idea what “step three” will look like!

This project is still in its infancy, but I’m looking at the ways in which “new astronomy” (i.e., spectroscopy) affected observatory design at the end of the nineteenth century. More specifically, I’m trying to track the intellectual shift of Indian astronomers away from the UK and toward the US in the era of solar astronomy. It seems that even though Kodaikanal Observatory was constructed in the (British) colonial era, the astronomers were working more closely with Mt Wilson and Lick Observatories than with their British counterparts. Maybe. Possibly. That’s the great thing about research questions: even if I come back with “wrong answer,” I’ll have learned something new.

The Science of the Solar System

28 03 2014
Pluto System, Hubble Space Telescope. Image credit: NASA, ESA, H. Weaver (JPL/APL), A. Stern (SwRI), HST Pluto Companion Search Team

Pluto System, Hubble Space Telescope. Image credit: NASA, ESA, H. Weaver (JPL/APL), A. Stern (SwRI), HST Pluto Companion Search Team

I’m the first to admit I don’t understand the MOOC (Massive Open Online Course) model of education. I can’t figure out how companies like Coursera make money by offering free courses and I can’t see how anyone thinks they MOOCs can replace a four-year university education. I’m an advocate of online education for some courses, in some forms, but not for an entire college education. But no one asked me, and as long as the instructor gets paid and the student gets some intellectual benefit, I have no complaints. I’ve taken one MOOC (on Thomas Jefferson, because hey, UVa), learned a lot, and found it a pretty good use of my spare time.

The preceding paragraph was just a warm-up for the real purpose of this post: to remind you that you’re running out of time to register for Mike Brown‘s free online course, The Science of the Solar System. Judging only from the intro video, it looks like it’s going to be a fun class. I saw Mike give a talk at NEAF last year and enjoyed it. His material was pitched at a good level, assuming his audience had enough knowledge to follow him, but was not made up of astrophysicists.

Plus, he was nice enough to autograph a copy of his book for my wife.

Also coming up is a MOOC on the technology of astronomy (AstroTech: The Science and Technology behind Discovery). I think I’ll be enrolled in this one. My research deals with Early Modern “astrotech” and it might be fun to look at a more contemporary perspective.

David Malin, The Invisible Universe

22 03 2014
David Malin, Dust and Gas Adrift in Orion (UKS 1). Image ©Anglo-Australian Observatory; ©Anglo-Australian Observatory/Royal Observatory, Edinburgh; ©Malin/IAC/RGO; ©Malin/Pasachoff/Caltech

Dust and Gas Adrift in Orion (UKS 1). ©Anglo-Australian Observatory; ©Anglo-Australian Observatory/Royal Observatory, Edinburgh; ©Malin/IAC/RGO; ©Malin/Pasachoff/Caltech

The Invisible Universe, the lovely online exhibition of David Malin’s astrophotography at the Joseph Bellows Gallery, will be available for viewing for at least a couple more weeks. According to the gallery site, it will be viewable through April 2, 2014. This is one exhibition I wish I could view in person—there are few things more stunning than platinum-palladium prints, regardless of the subject.

David Malin was at the Anglo-Australian Observatory (now the Australian Astronomical Observatory, AAO) for twenty-six years as a photographic scientist-astronomer. If you are a fan of astrophotography, you have undoubtedly seen his most popular books, The Invisible Universe (1999) and Ancient Light (Phaidon, 2009).

The AAO owns the copyright for any of Malin’s images that required the use of the observatory’s instruments. David Malin Images manages the copyrights: follow this link for more information about photosales and reproduction rights.

Project Yosemite

3 03 2014

I’ve mentioned Yosemite a few times over the past two years. I have family in California’s Central Valley, and when we visit, it sometimes seems as if the mountains are literally calling to me. Skywatching is amazing up there (if you can get past your fear of being eaten by a cougar) and there is no shortage of photographs and films to prove it. To wit: Project Yosemite recently released a second timelapse, ostensibly documenting a 200+ mile backpacking trip, but really giving us a good view of the park’s changing skies. Their first video, released in 2012, was stunningly beautiful. Yosemite HD II may be even better.

ETA: The air traffic over Yosemite never ceases to amaze me.