Tag Archives: Solar Spectroscopy

Remembering The Godfather Of Solar Astronomy, Robert “Barlow Bob” Godfrey

Posted on June 20, 2014 6:31 pm - - 6 Comments

The field of amateur astronomy hosts many different personalities. Some love to know anything and everything about astronomy equipment. Some prefer the study of astronomy through the ages. Some enjoy the banter around a large scope with others at midnight. Some enjoy the quiet solitude of a small dome or open field. Still others enjoy setting their equipment up in the middle of the chaos of a large group of people to show them the sights. Some take their love of outreach well past the observing field, taking it upon themselves to educate others by taking what they know (or don’t yet know) and making it accessible to the larger audience of amateurs and non-observers alike.

Amateur astronomy has seen a few key players pass this year, starting with John Dobson this past January and the noted comet hunter Bill Bradfield just a week ago. Both are noteworthy in their passing in that, amongst a large, large number of astro-hobbyists, their names are held in higher esteem because of their unique contributions to amateur astronomy. In the case of Bill Bradfield, he singly was responsible for finding 18 comets that bear his name, making him responsible for helping map part of the contents of our own Solar System from his home in Australia (reportedly taking 3500 hours to do so). In the case of John Dobson, he not only synthesized many great ideas in scope building with his own to produce the class of telescope that bears his name, but he also made it part of his life’s work to bring the distant heavens to anyone and everyone through his founding of what we call today “sidewalk astronomy.”

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Barlow Bob at the center of the 2014 NEAF Solar Star Party. Click for a larger view.

The CNY amateur astronomy community learned of the passing of Barlow Bob on June 13th through an email from Chuck Higgins of MVAS. I suspect most people in the community didn’t even know his real name was Robert Godfrey until the announcement of his passing. The announcement of his passing had much farther to go, as the list of people and clubs that Barlow Bob had made better through his own outreach is as large as his many contributions to solar astronomy. For the record, below is a snippet of his contributions to the CNY astronomy community generally and to me specifically.

The Postman And Telephone Operator of Northeast Astronomy

I have a decent handle on all of the astronomy clubs in the Northeast thanks to Barlow Bob’s habit of forwarding newsletters and email announcements around to his email list. Those who’ve not edited a club newsletter do not know how much this simple gesture was appreciated! In my 2008 reboot of the Syracuse Astronomical Society newsletter the Astronomical Chronicle, the biggest problem facing its monthly continuation was new content. Not only did Barlow Bob provide a steady stream of articles for “Barlow Bob’s Corner,” but I learned about several free sources of space science news from these other newsletters (the NASA News Feed and the NASA Space Place being chief among them – still sources of news and updates freely available to all). He saved myself, and the SAS, several months of organizing content and finding relevant material. Those newsletters remain available in PDF format on the SAS website, many peppered with varied hot topics in solar astronomy that Barlow Bob chose to write about for “Barlow Bob’s Corner.”

As part of his aggregative exploits, amateur astronomers in his email loop were also treated to a yearly events calendar of nearly all of the East Coast star parties and special events. His and Chuck Higgins’ 2014 Events Calendar makes up the majority of the non-celestial phenomena listed in CNYO’s current calendar.

I also had the pleasure of being one of the recipients of his many (many!) phone calls as a regular of his “astro-rounds” call list, during which I learned early on to have a pen and paper ready for all of the companies to check out and solar projects to search for. Barlow Bob loved being on the edge of solar observing technology, both in pure observational astronomy and in solar spectroscopy (his Solar Spectroscopy History article is among the most concise stories of the history of the field). A number of his voice messages lasted little more than 15 seconds, but provided enough detail for a requisite google search and email exchange after.

“You keep writing them, I’ll keep publishing them.”

Barlow Bob was, by all metrics, a prolific writer on the topic of solar astronomy. My Barlow Bob CD contains at least 50 full articles along with pictures, equipment reviews, and society newsletters including his articles. Barlow Bob took great pleasure equally in his own understanding some aspect of solar astronomy and his committing that understanding to keyboard and computer screen for others. While many amateur astronomers delight in knowing something well enough to be able to talk about it with authority, precious few in the community actually take the next step and distill all they know into something others far beyond their immediate sphere can appreciate. Even those who’ve never been to NEAF likely knew of Barlow Bob through his writings. Along with his founding of the NEAF Solar Star Party, his many articles will serve as his lasting contribution to the field. We will continue to include Barlow Bob’s articles on the CNYO website and we hope that other societies will consider doing the same. Some of those articles are available on his dedicated webpage at NEAF Solar, http://www.neafsolar.com/barlowbob.html.

The Bob-o-Scope Comes To Syracuse

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Barlow Bob and “the works” at Darling Hill Observatory. Click for a larger view.

While Syracuse only managed to have one solar session hosted by Barlow Bob, that one session provided a number of lasting memories. After a few months of planning around available weekends and Barlow Bob’s own vacation schedule, we finally settled on the early afternoon of 30 July 2011 for a solar session (with a lecture by CNY’s own Bob Piekiel to follow that evening, making for one of the better amateur astronomy weekends in Syracuse) at Darling Hill Observatory, home of the Syracuse Astronomical Society.

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Very likely him at Darling Hill Observatory. Click for a larger view.

Our initial plan was for an 11 a.m. set-up and a noon to 3-ish observing session. Saturday morning started a bit earlier than I expected with a phone call at 9:30 a.m. – Barlow Bob, ever ready to be out and about on a clear day, was outside the locked front gate of Darling Hill Observatory. A frantic prep and drive out later, Barlow Bob and I set up and placed his many scopes on the observing grounds to the delight of about 30 attendees. I myself took one look through the Bob-o-Scope and began calling people, telling them “you have to come and see this.” A full day of observing in, Barlow Bob didn’t end up leaving Darling Hill until just before 5 p.m. The hour we took to leisurely pack his station wagon with all of his gear was full of shop talk, people and equipment to be made aware of, and plans on a similar event at some point in the future. That hang and the view through his Bob-o-Scope are two of my favorite memories during my tenure as SAS president.

Barlow Bob and a spectroscopy mini-lecture at Darling Hill Observatory, 30 July 2011.

The Sun, being the excellent, usually accessible target that it is, is ideal for hosting impromptu observing sessions at most any location. Members of CNYO now do as a small group (and with cheaper equipment) what Barlow Bob would do single-handedly – set up and observe “with attitude.”

Not Just NEAF

Barlow Bob is known to many in the community as the founder of the NEAF Solar Star Party and as the author of articles for “Barlow Bob’s Corner.” To those of us with a bent towards public outreach, Barlow Bob is an example of someone who could take some fancy equipment and his own know-how and run a one-host show. Barlow Bob committed a great deal of his own time and talent to doing for our nearest star what those like John Dobson did for far more distant objects. Despite the many, many amateur astronomers in the world today, it’s still a field where a single person can have a strong influence simply by being a perfectly-polished primary mirror that reflects their own love of the field for others to appreciate. Amateur astronomy outreach can learn a lot from Barlow Bob’s example and CNYO will continue in his footsteps of making safe, variously-filtered solar sights available to the public as part of our observing efforts. May we all become a bit more familiar with our nearest star, following in Barlow Bob’s footsteps to observe it “with attitude.”

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“It’s like looking in a mirror!” Barlow Bob and I at Kopernik’s 2013 Astrofest.

* Announcement of his passing on Cloudy Nights: cloudynights.com/ubbthreads/showflat.php/Cat/0/Number/6581115/Main/6578514

* David Eicher’s announcement at astronomy.com: cs.astronomy.com/asy/b/daves-universe/archive/2014/06/16/solar-astronomy-guru-quot-barlow-bob-quot-dies.aspx

* A memorial webpage at forevermissed.com: http://www.forevermissed.com/robert-a-godfrey/

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Barlow Bob’s Corner – The Solar Spectroscopy Project

Posted on September 26, 2013 8:58 pm - - Leave a Comment

The following article has been provided by Barlow Bob, founder & organizer of the NEAF Solar Star Party and regional event host & lecturer on all things involving solar spectroscopy. You can read more about Barlow Bob and see some of his other articles at www.neafsolar.com/barlowbob.html.

Most solar amateur astronomers observe sunspots on the surface of the Sun through a white light (Baader) solar filter. Some also observe prominences and other features above the surface of the Sun through a Hydrogen-Alpha solar filter. If you are an amateur solar astronomer who shares your safe solar telescope at educational outreach events, please consider including solar spectroscopy at these events.

You do not have to make an expensive investment to purchase a solar spectroscope or spectrometer. Science First (www.sciencefirst.com) and Edmund Scientific (www.scientificsonline.com) both sell several inexpensive types of low-resolution spectroscopes and spectrometers for under $40.00.

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The very affordable Quantitative Spectroscope from Science First.

A spectroscope is an instrument for producing and examining spectra, producing spectra of visual electromagnetic radiation (visible spectra). A spectrometer is an instrument for dispersing electromagnetic radiation and analyzing the location of the spectrum lines. A spectrograph is an instrument for dispersing electromagnetic radiation and recording the spectrum.

These spectroscopy products are all easy to use. Laminate an 8.5-by-11 inch sheet of white paper and place this laminated sheet on a table next to your solar telescope. Point the spectroscope down at the sheet of paper. Sunlight reflected off of the laminated sheet enters the front of the spectroscope to the grating or prism. You then can observe the dark Fraunhofer lines of the solar absorption spectrum. These are thin, vertical dark lines in the horizontal colors from red to violet.

Turn a cardboard carton on its side and put it on a table next to your solar telescope. Place a lighted camp lantern with florescent bulbs inside the carton. You can see the lighted lantern better in bright sunlight. Observe the emission spectra of the element mercury inside of the florescent bulb. You can use this demonstration to explain how astronomers discovered what the dark Fraunhofer lines were in the solar spectrum.

You can allow people to observe the dark absorption lines of the solar spectrum through a spectroscope. They can compare these dark absorption lines to the bright emission lines of the florescent light bulb.

The gas in the interior of a star like the Sun is under high pressure. The gas in the outer atmosphere of the Sun is under lower pressure. A photon (a piece of light) moves from the interior to the surface of the Sun and passes through the outer atmosphere. When it passes through the outer layer of the Sun, this outer layer absorbs the wavelengths of the specific elements in this outer layer while the remaining light passes through. The spectra of the elements in the outer layer appear as dark vertical lines in the spectroscope as those photons were absorbed by those elements in the Sun’s atmosphere.

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The solar spectrum (Fraunhofer lines and all).

In 1802, William Hyde Wollaston (1766 – 1828), an English Chemist and Physicist, discovered the spectrum of sunlight is crossed by a number of dark lines. This was the birth of solar spectroscopy.

In 1814, Joseph Von Fraunhofer (1787 – 1826), a German glass maker, rediscovered the dark lines in the solar spectrum noted by William Hyde Wollaston and determined their position with improved precision. He made careful measurements of over 500 dark lines in the Sun’s spectrum. He never tried to find out what the lines were or where they came from. Today we honor his careful benchmark investigations by referring to the dark absorption lines of this type as Fraunhofer lines.

Fraunhofer needed a way to measure small differences in the composition of his glass from one melt to another. When white light comes into the prism, the different wavelengths are bent through different angles, resulting in a spread of colors. Prisms made of slightly different pieces of glass will bend the same wavelength of light through different angles. He therefore needed some sort of calibration standard. He used a series of dark bands superimposed at regular intervals over the colored spectrum of light to solve his calibration problem. However he had no idea what these lines were.

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An idealized prism in action.

In 1959 Germans Gustav Robert Kirchoff (1824 – 87), a physicist, and Robert Bunsen (1811 – 99), a chemist, observed the bright emission spectrum lines of different heated elements through a prism spectrometer. They discovered that dark Fraunhofer lines appeared when they observed the light from a fire in their city through smoke. When they compared the dark absorption spectra lines to the bright emission spectra lines in their laboratory, they realized that they discovered that they now had a way to analyze the chemical elements by observing the dark Fraunhofer absorption lines. This was the start of astrophysics to analyze stars.

Kirchoff studied light spectra using the spectrometer he developed with Bunsen. He observed that individual atoms and molecules emit certain colors when heated. Kirchoff realized that each element produces a distinct spectrum of colored emission lines that can be used to identify the element.

Kirchoff and Bunsen observed the light from a distant fire through their spectrometer. They observed dark Fraunhofer absorption lines of light from the fire as its light passed through smoke. They noticed that these dark absorption lines appeared in the same location as the bright emission lines of elements they observed in their laboratory.

In 1861, Bunsen and Kirchoff performed experiments leading to the conclusion that the dark lines in the solar spectrum, observed by Wollaston and Fraunhofer, arise due to the absorption of light by gases in the solar atmosphere that are cooler than those emitting the light.

In 1872, Henry Draper, a wealthy American physician and amateur astronomer, was the first person to photograph the Fraunhofer absorption spectrum of a star using a prism spectrograph. This introduced the world to a powerful tool for probing the physical properties of stars. For the first time, the Henry Draper (HD) Catalogue of spectral data was available as an astronomy research resource.

When Henry Draper died in 1882, his widow Anna Parker Draper funded the HD catalogue. Edward C. Pickering, the Harvard College Observatory director, continued creating Henry Draper’s catalogue. Hired women, called computers back in the day at Harvard College, examined the spectra of thousands of stars in these photographic plates. They noticed that the series of dark Fraunhofer lines of red stars had a similar pattern. Other star colors each had similar dark line patterns. These women created the OBAFGKM system to organize this catalogue of star spectra. These computers worked seven-hour days for six days a week and were paid 25 cents per hour. For these women, the opportunity to contribute to science was more important than the salary. By the middle of the 20th century, Henry Draper’s namesake catalogue would contain position and spectral information for nearly a quarter of a million stars.

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Pickering and the Harvard computers. From wikipedia.

Spectroscopy is still used today. Astronomers use spectroscopy today to analyze the fingerprints of stars and other celestial objects. Manufacturers of food, drug and chemical products use spectroscopy to analyze the quality of their products. Government agencies including the FBI, FDA and OSHA also use spectroscopy for analysis.

You can allow people to observe the dark absorption Fraunhofer lines of the solar spectrum through the spectroscope, then allow them to observe the bright emission lines of elements in the florescent light bulb in the camp lantern. These two observations can be used to explain how astronomers use spectroscopy to analyze starlight.

You do not have to wait until sunrise to do solar spectroscopy. You can observe the solar spectrum reflected off of the Full Moon at midnight. You can recreate how Fraunhofer, Kirchoff and Bunsen discovered absorption and emission spectra for kids of all ages – and this could be someone’s excellent science fair project.

© 2013 Barlow Bob

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