Wallpaper Wednesday: NGC 6902

5 06 2019
The spiral galaxy NGC 6902 was discovered in 1836 by John Herschel.
ESO / SPECULOOS Team / E. Jehin

The SPECULOOS Southern Observatory saw first light in December 2017. Located at ESO’s Paranal Observatory in Chile, SPECULOOS is designed to hunt for exoplanets around small, cool stars.

This image of NGC 6902, a galaxy about 120 million light-years from Earth in the direction of Sagittarius, was taken to test one of the four 1-meter telescopes that comprise SPECULOOS.

Visit the ESO site to download high-res versions of this image.

Wallpaper Wednesday: M75

24 04 2019
Globular Cluster Messier 75
Messier 75. Look for it in Sagittarius.
Image credit: ESA/Hubble & NASA, F. Ferraro et al.

Messier 75 is a lot less dazzling through the telescope. Although I can nearly always detect a brightening at the core, it takes more than a 10-inch scope to resolve individual stars (I’m not sure I’ve ever resolved any). Still, M75 is a fun target. It’s a noticeably non-stellar patch of circular fuzz.

Click through the image to download a screen-size .jpg or publication quality .tiffs.

How the Magic Happens

2 01 2019

Celestial Calendar always starts on page 48.

Snapshots of the March 2018 Celestial Calendar.

Have you ever wondered what goes into producing the Celestial Calendar for an issue Sky & Telescope? Conceptually, it’s simple: look at various sources of information, find out what’s going on in the sky in a given month, and write 2–3 pages about it. Easy! But it sure didn’t feel easy when I took over CelCal in 2017.

Actually, I’ve been responsible for several parts of CelCal since 2014. Once a year, I retrieve predictions for the Phenomena of Jupiter’s Moons from IMCCE. Each month, I take the relevant section and format it for the magazine and website. I also run all the Algol predictions as well as the Great Red Spot predictions for the magazine, using proprietary software developed by Roger Sinnott (our online tools were designed mostly by Adrian Ashford).

New to me in 2017 was writing the “Action at Jupiter” section (though it’s an easy task, since I pay a lot of attention to Jupiter anyway). I knock that out in much less than an hour. Being responsible for the Jupiter’s Moons “wigglegram” was also new to me. Roger still produces the wigglegram each month and submits it to our design department. After they are done with it, I proof it and okay it for the magazine.

So, that covers about 1 to 1-1/2 pages of CelCal. I fill the other 3 (sometimes 4, as we don’t run Algol predictions in the summer, and we don’t run Jupiter info when Jupiter is in conjunction with the Sun) with whatever I think best fits the month.

I use both a paper and computer file system for planning. The computer files mostly hold data I’ve collected to create our annual Observing Calendar. I do that work more than a year ahead (for instance, it’s January 2019 as I write this, but I finished the data for the 2020 calendar a month ago), so I always have a lot data on hand, well in advance.

A Word doc I used to plan the 2018 S&T Observing Calendar.

My paper system includes a manila folder each month. I sort the hard copies of anything I used for the Observing Calendar into them: photocopies from the Astronomical Almanac and Sun, Moon and Planets (Meeus), printouts of maps and predictions for lunar and solar eclipses, early comet predictions, hard copies of meteor shower data from IMO, preliminary lists of asteroid/lunar occultations (I use Occult v.4.x to check final predictions), and so on, into the appropriate folders. I print sheets from our in-house planet visibility program. Ditto for meteor showers. Everything is heavily marked up (usually with green highlighter), because by the time I use the pages to write CelCal, I’ve already used them for the Observing Calendar and for SkyWatch.

My CelCal folders. Photo bomb by the S&T Jumbo Pocket Sky Atlas.

I always have Meeus, the Astronomical Almanac, and the RASC Observer’s Handbook on my desk. I keep whatever random almanacs I have close by, too, just in case. I have an extensive library of atlases, reference books, history books, back issues, etc. in my own office, plus I can use whatever book I find in another editor’s office or in our main office bookshelves. I use a few different planetarium programs, such as TheSkyX and Stellarium. It’s hard to list all the websites I use for data. My favorite for checking things like sunrise, sunset, Moon phase, etc., is the USNO site, but of course I use a lot of NASA data (thank you HORIZONS web interface!). I think the main point is: I never trust one answer, no matter how reliable the source. For instance, I’m working the upcoming Pallas opposition right now, and normally I would trust Meeus, but HORIZONS gives me a different opposition date. How to resolve? In this case, I asked two other editors to run the data, and they came up with the same thing I did (agrees with HORIZONS). Then we asked one of our contacts at NASA to double-check our answers.

Although it’s the art department that ultimately decides the layout of each page, I like to do a small mock up before I start writing, just to see how I think things will fit. It’s very low tech. The spread for March 2018 at the top of this post first looked like this is my notebook.

Notes for March 2018 CelCal layout.

I have a spiral notebook I use to work out basic ideas. I scribble a bunch of random notes in it, maybe form a paragraph or two, then go back to my computer to write a first draft. The notebook also has about 10 pages dedicated to “stuff about meteor showers that doesn’t really change,” so I have to keep it around even though it’s almost full. My best guess is that it takes 18 months of CelCal and one issue of SkyWatch to fill a notebook.

Notes for column on Mercury. The slash means “old month, do not read, out of date”.

Notes for Mercury sidebar.

I usually plan for the main story to take two pages. Although the March 2018 CelCal didn’t require a finder chart, if I’d been writing about a comet or an asteroid opposition, I would have needed one. I draw charts with an in-house program, then work with our design department to bring them into our house style/make them more useful. It usually takes me a few hours (creating, proofing, submitting to design, proofing the version finished by design) to make a chart. The typical opening CelCal spread has text, an image (or two), and a finder chart. I got to write a Mercury sidebar for March 2018 to fill the space where a chart would have been placed.

The second 2-page spread of CelCal is where I put things like occultations, major meteor showers that will be Mooned-out, etc. I can write about these in shorter paragraphs, so I can sometimes fit three topics in, depending on whether Algol predictions run or I need to write a lot about Jupiter.

March 2018 CelCal occultation predictions.

Roger Sinnott does the wigglegram, and I’m grateful to the IMCCE for sharing data.

After I get all the text written, I compile it into one document and format it to meet our house styles. This includes coming up with titles, subtitles, run-heads, captions, captions ledes, table headings, and so on. I select the images and charts that I want to run with the column as I go. Images need to get art-department approval, so I’m required to run my choices by them early in case I need to find something else. Once I have everything in a complete state, I give it all over to our Observing Editor. She double-checks everything I’ve written, right down to the extra blank space I tend to leave at the end of my paragraphs (you never know, that blank space might mess up the formatting of a paragraph one day). After she makes corrections, I go through the document again to see if I agree with the changes she’s made (usually I do, but not always. It makes me feel good to press “REJECT” every once in awhile).

After we come to an editorial consensus, which can take a bit of back and forth, I submit the full text and images to the art department. The art department does the layout as they see fit, trying to strike a balance between “communicates clearly” and “looks great.” Sometimes surprises happen at this point — an image doesn’t work after all, I messed up something on a chart, my text is too long, my text is too short, I wrote “standard time” instead of “daylight-saving time” — but usually the surprises are small and everything can move forward. I proof the proposed layout, then send it back to the art department. They finalize the layout, and send it to the Editor in Chief. He proofs the final layout. I proof it again. And then it all goes back to the art department for final production packaging. The entire magazine is sent to production at some point (not my job!), and soon after that, the digital files come back to our office for a final check by the Editor in Chief and Art Director before printing.

First run at asteroid occultation.

A lot of people work on those four pages! Editorially, I’m pretty independent. I’m best situated to know what’s “important” in the sky in any given month, so I choose the topics I’ll cover as I see fit. But in the end, many people collaborate to finish the pages — two editors (minimum), the design department, the art department, the Editor in Chief — so I can’t take the credit even if my name is at the top of the page.


Map of the Sun, Tokyo Astronomical Observatory

11 10 2017

Tokyo Astronomical Observatory Map of the Sun, March 21, 1959. Image: Kodaikanal Observatory Library / JR

I found a whole book of these maps of the Sun made for the International Geophysical Year (July 1, 2957 to December 31, 29158) in the library at Kodaikanal Observatory. It took me awhile to track down their origin, but I finally found the entire collection online at the Solar Science Observatory of the National Astronomical Observatory, Japan. (Scroll down to the section of the table that says “Map of the Sun in the IGY period),

According to the Historical Sunspot Drawing Resource Page:

  • The Toykyo Astronomical Observatory moved to Mitaka (near Tokyo) in 1924 (construction began 1904)
  • Sunspot observations made from January 1929 to March 1999
  • 203-mm f/18 Zeiss refractor
  • Observation method: Eyepiece projection method, 24-cm image
  • Solar projection unit at NOAJ: Cloudy Nights
  • Drawings archived at Solar Activity World Data Center, Tokyo
  • An extensive database of drawings and observations is available online

According to the National Observatory of Astronomy Japan (NOAJ), the dome housing the 20-cm refractor built in 1921 by Mr. Chodayu Nishiura. The refractor, set on an equatorial mount with clock drive, was used to map sunspots from 1938 to 1999.



The dome for the 203-mm f/18 Zeiss refractor at the NOAJ Mitaka campus.
Image: おむこさん志望 / Wikimedia Commons / CC BY-SA 3.0

Venus-Mars Conjunction

6 10 2017

Venus and Mars with Sigma Leonis, October 5, 2017. Image: JR

To say that I got up early to view yesterdays’ close conjunction of Venus and Mars would be stretching the truth. My alarm went off the same time it does every weekday morning, so viewing it took no special effort on my part. And If I’m telling the 100% truth, I’m saying that I can see Venus from an upstairs window, so technically, I didn’t even have to go outside for a decent naked-eye or binocular view of the event. (Remember, I’m the person who once did an entire day of solar observing with a 130-mm reflector from inside the house.)

Mars and Venus were about 1/4° apart yesterday  morning (October 5th) as viewed from Metrowest. Sigma Leonis was something like 19 arcminutes from Venus. Through binos, the difference between 15 and 19 arcminutes is obvious.

Mars and Venus had moved on this morning. Detectably orange Mars stood about 1/2° upper right of Venus (1 o’clock on the dial), with Sigma  about 1-1/4° directly above Venus.

3122 Florence

31 08 2017

Sometimes I think successful observing is all a matter of confidence. I go through this same sequence every time I look for some moving target: an asteroid, a dim planet, a comet. I study the starfield, sketch what I see, but nearly always convince myself I’m looking in the wrong place because the field doesn’t look quite right. Well, there’s a reason it doesn’t look right, and that reason is either a comet, an asteroid, or a dim planet. My first view of Uranus or Neptune in the fall? I have to starhop over and over to the field because something seems off. Find a comet? Same thing. Finding an asteroid? Same deal. It took me forever to believe I was really seeing Florence. Not sure why I don’t just trust my eyes.

Asteroid 3122 Florence, viewed from Metrowest, August 30, 2017, 15×70 binos. Image: JR

Scenes from a Star Party

30 06 2017

This was our first trip to the Cherry Springs Star Party. I wrote a fairly comprehensive summary for the S&T site awhile back. Here are a few random photos from the trip. One advantage of being the Observing Editor at S&T is that I can stay late at work at draw my own star charts. Before going to Cherry Springs, I put one together for Comet Johnson (C/2015), and I have to say, it was admirably accurate.

Stuffed animals make good rattle reducers. Image: JR

All set up at Cherry Springs, just waiting for clouds to go away. Image: JR

Next year, remind me to park on the other side of the tent. I thought this would give us some privacy from neighbors on the west side, but it turns out they left for a hotel every night anyway. If I’d parked on the other side, I would’ve had better protection from the morning Sun.

Observing table, ready to go but crowded. Image: JR

One good thing about attending a star party within driving distance is that you can pack a lot of stuff in even a small car. This is the first star party in a long time where I’ve had at least one decent observing table. In an ideal world, Catherine and I would both have our own tables plus a couple of side tables. I prefer print atlases and they take up a lot of room. Plus, we both have 3-ring binders we use as observing notebooks, and then we both have sketch books. There’s pens and pencils, a bin for extra batteries, a bin for setting our lights (so I can always find it again in the dark).

Meade Lightbridge, finally uncovered. Image: JR

I guess another advantage of working at S&T is that I can borrow one of the random scopes sitting around the office when I need to. My 10-inch is way to heavy to drag across state lines, so I bogarted the Lightbridge that lives on the landing of our office staircase for the week. Really easy to transport and set up, I would definitely consider buying one of these if I had $700 burning a hole in my pocket. I saw many 12-inch and 16-inch Lightbridges in use this summer. I think the 16-inch would fall into the “too heavy to move around” category for me, but I wouldn’t say no to the 12-inch.

Good height for short person. Image: Catherine Johnson-Roehr

As you can see from this photo, the Lightbridge is a good height for me (I’m 5′ 1″ tall). Like all Dobs, it can get a bit awkward when looking at objects close to the horizon (on this night, I was showing off the Andromeda Galaxy to other observers, basically from a crouched position), but when I’m 1/2-way up the sky or more, I find it very comfortable.

Star splitter extraordinaire. Image: JR

Catherine seems really comfortable with her refractor these days. She’s been using it for double stars, plus doing a lot of bino observing. This summer, she used the Irish Federation of Astronomical Society’s Binocular Certificate Handbook to build her observing lists.

Finally, one clear night. Image: JR

We had one clear night of observing only, so I didn’t make much headway on my observing list. I had planned to do some mapping of the Virgo Cluster, but the light management on Saturday night was really, really bad. Our neighbors to the west opened their trunk at least 5 times, destroying my night vision over and over again. The experience was frustrating enough for me that next time I’ll take a little more time to think about how to isolate my scope from the public — not usually my goal at a star party, but possibly a necessary step to enjoy this one to the fullest.

Comet Johnsons widefield

Tracked down Comet Johnson with the 15 × 70 binos before going after it with the scope. Image: JR

Needle Galaxy and M109. Image: JR

Clear Sky Chart, Acton, MA

20 06 2017

In the Beginning

4 05 2017

Digging through back issues of S&T yesterday, I found the ad that shaped my first telescope-buying decision:

Sky & Telescope, August 1983, p. 145.

And I found the ad that probably shaped my friend Mike’s first telescope-buying decision:

Sky & Telescope, August 1983, p. 151.

Paper Observatory Domes

3 05 2017

Digging through notes I made during my research in the Lick Observatory archives in 2013, I found an intriguing letter written by Thomas Fraser, the foreman during the construction of the observatory, addressed to Richard Floyd, the chairman of the Lick Trust. Fraser wrote it while traveling in the spring and early summer of 1885, when he represented the observatory’s interests before various dignitaries and astronomers and studied extant dome designs in various eastern U.S. cities.

The Journey Begins

Fraser’s trip would be the envy of any amateur astronomer now. In New Orleans, he visited “the Exposition” (the World Cotton Centennial, which ran from December 1884 to June 1885 on the current site of the Audubon Park and Zoo) before moving on to Washington, D.C. via Mobile, Savannah, and Charleston. In D.C., Fraser enjoyed Grover Cleveland’s (first) inauguration and visited the Smithsonian Institute before visiting Fauth & Co., where he examined a “dividing engine for circles” and a 6-inch refractor that “beats Warner and Swaisey [sic] all to peaces [sic].” (Spelling, grammar, and punctuation were definitely not Fraser’s strong suits.)

Title page of Fauth & Co. catalogue, 1883, full text available at archive.org.

From D.C., Fraser traveled with Edward Holden (then President of the University of California, soon to be director of the Lick Observatory) to Charlottesville, VA, where they were met by Ormond Stone, director of the Leander McCormick Observatory at UVa. Fraser wasn’t much impressed with the observatory’s dome, writing that “There is many good points about this Dome for this place, but for our place this is many bad ones which must be remedied before we could adopted such a style of Dome … ” Fraser didn’t like the rigidity of the ring designed by the Warner & Swasey Company, nor did he think the gear for rotating the dome was sufficient to really get the job done. He did, however, like the shutters, even though “they are far from rain and snow proof.”

From Virginia, Fraser traveled to Boston via New York, where he tried but apparently failed to meet with Henry Draper. In the Boston area, Fraser first visited Alvan Clark’s workshop in Cambridgeport, MA (about 2-1/2 miles from where I’m sitting; the Central Square Branch of the Cambridge Public Library now sits on that site) to look at the 30-inch refractor Clark was building for Pulkovo Observatory. He then visited Charles Pickering at the Harvard College Observatory.

Fraser was busy in Boston (but not too busy to take a vacation in Lisbon, Maine, with his wife), wooing potential donors (James Francis up in Lowell), trying to sort out (by letter) issues with the lenses being constructed by Charles Feil in Paris, and so on. It took him awhile to move on. When he did, he stopped in New York and New Jersey to look at Princeton’s dome before heading to the United States Military Academy at West Point, NY, to study the dome at that school’s new observatory. What was special about this dome? It was made of paper.

Paper Boats and Things

West Point was only one of several U.S. observatories with paper domes at the end of the 19th century. I can see the allure of paper as a building material, at least in theory. It was lightweight, for one, and if you’ve ever played with papier-mâché, you’ll have some idea as to how it would work in a mold. It’s durability was already being tested in other areas of construction. Paper boats really were a thing back then, specifically, boats made by George and Elisha Waters (E. Waters & Sons) in upstate New York. It doesn’t seem like too much of a creative leap, anyway, to think about paper if you’re searching for a thin, durable, dome skin. The Annual Report of the Commissioner of Patents for 1881 indicates that E., C.W., and G.A. Waters filed a patent for paper domes on May 3rd. But were paper domes any good, or did Fraser find they, too, had “many bad points”?

Patent brief from Official Gazette of the United States Patent Office, 1881.


“Paper Domes for Observatories,” The Printers’ Circular and Stationers’ and Publishers’ Gazette Vol. 18, 1883.

Rensselaer Polytechnic Institute

The first paper dome manufactured by E. Waters & Sons went to the Williams Proudfit Observatory at Rensselaer Polytechnic Institute in the Waters’ hometown of Troy, NY. Although the manufacturing process was kept a trade secret, the basics were reported fairly widely. The dome hemisphere was divided into sections and built out of molded wood ribs. The ribs were covered with linen paper molded to the right shape and treated with a (secret formula) resin. The individual wood-and-paper sections were then bolted together to form the dome. Allegedly RPI’s dome, which rotated on oversized ball-bearings on an iron track, worked just fine.

Part 1, “Paper Observatory Dome,” from Scientific American, February 22, 1879.

Part 2, “Paper Observatory Dome,” from Scientific American, February 22, 1879.

West Point

Given its proximity to RPI, it’s not surprising that the United States Military Academy (West Point) also ended up with a paper dome at its new observatory. West Point’s original observatory was part of the “old” Cadet Library, built in 1841.

William H. C. Bartlett, “Account of the Observatory and Instruments of the United States Military Academy at West Point; With Observations on the Comet of 1843,” Transactions of the American Philosophical Society
Vol. 9, No. 2 (1845), pp. 191-203.

This library observatory was described well in “Observatories of the United States,” published in Harper’s New Monthly Magazine for March 1874 (West Point is covered on pages 539-541). The same article announced that the observatory was in peril, for the West Shore Railroad Company had purchased the right of way to build a tunnel directly beneath the observatory property, necessitating the moving of equipment (the 12-inch Clark refractor, specifically) to a new site. The new site turned out to be a knoll on the east shore of Lusk Reservoir.

Landscape program proposed by Olmsted Brothers, from Sylvester Baxter, “The New West Point,” Century Illustrated Monthly Vol. 69, no. 3 (July 1904), p. 338.


I’m surprised how little has been written about the “new” West Point observatory, particularly since Holden ended up there as a librarian — or maybe that’s the reason. After Holden’s acrimonious departure from Lick in 1897, he more or less abandoned astronomy, taking up a librarian position at West Point in 1901. Or possibly it’s because the heavy-lifting was done by the U.S. Naval Observatory, not at West Point. At any rate, images of the observatory are difficult to find. A report on the observatory published in the Publications of the Astronomical Society of the Pacific in 1891 describes the instruments, but not the building. I found a campus map in the West Point archives that shows a cruciform floor plan, as well a photo-engraving that shows the exterior of the building.

Observatory footprint (3) from West Point yearbook, the Howitzer. Image: West Point Archives, U410.N5.H84 1946.


From Aldolph Whitman, U.S. Military Academy, West Point, N.Y.: photo-gravures, 1896. Archives identifier U410.L3 W783 1896.


Detail from Aldolph Whitman, U.S. Military Academy, West Point, N.Y.: photo-gravures, 1896. Image: West Point Archives, U410.L3 W783 1896.


It’s difficult to tell anything from that image, but that should be the paper dome, since the photo was taken only 13 years after the observatory was built. Was that paper dome great? Fraser didn’t seem to think so. This quote comes from the letter he wrote to Floyd, dated April 28, 1885, just two years after the observatory was built. The passage is a bit long, but interesting (if only for the spelling):

“I have been at West Point today to see the 30 foot Paper Dome covering a Clarks 12″ Objective I am free to say that Paper Covering for Domes is a failure in the full sense of the word the paper althou almost new is now cracked in lots of places and has pealed of in other places the paper was never pressed to the shape of the Dome but is a flat surface between the wooden ribs the shutter is hung inside of the Dome on a centre pivot at the top and swings round on a track or rail inside the dome it leakes and works bad the live ring is all rong and works with a watch takel and is awful hard they had a rope to revolve it but it worked so bad they toke it off [1v] you can’t reach the end of the tube frome the floor as the floor is too low they have a great big chair that costs heaps of money to make revolve around the pier on rails, they have a transit circle roome for a 7 ½” or 8” Repsolds Circle the Roome is not larger than our Transit House about 15×20 inside with 3 feet sonte walls and small windows there ventilation will be simpley horiable I should think money has been badely wasted here just the same as all the Observatorys I have seen ours beats them all to peaces there instrument the 12” and its mounting is rusty just like all the rest I expected better of the West Point boys I wonder will Prof Holden have his in good order if not we better never turn our Observatory over to an astronomer from what I have seen of them”

Ouch. Fraser expected better of the West Point boys, and judging from his evaluation, I would’ve expected the dome to fail a week or two later. Of course, it didn’t, and we know Fraser was a bit … hard to please … when it came to domes, so it probably wasn’t the disaster he described. Although the dome was repaired at one point in its long life, it was never replaced.

According to Jim Chung (Astro-Imaging Projects for Amateur Astronomers: A Maker’s Guide, Springer 2002), the observatory and refractor were restored in 1938 by a sophomore cadet named Alan Edward Gee, but after Gee graduated, no one used the observatory. I dug deep into the S&T archives and found a mention of a visit to the West Point Observatory made by members of the Amateur Astronomers League of America (A.A.A.) in May 1941 (“Notes on the A.A.V.S.O. Spring Meeting,” The Sky Vol. V, No. 9 (July 1941): 16). The group operated the “fine 12-inch refractor which is unfortunately not used at the present time” during their visit, as well as the dome, though no one described the dome in print. The author of an article on paper canoes in the February 1951 issue of Popular Science claimed that the West Point dome was “still good as new.” However, a 2004 historic structures report on the redoubts of West Point noted that the observatory was demolished in the 1950s, so it seems unlikely that the dome was in pristine condition at that late a date.

Other Paper Domes

At least two other college observatories sported paper domes: Beloit College and Columbia. Beloit’s Smith Observatory welcomed its paper dome on September 6, 1882. The dome apparently stood until the observatory building was demolished in 1969.

Smith Observatory
Image: Beloit College Archives

The dome for the new observatory at Columbia (then College, now University) necessarily needed to be lightweight. The observatory was built on top of the college library, 110 feet above grade, on iron girders “entirely independent of the floor.” According to the Printers’ Circular reproduced above, Columbia’s dome was 20 feet in diameter and 11 feet tall, “yet so light that it [could] readily be turned with one hand.” That would certainly be handy. But a historical sketch of Columbia, written in 1893, noted that “the position of the observatory in the middle of a city block close by one of hte largest railroads in the country, and surrounded by smoky chimneys and brilliant electric lights, makes it a poor place generally for observation.” Plans were already in the works for a new observatory at 116th Street. So the longevity of the paper dome was probably the least of the university’s worries.


Did the paper dome “craze” last? Not in a professional context. Certainly it wasn’t practical for the large-scale domes like the one at Lick (interested parties can send me their calculations for live loads on a paper observatory roof — could it hold the snow?). But I recently came across this thread on Cloudy Nights, and it seems the paper dome still has a place in amateur astronomy.