The Gloucester Area Astronomy Club

by Glenn Chaple

NGC 891  – Spiral Galaxy Cluster in Andromeda (Magnitude 9.9, Size 12’ X 2’)

If you’re a fan of TV sci-fi shows and are old enough, the accompanying image of the edge-on spiral galaxy NGC 891 taken by astroimager Mario Motta should look oddly familiar. It appeared, along with images of other galaxies, during the closing credits of the mid-1960s sci-fi anthology “Outer Limits.”

Typical of edge-on spirals, NGC 891 displays a luminous spindle shape bisected by a dark lane. This lane, created by dust clouds that inhabit the spiral arms, obscures the galaxy’s bright nucleus. As a result, NGC 891 is much darker than its listed magnitude of 9.9 might indicate. Although glimpsed with difficulty with apertures as small as 4 inches, this low surface brightness galaxy more realistically requires an aperture of 8 to 10 inches under a dark sky environment.

To find NGC 891, owners of GoTo telescopes need only enter its 2000.0 coordinates RA 2h22m33s and DEC +42o20’53” and press the button on the control paddle. I recommend, however, that you eschew the electronics and “go to” NGC 891 via the star-hop method. The reason? Your starting point is gamma (γ) Andromedae (Almach), 3 ½ degrees due west. Mirach is one of the finest double stars in the night sky, a dazzling amber and blue pair whose magnitude 2.3 and 5.0 components are 9.5 arc-seconds apart. What a great way to begin your journey to NGC 891!

NGC 891 was discovered by (who else?) William Herschel on 6 October 1784 with an 18.7 inch reflecting telescope. He described it as “Considerably bright, much extended above 15' 3' broad, a black division 3 or 4' long in the middle.”

Most references assign a distance to NGC 891 of 30 million light years. Its apparent 12 arc-minute breadth translates to an actual size of 100,000 to 120,000 light years.

Here are your NGC 891 challenges: 1. Can you behold the beauty of the topaz and sapphire gem set Almach without being moved to tears? (OK, maybe hyperbole on my part, but this colorful pair is a stunning can’t miss sight.) 2. Can you glimpse NGC 891 with a telescope aperture less than 8 inches? 3. What is the smallest aperture that will capture the galaxy’s dust lane?

David H. Levy

Palomar Mountain Observatory

Last month I drove all the way from my Vail, Arizona home to Palomar Mountain Observatory.  As most of this column’s readers know, I have visited this place many dozens of times from my first encounter in March of 1974, and regularly from the late summer of 1989 to the late spring of 1996.  I have always loved this magical place.  Each visit, as I would drive in, I would pass the expansive dome of the mighty 200-inch Hale Telescope.  As I drove by I felt the telescope waving at me.  It and I are the same age.  The telescope was officially inaugurated on June 3, 1948, just thirteen days after my birth on May 22 that year.  We are both 76. (I was probably too young to give a speech, with a poetic quotation, at that event.)  

The purpose of this visit was to watch the September 16th partial eclipse of the Moon with my close friend Jean Mueller.    I have known Jean for decades.  Jean operated telescopes at Palomar, mostly the 48-inch Samuel Oschin Schmidt telescope which opened just before the giant 200-inch. While there, she exposed many photographic plates for the second POSS (Palomar Observatory Sky Survey)  survey.  Mueller would scan the plates for stars that appeared in and around galaxies and mark a galaxy. She would then compare that galaxy with a picture from earlier to see  if the star had newly appeared. If it had, she would measure the position of the star, and then an astronomer would confirm her discovery on the 200-inch. This meticulous work enabled Mueller to discover 107 supernovae in addition to fifteen comets and thirteen now-numbered  asteroids.  Jean Mueller is a prime, absolutely first-rate astronomer and observer of the night sky, and she is admired and highly respected around the world.

[Image left: Comet Tsuchinshan ATLAS]

It has been thirty years since I last visited Palomar, and I was overdue for a return.  As I cruised by the colossal dome housing the 200-inch Hale telescope, at one time the largest in the world; this was not my reason for visiting Palomar all those years ago.  Instead, I drove on some meters on to see the 18-inch Schmidt camera telescope.  This beautiful instrument was the first and is the oldest telescope on this mountain, and its record of discovery is dazzling.  It helped Fritz Zwicky discovered 121 exploding stars, or supernovae, in distant galaxies.  It has a historic record of discovery of asteroids and comets, by far the most important of which is Comet Shoemaker-Levy 9 on March 23, 1993.  In July of 1994 the pieces of this shattered comet slammed into Jupiter.  Colliding at a velocity of 37 miles per second, each fragment left a very bright flash and a large brownish cloud that persisted for months.

During my March visit I learned how the 18-inch was moved to the observatory museum where it has become a lovely exhibit.  Whwen I saw my old friend again; I almost cried.  I then visited the outside of the dome that was our home for so long, and while there the treasured memories of working with Gene and Carolyn flooded back like an incoming ocean tide.  This time I could not hold back the tears of joy.

[Image left: Hale 200-inch telescope dome at twilight]

With the possible exception of our discovery of Comet Shoemaker-Levy 9, this was by far the most emotive visit I’ve ever had to Palomar.  For the first time in my long association, the overwhelming history of the place really struck me.  I felt I was standing next to Russell Porter as he drew a sketch of the telescope, even before its mirror was installed, pointed towards the north.  He even flashed me his legendary grin.  Porter became famous long before he helped design the 200-inch.  In the November 1925 issue of Scientific American,  he published its lead article “The Heavens Declare the Glory of God.”  That piece of writing also marked the opening of Stellafane, the telescope makers conference still held every year atop Breezy Hill in Vermont. Last year Stellafane celebrated 100 years of its legendary pink clubhouse.

On that incredible evening of September 17, we watched a wonderful partial lunar eclipse.  Only 7% of the Moon was covered in the Earth’s central or umbral shadow, but the outer penumbra shadow dimmed much of the rest of the Moon.  And just five weeks later, mighty Comet Tsuchinshan-ATLAS painted its rosy picture across the evening sky.    May these haunting events add to our joy in the night sky that shall be remembered forever.

by Glenn Chaple

Messier 2 – Globular Cluster in Aquarius (Mag 6.5; Size 6-8” [visual], 12-16’ [photographically])

Autumn can be a wistful time of year for the globular cluster aficionado as the globular-rich constellations of summer, notably Ophiuchus, Scorpius and Sagittarius, are rapidly disappearing in the western sky. Fortunately, a few stragglers remain visible on October evenings, including the bright globular cluster Messier 2 (NGC 7089) in Aquarius.

Charles Messier found and cataloged it on the evening of September 11, 1760, 14 years to the day after it was stumbled upon by the Italian-born French astronomer Jean-Dominique Maraldi while observing de Chéseaux’s Comet. To both Maraldi and Messier, the object appeared nebulous. It was William Herschel who, in 1783, was able to resolve M2 into its individual stars.

M2 is located at the 2000.0 coordinates RA 21h33m27,0s and DEC -00o49’23.7”, some 5 degrees north of the 3rd magnitude star beta (β) Aquarii and roughly 10 degrees east and slightly north of 3rd
magnitude alpha (α) Aquarii.

M2 photo (left) by Mario Motta.

To find it manually, aim your telescope towards this location (refer to the finder chart, below) and conduct a low-power sweep until a hazy circular patch of light enters the field of view. From there, switch to higher magnifications for that “up close and personal” view.

M2 offers several challenges for the visual observer. 1. Can you see it with the unaided eye? At
magnitude 6.3, M2 should be barely visible from a dark-sky location on a clear, moonless night. 2. What’s the smallest aperture that will resolve M2 into its component stars? This would be an interesting activityfor an astronomy club whose members would observe M2 with different-sized telescopes and comparenotes. 3. Can you see a dark curving lane that crosses the northeast edge of M2? In The Messier Album,co-author John Mallas includes a sketch of M2 and the dark lane as they appeared in a 4-inch refractor. Most resources cite a distance to M2 of 37,000 light-years. It has a calculated diameter of 150 to 175 light-years and contains an estimated 100,000 to 150,000 stars.

(NOTE: Messier 2 was previously featured as the August, 2009, Observer’s Challenge)

Morello's outline there is wrongly traced,
His hue mistaken; what of that? or else,
Rightly traced and well ordered; what of that?
Speak as they please, what does the mountain care?
Ah, but a man's reach should exceed his grasp,
Or what's a heaven for? 

Robert Browning, Andrea del Sarto, 1855.

Decades ago during the fall of a year that I recall might have been 1972, I attended Yom Kippur services at our family synagogue in Montreal, Congregation Shaar Hashomayim. The Congregation had instituted a new feature that year, a Yom Kippur Teach-in. I decided to give it a try. The topics were completely open that year, and the audience applauded every comment. I was a trifle nervous about saying anything, but I stood up and made a comment about God, and how our concepts of God are as
different as each of us might be. I ended my comment with these two lines from Robert Browning’s famous Andrea del Sarto:

Ah, but a man's reach should exceed his grasp,
Or what's a heaven for? 

My comment did get a smattering of applause. Afterward my life went on, and on, until a few days ago, when writing a book featuring poetry about the night sky, I chanced upon Browning’s poem again.

This Browning poem is surely one of his most famous and insightful. The poet suggests that Mount Morello, in Italy near Florence, is “wrongly traced.” He then supposes that the mountain itself, if it has consciousness, wouldn’t care if its outline was correct or not: “what does the mountain care?” In the final two lines of this section the poet transcends geographically from Morello to infinity, from earthly cares to the outermost reaches of space and time”-- “Or what’s a heaven for?”

It is not often that someone can compare the reading of a great and fabulous poem with a sporting event, but here I try :

I like to compare these lines of “Andrea del Sarto” with watching a baseball game. In my experience a typical baseball game consists of lengthy stretches of strike-outs, some walks, breaks between innings, and other trivia.

But these breaks are interspersed with exciting base hits, doubles, triples, and home runs. These events often happen without warning, and a large crowd in the stands can be electrified instantaneously, rising to its feet as the ball heads off the field, into the stands. It does seem odd to compare a work of English Literature to a baseball game, but in this case, it works, offering us yet another way to enjoy the night sky.

Writing about ball games, I have missed a football game to see a deep partial eclipse of the Moon.

Observer’s Challenge – September, 2024 by Glenn Chaple

NGC 6822 – Barred Barred Irregular Galaxy in Sagittarius (Mag 9.3; Size 15.5” X 13.5’)

Last month’s Observer’s Challenge, the galaxy NGC 6703 in Lyra, escaped the eyes of both William Herschel and his son, John, primarily because of its relative faintness (magnitude 11.3) and small size (just 2.4 arc-minutes). Would a brighter and larger galaxy be easier to view? Ask anyone who has tried to catch a glimpse of this month’s Challenge, NGC 6822 (“Barnard’s Galaxy” in Sagittarius), and you’ll get a resounding “No!” See Mario Motta's image, below.

Barnard’s Galaxy is a full two magnitudes brighter than NGC 6703, but its light is spread out into an oval-shaped area that’s half the moon’s apparent diameter. And, yes, the Herschels missed this one as well. Barnard’s Galaxy bears the name of its discoverer, the American astronomer Edward Emerson Barnard. He spotted it with a small refracting telescope (sources disagree as to whether it was 5 or 6 inches in aperture) in 1884. And therein lies the secret to visually capturing this elusive galaxy – use small aperture and low magnification to encompass a field at least a degree across. In the early 1920s, Edwin Hubble noted that Barnard’s Galaxy was better viewed with low power in a 4-inch finderscope than with the primary focus of the 100-inch Mt. Wilson reflector! You can even see it with binoculars in areas where skies are exceptionally dark and transparent.

Barnard’s Galaxy is located at the 2000.0 coordinates RA 19h44m 56.6s and DEC -14o47’21”. Starhoppers can find their way using the accompanying chart, courtesy of www.skyledge.net. If, after an extensive effort, you’re unable to spot Barnard’s Galaxy, don’t leave the area! In the same low-power field, a little over a half-degree NNW at 2000.0 coordinates RA 19h43m 57.8s and DEC -14o09’12”, is the tiny (22 by 15 arc-second) planetary nebula NGC 6818. Under low magnifications, it may be mistaken for a 10th magnitude star. An eyepiece yielding 60X or more will reveal its fuzzy nature. Barnard’s Galaxy is classified as a dwarf barred irregular galaxy. At a distance of 1.5 million light-year, it has a diameter of around 700,000 light-years. It’s a member of the Local Group of galaxies that includes our Milky Way and the Andromeda Galaxy.

David Levy's Skyward for August 2024

Area 377

By David H. Levy

For the first time in this series of articles, I am writing about the same subject, Comet Olbers, twice in a row.  This time I observed the comet using an unusual small telescope, a 4-inch reflector named Cole.  Joshua Cole is the central character in one of my Dad’s favorite childhood novels, Cole of Spyglass Mountain.  At the end of this beautiful story, Cole is informed that his discovery of life on Mars has been confirmed, and the book’s closing thought is this:  “First to Report Discovery:  Cole of Spyglass Mountain, famous in a night.”

On Sunday, evening, 7 July 2024, I joined my colleagues Tim Hunter and James McGaha at Tim’s Grasslands Observatory. While they prepared for an evening of astrophotography,  I set Cole up outside and began an hour of comet hunting in the northwest.  At first the comet seemed elusive.  But as I searched I noticed a familiar 10-square degree patch of sky.  This was area 377, and right away it brought me back to my teenage years, when I began observing with friends at the Montreal Centre of the Royal Astronomical Society of Canada.    Among their many observing programs was an organized comet and nova search.  The sky was divided into 438 discrete areas, and I was assigned two:  Area 40, which included Vega and its constellation of Lyra, and 377, south of the Big Dipper’s bowl.   For years I faithfully checked these areas until the program, like some of the comets it never found, faded away more than half a century ago.  

Tonight was different. By sighting along some of the star patterns in area 377 I found a spot.  Slowly I moved Cole through this region of stars.  And then, just like that!  There it was, Comet Olbers, a little east of Area 377, brighter than it was last month, and sporting a nice 1-degree long tail.  Tim and James were able to spot it using Cole, and later through binoculars.  

Comets mark the passage of our lives.  My great-grandson Beau will be nearing the middle of his life when Halley returns, and his grandchildren may pause to take a look at Olbers’s comet when it next visits at the end of this century.  But whether they see these celestial apparitions or not, may they at least have the will to pause in their lives, and reflect upon the great cosmic clock that chimes not on the hour but at any minute when something new, different, and mesmerizing pays a visit to the planet that is our home.

Pons-Brooks:  A comet for the centuries.

When David Rossetter and I began our observing session at the Tucson Amateur Astronomy Association’s  Chiricuaha Astronomy Complex on the evening of August 5, 2023,  we did not expect that  we would be treated to an evening of cosmic history.  That was the night we glimpsed Comet Pons-Brooks, a comet with an orbit that, like Halley’s comet, takes almost a human lifetime to orbit the Sun  .I might have spotted it the night before, but on this night David and I saw the same thing, a spot of haze in the darkness.  It was a faint misty cloud that bears the names of two of the most famous comet discoverers in all history, a spot of haze with quite a story to tell.

Comet Pons-Brooks was first identified by Jean-Louis Pons, the great French comet hunter, during the summer of 1812. In the late summer of  1883, on its subsequent pass around the Sun, it was rediscovered by another famous comet hunter, William Robert Brooks. I first encountered Brooks in a Sky & Telescope article I read in the second issue I received, at age 14, in April 1963.  As I digested the story, I learned how Brooks might have politely entertained a visitor to his observatory, and how that visitor eventually learned that Brooks was one of the world's most famous comet discoverers. As I relished these words, I foresaw myself, some day, also as a hunter of comets.  Not a discoverer, because that would be hard.  But as a hunter, that's easy. Those ideas stayed with me until December 17, 1965, when I began my program of searching for comets. Since then, my own life has been punctuated by several sparks of cometary light, as each new comet added brightness to the field of my telescope. I joined a group of people linked not by nation, nor either by continent, but by being citizens of the world united by a love of comets.

Emboldened by the offer by Hulbert Harrington Warner of an award of $200 for each comet discovered, Brooks managed to find three comets within five weeks of each other, on April 17,  April 30, and May 22 , 1886.   He must have known how his colleague Edward Emerson Barnard built his “comet house” partly out of funds also earned from Warner’s award.  (The Warner prize has survived through history.  The Astronomical Society of the Pacific offered its “Donohoe Comet Medal”  for a time, and later Roger Tuthill gave a plaque, and now there exists the Edgar Wilson Award, which is sponsored by the Central Bureau for Astronomical Telegrams [CBAT] of the International Astronomical Union.)

Like all serious comet hunters, Brooks was far more interested in discovering comets than in the money he could earn from these finds.  In later years his success as a a comet hunter earned him a professorship in astronomy at Hobart College in Geneva, New York.  With Brian Marsden’s 1979 Catalogue of Comet Orbits as a guide, we can surmise that Brooks discovered a minimum of 22 comets in his lifetime.

Despite this remarkable accomplishment, Brooks is only the second most prolific comet finder in world history,  The winning ticket goes to Jean-Louis Pons himself, who was “the first “discoverer” of Comet Pons-Brooks.  Truly, Pons was also not the first.  This comet might have been observed by Chinese astronomers in the late summer of 245 CE, then definitely by the Chinese in 1385, and in 1457 by Paolo del Pozzo Toscanelli.   Pons today is considered to have discovered about thirty comets.    Over the decades I observed a second Pons periodic comet, Pons-Gambart, in January 2013.   By the way, Pons had a most humble and trusting nature, and in his younger years he was ridiculed by astronomers who should have known better.

These days,  it is almost impossible for an individual to discover more than half a dozen comets.  My total is 23, but as CBAT director Dan Green (possibly correctly) stated, “he discovered 9 comets and lucked out on 11 more,” before graciously adding Comet Shoemaker-Levy 9 to my total.

Pons and Brooks shared a passion for telescopes and the fleeting comets they could detect parading about the sky.  I like to imagine that finding new comets was secondary to their pure enjoyment of the night sky, its treasures, and the secrets that it infrequently shared with those people who truly lived, and live, for its precious hours of darkness.

Image credit: H.C. Wilson, E.E. Barnard

Skyward, April 2022

Omicron!

        Over the last few months you must have read dozens of articles, online or in print, about the Omicron variant of COVID-19.  Fortunately, this is not one of them. This article is about Omicron² Eridani. It is a faint star in the constellation of Eridanus, the River.

        Actually, there are two Omicron stars in that constellation.  The first is brighter, and is a variable star.  The second one is one of the closest stars to the Sun. Omicron², also known as 40 Eridani, happens to be not a disease but one of the most interesting star systems in the entire sky.

Omicron² is a triple star system that is only about 16 light years away.  Its brightest component is a Sun-like star faintly visible to the unaided eye on a good night. It lies in northern Eridanus, the River, just a few degrees west of Rigel at the foot of Orion.  The secondary is a white dwarf star.  Unlike the companion of Sirius,  this star is 9^th magnitude and not near the brighter star so it is easy to see in a small telescope.   The third star is not far from the secondary, but at 11^th magnitude it is also not difficult to spot.  This third star is a red dwarf.

       Although red dwarf stars are the most plentiful, by far, in our region of the Milky Way galaxy, they are almost impossible to see because they are so small.  The closest one to us is Proxima Centauri, or Alpha Centauri C, which at 4.24 light years is the closest star to the Sun.    Also because they are so small and intrinsically faint, only a few of them are easy to find.  40 Eridani C is one of the easiest to find.

       This interesting star has something else going for it.  In 2018 astronomers discovered a planet orbiting the primary star.  With a rapid orbit around Omicron², such a planet would receive much more radiation from the primary star than Earth gets from the Sun.  But in 2021 new observations cast doubt on whether this planet exists at all.

        Whether Omicron² Eridani really hosts a planet is subject to debate.  But in the universe of Star Trek, it surely does.  It is the home of Vulcan, Mr. Spock’s home world. In the episode “Operation Annihilate”, which appears near the end of the first season, Spock is blinded by the intense light used to immobilize the invading parasites on the planet Deneva.  However his blindness is temporary because of the existence of an inner eyelid.    Vulcan is said to orbit Omicron² Eridani’s primary star, and since it is so much  brighter than our Sun,  even though Vulcan is at the same distance that Earth is from our Sun, they need the inner eyelid to protect their eyes.

       I rather enjoy the idea that the fictitious Vulcan happens to orbit one of my favorite real stars.  And unlike the Omicron variant, which one hopes will be eradicated soon, we admire Omicron² Eridani, the real star, and wish it to ”Live long and prosper.”