Sunday, April 21, 2013
My Favorite Fuzzies: M74
I was P.O. ed. “Put out,” that is, muchachos—this
is a family-friendly blog, after all. It was the 1994 Deep South Regional Star
Gaze, I was about to make the observation of a lifetime, and I was awful mad at
my telescope. But I persevered, thank whatever gods there be that watch over silly
amateur astronomers.
I’ve told
the story of DSRSG 1994 and my 12-inch Dobsonian, Old Betsy, before, but I
haven’t gone into detail about the best thing I saw there. The best look at any
deep sky wonder I had had up till then, I think. The observation I’d been
trying to make for thirty years. I finally really
saw M74.
What’s so
special about M74? It’s a spiral galaxy.
So? There was something about classic spirals that fired my imagination when I
was a little kid. That thrilled me the second I laid eyes on the one on the cover of my first
astronomy book, Universe from the old
subscription science book(let) people, The Science Service.
The painting
of the spiral on the book’s cover, possibly M81, simply fascinated—in the true
sense of that word—grasshopper Rod. What was even better were the face-on Scs
(I certainly didn’t know those terms then) I found in a picture book in Mama’s
library at Kate Shepard Elementary: M101
and her sister M74. That was how a galaxy should look, with those numinous spiral arms slapping
you in the face with their mystery and majesty.
Fifty odd
years later, I still don’t know exactly what it was in those giant night birds
that so called to me, but there was a something, a certain something, that is
as responsible as Patrick Moore and Stephanie's Telescope for me taking up astronomy as an avocation, a
vocation, and an obsession.
Let’s step
off the artsy-fartsy philosophical path for just a moment, y’all, and do the Just the Facts Ma’m thing with Messier
74, a.k.a. NGC 660, MCG 3-5-11, UGC 1149, and PGC 5974. M74 was discovered not
by Charles Messier but by his friend Pierre Méchain in 1780. Mssr. Méchain
told Messier all about what he’d seen, and the galaxy was soon occupying
position 74 in Chuck’s famous catalog. NED, NASA’s Extragalactic Database (which you should come to know and love if you
are observing galaxies or are interested in observing galaxies) says it is an SA(s)c
of magnitude 9.95, with a size of 10.5’ x 9.5’.
What does
the above mean to me and you and Sister Sue? The “SA(s)c” means that in the De Vaucouleurs system of galaxy morphological classification
(which builds on the older Hubble classification scheme) M74 is a non-barred
“pure” spiral galaxy with loosely wound arms. It is bright in magnitude as
galaxies go, 9.95, but is also quite large, over 10-minutes of arc across its
longest dimension (it’s not quite round). Why the “but”? As we’ll see directly,
that nice high magnitude figure is negated by the galaxy’s considerable size.
That’s what the bright boys have to say about M74. How about the
amateur literature? The first place I turn for that is still Burnham’s Celestial handbook. Ol’ Bob
doesn’t always have all the details correct, and he doesn’t always know the
best way to observe a particular object, but he always gives me a better feel than anybody else for how a deep
sky target will look in the eyepiece. Says Mr. B.: “M74 is one of the most perfect examples of a
face-on sc-type spiral, resembling the large M101 in Ursa Major but somewhat
more symmetrical in form.”
I was a little disappointed Burnham didn’t take off on one of
his semi-poetic flights of fancy as he does with most famous objects. Maybe
this one was not one of his favorties. Perhaps because, even with good skies
and considerable telescope horsepower, he found, as many visual observers have before
and since, that M74 is one tough nut to crack. In fact, Burnham refers to this
galaxy as “One of the faintest and most elusive of the Messier objects.”
Sure got that
right. As a matter of fact, I’d call M74 the
most difficult Messier, period. Yes, M101 is hard, large and dim, too, but I’ve
found M74 to be even worse. I’m not alone. The nickname for this one is not
“The Spiral Palooza” or “The Little Pinwheel,” it’s The Phantom Galaxy.
I am usually able to see M101 when it’s at 30-degrees of altitude
or more. When I was doing the observing for The Urban Astronomer’s Guide its central area was often visible with my Synta 8-inch f/5 Newtonian from badly light polluted skies. M74
under similar conditions? It was sometimes visible in the 8-inch f/5, but not nearly as often. I could usually see it in the C11, but it was frequently tough even in that telescope. Very tough. Night after night over the last forty-something years this
low surface brightness Phantom has skunked me. Often I don’t see a thing, but sometimes I do seem to hear a ghostly, mocking laugh.
My quest for spiral arms didn’t begin with M74, but with M31,
ironically in retrospect. M31 is the closest large galaxy, but its shallow
inclination to us makes the arms extremely difficult to pick out. The best you
can hope to do visually is spot one or two (if you have a dark sky) of the dark
lanes that define those arms. After I got my first telescope, a 3-inch Tasco Newtonian, in
the spring of 1965, I waited anxiously all through the summer for the return of
“Andromeda” as me and my bubbas in The Backyard Astronomy Society called Messier
31. When I finally managed to get the little scope on it, it was not much more
than a smudge. Hell, hardly even that. This thing was bright and close. I could
see it as a fuzzy star from the backyard in them days. Why couldn’t I see it as
a spiral? Was my telescope busted?
Lucky for li’l Unk, my fellow BAS member and buddy Wayne Lee
had read somewhere (I was always amazed to hear he’d read anything other than a
Sgt Rock comic book) that the arms of
M31 are impossible to see because of its tilt with respect to us. I stopped
worrying about my telescope and started looking for some other galaxy that could
show me what I longed to see. A review of the literature (my copy of Stars
and the paltry few astronomy books in Mama’s library) seemed to indicate that
would be M101 or M74.
In the spring, you’d find me out in Mama and Daddy’s backyard
with my Tasco or, a little later, my 4-inch Edmund Palomar Junior hunting M101.
In the fall, I’d be after M74. I saw exactly nothing of either. I never caught
a glimpse, even a trace, of The Catherine Wheel or The Phantom. Not realizing
how hard they were made my quest even more frustrating. They were wide open,
showing off their arms better than any other spirals I had seen pictures of,
which gave me the idea these two ought to be the easiest.
I’m not sure my quests were completely in vain. Frustrating,
yeah, but in the course of my searches, my sweeps,
as I began to call them after I read about William and Caroline Herschel in a
kids’ science encyclopedia Mama had, I ran across a lot of cool stuff. I also
learned a little about star hopping and deep sky observing in general. But no
74s or 101s did I see. I finally decided they were indeed too hard for my
telescopes. I wasn’t sure why they
were too hard, but they were. I gave up on both, didn’t get a look at either
for almost ten years, and didn’t get good
looks at ‘em for dang near twenty years after
that.
“So why the heck are they so hard, Unk? You done told us M74
has a mag value of about 10, and M101 is at pea-picking 8.3…” Yep, and that’s
what I’d based my opinions on when I was a sprout, but you know what they say
about “opinions.” The reason the two galaxies are so hard is that they are large. In addition to being large, they
are face-ons, which means their light is more spread-out than it would be if
they were edge-on, for example. That is the long and short of it.
Still don’t glom onto what I am talking about, Jane Newbie?
OK, consider this. Yes, M74 is about magnitude 10, which is not overly dim—for
a star. And that is exactly how bright M74 would be if it were squished down to
the size a star. But it is not a star. Next time you are out with the scope,
point it at some 10th magnitude sun and rack the star out of focus until it is
a blob 10’ in diameter. Till it almost fills the field of a medium power,
medium AFOV ocular. Dim, ain’t it? Dang right it is.
So how do you go about seeing such a thing? The two things
that will have the most effect are observing from dark skies and increasing contrast
between the object and the background sky. If you spend your nights viewing
from the typical suburban site and have never observed from a truly dark location,
you will be amazed at what you can do with modest instruments from one.
Take Spruce Knob Mountain, site of the annual Almost Heaven Star Party in West Virginia. It is one of the darkest sites I’ve
visited east of the Mississippi, and I was able to put M101 into the ground
with a freaking pair of Celestron 10x50 binoculars there one night. It was
crazy easy. Why? The 10x magnification kept M101 small enough for it to remain
bright. And… the sky background was
still dark at low power due to the absence of light pollution. If you use
binoculars in the typical suburban backyard, you know their large exit pupils make
the background sky bright enough to totally extinguish The Phantom. Without
that high background sky brightness, M101 was a cheerful and easy little thing
in West Virginny.
“So I should run off to Spruce Knob or Prude Ranch to look at
101 and 74?” That wouldn’t be a bad idea, but you don’t have to. You probably won’t
see much of either from your backyard, but both can look incredibly good from
middling dark locations like an astronomy club dark site. The secret ain’t so
much the scope as it is the correct eyepiece.
What you need is an eyepiece that makes M74 (or M101) small
enough that it remains reasonably bright,
but also one that keeps the background sky reasonably dark. You don’t want so high a power that M74 fills the field
completely. You need some dark sky framing it to provide contrast so the galaxy
will pop out atcha, but you’ve got to have enough power, a sufficiently small
exit pupil, to damp down the background skyglow.
The best focal length and design of eyepiece will depend on your
scope, your site, and your eyes. You will need to experiment. Me? I’ve found
the ocular focal lengths that bust these suckers best for me are in the 12 –
16mm range whether used with my f/10 C8 or my f/4.8 12-inch Dobsonian. What did
I use most for 101 and 74 hunting over the last decade or two? My much-loved
12mm Nagler Type II (which, alas, had to go on the pea-picking Astromart to
finance a 13mm Ethos). The bottom line? Get M74 or M101 in the field and start
experimenting with eyepieces.
M74 can still give me fits, but usually only on Messier
Marathon nights. It is, in fact, the bane of Marathon runners. Folks talk about
how hard M30 is in the morning, but in this old boy’s opinion The Phantom,
which is in the evening sky at MM time, is way harder. Wait too late after
Sunset, or try for it a day too late in the Marathon window, and you will be
cussing up a storm.
Even on an optimum Marathon night, it is low in the west and in
the horizon trash, the eyepiece field background is bright no matter what you
do, and in Old Betsy it is a phantom of a phantom. I don’t try to star hop to
it, nossir buddy. You cannot waste time; you have to get it in that short period
after the sky is dark enough but while the galaxy is still high enough. Sky
Commander digital setting circles all the fracking way.
I finally got the view of M74 I’d always wanted, but not
until eighteen years after I saw it for the first time back in the seventies,
not till November of 1994. What made the difference that year? It wasn’t just the
location, which was the old Deep South Regional Star Gaze site at McComb,
Mississippi where the skies were dark but not real dark. It was also the combo of aperture/focal length that Old
Betsy, who’d come to live at Chaos Manor South just a few months previously,
brought to the table, I reckon. That and a sky that was better than it should
have been one night.
I’d assembled Betsy in the front parlor of Chaos Manor South
when she arrived the previous September. I admit I kinda rushed that. Miss Dorothy and I would be married
in that front parlor the very next day, and I wanted to get Bets put together
and the resulting detritus cleared ASAP. I was probably a little too cavalier
about the washers Meade furnished for the rocker box’s central pivot.
If you’ve built or assembled a Dobsonian, particularly an
old-timey solid tube Dobbie like Betsy was in the beginning, you know there are
usually a few washers that go around the central pivot bolt. Their function is
to lift the rocker box slightly off the ground board so azimuth motion is a
little easier than if all the weight were riding on the bearing pads.
I tried all the washers Meade shipped and found that made the
mount wobbly; the rocker box was not in good enough contact with the bearings.
I threw a couple out, put the scope together, and let that be that rather than
experimenting. The result was that Betsy’s azimuth motion was more “sticky”
than “buttery,” but wasn’t too bad.
The real trouble was her altitude motion. Too hard, but,
ironically, there still wasn’t enough friction to make the tube easy to
balance. That was the result of the too-small side bearings Meade used—and which
Chinese Dobsonian makers insist on using to this day. The scope tended to swing
up when you removed a heavy eyepiece and swing down when you put one back in
the focuser.
I partially rectified the altitude balance problem before the
star party that was to be Betsy’s dark-site-first-light by buying a
counterweight system from Orion. That was composed of a long Velcro-covered plate
that screwed onto the tail-end of the tube, and a beanbag filled with lead shot
and covered with Velcro of the opposite type. You stuck the beanbag onto the plate in a place along the plate's length that made the scope balance.
It worked OK for balancing the telescope most of the time,
but did nothing for the hard, sticky altitude motion, which was maybe even more
noticeable with the tube close to balance. In hopes of making the tube easier
to balance, I guess, Meade had not used Teflon for the altitude bearings. They
used small squares of Nylon, which caused “stiction,” the combination of too
much friction and too much stickiness. That didn’t help overmuch with balance,
but it did make the scope harder to move and, especially, track. It also caused
weird sounds to echo across the observing field. Good thing it was dark on that
field, ‘cause poor Unk was red with embarrassment every night at DSRSG.
I would move the tube in altitude and the Nylon bearing pads
would tend to stick to the metal side bearings. As I moved the heavy scope,
that would force both sides of the particleboard rocker box apart. Suddenly,
the increasing pressure from the sides would overcome the stiction and the
sides of the rocker box would snap back into place with an audible pop. I know
it sounded louder to me than it was, but I thought the scope sounded like a
cotton-picking Ma Deuce (machine gun) as I star hopped. Yeah, embarrassing.
After I got home, I was determined to fix the altitude
problem. I’d heard about Magic Sliders from one of the inmates of the old
sci.astro.amateur bulletin board, which was going strong at the time. These
were furniture sliders, designed to let you move a couch around without marring
the floor. They were Teflon and sounded just right to serve as Dobsonian
bearings. I hied myself to K-Mart, got a set, and replaced those Nylon altitude
pads with Teflon.
That made the scope’s altitude motion oh-so-smooth. Too
smooth, in fact, because of the small side bearings. Betsy was impossible to
balance even with the aid of the counterweight. What worked was replacing one Slider
on each side with one of the original Nylon jobs. Not quite as easy to move,
but it balanced better. I replaced all the azimuth pads, which were also Nylon,
with Sliders, too, and moved them a little closer to the central pivot. After I
was all done, I never had reason to complain about Betsy’s motions again.
I was so pleased with the results of my simple mods that I
wrote a letter to Meade outlining the problems I’d had with their StarFinder
12-inch and how I cured ‘em. Naturally, nobody at Big Blue could be bothered to
reply with even a form letter or a postcard.
“But how about M74, Unk? What about
M74?” I’m getting to that Skeezix, I’m a-getting to that. The
machine-gunning rocker box did not prevent me from seeing as much as the 1994
DSRSG’s semi-punk skies would allow. Including M74.From years of sometimes-bitter experience, I knew precisely where M74 was to be found alongside the huge “V” of Pisces. As soon as The Fishes were high enough above the eastern tree line for me to see ‘em from my usual spot on the east side of the DSRSG field, I went after M74 with Telrad and 50mm finder. I had Sky Atlas 2000 by my side, but didn’t need to touch it. I knew where The Phantom was, but I sure didn’t expect to see much of him on this night. The final piece of the puzzle for observing M74 and M101 is dry as well as dark skies, and our skies were anything but dry.
I’ve found that observing M74 and M101 in low humidity
conditions improves their appearance considerably. Any moisture in the air
seems to steal form and substance from them, and is almost as bad as light
pollution. Was DSRSG ’94 humid on Thursday evening? Was it ever. We were sweltering under almost summer-like weather in
advance of a tremendous cold front that would soon batter us with
thunderstorms. It was like observing through soup.
Just when you think you have the sky figured out, it
surprises you. Theoretically, all I should have seen of The Phantom that night
was the all-too-familiar barely visible round glow of the galaxy’s center. That
wasn’t what I saw in the 16mm Konig when I put my eye to the eyepiece. The
moisture in the sky and the light dome from little McComb, Misissippi just
didn’t matter. Why they didn’t matter I didn’t know and still don’t know—I
suspect the steady seeing helped—but there before me was a wheeling spiral
galaxy just like in the pictures all those years ago.
At first, the spiral form was only visible with averted vision,
but as I continued to look, it began to be obvious when I stared directly at
the galaxy. If that weren’t enough, more looking and I began to see details, starting with the galaxy’s tiny
star-like nucleus. Eventually, I was spotting clumps, HII regions maybe, along
those graceful arms. What was the total effect? Have you ever seen Lord Rosse’s
sketch of M51? Erase NGC 5195 and maybe cut back a little on the multiple
spiral arms he drew, and my impression was “just like that.”
How about a twofer? I’d had the best of intentions of staying
up real one night late to get M101, but the weather on the first nights and the
looming drive home on the last night of the star party, when we got our only
superior skies, natch, prevented me. Even 19 years ago, Unk wasn’t always up
for hanging in until the 3:30 a.m. Ursa Major would have required at that time
of year. I did get M101 in every bit as good a fashion as M74, but it was over
a year later before I did that, in the spring of ’96 at the Mid South Star Gaze. That was
maybe an even more amazing (to me) observation, since I did it with my “little”
C8.
God only knows how long I could have ogled M74 that Thursday
night at Deep South. For once, it’s not exaggeration to say, “The more I looked
the more I saw.” I could have happily observed just 74 and nothing else that
night. I was finally seeing what I had been longing for for over thirty years.
Actually, that was practically all I
saw that night. The front began to creep ever closer and the skies faded away
before 1 a.m. I didn’t care. M74, it turned out, was what I’d come for, and if
I hadn’t viewed another single object during the whole star party that would
have been just OK, muchachos.
Next Time: Watcha Lookin' at Mister?…
Comments:
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Uncle Rod:
Have enjoyed your writing for several years now. We seem to have grown up "or not yet" during the same period. I have seen you refer to Burnham's Celestial Handbook a few times. You and your readers might enjoy an article that was found by the writers of the "Star-Splitters" Blog. Another excellent, not to miss site.
http://www.phoenixnewtimes.com/1997-09-25/news/sky-writer/
I still constantly use his three volume masterpiece.
Keep up the good work and congrats on the retirement. Looking forward to your next installment!
Rich McCormick
skynotesbyrich.blogspot.com/
Have enjoyed your writing for several years now. We seem to have grown up "or not yet" during the same period. I have seen you refer to Burnham's Celestial Handbook a few times. You and your readers might enjoy an article that was found by the writers of the "Star-Splitters" Blog. Another excellent, not to miss site.
http://www.phoenixnewtimes.com/1997-09-25/news/sky-writer/
I still constantly use his three volume masterpiece.
Keep up the good work and congrats on the retirement. Looking forward to your next installment!
Rich McCormick
skynotesbyrich.blogspot.com/
No kidding about M74 being a bear on M.Marathon night! I could not even see it from the side of Mauna Kea when doing a marathon there a few springs ago, despite knowing without a doubt I had its location nailed in the 1-deg FOV. I think the combination of inversion moisture that had not descended the mountainside far enough yet, plus the zodiacal light, killed it. A frustrating start to what I thought would be a piece-of-cake Marathon!
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