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E<br />
SECRETSKY<br />
Part of the wonder of<br />
backyard observing<br />
is that we, with our<br />
modest telescopes,<br />
can probe deeply<br />
into the universe. And by<br />
pushing the limits of those<br />
instruments, we can edge ever<br />
closer to the beginning of time<br />
— not as close as Hubble, but<br />
close nevertheless.<br />
In the June night sky after<br />
sunset, two quasars, one much<br />
more distant than the other,<br />
culminate for visual observers.<br />
Quasars are the universe’s<br />
most luminous objects. They<br />
represent the blazing cores of<br />
early galaxies whose tremendous<br />
light output (each is billions<br />
of times more luminous<br />
than our Sun) comes from gas<br />
falling into a supermassive<br />
black hole.<br />
As the gas spirals inward, it<br />
unleashes a tsunami of raw<br />
energy into space. So powerful<br />
are quasars that, despite their<br />
vast distances (billions of lightyears),<br />
we amateur astronomers<br />
can spot the brightest<br />
ones through even modest<br />
telescopes.<br />
BY STEPHEN JAMES O’MEARA<br />
Halfway to the<br />
edge<br />
You can view an amazingly distant<br />
object this month.<br />
N<br />
3C 273<br />
Let’s explore these two powerhouses<br />
of light. The first quasar<br />
astronomers designated as<br />
3C 273 because it’s the 273rd<br />
entry in the Third Cambridge<br />
Catalogue of Radio Sources.<br />
This object is the nearest and<br />
brightest of these super-energy<br />
sources. It radiates with a luminosity<br />
equal to 2 trillion Suns!<br />
When at its brightest, 3C<br />
273 can shine at a respectable<br />
magnitude 11.7, the brightness<br />
of Saturn’s moon Enceladus;<br />
when faintest, it glows at magnitude<br />
13.2, only about 0.5<br />
magnitude brighter than Pluto<br />
at opposition. The quasar lies<br />
about 2.5° from the magnitude<br />
5.0 star 16 Virginis.<br />
The other quasar I want to<br />
mention is from the Palomar-<br />
Green Bright Quasar Survey.<br />
Usually designated PG<br />
1634+706, it may be the most<br />
distant object visible through<br />
an amateur telescope. It has a<br />
redshift of 1.337, which means<br />
its light has been traveling<br />
some 8.8 billion years to reach<br />
us. That works out to a distance<br />
nearly halfway to the<br />
beginning of time.<br />
16<br />
VIRGO<br />
Use these finder charts to zero in on the two quasars. ASTRONOMY: RICHARD TALCOTT AND ROEN KELLY<br />
1°<br />
E<br />
DRACO<br />
N<br />
PG 1634<br />
+706<br />
BROWSE THE “SECRET SKY” ARCHIVE AT www.<strong>Astronomy</strong>.com/OMeara.<br />
Astronomers classify PG<br />
1634+706 as a hyperluminous<br />
infrared galaxy, one of the<br />
intrinsically brightest objects<br />
in the sky. When it reaches<br />
maximum, it shines at magnitude<br />
14.24. At its faintest, the<br />
galaxy dips to magnitude 14.7,<br />
making it a decent challenge<br />
for trained visual observers<br />
15<br />
FROM OUR INBOX<br />
Spectacular<br />
WOW! I just received my March issue of <strong>Astronomy</strong> magazine.<br />
The graphic cover image of our universe is spectacular. Great<br />
illustration and perspective by Don Dixon. — John White,<br />
Martinez, Georgia<br />
Cosmic wonders<br />
Thanks to Stephen James O’Meara for his fine column “The face<br />
of beauty?” — p. 22, February 2016. I have five of his Deep-Sky<br />
Companions books and follow his articles with great interest.<br />
As a retired symphony orchestra musician and now keen<br />
visual astronomer, I can strongly relate to the aesthetic elements<br />
in his article, where I can easily move between musical and cosmic<br />
wonders.<br />
Only last evening I was being seduced by the Orion Nebula<br />
(M42) via my short 6-inch refractor and binoviewer — yes, the<br />
wonder and beauty in all that swirling chaos! Having had the<br />
privilege of performing the great musical works, I find that<br />
Josef Strauss’ “Music of the Spheres” still has a special ethereal<br />
resonance every time I hear it.<br />
I must investigate the novel Orfeo, which sounds like my sort<br />
of read. I suppose that striving for concord amongst life’s dissonance<br />
is an essential quest for us.<br />
Perhaps I’m a 19th-century astronomer at heart, just outside<br />
absorbing the wonder of the Music of the Spheres!<br />
— Greg Blackman, Adelaide, Australia<br />
Correction<br />
In the February 2016 issue’s “Land of mystery and enchantment,”<br />
p. 35, we misspelled David Blewitt. It should be David<br />
Blewett. — <strong>Astronomy</strong> Editors<br />
URSA<br />
MINOR<br />
1°<br />
using at least a 10-inch telescope<br />
under a dark sky.<br />
PG 1634+706 was brightest<br />
around the year 2000, but is<br />
now nearing its dimmest.<br />
Luckily, PG 1634+706 lies in a<br />
fine field, being only about 7'<br />
southwest of a pair of 8thmagnitude<br />
stars. Furthermore,<br />
this pair lies about 2° northnortheast<br />
of the magnitude 5.0<br />
star 15 Draconis, now culminating<br />
in the north.<br />
Despite my suggested apertures<br />
above, I hate to put a size<br />
limit on what telescope is<br />
needed to see these quasars<br />
(especially PG 1634+706). I<br />
never want to scare off keeneyed<br />
observers who would get a<br />
thrill from snagging this object<br />
through smaller-than-expected<br />
apertures. So fear not and test<br />
the limits of your vision. As<br />
always, let me know how you<br />
do at sjomeara@gmail.com.<br />
18 ASTRONOMY • JUNE 2016
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