One of the items on my "life's list" is to experience each of the
significant meteor showers at least once. One that had yet to be checked off
was the south delta Aquarids, which emanate from far in the south during
the lingering days of perpetual twilight way up here in the Baked White North
(N. 53.55°, W. 113.55° ). But as I left my Odyssium Observatory shift at 11:30
Monday evening July 28, I looked at the calm and cooling skies, no sign of a
Moon anywhere, a rising beacon marking the radiant, and decided in the words
of Tracy Chapman, "if not now, then when?" So I pulled on a couple of
hoodies (what my kid calls a kangaroo jacket) and headed to the outskirts of
Edmonton, happening on a
moderately dark site with a clear south horizon that I will use
again. The Milky Way was readily visible, especially in the familiar
region of the Cygnus star cloud. I settled in at 1:40 a.m. MDT to keep count.
I have had
precious little luck with other versions of the Aquarids, notably the eta
Aquarids of early May. I have tried to observe them the last two years in
conjunction with the Sky Scan radio meteor detection project,
seeing exactly zero on both occasions and feeling lucky to see even that many
:), given the strong southern bias of this particular shower. For the
south deltas, the radiant is another 15 degrees further south, hardly
promising. But a key difference between the showers is that both
radiants are near the same right ascension, despite being separated by almost
three months on the calendar, meaning the south delta radiant rises some five
hours earlier and actually transits the meridian in darkness. So its effective
altitude is higher, for longer, than the Sun-chased etas.
Mild aurora and forest fire smoke conspired to keep the limiting magnitude to
a modest 5.0 or so, so I knew counts wouldn't be particularly high, but it's
easy to be patient when one has the beautiful night sky to keep one company.
The highlight (if not high enough) was Mars, dominating the southern sky like
a pink Jupiter less than five degrees from the radiant, and arranged in a
tight right triangle with tau 2 and with delta Aquarii itself. I noted with
amusement that rising Mars was being doused by the Water Jar of Aquarius
directly above. While there was no sign of steam rising from the fiery planet,
I fearlessly predicted that Mars would stop to reconsider, and back up a few
degrees before speeding through the cascade several months from now. In the
interim, we will have a splendid look at our elusive neighbour. As I admired it, a very slow
2nd magnitude sparkler whizzed by just to the east.
As I waited and watched, at 2:07
a.m. a brilliant Iridium flare of at least mag -6 materialized
right in the tiny asterism known as Job's Coffin (a.k.a. The Diamond of
Delphinus). On my taped notes I suggested I might need the patience of Job on
this night.
With that, at last a few meteors started falling, or rising in some
cases from southern radiants. At 2:13
a.m., I finally saw my first (identified) Aquarid meteor of any
type, a 2nd magnitude streak heading east of Mars, midway between
Ares and Aries.
Just two minutes later I experienced a very peculiar sight that I keep
meaning to ask my friends on meteorobs about, a suspected sighting of a "dark
meteor". It resembled a photographic negative, a dark streak also emanating
from Job's Coffin passing in front of the Milky Way, which is presumably the
only place where such an apparition could be seen. This is maybe the fourth
that I have spotted in all my years of meteor watching, and every time I rub
my eyes and ask myself if I'm seeing things. So, am I?
After another dry spell, I mentioned to my recorder that things are a
bit too serene and peaceful, and
I'd like to see a little upper-atmospheric violence. Within seconds of hitting
the stop button, a 1st magnitude delta Aq split the arrow of
Sagitta.
A little burst followed with an assortment of meteors from various
radiants. In my rush to get out of town I had stupidly forgotten to read up on
minor showers in progress, so I made careful taped notes of the positions of
each meteor. They were few enough that I could visualize each as I transcribed
my notes the next day, identifying them as alpha Capricornids, a north delta
Aquarid, and anthelion meteors. And there were a couple of early Perseids that
I needed no help identifying.
As the night wore on I spotted the late-rising lonely luminary
Fomalhaut, twinkling weakly away as if under water directly below Mars.
Forever trapped within six scintillating degrees of my horizon, Fomalhaut
seems to foam (a lot!) at the foot of the falls beneath the Water Jar.
Even recognizing that the creation of fanciful asterisms is a fun pastime
during prolonged meteor-free periods, round about this point I concluded I was
getting punchy enough to call it a night. I spotted one last
meteor at 3:59, a south delta that
appropriately enough disappeared into Job's Coffin. Excluding the dark meteor,
in 150 minutes of observing I saw 15 meteors, exactly one per ten-minute bin,
as follows:
5 south delta Aquarids
(magnitudes 2, 1, 0, 2, 3).
1 north delta Aquarid (3)
3 alpha Capricornids (4, 1.5,
1)
2 Perseids (3, 2)
2 Anthelion (2, -1)
2 sporadic (2, -2)
Mediocre limiting magnitudes and southern radiants conspired to keep my
counts low to the point where I feel calculating ZHRs would be all but
meaningless. That said, and as usual, I felt inspired by my night's "work". Of
all observing activities, meteor observing best confirms Earth's status as an
active participant in the cosmos.
Anybody who cares to can have a front row seat observing the
upper-atmospheric frontier between heavens and Earth.
regards, Bruce