My first Magazine Sky & Telescope - 02.2019 | Page 52

FEBRUARY 2019 OBSERVING
Celestial Calendar
Action at Jupiter
JUPITER SHINES in Ophiuchus on
Asteroid Occultation
EARLY ON THE MORNING of February
11th, the 15.5-magnitude asteroid 301
Bavaria temporarily blocks the light of
a 9.3-magnitude star for observers in
parts of North America. The occulted
F6/F7-type main-sequence star, HD
144893 (HIP 79094), lies 390 light-years
away in the direction of Scorpius. At
the time of occultation, 301 Bavaria, a
55.5-km-wide main belt asteroid, will
be about 2.6 astronomical units from
Earth. The occultation lasts a maximum
of 2.3 seconds.
Johann Palisa, observing from the
University of Vienna with a 27-inch
f/15.4 Grubb refractor, discovered 301
Bavaria on November 16, 1890. It was
his 75th asteroid discovery. The aster-
oid’s Germanic name was suggested
the next year by Benjamin Gould,
founder of the Astronomical Journal.
He proposed using the designation to
commemorate the August 1891 meeting
of the German Astronomical Society
(Astronomische Gesellschaft) in Munich,
Bavaria’s capital.
The predicted path of visibility
crosses North America from Colorado
through South Carolina to Bermuda.
The region of visibility for an occulta-
tion of a star by an asteroid (minor
planet) can be uncertain by about 0.5
path widths (pw) for most events. In
this case, the uncertainty is 0.35 pw,
meaning the path may actually be a bit
narrower or broader. Multiple observa-
tions from across (and beyond) the
predicted path will produce a more
accurate outline of 301 Bavaria’s shape.
The 6.2-magnitude drop in bright-
ness should occur within a minute or
two of 10:17 UT for observers in the
central United States (3:17 MST for Fort
Collins, 4:17 CST for Kansas City and
Nashville) and within a minute or two
50
FE B RUA RY 2 019 • SK Y & TELESCOPE
of 10:18 UT for those in the southeast
(5:18 EST for Charleston). The involved
star, which shines about 3½° north-
northeast of Nu (ν) Scorpii, stands
fairly high at these times, around 20°
high for Kansas and 35° high for South
Carolina.
Precise predictions and a path map
are available from Steve Preston’s
minor-planet occultation website
( astero idoccultation.com ). For more
on planning your observations, setting
up your equipment, and reporting your
results, visit the International Occulta-
tion Timing Association (IOTA) website
( occultations.org ). Asteroid and lunar
occultation enthusiasts may also join
an active online discussion group at
groups.yahoo.com/neo/groups/IOTA-
occultations .
Minima of Algol
Jan. UT Feb. UT
3
6 15:53
12:42 1
4 8:06
4:55
9 9:32 7 1:45
12 6:21 9 22:34
15 3:10 12 19:23
17 23:59 15 16:13
20 20:49 18 13:02
23 17:38 21 9:51
26 14:27 24 6:41
29 11:17 27 3:30
These geocentric predictions are from the
recent heliocentric elements Min. = JD
2445641.554 + 2.867324E, where E is any
integer. For a comparison-star chart and
more info, see skyandtelescope.com/algol.
• FIND YOUR CLUB:
skyandtelescope.com/astronomy-
clubs-organizations
February mornings, rising before 4
a.m. local standard time. As its west-
ward elongation increases through
the month, the giant planet rises a bit
earlier. Jupiter grows bigger and bolder
every morning, brightening from mag-
nitude –1.9 to –2.0 and fattening from
33½″ to 36″ wide by the 28th.
Any telescope shows the four big
Galilean moons, and binoculars usu-
ally show at least two or three. Use the
diagram on the facing page to identify
them at any date and time. The dates at
the diagram’s left are in Universal Time.
Virtually any telescope shows the
interaction of the Galilean moons and
their shadows with Jupiter. All of the
February interactions are tabulated on
the facing page. Find events timed for
when Jupiter is at its highest in the early
morning hours.
More aperture and steady seeing
will reveal Jupiter’s Great Red Spot
(GRS). Here are the times, in UT, when
the GRS should cross Jupiter’s central
meridian. The dates, also in UT, are
in bold. (Eastern Standard Time is UT
minus 5 hours.)
Jan. 1, 3:12, 13:07, 23:03; 2, 8:59,
18:55; 3, 4:51, 14:46; 4, 0:42, 10:38,
20:34; 5, 6:30, 16:25; 6, 2:21, 12:17,
22:13; 7, 8:09, 18:04; 8, 4:00, 13:56,
23:52; 9, 9:47, 19:43; 10, 5:39, 15:35;
11, 1:31, 11:26, 21:22; 12, 7:18, 17:14;
13, 3:09, 13:05, 23:01; 14, 8:57, 18:53;
15, 4:48, 14:44; 16, 0:40, 10:36, 20:31;
17, 6:27, 16:23; 18, 2:19, 12:15, 22:10;
19, 8:06, 18:02; 20, 3:58, 13:53, 23:49;
21, 9:45, 19:41; 22, 5:36, 15:32; 23,
1:28, 11:24, 21:20; 24, 7:15, 17:11; 25,
3:07, 13:03, 22:58; 26, 8:54, 18:50; 27,
4:46, 14:41; 28, 0:37, 10:33, 20:29; 29,
6:24, 16:20; 30, 2:16, 12:12, 22:07; 31,
8:03, 17:59.
Feb. 1, 3:55, 13:50, 23:46; 2, 9:42,
19:38; 3, 5:33, 15:29; 4, 1:25, 11:21,
21:16; 5, 7:12, 17:08; 6, 3:04, 12:59,
22:55; 7, 8:51, 18:47; 8, 4:42, 14:38; 9,
0:34, 10:29, 20:25; 10, 6:21, 16:17; 11,
2:12, 12:08, 22:04; 12, 8:00, 17:55; 13,
3:51, 13:47, 23:43; 14, 9:38, 19:34; 15,
5:30, 15:25; 16, 1:21, 11:17, 21:13; 17,