Sky and Telescope - February 2018 - 50

FEBRUARY 2018 OBSERVING
Celestial Calendar

* FIND YOUR CLUB:

Asteroid Occultations
If you're in the north, plan to observe
an asteroid occultation on the night
of February 16th, when the 146-kmdiameter asteroid 20 Massalia passes
in front of a star in Taurus. Observers
along a path across southern Canada
and the northern United States will
see 9.2-magnitude HD 35003 (TYC
1308-01348-1) disappear for up to 19
seconds.

The region of visibility for an occultation of a star by a minor planet can
be uncertain by about 0.5 path widths
(pw) for most events, but because 20
Massalia is a well-known, well-tracked
asteroid, the uncertainty here is only
0.05 pw. A line drawn on a map from
Spokane, Washington, through Winnipeg, Manitoba, to St. John's, Newfoundland and Labrador, will give you

Action at Jupiter
Jupiter's westward elongation gradually
increases in February, so the striped
planet rises earlier each morning. By
the second half of the month, it's visible half the night - the second half.
Jupiter brightens from magnitude -2.0
to -2.2 over the course of February and
increases its girth from 36″ to 39″.
Any telescope shows Jupiter's four big
Galilean moons, and binoculars usually show at least two or three. Use the
diagram on the facing page to identify
them at any date and time.
All of the February interactions
between Jupiter and its satellites and
their shadows are tabulated on the facing page. Find events timed for when
Jupiter is at its highest in the early
morning hours.
And here are the times, in Universal
Time, when the Great Red Spot should
cross Jupiter's central meridian. The
dates, also in UT, are in bold. (Eastern
Standard Time is UT minus 5 hours.)
February 1, 6:26, 16:21; 2, 2:17,
12:13, 22:08; 3, 8:04, 18:00; 4, 3:55,
13:51, 23:47; 5, 9:42, 19:38; 6, 5:34,
15:29; 7, 1:25, 11:21, 21:17; 8, 7:12,
17:08; 9, 3:04, 12:59, 22:55; 10, 8:51,
18:46; 11, 4:42, 14:38; 12, 0:33, 10:29,
20:25; 13, 6:20, 16:16; 14, 2:12, 12:07,
22:03; 15, 7:59, 17:54; 16, 3:50, 13:46,
23:41; 17, 9:37, 19:33; 18, 5:28, 15:24;
50

FE B RUA RY 2 018 * SK Y & TELESCOPE

19, 1:20, 11:15, 21:11; 20, 7:07, 17:02;
21, 2:58, 12:54, 22:49; 22, 8:45, 18:41;
23, 4:36, 14:32; 24, 0:27, 10:23, 0:19;
25, 6:14, 16:10; 26, 2:06, 12:01, 21:57;
27, 7:53, 17:48; 28, 3:44, 13:40, 23:35.
March 1, 9:31, 19:27; 2, 5:22, 15:18;
3, 1:13, 11:09, 21:05; 4, 7:00, 16:56;
5, 2:52, 12:47, 22:43; 6, 8:38, 18:34;
7, 4:30, 14:25; 8, 0:21, 10:17, 20:12; 9,
6:08, 16:04; 10, 1:59, 11:55, 21:50; 11,
7:46, 17:42; 12, 3:37, 13:33, 23:29; 13,
9:24, 19:20; 14, 5:15, 15:11; 15, 1:07,
11:02, 20:58; 16, 6:53, 16:49; 17, 2:45,
12:40, 22:36; 18, 8:31, 18:27; 19, 4:23,
14:18; 20, 0:14, 10:10, 20:05; 21, 6:01,
15:56; 22, 1:52, 11:48, 21:43; 23, 7:39,
17:34; 24, 3:30, 13:26, 23:21; 25, 9:17,
19:12; 26, 5:08, 15:04; 27, 0:59, 10:55,
20:50; 28, 6:46, 16:42; 29, 2:37, 12:33,
22:28; 30, 8:24, 18:20; 31, 4:15, 14:11.
These times assume that the spot
will be centered at System II longitude 285°. If the Red Spot has moved
elsewhere, it will transit 12/3 minutes
earlier for each degree less than 285°
and 12/3 minutes later for each degree
more than 285°.
Features on Jupiter appear closer to
the central meridian than to the limb
for 50 minutes before and after transiting. A light blue or green ﬁlter slightly
increases the contrast and visibility of
Jupiter's reddish and brownish markings.

skyandtelescope.com/astronomyclubs-organizations

a good idea of where you'll want to be
that night.
The long duration and small pw
uncertainty makes this an easier event
to view than the occultation of a star
by asteroid 540 Rosamunde, visible
along a path connecting Baja California
Sur to central Florida on the night of
February 13th. While the 7.0-magnitude drop in brightness will be dramatic

Minima of Algol
Feb.

UT

Mar.

UT

2

4:30

2

20:43

5

1:19

5

17:32

7

22:09

8

14:22

10

18:58

11

11:11

13

15:47

14

8:00

16

12:37

17

4:50

19

9:26

20

1:39

22

6:15

22

22:28

25

3:05

25

19:17

27

23:54

28

16:07

31

12:56

These geocentric predictions are from the recent
heliocentric elements Min. = JD 2445641.5540+
2.86732400E, where E is any integer. For a
comparison-star chart and more info,
see skyandtelescope.com/algol.

29
30

18

PERSEUS
38

Algol

21

TRIANGULUM

34
http://www.skyandtelescope.com/astronomy-clubs-organizations http://www.skyandtelescope.com/algol
Sky and Telescope - February 2018

Table of Contents for the Digital Edition of Sky and Telescope - February 2018
