Sky & Telescope - March 2019 - 50

MARCH 2019 OBSERVING
Celestial Calendar

Action at Jupiter

Lunar Occultation
THERE ARE NO OCCULTATIONS

of 1st-magnitude stars by the Moon
visible from North America in 2019.
The brightest stars to be hidden by
the Moon (at least for our continent)
range only from magnitudes 2.9 to 3.9:
Delta1 Tauri; Zeta Tauri; Delta, Eta, and
Mu Geminorum; Gamma Librae; and
Gamma Capricorni. The next 1st-magnitude event involves Antares in 2023,
with visibility limited to Florida.
In the meantime, we enjoy the dimming of lesser lights. On the night of
March 12-13, the Moon passes in front
of Delta1 (δ) Tauri (HD 27697) in the
Hyades for western North America. The
waxing crescent will be heading toward
its set, standing only 20° or 25° high
when the dark leading limb slips across
the 3.8-magnitude star. Delta1 disappears at the Moon's northeastern edge
near or after 6h UT and reappears at
the west-northwestern edge less than
an hour later. The reappearance may
be difﬁcult to detect as it occurs at the
Moon's bright limb. The Moon is only
10° or 15° above the horizon at most at
that point, so atmospheric effects add
to the challenge.
About 25 or 30 minutes after Delta1
goes missing, the Moon occults Delta2
(HD 27819). The 4.8-magnitude star
disappears behind the Moon's eastern,
dark limb. We won't see the star again
this night, as the Moon sets before the
star reappears at its bright limb.
Observers near Seattle, Salt Lake
City, and other places along the
northern limits of the occultation path
should watch for a grazing event, when
Delta1 seems to skim by the Moon's
northern limb, very near the terminator. Look for the star to blink on and
off as it's covered and revealed by the
moving Moon's valleys and mountains.
A few minutes after the graze event, the
50

M A RCH 2 019 * SK Y & TELESCOPE

Moon's leading edge covers Delta2.
Delta1 is a known double, and
observations of the occultation are
highly desired by the International
Occultation Timing Association (IOTA).
Timetables are available from the IOTA
website (https://is.gd/IOTApredict). You
can also calculate predictions for your
observing site using IOTA's free software program, Occult (https://is.gd/
IOTAoccult).
Here are some times for a few major
cities. For Delta1: Sacramento, disappearance 10:56 p.m., reappearance 11:45
p.m. PDT; Los Angeles, d. 10:58 p.m.,
r. 11:53 p.m. PDT; Seattle, graze 11:13
p.m. PDT; Denver, d. 12:11 MDT, gr.
12:20 MDT; Salt Lake City, gr. 12:18
a.m. MDT.
For Delta2: Seattle, d. 11:16 p.m.
PDT; Sacramento, d. 11:22 PDT; Los
Angeles, d. 11:27 p.m. PDT; Salt Lake
City, d. 12:23 a.m. MDT; d. Denver,
12:25 a.m. MDT.

Minima of Algol
Feb.

UT

Mar.

UT

1
4

8:06
4:55

2
4

0:19
21:09

7

1:45

7

17:58

9

22:34

10

14:47

12

19:23

13

11:36

15

16:13

16

8:26

18

13:02

19

5:15

21

9:51

22

2:04

24

6:41

24

22:54

27

3:30

27

19:43

30

16:32

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.

JUPITER SHINES on in Ophiuchus in
March, rising about 2 a.m. local standard time as the month opens. By the
31st, its rise time has crept forward only
to about 1:30 a.m., thanks to daylightsaving time.
Jupiter stands highest in the south
as the Sun rises. You may notice an
improvement in visibility as the planet
brightens from magnitude -2.0 to -2.2
over the course of the month. Jupiter
broadens in March as well, its equatorial diameter increasing from 36″ wide
to 40″ wide by the 31st.
Any telescope shows the 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.
The March 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.
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
Daylight Time is UT minus 4 hours.)
Feb. 1: 4:01, 13:57, 23:53; 2: 9:48,
19:44; 3: 5:40, 15:36; 4: 1:31, 11:27,
21:23; 5: 7:19, 17:14; 6: 3:10, 13:06,
23:02; 7: 8:57, 18:53; 8: 4:49, 14:45; 9:
0:40, 10:36, 20:32; 10: 6:28, 16:23; 11:
2:19, 12:15, 22:11; 12: 8:06, 18:02; 13:
3:58, 13:53, 23:49; 14: 9:45, 19:41; 15:
5:36, 15:32; 16: 1:28, 11:24, 21:19; 17:
7:15, 17:11; 18: 3:06, 13:02, 22:58; 19:
8:54, 18:49; 20: 4:45, 14:41; 21: 0:36,
10:32, 20:28; 22: 6:24, 16:19; 23: 2:15,
12:11, 22:06; 24: 8:02, 17:58; 25: 3:54,
13:49, 23:45; 26: 9:41, 19:36; 27: 5:32,
15:28; 28: 1:23, 11:19, 21:15
Mar. 1: 7:11, 17:06; 2: 3:02, 12:58,
22:53; 3: 8:49, 18:45; 4: 4:41, 14:36; 5:
0:32, 10:28, 20:23; 6: 6:19, 16:15; 7:
2:10, 12:06, 22:02; 8: 7:57, 17:53; 9:
3:49, 13:45, 23:40; 10: 9:36, 19:32; 11:
5:27, 15:23; 12: 1:19, 11:14, 21:10; 13:
7:06, 17:01; 14: 2:57, 12:53, 22:48; 15:
8:44, 18:40; 16: 4:35, 14:31; 17: 0:27,
10:22, 20:18; 18: 6:14, 16:09; 19: 2:05,
12:01, 21:56; 20: 7:52, 17:48; 21: 3:43,
https://www.is.gd/IOTApredict https://www.is.gd/IOTAoccult https://www.is.gd/IOTAoccult http://www.skyandtelescope.com/algol
Sky & Telescope - March 2019

Table of Contents for the Digital Edition of Sky & Telescope - March 2019
