IF IT’S CLEAR
By Fulton Wright Jr.
Prescott, AZ

Celestial events (from Sky & Telescope magazine, Astronomy magazine, and anywhere else I can find information) customized for Prescott, Arizona. 

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May 2017

Comet hunters, check out Sky & Telescope, May 2017, p. 50 for information about comets this month.

On Tuesday, May 2, the Moon is at first quarter phase and sets at 1:39 AM (Wednesday). The phase occurs at 7:48 PM (Tuesday). You might want to check how close to half lit the Moon appears at that time.

On Wednesday, May 10, at 7:19 PM, the full Moon rises spoiling any chance of hunting for faint fuzzies for the night.
At 11:20 PM the full Moon occults the 4th magnitude star, Gamma Librae. The star reappears at 12:52 AM (Thursday). This will be a difficult observation because of the glare from the full Moon. Use a big telescope and high power.

On Thursday, May 18, the Moon is at last quarter phase and rises at 1:31 AM (Friday).
From 8:53 PM (Thursday) to 9:38 PM, both Io’s and Europa’s shadows will be on Jupiter.

On Thursday, May 25, it is new Moon and you have all night to hunt for faint fuzzies.
From 10:47 PM to 12:14 AM (Friday), both Io’s and Europa’s shadows will be on Jupiter.

On Sunday, May 28, starting about 8:00 PM, you can see Mare Crisium at its best. The phase is good and libration tips that part of the Moon toward us.

On Wednesday, May 31, at 9:28 PM, the nearly first quarter Moon occults the 4th magnitude star, Rho Leonis. The star reappears on the bright limb of the Moon at 10:37 PM. The star may be a very close double star and make its transition in two steps.

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June 2017

For the comet hunters among you, check out the article in the June 2017 issue of Astronomy Magazine, p. 42. Also check out the June 13 entry in this article.

On Thursday, June 1, at 8:00 PM the Moon just misses Roe Leonis. Starting at 10:16 PM, you can observe a double shadow transit on Jupiter. Here is the schedule:
10:16 PM Europa moves in front of the planet.
11:38 PM Io moves in front of the planet.
12:29 AM (Friday) Europa’s shadow falls on the planet (1 shadow).
12:42 AM Io’s shadow falls on the planet (2 shadows).
12:44 AM Europa appears at the edge of the planet.
01:48 AM Io appears at the edge of the planet.
02:29 AM Jupiter sets (with both shadows on it).

On Saturday, June 3, you can observe a double shadow transit on Jupiter. Io is already in front of the planet. Ganymede has already passed the planet. The Moon is near Jupiter while all this is happening. Here is the schedule:
07:10 PM Io’s shadow falls on the planet (1 shadow).
07:16 PM Ganymede’s shadow falls on the planet (2 shadows).
07:39 PM Sunset.
08:10 PM You might be able to spot the planet.
08:16 PM Io appears at the edge of the planet.
09:18 PM Io’s shadow leaves the planet (1 shadow).
09:29 PM Ganymede’s shadow leaves the planet.
09:55 PM The red spot transits (crosses the meridian of) the planet.

On Thursday, June 8, the full Moon rises at 7:01 PM, spoiling the whole night for faint fuzzy observation.

On Saturday, June 10, at 11:18 PM we almost have a double shadow transit on Jupiter as Io’s shadow leaves at the same time that Ganymede’s falls on the planet.

On the night of Sunday, June 11, all of Saturn’s bright moons are on the west (IAU, terrestrial) side of the planet.

On Tuesday, June 13, at 11:10 PM, The 6.7 magnitude comet, C/2015 V2 (Johnson), passes within 20 arc-seconds of the 6.2 magnitude star, HR 5394 (SAO 120436). (Remember, estimates of comet brightness are just guesses.) You should be able to detect motion of the comet in just a few minutes.

On Wednesday, June 14, Saturn reaches opposition, which means it will be visible all night.

On Friday night, June 16, the third quarter phase Moon rises at 12:43 AM (Saturday).

On Saturday, June 17, you can see a number of events with Jupiter’s moons. Here is the schedule:
09:48 PM Io moves in front of the planet.
09:53 PM Europa moves behind the planet.
10:17 PM Ganymede moves in front of the planet.
11:00 PM Io’s shadow falls on the planet.
11:58 PM Io moves from in front of the planet.
12:45 AM (Sunday) Ganymede moves from in front of the planet.
01:07 AM Io’s shadow leaves the planet.
01:26 AM Jupiter sets.

On Wednesday, June 21, the Sun reaches the Summer Solstice (in the Northern hemisphere), so we have shortest (but perhaps the warmest) night of the year.

On Friday, June 23, it is new Moon, and you have all night to hunt for faint fuzzies.

On Saturday, June 24, at 8:19 PM, just when you can find Jupiter in the twilight, Io emerges from the face of Jupiter. Io’s shadow is in the middle of Jupiter, and the satellite Europa is North (right above) it. They both exit about 9:30 PM. Europa’s shadow lands on the planet about 10 minutes later. It’s on the planet till midnight.

On Friday night, June 30, At 7:45 PM the Moon just misses Porrima (Gamma Virginis). The first quarter Moon sets at 12:40 AM (Saturday).