April Calendar by Dave Mitsky

All times are UT (subtract 4 hours and when appropriate 1 calendar day for EDT after April 2)

4/1 The Galilean satellites Io and Callisto are both the same distance west of Jupiter at 3:31; maximum lunar libration of 7.0 degrees occurs at 22:00
4/2 Last Quarter Moon occurs at 00:50
4/3 Daylight Saving Time begins; Jupiter subtends 44.2" and shines at -2.5 magnitude when it reaches opposition at 16:00; Mars is 4 degrees north of the Moon at 22:00
4/4 Neptune is 5 degrees north of the Moon at 9:00; the Moon is at perigee, subtending 32'26" from a distance of 368,493 kilometers, at 11:00
4/5 Uranus is 3 degrees north of the Moon at 22:00
4/7 Mercury is 3 degrees north of the Moon at 14:00
4/8 Mars is 0.7 degree south of Theta Capricorni today; minimum lunar libration of 4.6 degrees occurs at 00:00; New Moon (lunation 1018) occurs at 20:32 - a rare hybrid eclipse, which runs from annular to total to annular, occurs along a narrow swath from east of New Zealand to Central America
4/9 Io, Europa, and Callisto form a slanted line to the east of Jupiter at 4:53
4/10 Mercury is at the descending node today; Saturn reaches eastern quadrature today
4/11 Mercury is stationary at 2:00; the Moon is 0.9 degree south of the open star cluster the Pleiades (M45) at 22:00
4/13 Mars (magnitude 0.8) is 1.2 degrees south of Neptune (magnitude 7.9) at 00:00
4/14 Jupiter is at aphelion today; Mars is 0.2 degree east of Iota Capricorni today
4/15 Maximum lunar libration of 6.9 degrees occurs at 2:00
4/16 Astronomy Day (USA); Saturn is 5 degrees south of the Moon at 1:00; First Quarter Moon occurs at 14:37; the Moon is at apogee, subtending 29'33" from a distance of 404,304 kilometers, at 19:00
4/20 Mars is 1.2 degrees north of Gamma Capricorni today
4/21 Mercury is at aphelion today
4/22 Mars is 1.1 degrees north of Delta Capricorni today; the peak of the Lyrid meteor shower (10-15/hour) occurs at 10:00 - it is compromised by strong moonlight; Jupiter is 0.6 degree north of the Moon at 18:00 - and occultation occurs in part of Antarctica, the southern Indian Ocean, and most of the southern half of Africa
4/24 Minimum lunar libration of 5.4 degrees occurs at 00:00; Full Moon (known as the Pink, Seed, Egg, Grass, or Awakening Moon) occurs at 10:06 - a penumbral lunar eclipse affecting the northern portion of the Moon takes place in North and South America
4/26 The Moon is 1.0 degree south of Jupiter at 16:00; Mercury (0.4 magnitude) is at greatest western elongation (27 degrees) at 17:00; the first magnitude star Antares (magnitude 1.1) is 0.7 degree south of the Moon at 23:00 - an occultation occurs in eastern Asia, northeast Africa, most of Europe, and parts of Great Britain
4/29 Mars is 0.5 degree north of Iota Aquarii today; maximum lunar libration of 6.8 degrees occurs at 21:00; the Moon is at perigee, subtending 32'23" from a distance of 369,029 kilometers, at 10:00
4/30 Uranus (magnitude 5.9) is 1.7 degrees southwest of the fourth magnitude star Lambda Aquarii

Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm

On April 26, Mercury can be seen a mere 4 degrees above the eastern horizon during its worst northern hemisphere morning apparition of 2005. By the end of the month, Mercury's altitude increases to about 10 degrees.

Venus is not an easy target until early May.

Mars travels from Capricornus to Aquarius in late April. It is visible low in the southeast during morning twilight.

Located in Virgo, Jupiter reaches opposition on April 3 and is visible the entire night. At midnight it is due south, shining at -2.5 magnitude. Since Jupiter attains aphelion just 11 days after it reaches opposition, it will be as small and dim as possible during this year's opposition. For observers in the eastern United States, the Great Red Spot transits Jupiter's central meridian at the indicated UT times on the following dates: 4/1 at 2:45, 4/2 at 8:32, 4/3 at 4:23, 4/4 at 00:15, 4/5 at 6:01, 4/6 at 1:53, 4/7 at 7:39, 4/8 at 3:31, 4/9 at 9:17, 4/10 at 5:08, 4/11 at 1:00, 4/12 at 6:46, 4/13 at 2:38, 4/14 at 8:24, 4/15 at 4:16, 4/16 at 00:07, 4/17 at 5:54, 4/18 at 1:45, 4/19 at 7:32, 4/20 at 3:23, 4/21 at 9:10, 4/22 at 5:01, 4/23 at 00:52, 4/24 at 6:39, 4/25 at 2:30, 4/26 at 8:17, 4/27 at 4:09, 4/28 at 00:00 and 9:55, 4/29 at 5:47, and 4/30 at 1:38.

Saturn, in western Gemini, appears particularly three-dimensional this month due to the prominence of its shadow on the rings to the east of the planet's disk. Titan is due north of the planet on the nights of April 4 and April 20 and is due south of it on the nights of April 12 and April 28. The 8th magnitude moon is due west of Saturn on April 8 and due east on April 16. Iapetus shines at brightest, 10.1 magnitude, when reaches greatest western elongation on April 24.

On April 30, Uranus is 1.7 degrees southwest of the fourth magnitude star Lambda Aquarii.

Neptune is 1.2 degrees north of Mars on the night of April 12/13. Mars subtends 6.2" and Neptune 2.2" at the time of this conjunction.

In early April, Pluto is located 24' north-northeast of Xi Serpentis. During the course of the month, it moves away from the star in a northwesterly direction.

A circumpolar object, Comet C/2004 Q2 (Machholz) travels through Draco towards Ursa Major during April. The comet, which has faded to seventh magnitude, may sport a short dust tail that points away from Polaris. At mid-month, Comet Machholz Q2 passes to the west of the ninth magnitude, barred spiral galaxy NGC 4236.

As it heads northward through Coma Berenices, the large asteroid 2 Pallas passes to the west of the spiral galaxy M99 on April 6 and to the east of the spiral galaxy M98 on April 8. Pallas is less than 30' from the fifth magnitude star 6 Comae Berenices from April 7 through April 9.

Seventy-five binary and multiple stars for April: h4481 (Corvus); Aitken 1774, Gamma Crateris, Jacob 16, Struve 3072, h4456, Burnham 1078 (Crater); h4311, Burnham 219, N Hydrae, h4455, h4465 (Hydra); 31 Leonis, Alpha Leonis (Regulus), h2520, Struve 1417, 39 Leonis, Struve 1421, Gamma Leonis (Algieba), Otto Struve 216, 45 Leonis, Struve 1442, Struve 1447, 49 Leonis, Struve 1482, 54 Leonis, Struve 1506, Chi Leonis, 65 Leonis, Struve 1521, Struve 1527, Struve 1529, Iota Leonis, 81 Leonis, 83 Leonis, Tau Leonis, 88 Leonis, 90 Leonis, Struve 1565, Struve 1566, 93 Leonis, h1201, S Leonis (Leo); h2517, Struve 1405, Struve 1432, 33 Leo Minoris, Struve 1459, 40 Leo Minoris, Struve 1492 (Leo Minor); Struve 1401, Struve 1441, Struve 1456, Struve 1464, 35 Sextantis, 40 Sextantis, 41 Sextantis (Sextans); Struve 1402, Sturve 1415, Struve 1427, Struve 1462, Struve 1486, Struve 1495, Struve 1510, Struve 1520, Xi Ursae Majoris, Nu Ursae Majoris, Struve 1541, 57 Ursae Majoris, Struve 1544, Struve 1553, Struve 1561, Struve 1563, 65 Ursae Majoris, Otto Struve 241 (Ursa Major)

Challenge binary star for April: Gamma Sextantis

One hundred deep-sky objects for April: NGC 4024, NGC 4027 (Corvus); NGC 3511, NGC 3513, NGC 3672, NGC 3887, NGC 3892, NGC 3955, NGC 3962, NGC 3981 (Crater); NGC 3091, NGC 3109, NGC 3145, NGC 3203, NGC 3242, NGC 3309, NGC 3585, NGC 3621, NGC 3717, NGC 3904, NGC 3936 (Hydra); M65, M66, M95, M96, M105, NGC 3098, NGC 3162, NGC 3177, NGC 3185, NGC 3190, NGC 3226, NGC 3227, NGC 3300, NGC 3346, NGC 3367, NGC 3377, NGC 3384, NGC 3389, NGC 3412, NGC 3437, NGC 3489, NGC 3495, NGC 3507, NGC 3521, NGC 3593, NGC 3607, NGC 3608, NGC 3626, NGC 3628, NGC 3640, NGC 3640, NGC 3646, NGC 3655, NGC 3681, NGC 3684, NGC 3686, NGC 3691, NGC 3810, NGC 3842, NGC 3872, NGC 3900, NGC 4008 (Leo); NGC 3245, NGC 3254, NGC 3277, NGC 3294, NGC 3344, NGC 3414, NGC 3432, NGC 3486, NGC 3504 (Leo Minor); NGC 2990, NGC 3044, NGC 3055, NGC 3115, NGC 3156, NGC 3166, NGC 3169, NGC 3246, NGC 3423 (Sextans); IC 750, M97, M108, M109, NGC 3079, NGC 3184, NGC 3198, NGC 3310, NGC 3359, NGC 3610, NGC 3665, NGC 3675, NGC 3738, NGC 3877, NGC 3898, NGC 3941, NGC 3953, NGC 3998, NGC 4026 (Ursa Major)

Challenge deep-sky object for April: Leo I

__________________
Chance favors the prepared mind.
De gustibus non est disputandum.
Never attribute to malice that which can be adequately explained by stupidity.

Thank you - Jupiter really is a show this month!

__________________
Science is wonderfully equipped to answer the question "How?" but it gets terribly confused when you ask the question "Why?"
Erwin Chargaff