April 2008 Calendar by Dave Mitsky

All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)

4/2 Pluto is stationary at 0:00; Mercury is 1.6 degrees south of Uranus at 7:00; Neptune is 0.002 degree south of the Moon - an occultation takes place in the Middle East, central Africa, and central South America - at 9:00
4/4 Uranus is 3 degrees south of the Moon at 10:00
4/5 Mars is at its greatest heliocentric latitude north today; Venus is 5 degrees south of the Moon at 1:00; a double Galilean shadow transit begins at 6:58
4/6 Asteroid 5 Astraea (magnitude 9.4) is at opposition at 0:00; New Moon (lunation 1055) occurs at 3:55; a minimum lunar libration of 6.2 degrees occurs at 7:00
4/7 The Moon is at perigee, subtending 33'06" from a distance of 361,080 km (224,365 miles), at 19:30
4/9 The Moon is 1.0 degree north of the bright open cluster M45 (the Pleiades) in Taurus at 2:00; Asteroid 7 Iris (magnitude 9.5) is at opposition at 9:00
4/10 Jupiter reaches western quadrature today; Asteroid 41 Daphne (magnitude 9.3) is at opposition at 21:00
4/11 A maximum lunar libration of 7.1 degrees occurs at 6:00
4/12 The lunar illumination event known as the Purbach Cross or the Werner X begins to appear at 0:00; Mars is 1.2 degrees south of the Moon - an occultation takes place in northern Scandinavia, Iceland, Greenland, and northeastern Canada - at 6:00; First Quarter Moon occurs at 18:32
4/13 The Moon is 0.1 degree north of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 20:00
4/15 The Moon is 0.9 degree south of the first magnitude star Regulus (Alpha Leonis) - an occultation takes place in Madagascar and part of Antarctica - at 14:00; Saturn is 3 degrees north of the Moon at 18:00
4/16 Mercury is in superior conjunction with the Sun at 7:00; a minimum lunar libration of 6.0 degrees occurs at 22:00
4/17 Jupiter is at the descending node today
4/18 Asteroid 3 Juno is stationary today
4/20 Mercury is at the ascending node today; Full Moon, known as the Egg or Grass Moon, occurs at 10:25
4/22 The peak of the Lyrid meteor shower (20/hour) occurs at 4:00; a maximum lunar libration of 6.6 degrees occurs at 9:00
4/23 The Moon is at apogee, subtending 29'26" from a distance of 405,943 km (252,241 miles), at 9:34; the Moon is 0.3 degree south of the first magnitude star Antares (Alpha Scorpii) - an occultation takes place in Polynesia, New Zealand, and southern Australia - at 17:00
4/24 Mercury is at perihelion today
4/26 A double Galilean shadow transit begins at 20:29
4/27 Jupiter is 3 degrees north of the Moon at 5:00
4/28 Last Quarter Moon occurs at 14:12; Mars is 5 degrees south of the first magnitude star Pollux (Beta Geminorum) at 19:00
4/29 Neptune is 0.3 degree south of the Moon - an occultation takes place in Hawaii, northern Australasia, and most of Indonesia - at 19:00

On the morning of April 22, the peak of the Lyrid meteor shower is compromised by the light from a waning gibbous Moon. At the end of the month, some early Eta Aquarid meteors may be visible.

The zodiacal light is visible from a dark site in the early evening during the first week of April.

At approximately 9:45 p.m. EDT on April 8, the three-day-old crescent Moon occults some of the stars (Pleiads) in the northern portion of the Pleiades. The occultation is visible from eastern Canada and the northeastern United States. The Moon is 24.3 days old at 0:00 UT on April 1. It's at its greatest southern declination of -28 degrees on April 24 and its greatest northern declination of +28 degrees on April 10. 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

The Sun is located in Pisces on April 1. The first photograph of the Sun was taken on April 2, 1845.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on April 1: Mercury (-0.6 magnitude, 5.2", 89% illuminated, 1.29 a.u., Pisces), Venus (-3.8 magnitude, 10.4", 95% illuminated, 1.61 a.u., Aquarius), Mars (0.8 magnitude, 7.0", 90% illuminated, 1.34 a.u., Gemini), Jupiter (-2.2 magnitude, 37.4", 99% illuminated, 5.27 a.u., Sagittarius), Saturn (0.4 magnitude, 19.6", 100% illuminated, 8.49 a.u., Leo), Uranus (5.9 magnitude, 3.4", 100% illuminated, 20.90 a.u., Aquarius), Neptune (7.9 magnitude, 2.2", 100% illuminated, 30.49 a.u., Capricornus), and Pluto (13.9 magnitude, 0.1", 100% illuminated, 31.00 a.u., Sagittarius).

During April, Mercury is located in the west at month’s end, Mars is in the southwest, and Saturn is in the southeast during the evening. Look for Mars in the west and Saturn in the southwest at midnight. In the morning, Jupiter can be seen in the southeast and Uranus in the east.

Mercury is not visible until the end of April for northern hemisphere observers. It can be seen low in the west-northwest during evening twilight.

On April 1, Venus rises little more than a half hour before the Sun for observers in the Northern Hemisphere. By mid-month, Venus rises about 30 minutes after the Sun and its current morning apparition comes to an end.

Mars shrinks from 7 to 6 arc seconds during April and decreases in magnitude from 0.8 to 1.2. It is one degree east of third magnitude Epsilon Geminorum as the month begins and passes five degrees south of equally bright Pollux by April 28. In the middle of April, Mars sets around 2:00 a.m. EDT.

The king of the planets rises about 3:00 a.m. EDT on April 1, at about the same time that Mars sets on April 15, and around 1:00 a.m. EDT on April 30. It brightens by 0.2 magnitude and grows in apparent size from 37 to 41 arc seconds during this time. Jupiter is 90 degrees to the west of the Sun on April 10, a condition known as western quadrature. As a result, Jupiter’s shadow falls well to the west of the planet. Click on http://skyandtelescope.com/observing...icle_107_1.asp to determine transits of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://www.skyandtelescope.com/obser...t/3307071.html

At the middle of the month, Saturn culminates at approximately 10:00 p.m. and sets in the west-northwest prior to 5:00 a.m. EDT. Saturn’s rings open to 9.9 degrees by late April. The ring tilt angle then begins to decrease as the rings become increasingly edge-on. Saturn continues its westward or retrograde motion towards Regulus by almost a degree during April. Eighth magnitude Titan, Saturn’s brightest satellite, passes north of the planet on the nights of April 10 and April 26 and south of Saturn on the nights of April 2 and April 18. Two-faced Iapetus is due east or west of Saturn by the listed separations on the following dates: April 2 (35" east), April 8 (40" east), April 16 (33" east), April 20 (25" east), April 24 (14" east), April 28 (2" east), and April 30 (4" west). On the night of April 28, Iapetus is positioned to the immediate south of Saturn. For further information on Saturn’s satellites, browse http://www.skyandtelescope.com/obser...t/3308506.html

Uranus remains a very difficult morning target this month.

Neptune lies in northeastern Capricornus, 2.4 degrees north of the third magnitude star Delta Capricorni and is also too low in the sky to observe readily.

The dwarf planet Pluto is located in northwestern Sagittarius.

Comet 46P/Wirtanen continues to fade as it passes through Auriga and into Gemini. It shines at only 12th magnitude when it nears the fourth magnitude star Theta Geminorum in mid-April.

The ninth magnitude asteroid 5 Astraea heads on a northwesterly course through the star-sparse constellation of Virgo this month. It passes 2 arc minutes south of a ninth magnitude star on the evening of April 21.

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

Notable variable star for April: S Ursae Majoris (Ursa Major)

Notable carbon star for April: V Hydrae (Hydra)

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 3630, 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)

Top ten deep-sky objects for April: M65, M66, M95, M96, M97, M105, M108, NGC 3115, NGC 3242, NGC 3628

Top ten binocular deep-sky objects for April: M65, M66, M95, M96, M97, M105, M108, M109, NGC 3115, NGC 3242

Challenge deep-sky object for April: Leo I (Leo)

The objects listed above are located between 10:00 and 12:00 hours of right ascension.

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