April 2004 Astronomical Data
April 2004 Astronomical Calendar
Dave Mitsky
Note: All times in UTC (subtract 4 hours and when appropriate 1 calendar day for DST)
| 4/1 | Maximum lunar libration of 9.0 degrees occurs at 10:00 |
|---|---|
| 4/2 | Saturn is at its greatest northern declination of 22 degrees 49' at 6:00; a double Galilean shadow transit begins at 15:35; Jupiter is 3 degrees south of the Moon at 19:00 |
| 4/3 | Venus is 0.6 degree south of M45 (the Pleiades) at 02:00 |
| 4/4 | Mars is just north of 4.3 magnitude Nu Tauri; Daylight Saving Time begins at 07:00; a double Galilean shadow transit begins at 09:06 |
| 4/5 | Full Moon, known as the Egg or Grass Moon, occurs at 11:03; Io, Europa, and Callisto are in close proximity at 21:00 |
| 4/6 | The Moon is 3.6 degrees north-northeast of the first magnitude star Spica at 01:00; a double Galilean shadow transit begins at 04:54; Mercury is stationary in right ascension at 21:00 - retrograde (western) motion commences |
| 4/7 | The Moon is at the descending node (longitude 221.3 degrees) at 05:06; minimum lunar libration of 1.6 degrees occurs at 19:00; only one of Jupiter's Galilean satellites, namely Callisto, is visible between 22:57 and 23:53 |
| 4/8 | The Moon is at perigee, subtending 32'47" from a distance of 364,547 km, at 02:00 |
| 4/9 | The Moon is 2.1 degrees north of the first magnitude star Antares at 04:00; a double Galilean shadow transit begins at 18:13 |
| 4/11 | A double Galilean shadow transit begins at 12:23 |
| 4/12 | Last Quarter Moon occurs at 03:46; Venus is at greatest heliocentric latitude north (3.4 degrees) at 14:00 |
| 4/13 | A double Galilean shadow transit begins at 07:31; Neptune is 5 degrees north of the Moon at 16:00 |
| 4/14 | Maximum lunar libration of 8.6 degrees occurs at 07:00 |
| 4/15 | Uranus is 4 degrees north of the Moon at 04:00; the equation of time equals zero (i.e., clocks and sundials are in agreement) at 06:00 |
| 4/16 | A double Galilean shadow transit begins at 20:50 |
| 4/17 | Mercury is at inferior conjunction (1.86 degrees north of the Sun) at 01:00 |
| 4/18 | The Sun enters Aries (ecliptic longitude 28.88 degrees) |
| 4/19 | New Moon (lunation 1006) occurs at 13:21; a partial solar eclipse is visible from southern Africa and portions of Antarctica |
| 4/20 | A double Galilean shadow transit begins at 08:08; the Moon is at the ascending node (longitude 41.2 degrees) at 11:43 |
| 4/21 | Minimum lunar libration of 2.3 degrees occurs at 13:00 |
| 4/22 | The Moon is 2.3 degrees south-southeast of M45 (the Pleiades) at 02:00; the peak of the Lyrid meteor shower (20/hour) occurs at 04:00 |
| 4/23 | Comet C/2002 T7 (LINEAR) is at perihelion at 01:00; Venus is 1.5 degrees north of the Moon at 10:00; Mars is 2 degrees south of the Moon at 21:00; Mercury is at the descending node at 21:00; a double Galilean shadow transit begins at 21:21 |
| 4/24 | Astronomy Day (USA); the Moon is at apogee, subtending 29'28" from a distance of 405,403 km, at 00:00 |
| 4/25 | Saturn is 5 degrees south of the Moon at 06:00; Venus (magnitude -4.5) is 5.6 degrees west-northwest of Mars (magnitude 1.6) at 23:00 |
| 4/26 | The Moon is 1.7 degrees south of the first magnitude star Pollux at 13:00 |
| 4/27 | A double Galilean shadow transit begins at 10:34; the Moon is 3.7 degrees north-northeast of M44 (the Beehive Cluster) at 17:00; First Quarter Moon occurs at 17:32 |
| 4/28 | Asteroid 5 Astraea (magnitude 9.8) reaches opposition today |
| 4/29 | Comet C/2003 (Tabor) reaches perihelion today; maximum lunar libration of 9.5 degrees occurs at 06:00; Mercury is stationary in right ascension at 10:00 - direct or prograde (eastward) motion resumes; the Moon is 4.5 degrees north-northeast of the first magnitude star Regulus at 12:00; asteroid 1 Ceres (magnitude 8.6) is 1.8 degrees north-northeast of Pollux (magnitude 1.2) at 15:00 |
| 4/30 | May Eve (Walpurgisnacht), a cross-quarter day; Jupiter is 4 degrees south of the Moon at 02:00 |
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 five naked-eye planets known to the ancients are visible at the same time during the first week of the month.
A tiny crescent Mercury (8.1", 32% illumination) is 28 degrees below Venus at the beginning of April but is soon lost in the Sun's glare as it heads for conjunction on the 17th.
Venus is within a degree of the Pleiades from April 1st to April 4th. On April 2nd Venus is less than 0.5 degree away from the star Merope. The next day it is even closer to Atlas. At mid-month Venus sets four hours after Sol. By the end of April it shines brilliantly at -4.5 magnitude as a 30% illuminated crescent with an angular diameter twice that of Saturn.
Mars, situated in Taurus, dwindles in brightness to 1.6 magnitude, more than 200 times dimmer than Venus. The two planets grow closer together until they reach a minimum separation of 5.6 degrees on April 25.
Decreasing slowly in magnitude to -2.2 by April 30th Jupiter still shines brightly in Leo.
Saturn is at its farthest northern point in its 29.5 year long orbit on April 2nd. The Ringed Planet appears particularly three-dimensional this month since it has just passed eastern quadrature. It is still the brightest object in the constellation of Gemini.
This month it is possible to observe Pluto in Ophiuchus late at night and Uranus in Aquarius and Neptune in Capricornus just prior to dawn.
Comet C/2002 T7 (LINEAR) is visible very close to the eastern horizon at morning twilight sometime in mid-April. On April 30th a second magnitude Comet /2001 Q4 can be seen from the southern United States well below Sirius.
Asteroid 1 Ceres continues its eastward trek through Gemini. In the latter part of April it passes between Castor and Pollux. By month's end it has dimmed to 8.6 magnitude.
Binary and Multiple Stars for April
Click here for list in tabular form.
h4311, N Hydrae, h4455, h4465 (Hydra); Alpha Leonis (Regulus), Gamma Leonis (Algieba), 54 Leonis, Sruve 1506, Chi Leonis, 65 Leonis, 83 Leonis, 88 Leonis, 90 Leonis (Leo); Struve 1432, Struve 1492 (Leo Minor); Struve 1401, Struve 1441, 35 Sextantis (Sextans); Struve 1402, Struve 1415, Struve 1462, Struve 1486, Struve 1495, Struve 1510, Struve 1520, Xi Ursae Majoris, 57 Ursae Majoris, Struve 1553, Struve 1563, 65 Ursae Majoris (Ursa Major)
| Deep-sky objects for April: | ||||||
|---|---|---|---|---|---|---|
| Hydra: | ||||||
| NGC 3109 | [info] | NGC 3242 | [info] | |||
| Leo: | ||||||
| M 65 | [info] | M 66 | [info] | M 95 | [info] | |
| M 96 | [info] | M 105 | [info] | NGC 3227 | [info] | |
| NGC 3251 | [info] | NGC 3377 | [info] | NGC 3384 | [info] | |
| NGC 3412 | [info] | NGC 3489 | [info] | NGC 3521 | [info] | |
| NGC 3593 | [info] | NGC 3607 | [info] | NGC 3628 | [info] | |
| NGC 3640 | [info] | NGC 3680 | [info] | NGC 3810 | [info] | |
| LeoMinor: | ||||||
| NGC 3344 | [info] | NGC 3504 | [info] | |||
| Sextans: | ||||||
| NGC 3115 | [info] | NGC 3166 | [info] | NGC 3169 | [info] | |
| UrsaMajor: | ||||||
| M 97 | [info] | M 108 | [info] | M 109 | [info] | |
| NGC 3079 | [info] | NGC 3184 | [info] | NGC 3310 | [info] | |
| NGC 3359 | [info] | NGC 3665 | [info] | NGC 3675 | [info] | |
| NGC 3877 | [info] | NGC 3898 | [info] | NGC 3941 | [info] | |
| NGC 3953 | [info] | NGC 3998 | [info] | NGC 4026 | [info] | |
| Click here for a printable deep sky summary. |
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