Astronomical Diary
MOON PHASES
lastquarterjpg newmoonjpg firstquarter.jpg
fullmoonjpg
Last Quarter New Moon First Quarter Full Moon
April 4
06:02 PM
April 12
10:31 AM
April 20
02:59 PM
April 27
11:32 AM
SPACE WEATHER
Current Condition
SOLAR WIND

Speed: 347.1 km/sec
Density: 5.9 protons/cm3
More Data: ACE, DSCOVR
Updated: Mar 31 at 0645 UT

***Sunspot AR2812 remains stable and quiet.

Credit: Solar Dynamics Observatory(SDO)/
Helioseismic and Magnetic Imager (HMI).
X-ray Solar Flares
6-hr max:
A4 0549 UT Mar31
24-hr: B7 2005 UT Mar30
Updated: Mar 31 at 0650 UT


Sun: 30 Mar 2021
DSun
Time (PST) of rise and set of some planets at 10-day interval
DATE MERCURY VENUS MARS JUPITER SATURN
Rise Set Rise Set Rise Set Rise Set Rise Set
April 01 5:03 AM 5:00 PM 6:01 AM 6:03 PM 9:49 AM 10:47 PM 3:15 AM 2:47 PM 2:31 AM 1:56 PM
April 11 5:22 AM 5:36 PM 6:02 AM 6:26 PM 9:35 AM 10:35 PM 2:42 AM 2:16 PM 1:55 AM 1:20 PM
April 21 5:48 AM 6:21 PM 6:05 AM 6:39 PM 9:22 AM 10:22 PM 2:09 AM 1:44 PM 1:18 AM 12:43 PM

* = Following day
Astronomical Events April 2021

Supermoon

April 27 Full Moon is considered as a supermoon. It is a full moon with a perigee distance of 357,378 km away from Earth. The closest that the Moon comes to the Earth in its elliptic orbit, resulting in a slightly larger-than-usual apparent size of the lunar disk as viewed from Earth. The technical name is a perigee-syzygy (of the Earth-Moon-Sun system).

The term supermoon is astrological in origin and has no precise astronomical definition. It was popularized by astrologer Richard Nolle. The real association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with an increased risk of events like earthquakes and volcanic eruptions, but no such link has been found.




Meteor Shower

The Lyrids meteor shower has been observed for more than 2,600 years. The meteor shower is created by bits of debris left behind by the repeated passages through the inner solar system of comet Thatcher (C/1861 G1). Chinese records show that "stars fell like rain" during the meteor shower of 687 B.C. However, in recent times, the Lyrids have generally been weak. The shower typically generates a dozen meteors per hour under optimal conditions with a brief maximum that lasts for less than a day. The shower’s peak this year will be in progress from April 22 to the predawn of April 23. Although not numerous, Lyrids are bright and fast meteors. Figure 1 shows the position of the radiant of the meteor shower at the constellation Lyra, the Lyre, on April 23 at around 2:00 AM.

Figure 1
Figure 1
Stars and Constellations

At around 7:30 PM, the seven stars that make up the Big Dipper and one of the most familiar patterns in the sky will be located in the northern hemisphere. The curved handle of the Big Dipper is pointing towards a bright orange star, Arcturus of the constellation Bootes, the Herdsman. Due south will be another bright star, Spica, the prominent star of the constellation Virgo, the Virgin. Figures 2 & 2a show how to locate the Big Dipper and these bright stars.

The Beehive Cluster, also known as Praesepe (Latin word for “manger”), M44, NGC 2632 or Cr 189, in the constellation Cancer, the Crab that spans more than a degree of the sky is shown in Figures 2b & 2c. It is an Open Type cluster of stars in which ten of its stars shine between magnitude +6.3 to +6.9. The Beehive is one of the nearest open clusters of stars in the Solar System. Under cloudless and dark sky conditions, it looks like a nebulous object to the naked eye, thus it has been known since ancient times. Ptolemy, a classical Greek astronomer called it “the nebulous mass in the breast of Cancer,” and it was the first object that Galileo studied with his telescope. The Beehive Cluster is a good target for an observer using a binocular with the aid of a star map.

Figure2
Figure 2
Figure2a
Figure 2a
Fig2b
Figure 2b
Fig2c
Figure 2c
Planets Whereabout

On 01 April, at 4:00 AM, Jupiter and Saturn will be found at about 20 and 10 degrees above the east southeastern horizon shining at magnitudes -2.1 and +0.8, respectively. They will remain visible throughout the month before sunrise. These Giant gas planets will be a good target for observations and astrophotography. To view Atmospheric features of these planets, satellites and rings will require a modest-sized telescope under a dark and clear sky condition.

At 7:00 PM, Uranus and Mars will be observed, standing at about 12 and 49 degrees above the west northwestern horizon with magnitudes +5.8 and +1.3, respectively. Uranus will be found among the background stars of the constellation Aries, the Ram while Mars abodes among the stars of the constellation Taurus, the Bull. Observing these planets will require a starmap under a dark and clear sky condition.

Venus, Mercury, and Neptune will be out for observations during the month due to their proximity to the Sun.

Figures 3 & 4 show how to compare apparent magnitudes and angular separation of celestial bodies such as planets and stars, respectively.

Fig3
Figure 3
Fig4
Figure 4


APRIL 2021
DATE
EVENT
TIME (PST)
7 Ceres in conjunction with Sun 3:00 PM
9 Neptune 4° N of Moon 7:00 PM
13 Juno stationary 10:00 AM
13 Uranus 2° N of Moon 8:00 PM
15 Moon at apogee (farthest distance to Earth = 406,119 km) 1:46 AM
17 Mars 0.1° N of Moon (occultation) 8:00 PM
19 Mercury in superior conjunction 10:00 AM
23 Vesta stationary 2:00 AM
27 Moon at perigee (nearest distance to Earth = 357,378 km)
FULL MOON (SUPERMOON)
11:22 PM
11:32 AM
29 Pluto stationary 3:00 AM
31 Uranus in conjunction with Sun 4:00 AM



ERRATA FOR THE ALMANAC FOR GEODETIC ENGINEERS 2020

Regarding the publication on page 2 of the ALMANAC FOR GEODETIC ENGINEERS 2020, which contains the data for the EPHEMERIS OF THE SUN, it was verified that the February 29, 2020 date is missing but the data for the particular date is the data printed as March 1, 2020. The data printed from April 3 to December 31 are all correct.

Kindly refer to the image/link below for the data errata on the Ephemeris of the Sun 2020.
Errata2020
Errata of AGE 2020, page 2
(Errata of AGE 2020 pdf file)