The phenomena of the month : April 2021 Times are given in UT for Aveiro (8° 38' 55" W, 40° 38' 20" N, zone Z). Date Hour Description of the phenomenon yyyy mm dd hh:mm

1 2021 04 01 11:46 Maximum of the variable star delta Cephei 2 2021 04 02 15:32 Minimum of the variable star Algol (beta Persei) 3 2021 04 03 18:16 Maximum of the variable star eta Aquilae 4 2021 04 04 00:00 EASTER DAY 5 2021 04 04 05:31 Beginning of occultation of 34-sigma Sgr, Nunki, (magn. = 2,05)

6 2021 04 04 05:34 Opposition of the asteroid 9 Metis with the Sun (dist. to the Sun = 2,500 AU; magn. = 9,5) 7 2021 04 04 06:55 End of occultation of 34-sigma Sgr, Nunki, (magn. = 2,05) 8 2021 04 04 10:02 LAST QUARTER OF THE MOON 9 2021 04 05 07:04 Close encounter between the Moon and Pluto (topocentric dist. center to center = 3,1°) 10 2021 04 05 12:21 Minimum of the variable star Algol (beta Persei)

11 2021 04 06 11:59 Close encounter between the Moon and Saturn (topocentric dist. center to center = 4,5°) 12 2021 04 06 20:33 Maximum of the variable star delta Cephei 13 2021 04 07 11:59 Close encounter between the Moon and Jupiter (topocentric dist. center to center = 4,8°) 14 2021 04 08 09:10 Minimum of the variable star Algol (beta Persei) 15 2021 04 09 16:28 Close encounter between the Moon and Neptune (topocentric dist. center to center = 4,2°)

16 2021 04 10 07:49 Maximum of the variable star zeta Gemini 17 2021 04 10 22:30 Maximum of the variable star eta Aquilae 18 2021 04 11 05:59 Minimum of the variable star Algol (beta Persei) 19 2021 04 12 02:31 NEW MOON 20 2021 04 12 05:21 Maximum of the variable star delta Cephei

21 2021 04 12 11:33 Minimum of the variable star beta Lyrae 22 2021 04 13 15:18 Close encounter between the Moon and Uranus (topocentric dist. center to center = 2,6°) 23 2021 04 14 02:49 Minimum of the variable star Algol (beta Persei) 24 2021 04 14 17:47 Moon at apogee (geocentric dist. = 406119 km) 25 2021 04 15 20:33 Beginning of occultation of 50-omega2 Tau (magn. = 4,93)

26 2021 04 15 21:34 End of occultation of 50-omega2 Tau (magn. = 4,93) 27 2021 04 16 23:38 Minimum of the variable star Algol (beta Persei) 28 2021 04 17 11:06 Close encounter between the Moon and Mars (topocentric dist. center to center = 0,7°) 29 2021 04 17 14:08 Maximum of the variable star delta Cephei 30 2021 04 18 02:43 Maximum of the variable star eta Aquilae

31 2021 04 19 01:48 SUPERIOR CONJUNCTION of Mercury with the Sun (geoc. dist. center to center = 0,6°) 32 2021 04 19 20:27 Minimum of the variable star Algol (beta Persei) 33 2021 04 20 06:59 FIRST QUARTER OF THE MOON 34 2021 04 20 11:26 Maximum of the variable star zeta Gemini 35 2021 04 20 21:17 Close encounter between the Moon and M 44 (topocentric dist. center to center = 2,4°)

36 2021 04 22 07:05 Meteor shower : Lyrids (18 meteors/hour at zenith; duration = 9,0 days) 37 2021 04 22 17:16 Minimum of the variable star Algol (beta Persei) 38 2021 04 22 20:45 Beginning of occultation of 46 Leo (magn. = 5,43) 39 2021 04 22 21:51 End of occultation of 46 Leo (magn. = 5,43) 40 2021 04 22 22:56 Maximum of the variable star delta Cephei

41 2021 04 23 11:56 Meteor shower : Pi Puppids (duration = 13,0 days) 42 2021 04 25 06:57 Maximum of the variable star eta Aquilae 43 2021 04 25 10:06 Minimum of the variable star beta Lyrae 44 2021 04 25 14:05 Minimum of the variable star Algol (beta Persei) 45 2021 04 27 01:00 Mercury at its perihelion (distance to the Sun = 0,30750 AU)

46 2021 04 27 03:31 FULL MOON 47 2021 04 27 06:36 Close encounter between Mars and M 35 (topocentric dist. center to center = 0,5°) 48 2021 04 27 15:24 Moon at perigee (geocentric dist. = 357378 km) 49 2021 04 28 07:43 Maximum of the variable star delta Cephei 50 2021 04 28 10:54 Minimum of the variable star Algol (beta Persei)

51 2021 04 30 01:29 Beginning of occultation of 42-theta Oph (magn. = 3,27) 52 2021 04 30 02:44 End of occultation of 42-theta Oph (magn. = 3,27) 53 2021 04 30 15:03 Maximum of the variable star zeta Gemini 54 2021 04 30 19:54 CONJUNCTION between Uranus and the Sun (geoc. dist. center to center = 0,4°)