The phenomena of the month : September 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 09 01 00:15 End of occultation of 132 Tau (magn. = 4,88) 2 2021 09 01 11:09 Maximum of the variable star eta Aquilae 3 2021 09 01 14:38 Minimum of the variable star Algol (beta Persei) 4 2021 09 01 19:48 Minimum of the variable star beta Lyrae 5 2021 09 01 23:55 Maximum of the variable star Mira (omicron Ceti)

6 2021 09 03 02:31 Beginning of occultation of 77-kappa Gem (magn. = 3,57) 7 2021 09 03 03:15 End of occultation of 77-kappa Gem (magn. = 3,57) 8 2021 09 03 03:26 Close encounter between the Moon and Pollux (topocentric dist. center to center = 3,5°) 9 2021 09 04 02:34 Maximum of the variable star delta Cephei 10 2021 09 04 03:40 Close encounter between the Moon and M 44 (topocentric dist. center to center = 2,4°)

11 2021 09 04 11:27 Minimum of the variable star Algol (beta Persei) 12 2021 09 05 20:45 Close encounter between Venus and Spica (topocentric dist. center to center = 1,6°) 13 2021 09 06 00:00 Mercury at its aphelion (distance to the Sun = 0,46670 AU) 14 2021 09 06 01:00 Simultaneous transits on Jupiter: two satellites and shadow of one satellite. 15 2021 09 07 00:52 NEW MOON

16 2021 09 07 08:15 Minimum of the variable star Algol (beta Persei) 17 2021 09 08 15:23 Maximum of the variable star eta Aquilae 18 2021 09 08 21:18 Comet 4P Faye at its perihelion (dist. to the Sun = 1,611 AU; magn. = 11,7) 19 2021 09 09 00:30 Close encounter between the Moon and Mercury (topocentric dist. center to center = 5,2°) 20 2021 09 09 05:17 Meteor shower : Sept. Perseids (5 meteors/hour at zenith; duration = 16,0 days)

21 2021 09 09 11:21 Maximum of the variable star delta Cephei 22 2021 09 09 13:50 Maximum of the variable star zeta Gemini 23 2021 09 10 04:00 Close encounter between the Moon and Venus (topocentric dist. center to center = 3,3°) 24 2021 09 10 05:04 Minimum of the variable star Algol (beta Persei) 25 2021 09 11 03:47 Opposition of the asteroid 2 Pallas with the Sun (dist. to the Sun = 3,145 AU; magn. = 8,5)

26 2021 09 11 10:06 Moon at perigee (geocentric dist. = 368461 km) 27 2021 09 13 01:53 Minimum of the variable star Algol (beta Persei) 28 2021 09 13 20:39 FIRST QUARTER OF THE MOON 29 2021 09 14 00:00 GREATEST EASTERN ELONGATION of Mercury (26,6°) 30 2021 09 14 09:22 OPPOSITION of Neptune with the Sun

31 2021 09 14 18:23 Minimum of the variable star beta Lyrae 32 2021 09 14 20:08 Maximum of the variable star delta Cephei 33 2021 09 15 19:38 Maximum of the variable star eta Aquilae 34 2021 09 15 22:41 Minimum of the variable star Algol (beta Persei) 35 2021 09 16 06:23 Close encounter between the Moon and Pluto (topocentric dist. center to center = 2,5°)

36 2021 09 17 05:38 Close encounter between the Moon and Saturn (topocentric dist. center to center = 4,0°) 37 2021 09 17 19:47 Comet 6P d'Arrest at its perihelion (dist. to the Sun = 1,356 AU; magn. = 9,9) 38 2021 09 18 09:21 Close encounter between the Moon and Jupiter (topocentric dist. center to center = 4,0°) 39 2021 09 18 19:30 Minimum of the variable star Algol (beta Persei) 40 2021 09 19 17:25 Maximum of the variable star zeta Gemini

41 2021 09 20 04:56 Maximum of the variable star delta Cephei 42 2021 09 20 11:46 Close encounter between the Moon and Neptune (topocentric dist. center to center = 4,1°) 43 2021 09 20 23:55 FULL MOON 44 2021 09 21 16:18 Minimum of the variable star Algol (beta Persei) 45 2021 09 21 23:46 Close encounter between Mercury and Spica (topocentric dist. center to center = 1,4°)

46 2021 09 22 19:21 AUTUMN EQUINOX 47 2021 09 22 23:53 Maximum of the variable star eta Aquilae 48 2021 09 24 13:07 Minimum of the variable star Algol (beta Persei) 49 2021 09 24 16:52 Close encounter between the Moon and Uranus (topocentric dist. center to center = 2,0°) 50 2021 09 25 13:43 Maximum of the variable star delta Cephei

51 2021 09 26 21:44 Moon at apogee (geocentric dist. = 404640 km) 52 2021 09 27 09:56 Minimum of the variable star Algol (beta Persei) 53 2021 09 27 16:58 Minimum of the variable star beta Lyrae 54 2021 09 29 01:57 LAST QUARTER OF THE MOON 55 2021 09 29 20:59 Maximum of the variable star zeta Gemini

56 2021 09 30 04:09 Maximum of the variable star eta Aquilae 57 2021 09 30 06:44 Minimum of the variable star Algol (beta Persei) 58 2021 09 30 22:30 Maximum of the variable star delta Cephei