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June 2021 Celestial Calendar

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#1 Dave Mitsky

Dave Mitsky


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Posted 31 May 2021 - 10:56 PM

June 2021 Celestial Calendar by Dave Mitsky


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


6/1   The middle of the eclipse season (i.e., the Sun is at the same longitude as the Moon’s ascending node, 70.9 degrees) occurs at 3:00; the Moon is 5.0 degrees south of Jupiter at 9:00
6/2   The Last Quarter Moon occurs at 7:24
6/3   The Moon is 4.1 degrees south-southeast of Neptune at 5:00
6/4   The Curtiss Cross, an X-shaped clair-obscur illumination effect located between the craters Parry and Gambart, is predicted to be visible at 00:28; Venus is 0.1 degrees north-northeast of the bright open cluster M35 in Gemini at 11:00; Mars is at its northernmost latitude from the ecliptic plane (1.8 degrees) at 18:00; a double Galilean satellite shadow transit (Ganymede’s shadow precedes Io’s) begins at 23:22

6/5   Venus is at its northernmost declination (24.4 degrees) at 12:00
6/6   Mars and Jupiter are at heliocentric conjunction (longitudes 140.7 degrees and 320.7 degrees) at 20:00; asteroid 3 Juno (magnitude +10.1) is at opposition in Ophiuchus at 22:00
6/7   The Moon is 2.1 degrees south-southeast of Uranus at 9:00
6/8   The Moon is at apogee, subtending 29' 25" from a distance of 406,226 kilometers (252,418 miles), at 2:27; the Moon is 5.0 degrees southeast of the bright open cluster M45 (the Pleiades or Subaru) in Taurus at 21:00
6/9   The Moon is 5.4 degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at 15:00; the Moon is at the ascending node (longitude 70.8 degrees) at 17:00
6/10 Mercury is at aphelion (0.4667 at 1:00; New Moon (lunation 1218) occurs at 10:52; an annular eclipse of the Sun begins at 08:12:20.5 UT1 and ends at 13:11:21.8 UT1; the Moon is 3.9 degrees north of Mercury at 13:00
6/11 Mercury is in inferior conjunction with the Sun (0.551 astronomical units from the Earth, latitude -3.7 degrees) at 1:00; the Moon is 1.1 degrees north-northeast of M35 at 13:00
6/12 A double Galilean satellite shadow transit (Io’s shadow precedes Ganymede’s) begins at 2:39; the Moon is 1.5 degrees north of Venus at 7:00; Venus is at perihelion (0.7184 astronomical units from the Sun) at 18:00; the equation of time, which yields the difference between mean solar time and apparent solar time, equals 0 at 21:00
6/13 The Moon is 6.7 degrees south of the first-magnitude star Castor (Alpha Geminorum) at 2:00; the Moon is 3.1 degrees south of the first-magnitude star Pollux (Beta Geminorum) at 7:00; the Moon is 2.8 degrees north-northeast of Mars at 22:00
6/14 The earliest sunrise of the year at latitude 40 degrees north occurs today; the Moon is 3.1 degrees north-northeast of the bright open cluster M44 (the Beehive Cluster or Praesepe) in Cancer at 9:00
6/16 The Moon is 4.7 degrees north-northeast of the first-magnitude star Regulus (Alpha Leonis) at 4:00;
6/17 The Purbach Cross or Lunar X, an X-shaped clair-obscur illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to be visible at 11:33
6/18 First Quarter Moon occurs at 3:54
6/19 Venus is 8.7 degrees south of Castor at 13:00
6/20 The Moon is 5.9 degrees north-northeast of Spica at 4:00
6/21 The summer solstice occurs at 3:32; Jupiter is stationary, with retrograde (westward) motion to begin, at 5:00; the Sun enters Gemini (longitude 90.46 degrees on the ecliptic) at 15:00; Venus is 5.2 degrees south of Pollux at 22:00
6/22 Mercury is 6.1 degrees east-northeast of the first-magnitude star Aldebaran (Alpha Tauri) at 22:00; Mercury is stationary, with prograde (eastern) motion to begin, at 23:00
6/23 The Moon exhibits its minimum libration for the year (0.05 degrees) at 6:00; the Moon is at the descending node (longitude 250.7 degrees) at 6:00; the Moon is 4.6 degrees north-northeast of the first-magnitude star Antares (Alpha Scorpii) at 7:00; the Moon is at perigee, subtending 33' 12" from a distance of 359,957 kilometers (223,666 miles), at 9:55; Mars is 0.03 degrees southeast of M44 at 23:00
6/24 Full Moon occurs at 18:40
6/26 A double Galilean satellite shadow transit (Callisto’s shadow precedes Io’s) begins at 5:03; Neptune is stationary, with retrograde (western) motion to begin, at 10:00
6/27 The latest sunset of the year at latitude 40 degrees north occurs today; the Moon is 3.9 degrees south-southeast of Saturn at 12:00
6/28 The Moon is 4.2 degrees south-southeast of Jupiter at 22:00
6/30 Mercury is at its southernmost latitude from the ecliptic plane (-7.0 degrees) at 7:00; the Moon is 4.0 degrees south-southeast of Neptune at 13:00


Giovanni Cassini (1625-1712), John Dollond (1706-1761), Charles Messier (1730-1817), William Lassell (1799-1880), George Ellery Hale (1868-1938), and Carolyn Shoemaker (1929) were born this month.


The British astronomer Edmund Halley discovered M13 on June 1, 1714.  The French astronomer Nicolas Louis de Lacaille discovered the globular cluster M55 on June 16, 1752.  A transit of the Sun by Venus was observed by Austrian, British, and French astronomers from various parts of the world on June 6, 1761.  The French astronomer Charles Messier discovered the globular cluster M14 on June 1st, 1764, the emission and reflection nebula M20 (the Trifid Nebula) on June 5, 1764, and the open cluster M23 on June 20, 1764.  The globular cluster M62 was discovered by Charles Messier on June 7, 1771.  The French astronomer Pierre Méchain discovered his first deep-sky object, the spiral galaxy M63 (the Sunflower Galaxy), on June 14, 1779.  The German/English astronomer William Herschel discovered the globular cluster NGC 6288 on June 24, 1784.  Neptune was independently discovered by the British astronomer John Couch Adams on June 5, 1846.  The Italian astronomer Giovanni Battista Donati discovered Comet C/1858 L1 (Donati), the first comet to be photographed, on June 2, 1858. A large storm on Saturn was observed by the American astronomer E. E. Barnard.  The Tunguska event occurred on June 30, 1908.  The largest known solar flare was recorded on June 27, 1984.  The Georgian astronomer Givi Kimeridze discovered a Type Ia supernova in the spiral galaxy M58 on June 28, 1989.  Namaka, a satellite of the dwarf planet Haumea, was discovered on June 30, 2005.  Kerberos, Pluto’s fourth satellite, was discovered by the Hubble Space Telescope team on June 28, 2011.


The minor Boötid meteor shower peaks on the morning of June 27th.  It is compromised by a waning gibbous Moon.  The source of Boötid meteors is the periodic comet 7P/Pons-Winnecke.  The radiant lies in northern Boötes at right ascension 14 hours 56 minutes, declination 48 degrees. 


Information on passes of the ISS, the USAF’s X-37B, the HST, Starlink, and other satellites can be found at http://www.heavens-above.com/


The Moon is 20.0 days old, is illuminated 65.2%, subtends 30.9 arc minutes, and is located in Aquarius on June 1st at 0:00 UT.  The Moon is at its greatest northern declination of +25.6 degrees on June 12th and at its greatest southern declination of -25.6 degrees on June 25th.  Longitudinal libration is at a maximum of +7.4 degrees on June 1st and +7.0 degrees on June 29th and a minimum of -6.9 degrees on June 17th.  Latitudinal libration is at a maximum of +6.8 degrees on June 2nd and +6.7 degrees on June 30th and a minimum of -6.8 degrees on June 17th.  Favorable librations for the following craters occur on the indicated dates: Boss on June 24th and Zeno on June 25th.  The Moon is at apogee (a distance of 63.69 Earth-radii) on June 8th and at perigee (a distance of 56.44 Earth-radii) on June 23rd.  New Moon occurs on June 10th.  The 15.5-day-old Moon occults the second-magnitude star Nunki (Omicron Sagittarii) from the western portion of the United States and Mexico on the morning of June 25th.  Browse http://www.lunar-occ...ota/iotandx.htm for additional information on lunar occultation events.  Visit https://saberdoesthe...does-the-stars/ for tips on spotting extreme crescent Moons and https://curtrenz.com/moon.html for Full Moon and other lunar data.  Browse https://skyandtelesc...ads/MoonMap.pdf and https://nightsky.jpl...ObserveMoon.pdf for simple lunar maps. Visit http://www.ap-i.net/avl/en/start to download the free Virtual Moon Atlas.  Consult http://time.unitariu...moon/where.html for current information on the Moon.  See https://svs.gsfc.nasa.gov/4874 for a lunar phase and libration calculator and https://quickmap.lro...vIBvAXwF1SizSg  for the Lunar Reconnaissance Orbiter Camera (LROC) Quickmap.  Click on https://www.calendar...endar/2021/june for a lunar phase calendar for this month.  Times and dates for the lunar crater light rays predicted to occur this month are available at http://www.lunar-occ...o/rays/rays.htm


The Sun is located in Taurus on June 1st.  It enters Gemini on June 21st.  An annular solar eclipse takes place on June 10th.  The eclipse is the 23rd of 80 in Saros series 147.  The annular phase is visible from far eastern Siberia, Greenland, and northeastern Canada.  A partial eclipse can be seen in northern and western China, most of Russia, most of Europe, a small portion of northwestern Africa, northern Canada, Alaska, and the northeastern United States.  The instant of greatest eclipse takes place at 10:43:07 TD (10:41:57 UT1).  See http://www.eclipsewi...un10Aprime.html and https://earthsky.org...n-june-10-2021/ for more on this event.  The Sun reaches its farthest position north for the year on June 20th (June 21st UT).  There are 15 hours and one minute of daylight at latitude 40 degrees north on that day.  At latitude 40 degrees north, the earliest sunrise occurs on June 14th and the latest sunset on June 27th.  For an explanation of why this occurs, click on https://earthsky.org...-jupiter-venus/


Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on June 1st: Mercury (+3.0, 11.2", 8% illuminated, 0.60 a.u., Taurus), Venus (-3.8, 10.3", 95% illuminated, 1.62 a.u., Taurus), Mars (magnitude +1.7, 4.2", 95% illuminated, 2.25 a.u., Gemini), Jupiter (magnitude -2.4, 41.2", 99% illuminated, 4.79 a.u., Aquarius), Saturn (magnitude +0.6, 17.6", 100% illuminated, 9.46 a.u., Capricornus), Uranus on June 16th (magnitude +5.8, 3.4", 100% illuminated, 20.49 a.u., Aries), Neptune on June 16th (magnitude +7.9,  2.3", 100% illuminated, 29.87 a.u., Aquarius), and Pluto on June 16th (magnitude +14.3, 0.1", 100% illuminated, 33.43 a.u., Sagittarius). 


Venus and Mars are in the west in the evening sky.  Jupiter and Saturn can be found in the east at midnight.  Mercury and Uranus are located in the east, Neptune in the southeast, and Jupiter and Saturn in the south in the morning sky.


Mercury is at aphelion on June 10th.  It achieves inferior conjunction on June 11th and is too close to the Sun to be seen until the last week of June.  Mercury is stationary on June 22nd.  The speediest planet shines at magnitude +1.0 and is located a bit more than eight degrees east of Aldebaran on the morning of June 30th.  Mercury is at its greatest heliocentric latitude south on that date.

Venus attains its most northerly declination of 2021 on June 5th.  The brightest planet passes 0.1 degrees north of the open cluster M35 on June 3rd.  A slender waxing crescent Moon passes less than two degrees north of Venus on June 12th, the day that Venus is at perihelion.  Venus is a bit more than six degrees south of Pollux on June 24th and is more than halfway across Cancer, some 2.7 degrees west of the open cluster M44, by the end of the month.  Venus is located slightly more than seven degrees to the west of Mars as June ends.


Mars departs Gemini and enters Caner this month.  It's at its greatest heliocentric latitude north on June 4th.  Mars and Jupiter are in heliocentric conjunction on June 6th.  A waxing crescent Moon passes three degrees northeast of the planet and less than five degrees northwest of the open cluster M44 on June 13th.  Mars passes through the center of M44 on June 22nd and 23rd.  The Red Planet and the Beehive Cluster will be just seven degrees above the horizon on June 23rd from mid-northern latitudes as evening twilight progresses.  A short article on the event appears on page 50 of the June 2021 issue of Sky & Telescope.  By June 30th, Mars decreases in size to less than four arc seconds in angular diameter and lies 4.5 degrees to the east of M44.  It sets at about 10:30 p.m. local time on that date.


Jupiter rises shortly before midnight local time and attains an altitude of some 40 degrees, the highest in four years, at 4:30 a.m. local time by month's end.  It brightens from magnitude -2.4 to magnitude -2.6 and grows from 41.2 to 45.1 arc seconds in angular size.  Jupiter's eastward motion ends when it reaches its first stationary point in central Aquarius on June 21st.  The waning gibbous Moon passes five degrees south of Jupiter on June 1st and four degrees south of the planet on June 28th.  Browse http://www.skyandtel...watching-tools/ or http://www.projectpl...om/jeve_grs.htm in order to determine transit times of Jupiter’s central meridian by the Great Red Spot.  GRS transit times are also available on pages 50 and 51 of the June 2021 issue of Sky & Telescope.  Javascript Jupiter at http://www.shallowsky.com/jupiter/ shows Galilean satellite events.  A list of selected Galilean satellite mutual events occurring place this month can be found on page 50 of the June 2021 issue of Sky & Telescope.  Double Galilean shadow transits take place on June 4th, June 12th, and June 26th.  Data on other Galilean satellite events is available on page 51 of the June 2021 issue of Sky & Telescope and online at http://www.skyandtel...watching-tools/


This month Saturn increases in brightness from magnitude +0.6 to magnitude +0.4 and in apparent size from 17.6 arc seconds to 18.3 arc seconds.  Its rings span 42 arc seconds and are inclined by 17 degrees by month's end.  Saturn rises not long after midnight, about an hour before Jupiter, as the month begins.  The waning gibbous Moon passes four degrees south of Saturn on June 26th.  Eighth-magnitude Titan is south of the Ringed Planet on June 8th and June 24th and north of it on June 16th. The peculiar satellite Iapetus brightens to eleventh magnitude when it reaches inferior conjunction on June 13th.  It continues to brighten to almost tenth magnitude by June 30th.  It lies 8.8 arc seconds due west of Saturn on that date.  For additional information on Saturn’s satellites, browse http://www.skyandtel...watching-tools/


Uranus lies about 20 degrees above the horizon during morning twilight but remains a rather difficult target.  It's located 11 arc minutes north of the sixth-magnitude star Omicron Arietis on June 30th.  The waning crescent Moon passes two degrees south of Uranus on June 6th.  A finder chart is available at http://www.nakedeyep...tm#finderchart 


Neptune is located 5.6 degrees east of the fourth-magnitude star Phi Aquarii on June 1st.  The Last Quarter Moon passes four degrees south of Neptune on June 13th.  Neptune reaches its first stationary point on June 26th and afterwards begins retrograde motion.  The waning gibbous Moon passes four degrees south of Neptune on June 30th.  See http://www.nakedeyep...htm#finderchart for a finder chart.


With sufficient aperture, Pluto is a potential target from a dark site this month.  The dwarf planet lies about 4.5 degrees southwest of the globular cluster M75 in eastern Sagittarius.  A finder chart can be found at page 243 of the RASC Observer’s Handbook 2021.

The periodic comet 7P/Pons-Winnecke glows faintly at around eleventh magnitude as it travels southeastward from Capricornus to Piscis Austrinus during June.  The comet's closest approach is on June 12th, when it comes within 0.44 astronomical units of the Earth.  Comet 7P/Pons-Winnecke passes less than a degree to the southwest of the planetary nebula NGC 7293 (the Helix Nebula) on June 15th.  Visit http://cometchasing.skyhound.com/ and http://www.aerith.ne...t/future-n.html and https://cobs.si/ for information on comets visible this month.


Asteroid 4 Vesta shines at approximately magnitude +7.6 as it heads southeastward from Leo into Virgo this month.  The main belt minor planet passes just seven arc minutes south of the fifth-magnitude star 73 Leonis on June 7th and less than one degree south of the Leo Trio/Triplet (M65, M66, and NGC 3628) from June 7th through June 12th.  Asteroid 3 Juno (magnitude +10.1) is at opposition in Ophiuchus on June 3rd.  It passes quite close to the globular cluster M10 in Ophiuchus on June 17th.  Asteroids brighter than magnitude +11.0 that reach opposition this month also include 63 Ausonia (magnitude +9.7) on June 2nd in Scorpius, 5 Astraea (magnitude +10.8) on June 19th in Sagittarius, and 419 Aurelia (magnitude +10.2) on June 21st in Sagittarius.  Information on some of the brighter asteroids and on asteroid occultations taking place this month is available at https://curtrenz.com/asteroids.html and at http://www.asteroido.../2021_06_si.htm respectively.


For more on the planets and how to locate them, browse http://www.nakedeyeplanets.com/


A wealth of current information on solar system celestial bodies is posted at http://www.curtrenz.com/astronomy.html and http://nineplanets.org/


Information on the celestial events transpiring each week can be found at https://stardate.org/nightsky and http://astronomy.com/skythisweek and http://www.skyandtel...ky-at-a-glance/


Free star maps for June can be downloaded at http://www.skymaps.com/downloads.html and https://www.telescop...thly-Star-Chart and http://www.kenpress.com/index.html


Data on current supernovae can be found at http://www.rochester...y.org/snimages/


Finder charts for the Messier objects and other deep-sky objects are posted at https://freestarcharts.com/messier and https://freestarcharts.com/ngc-ic and http://www.cambridge..._april-june.htm


Telrad finder charts for the Messier Catalog and the SAC’s 110 Best of the NGC are posted at http://www.custerobs...cs/messier2.pdf and http://sao64.free.fr...xD5iw4jCil5nhTg respectively.


Information pertaining to observing some of the more prominent Messier galaxies can be found at http://www.cloudynig...ur-astronomers/


Stellarium and Cartes du Ciel are two excellent freeware planetarium programs that are available at http://stellarium.org/ and https://www.ap-i.net/skychart/en/start


Deep-sky object list generators can be found at http://www.virtualcolony.com/sac/ and http://tonightssky.com/MainPage.php and https://dso-browser.com/


Freeware sky atlases can be downloaded at http://www.deepskywa...-atlas-full.pdf and https://www.cloudyni...ar-charts-r1021 and https://allans-stuff.com/triatlas/


Forty binary and multiple stars for June: Struve 1812, Kappa Bootis, Otto Struve 279, Iota Bootis, Struve 1825, Struve 1835, Pi Bootis, Epsilon Bootis, Struve 1889, 39 Bootis, Xi Bootis, Struve 1910, Delta Bootis, Mu Bootis (Bootes); Struve 1803 (Canes Venatici); Struve 1932, Struve 1964, Zeta Coronae Borealis, Struve 1973, Otto Struve 302 (Corona Borealis); Struve 1927, Struve 1984, Struve 2054, Eta Draconis, 17-16 Draconis, 17 Draconis (Draco); 54 Hydrae (Hydra); Struve 1919, 5 Serpentis, 6 Serpentis, Struve 1950, Delta Serpentis, Otto Struve 300, Beta Serpentis, Struve 1985 (Serpens Caput); Struve 1831 (Ursa Major); Pi-1 Ursae Minoris (Ursa Minor); Struve 1802, Struve 1833, Phi Virginis (Virgo)


Notable carbon star for June: V Coronae Borealis


Fifty deep-sky objects for June: NGC 5466, NGC 5676, NGC 5689 (Bootes); M102 (NGC 5866), NGC 5678, NGC 5879, NGC 5905, NGC 5907, NGC 5908, NGC 5949, NGC 5963, NGC 5965, NGC 5982, NGC 5985, NGC 6015 (Draco); NGC 5694 (Hydra); NGC 5728, NGC 5791, NGC 5796, NGC 5812, NGC 5861, NGC 5878, NGC 5897 (Libra); M5, NGC 5921, NGC 5957, NGC 5962, NGC 5970, NGC 5984 (Serpens Caput); M101, NGC 5473, NGC 5474, NGC 5485, NGC 5585, NGC 5631 (Ursa Major); NGC 5566, NGC 5634, NGC 5701, NGC 5713, NGC 5746, NGC 5750, NGC 5775, NGC 5806, NGC 5813, NGC 5831, NGC 5838, NGC 5846, NGC 5850, NGC 5854, NGC 5864 (Virgo)


Top ten deep-sky objects for June: M5, M101, M102, NGC 5566, NGC 5585, NGC 5689, NGC 5746, NGC 5813, NGC 5838, NGC 5907


Top five deep-sky binocular objects for June: M5, M101, M102, NGC 5466, NGC 5907


Challenge deep-sky object for June: Abell 2065


The objects listed above are located between 14:00 and 16:00 hours of right ascension.


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