September Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
9/1 New Moon (lunation 1159) occurs at 9:03; an annular solar eclipse visible from Africa, the southwestern Middle East, Antarctica, the Atlantic Ocean, and the Indian Ocean reaches greatest eclipse at 9:06
9/2 Asteroid 1 Ceres is stationary at 13:00; Neptune (magnitude +7.8, apparent size 2.4") is at opposition at 17:00; Jupiter is 0.4 degree south of the Moon, with an occultation taking place in the Caribbean, northern South America, Central America, the southwestern USA, and eastern Russia, at 22:00
9/3 Venus is 1.1 degrees south of the Moon, with an occultation taking place in northern Siberia and central Russia, at 11:00
9/4 Mercury is at its greatest heliocentric latitude south today
9/6 The Moon is at apogee, subtending 29' 30" from a distance of 405,055 kilometers (251,689 miles), at 18:45
9/8 The Lunar X (the Purbach or Werner Cross), an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 23:15
9/9 First Quarter Moon occurs at 11:49
9/13 Mercury is in inferior conjunction at 0:00
9/15 Neptune is 1.2 degrees south of the Moon), with an occultation taking place in western Russia and Europe, at 20:00
9/16 Full Moon (known as the Barley, Corn, or Fruit Moon) occurs at 19:05; a deep penumbral lunar eclipse visible from Europe, Africa, and Asia, begins at 16:54 and ends at 20:54
9/18 The Moon is at perigee, subtending 33' 01" from a distance of 361,896 kilometers (224,872 miles), at 17:00
9/21 Mercury is stationary at 10:00; the Moon is 0.2 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation taking place in central and some of southern Asia, the Middle East, and eastern Africa, at 23:00
9/22 The autumnal equinox occurs in the northern hemisphere at 14:21
9/23 Mercury is at the ascending node today; Last Quarter Moon occurs at 9:56
9/25 The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 1:15
9/26 Venus is at the descending node today; Jupiter is in conjunction with the Sun at 7:00
9/27 The Moon is 1.7 degrees south of the first-magnitude star Regulus (Alpha Leonis) at 23:00
9/28 Mercury is at perihelion at 15:00; Mercury is at its greatest western elongation (18 degrees) at 20:00
9/29 Mercury is 0.7 degree north of the Moon, with an occultation taking place in parts of Antarctica, far southern South America, and eastern South America, at 11:00
Karl Harding discovered asteroid 3 Juno on September 1, 1804. E. E. Barnard discovered Jupiter’s fifth satellite, fourteenth-magnitude Amalthea, using the 36-inch refractor at the Lick Observatory on September 9, 1892. On September 19, 1848, William Bond discovered Saturn’s fourteenth-magnitude satellite Hyperion, the first irregular moon to be discovered. Neptune was discovered by Johann Gottfried Galle on September 23, 1846, using Urbain Le Verrier’s calculations of its position.
The minor meteor shower known as the Epsilon Perseids, which has a maximum hourly rate of just 5 per hour, peaks on the evening of September 9th. The radiant is located near the second-magnitude star Algol (Beta Persei) at 03h15m, +40 degrees.
Information on Iridium flares and passes of the ISS, the Tiangong-1, the USAF’s X-37B, the HST, and other satellites can be found at http://www.heavens-above.com/
The zodiacal light, or the false dawn, is visible about two hours before sunrise from a dark site during the latter part of September. Articles on the zodiacal light appear at http://www.atoptics....ighsky/zod1.htm and http://oneminuteastr...zodiacal-light/
The Moon is 29.1 days old, subtends 30.4 arc minutes, is illuminated 0.2%, and is located in Leo on September 1st at 0:00 UT. A penumbral lunar eclipse reaches its maximum at 18:54 UT on September 16th. Browse http://eclipse.gsfc....E2016Sep16N.pdf for more on this event. The Moon is at its greatest northern declination (+18.4 degrees) on September 24th and its greatest southern declination (-18.4 degrees) on September 11th. Longitudinal libration is at a maximum of +6.6 degrees on September 26th and a minimum of -6.3 degrees on September 13th. Latitudinal libration is at a maximum of +6.6 degrees on September 26th and a minimum of -6.9 degrees on September 9th. The Moon occults Aldebaran from some parts of the world on September 2st. Consult http://www.lunar-occ...ota/iotandx.htm for further information. Visit http://saberdoesthes...does-the-stars/ for tips on spotting extreme crescent Moons and http://www.curtrenz.com/moon06.html for Full Moon data. Times and dates for the lunar light rays predicted to occur in June are available at http://www.lunar-occ...o/rays/rays.htm
The Sun is located in Leo on September 1st. An annular solar eclipse, the 39th of Saros 135, takes place on September 1st. Click on http://eclipse.gsfc....E2016Sep01A.GIF for additional information. On September 16th, the Sun enters Virgo. The Sun crosses the celestial equator from north to south at 14:21 UT on September 22nd, the date of the autumnal equinox.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on September 1st: Mercury (magnitude +1.3, 9.6", 21% illuminated, 0.70 a.u., Virgo), Venus (magnitude -3.8, 10.9", 92% illuminated, 1.53 a.u., Virgo), Mars (magnitude -0.3, 10.5", 85% illuminated, 0.90 a.u., Scorpius), Jupiter (magnitude -1.7, 30.8", 100% illuminated, 6.40 a.u., Virgo), Saturn (magnitude +0.5, 16.7", 100% illuminated, 9.97 a.u., Ophiuchus), Uranus (magnitude +5.7, 3.7", 100% illuminated, 19.08 a.u. on September 16th, Pisces), Neptune (magnitude +7.8, 2.4", 100% illuminated, 28.96 a.u. on September 16th, Aquarius), and Pluto (magnitude +14.2, 0.1", 100% illuminated, 32.80 a.u. on September 16th, Sagittarius).
This month Venus and Jupiter are located in the west, Mars is in the south, Saturn is in the southwest, and Neptune is in the southeast during the evening. At midnight, Uranus can be found in the southeast and Neptune in the south. Mercury lies in the east, Uranus in the southwest, and Neptune in the west in the morning sky.
For observers at latitude 40 degrees north at midmonth, Venus sets at 8:00 p.m. local time and Mars and Saturn set at 11:00 p.m. local time.
Mercury lies low in the east just before sunrise during the final third of the month. Northern hemisphere observers are favored for this predawn apparition of the planet, the best one of the year. On September 4th, Mercury is at its greatest heliocentric latitude south. It is in inferior conjunction on September 13th and is stationary on September 18th. Mercury is at perihelion and is also at a greatest western elongation of 18 degrees on September 28th. The speediest planet is 0.7 degree south of the Moon on September 29th.
During September, Venus grows in apparent size from 10.9 to 12.1 arc seconds but decreases in illumination from 92% to 86%. Venus is occulted by the Moon from some parts of the world on September 3rd.
Mars is some five degrees east of Antares, the rival of Mars, on September 1st. It departs Scorpius and enters Ophiuchus on September 2nd. Syrtis Major is well-placed for observers in North America during the first week of the month. The Red Planet enters Sagittarius on September 21st. Mars becomes fainter than magnitude 0.0 in apparent brightness on September 25th. On September 28th, it passes 1.5 degrees south of the bright emission nebula M8 (the Lagoon Nebula). Mars displays its maximum phase effect of 85% illumination and shrinks in apparent size from 10.5 arc minutes to 8.4 arc minutes this month.
Jupiter disappears into the glare of the Sun in early September. The gas giant is at conjunction with the Sun on September 26th.
Saturn sets about 11:00 p.m. local daylight time this month. Its rings span 37 arc seconds and are tilted 26 degrees with respect to the Earth. Eighth-magnitude Titan, Saturn’s largest satellite, is due north of Saturn on September 9th and September 25th and is due south on September 6th. Iapetus shines at eleventh magnitude when it is positioned 2.1 arc minutes due north of the planet on September 28th. Titan is 2.6 arc minutes east of Saturn on that date. For further information on Saturn’s satellites, browse http://www.skyandtel...watching-tools/
Uranus retrogrades through Pisces this month. It lies 2.5 degrees from the fifth-magnitude star Mu Piscium throughout September.
Neptune (magnitude +7.8, apparent size 2.4") reaches opposition on September 2nd. The eighth planet is located approximately 1.3 degrees southwest of the fourth-magnitude star Lambda Aquarii on that date. By the end of the month, that distance increases to some two degrees.
This month Pluto is situated not far to the southwest of the third-magnitude star Pi Sagittarii, which is part of the Sagittarius Teaspoon asterism. The dwarf planet is highest in altitude in the late evening. Articles on locating and observing Pluto are available on pages 48 and 49 of the July issue of Sky & Telescope and pages 64 and 65 of the July issue of Astronomy and a finder chart appears online at http://www.bluewater.../Pluto-2016.jpg
For more on the planets and how to locate them, see http://www.nakedeyeplanets.com/
The periodic comet 43P/Wolf-Harrington passes southeastward through Cancer this month. The twelfth-magnitude comet lies south of the stars 45 and 50 Cancri on September 14th and 15th. For further information on comets visible in September, browse http://cometchasing.skyhound.com/ and http://www.aerith.ne...t/future-n.html
Asteroid 2 Pallas shines at ninth-magnitude as it travels southwestward through Equuleus during September. It passes one degree to the west of the fourth-magnitude star Alpha Equulei (Kitalpha) on September 11th. Asteroids 1 Ceres (magnitude +8.2) and 18 Melpomene (magnitude +8.8) are just 0.8 degree on the nights of September 7th and 8th. A finder chart is available on page 51 of the September issue of Sky & Telescope. Asteroid 51 Nemausa (magnitude +11.5) occults a 7.5-magnitude star along a path stretching from Baja California into Canada on September 2nd-3rd (for additional information see http://www.universet...-north-america/ and page 50 of the September issue of Sky & Telescope). Data on this and other asteroid occultations taking place this month is available at http://www.poyntsour.../New/Global.htm and http://www.asteroido.../2016_09_si.htm
On September 23rd, the eclipsing variable star Algol (Beta Persei) shines at minimum brightness (magnitude +3.4) for approximately two hours on centered on 11:19 p.m. EDT (3:19 UT on September 24th). For more on Algol, see http://stars.astro.i.../sow/Algol.html and http://www.solstatio...ars2/algol3.htm
Eighty binary and multiple stars for September: 12 Aquarii, Struve 2809, Struve 2838 (Aquarius); Alpha Capricorni, Sigma Capricorni, Nu Capricorni, Beta Capricorni, Pi Capricorni, Rho Capricorni, Omicron Capricorni, h2973, h2975, Struve 2699, h2995, 24 Capricorni, Xi Capricorni, Epsilon Capricorni, 41 Capricorni, h3065 (Capricornus); Kappa Cephei, Struve 2751, Beta Cephei, Struve 2816, Struve 2819, Struve 2836, Otto Struve 451, Struve 2840, Struve 2873 (Cepheus); Otto Struve 394, 26 Cygni, h1470, h1471, Omicron Cygni, Struve 2657, 29 Cygni, 49 Cygni, 52 Cygni, 59 Cygni, 60 Cygni, 61 Cygni, Struve 2762 (Cygnus); Struve 2665, Struve 2673, Struve 2679, Kappa Delphini, Struve 2715, Struve 2718, Struve 2721, Struve 2722, Struve 2725 (in the same field as Gamma Delphini), Gamma Delphini, 13 Delphini, Struve 2730, 16 Delphini, Struve 2735, Struve 2736, Struve 2738 (Delphinus); 65 Draconis, Struve 2640 (Draco); Epsilon Equulei, Lambda Equulei, Struve 2765, Struve 2786, Struve 2793 (Equuleus); 1 Pegasi, Struve 2797, h1647, Struve 2804, Struve 3112, 3 Pegasi, 4 Pegasi, Kappa Pegasi, h947, Struve 2841, Struve 2848 (Pegasus); h1462, Struve 2653, Burnham 441, Struve 2655, Struve 2769 (Vulpecula)
Notable carbon star for September: LW Cygni
Fifty deep-sky objects for September: M2, M72, M73, NGC 7009 (Aquarius); M30, NGC 6903, NGC 6907 (Capricornus); B150, B169, B170, IC 1396, NGC 6939, NGC 6946, NGC 6951, NGC 7023, NGC 7160, NGC 7142 (Cepheus); B343, B361, Ba6, Be87, Cr 421, Do9, IC 4996, M29, M39, NGC 6866, NGC 6871, NGC 6888, NGC 6894, NGC 6910, NGC 6960, NGC 6992, NGC 6994, NGC 6995, NGC 7000, NGC 7008, NGC 7026, NGC 7027, NGC 7039, NGC 7048, NGC 7063, NGC 7086 (Cygnus); NGC 6891, NGC 6905, NGC 6934, NGC 7006 (Delphinus); NGC 7015 (Equuleus); M15 (Pegasus); NGC 6940 (Vulpecula)
Top ten binocular deep-sky objects for September: IC 1396, LDN 906, M2, M15, M29, M30, M39, NGC 6939, NGC 6871, NGC 7000
Top ten deep-sky objects for September: IC 1396, M2, M15, M30, NGC 6888, NGC 6946, NGC 6960, NGC 6992, NGC 7000, NGC 7009
Challenge deep-sky object for September: Abell 78 (Cygnus)
The objects listed above are located between 20:00 and 22:00 hours of right ascension.