September 2013 Celestial Calendar

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Dave Mitsky
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Location: PA, USA, Planet Earth

September 2013 Celestial Calendar

Post by Dave Mitsky »

September Celestial Calendar by Dave Mitsky

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

9/2 Mars is 6 degrees north of the Moon at 10:00
9/5 New Moon (lunation 1122) occurs at 11:36; Venus is 1.8 degrees north of the first-magnitude star Spica (Alpha Virginis) at 13:00
9/8 The Moon is 0.8 degree north of the first-magnitude star Spica (Alpha Virginis), with an occultation visible from western Russia, central Asia, the Arabian Peninsula, northern Africa, Europe, southern Greenland, and eastern Canada; at 8:15; a double Galilean satellite shadow transit (Callisto’s shadow follows Io’s) begins at 15:20; Venus is 0.4 degrees north of the Moon, with an occultation visible from the Falkland Islands, southern South America, the Pitcairn Islands, French Polynesia, and Kiribati at 21:00; Mars lies within the boundaries of the bright open cluster M44 (Praesepe or the Beehive) in Cancer at 22:00
9/9 Saturn is 2 degrees north of the moon at 17:00
9/12 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 6:42; First Quarter Moon occurs at 17:08
9.13 Asteroid 324 Bamberga (magnitude 8.1) is at opposition at 18:00
9/14 Mercury is at the descending node today
9/15 The Moon is at perigee, subtending 32 arc minutes from a distance of 367,391 kilometers (228,286 miles), at 17:00
9/17 Neptune is 6 degrees south of the Moon at 23:00
9/19 Full Moon (known as the Barley, Corn, or Fruit Moon), this year’s Harvest Moon, occurs at 11:13
9/20 Venus is 4 degrees south of Saturn at 0:00; Pluto is stationary at 5:00; asteroid 3 Juno is stationary at 16:00
9/22 The autumnal equinox occurs in the northern hemisphere at 20:44
9/24 Mercury is 0.8 degrees north of Spica at 19:00
9/25 Mercury is at aphelion today; asteroid 89 Julia (magnitude 8.5) is at opposition at 3:00
9/27 Last Quarter Moon occurs at 3:55; the Moon is at apogee, subtending 29 arc minutes from a distance of 404,308 kilometers (251,225 miles), at 18:00
9/28 A double Galilean satellite shadow transit (Io’s shadow follows Europa’s) begins at 0:46; Jupiter is 5 degrees north of the Moon at 9:00; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 9:52

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 zodiacal light, or the false dawn, is visible about two hours before sunrise from a dark site during the first half of September. An article on the zodiacal light appears on pages 54 and 55 of the September issue of Sky & Telescope.

The Moon is 25.1 days old and is located in Gemini on September 1 at 0:00 UT. The Moon is at its greatest northern declination (+19.6 degrees) on September 26 and its greatest southern declination (-19.7 degrees) on September 12. Longitudinal libration is at a maximum of +5.9 degrees on September 21 and a minimum of -4.8 degrees on September 7. Latitudinal libration is at a maximum of +6.7 degrees on September 2 and +6.8 on September 30, a minimum of -6.7 degrees on September 16. Visit ... the-stars/ for tips on spotting extreme crescent Moons and for Full Moon data. Times and dates for the lunar light rays predicted to occur in June are available at

The Sun is located in Leo on September 1. It crosses the celestial equator from north to south on September 22, 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 1: Mercury (magnitude -1.2, 4.9", 98% illuminated, 1.38 a.u., Leo), Venus (magnitude -4.0, 14.8", 74% illuminated, 1.12 a.u., Virgo), Mars (magnitude 1.6, 4.1", 96% illuminated, 2.29 a.u., Cancer), Jupiter (magnitude -2.0, 34.8", 99% illuminated, 5.66 a.u., Gemini), Saturn (magnitude 0.7, 16.1", 100% illuminated, 10.34 a.u., Leo), Uranus (magnitude 5.7, 3.7", 100% illuminated, 19.08 a.u. on September 16th, Pisces), Neptune (magnitude 7.8, 2.4", 100% illuminated, 29.04 a.u. on September 16th, Aquarius), and Pluto (magnitude 14.1, 0.1", 100% illuminated, 32.22 a.u. on September 16th, Sagittarius).

This month Mercury is located in the west, Venus and Saturn in the southwest, Uranus in the east, and Neptune in the southeast during the evening. At midnight, Uranus can be found in the southeast and Neptune in the south. Mars and Jupiter are in the east and Uranus is in the west in the morning sky.

For observers at latitude 40 degrees north at midmonth, Venus sets at 9:00 p.m. local time, Mars rises at 3:00 a.m. local time, Jupiter rises at 1:00 a.m. local time, and Saturn sets at 9:00 p.m. local time.

Mercury is extremely close to the horizon during evening twilight this month. It passes 0.8 degree north of Spica on September 24 and reaches aphelion on September 25.

As September progresses, Venus brightens to magnitude -4.2, increases in apparent size from 14.8 to 18.3 arc seconds, and decreases in phase by 10%. On the evening of September 5, Venus lies 1.8 degrees north of Spica. The brilliant planet is just 0.4 degree north of the waxing crescent Moon on September 8. Venus departs Virgo and enters Libra on September 18. Venus is four degrees south of Saturn on the evening of September 19.

Mars passes through Cancer and enters Leo in late September. It is six degrees north of the Moon on September 2. The Red Planet traverses M44 on the mornings of September 8 and September 9 (see page 52 of the September issue of Sky & Telescope). Mars increases to 4.4 arc seconds in apparent size by month’s end.

Jupiter increases in apparent size to 37.5 arc seconds and brightens from magnitude -2.0 to magnitude -2.2 this month. The first shadow transit by Callisto visible to North American observers since 2010 starts at 5:15 am EDT on September 25. The King of the Planets is five degrees north of the waning crescent Moon on September 28. Click on ... page=1&c=y to determine transit times of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at ... 07071.html

On the evening of September 8, Saturn is located 11 degrees east of Venus. The two planets are separated by only four degrees on the evening of September 19. Saturn’s rings span 36 arc seconds and are tilted 18 degrees with respect to the Earth this month.

Uranus is located 3.9 degrees southwest of the fourth-magnitude star Delta Piscium at the start of September. The gap widens to 4.7 degrees by month’s end.

Neptune lies 1.9 degrees west of the fifth-magnitude star Sigma Aquarii early this month. By September 31, the eighth planet’s retrograde motion places it 2.6 degrees from the star.

Finder charts for Uranus and Neptune can be found at ... e-2013.pdf and on page 81 of the August issue of Astronomy.

The dwarf planet Pluto is located in northern Sagittarius just to the southeast of the open cluster M25. It culminates as evening twilight ends. Detailed finder charts are available on pages 52 and 53 of the June issue of Sky & Telescope, on page 63 of the July issue of Astronomy, and on page 243 of the RASC Observer’s Handbook 2013. Online finder charts are posted at and

For more on the planets and how to locate them, see

Comet C/2012 S1 ISON travels southeastward through Cancer this month. It's just north of the fifth-magnitude star Asellus Borealis (Gamma Cancri) on September 2. The so-called comet of the century passes two degrees north of Mars on the morning of September 27. For additional information on comets visible in September, browse and

The large main-belt asteroid 324 Bamberga shines at magnitude 8.1 when it reaches opposition on September 13. On that date, the C-type asteroid is 0.81 astronomical units from the Earth in Pisces and is at its closest approach in 22 years. A finder chart appears on page 51 of the September issue of Sky & Telescope. Asteroid 7 Iris shines at magnitude 8.1 in Aquarius on September 1. Page 52 of the September issue of Sky & Telescope features a finder chart. Data on asteroid occultations taking place this month is available at and

A free star map for September can be downloaded at

Browse for an informative video on astronomical events taking place this month.

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

Forty-five 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 4343, B361, Ba6, Be87, Cr 421, Do9, IC 1369, IC 4996, IC 1516, LDN 906, M29, M39, NGC 6866, NGC 6871, NGC 6888, NGC 6894, NGC 6910, NGC 6960, NGC 6992, NGC 7000, NGC 7008, NGC 7026, NGC 7027, NGC 7039, 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.
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