October 2011 Celestial Calendar & Observing Notes c/o Dave Mitsky

[Big Dipper]

October 2011 Celestial Calendar & Observing Notes courtesy of Dave Mitsky (calendar data also reproduced in our forum calendar).

All times, unless otherwise noted, are UT.

10/1 Mars is 0.5 degree south of the bright open cluster M44 (Praesepe or the Beehive Cluster) in Cancer at 1:11

10/3 Venus is 3 degrees north of the first-magnitude star Spica (Alpha Virginis) at 12:00; asteroid 27 Euterpe is at opposition at 3:00

10/4 First Quarter Moon occurs at 3:15; the Lunar X, also known as 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 12:38

10/8 Neptune is 6 degrees south of the Moon at 3:00; the peak of the Draconid meteor shower (10 to 30 per hour) occurs at 20:00

10/10 Uranus is 6 degrees south of the Moon at 22:00

10/11 Mercury is at the descending node today

10/12 Full Moon, known as the Blood Moon and this year’s Hunter’s Moon, occurs at 2:06; the Moon is at apogee, subtending 29'22" from a distance of 406,434 kilometers (252,863 miles), at 12:00

10/13 Jupiter is 5 degrees south of the Moon at 20:00; Saturn is in conjunction with the Sun at 21:00

10/20 Last Quarter Moon occurs at 3:30; the Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 16:16

10/21 The peak of the Orionid meteor shower (10 to 20 per hour) occurs at 22:00

10/22 Mars is 6 degrees north of the moon at 0:00; Mercury is at aphelion at 0:00

10/23 Asteroid 3 Juno is in conjunction with the Sun at 1:00

10/24 A double Galilean satellite shadow transit (Io’s shadow follows Ganymede’s) begins at 14:23

10/26 Venus is at the descending node today; the Moon is at perigee, subtending 33'33" from a distance of 357,052 kilometers (221,298 miles), at 12:00; New Moon (lunation 1099) occurs at 19:56

10/28 Mercury is 0.2 degree north of the moon, with an occultation taking place in French Polynesia, New Caledonia, New Zealand, Australia, southeast Papua New Guinea, Malaysia, and Indonesia, at 2:00; Venus is 1.8 degrees north of the moon at 5:00

10/29 Jupiter (magnitude -2.9, apparent size 49.6") is at opposition at 2:00

10/31 Saturn is 5 degrees north of the first-magnitude star Spica (Alpha Virginis) at 5:00; a double Galilean satellite shadow transit (Ganymede’s shadow follows Io’s) begins at 17:48

Ejnar Hertzsprung and Henry Norris Russell were born this month.

An outburst during the Draconid (formerly the Giacobinid) meteor shower of as many as 600 meteors per hour is possible on October 8. Observers in Europe are favored by one prediction (19:57 UT). Unfortunately, the waxing gibbous Moon will be quite bright. The Orionid meteor shower peaks during the morning of October 21, when a waning crescent Moon will grace the sky.

During the second half of the month, the zodiacal light may be visible in the pre-dawn eastern sky from a dark site.

The Moon is 4.1 days old and is located in Libra on October 1 at 0:00 UT. The Moon reaches its greatest northern declination on October 17 (+22.7 degrees) and its greatest southern declination on October 2 and on October 29 (-22.7 degrees). Longitudinal libration is at a maximum of +7.6 degrees on October 4 and a minimum of -7.6 degrees on October 20. Latitudinal libration is at a maximum of +6.7 degrees on October 23 and a minimum of -6.7 degrees on October 9. The smallest Full Moon of the year occurs on October 26. Large tides will occur from October 26 through October 29. Mercury is occulted by the Moon from the southwestern Pacific to Indonesia on October 28. See Occultation of planets by Moon >> Occultation of Mercury on 2011 Oct 28 [272] for information on this event. Visit Saber Does The Stars saberdoesthestars for tips on spotting extreme crescent Moons and Moon 06 for Full Moon data. Times and dates for the lunar light rays predicted to occur this month are available at Lunar Sunrise/Sunset Crater Rays

The Sun is located in Virgo on October 1 at 0:00 UT. The first recorded solar eclipse took place on October 22, 2136 B.C.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on October 1: Mercury (magnitude -1.6, 4.8", 100% illuminated, 1.41 a.u., Virgo), Venus (-3.9 magnitude, 10.0", 98% illuminated, 1.67 a.u., Virgo), Mars (magnitude 1.3, 5.2", 92% illuminated, 1.81 a.u., Cancer), Jupiter (magnitude -2.8, 48.4", 100% illuminated, 4.08 a.u., Aries), Saturn (magnitude 0.8, 15.6", 100% illuminated, 10.65 a.u., Virgo), Uranus (magnitude 5.7, 3.7", 100% illuminated, 19.08 a.u., Pisces), Neptune (magnitude 7.9, 2.3", 100% illuminated, 29.22 a.u., Capricornus), and Pluto (magnitude 14.1, 0.1", 100% illuminated, 32.13 a.u., Sagittarius).

During October evenings, Mercury and Venus lie in the southwest, Jupiter and Uranus in the east, and Neptune in the southeast. At midnight, Jupiter is located in the southeast, Uranus in the south, and Neptune in the southwest. Mars is in the southeast, Jupiter is in the west, and Saturn is in the east in the morning sky.

At midmonth, Mercury can be seen during evening twilight, Venus sets at 7:00 p.m. local time, Mars rises at 2:00 a.m. local time, and Jupiter is visible for the entire night for observers at latitude 40 degrees north.

Mercury (magnitude -0.3) and Venus (magnitude -3.8) are two degrees apart on the evening of October 27. Both are very close to the horizon at the time. Mercury is just one degree in altitude one half-hour after sunset and Venus three degrees. The two planets remain in close proximity for several weeks.

Brilliant Venus passes three degrees north of Spica on October 3. On the evening of October 28, a thin crescent Moon lies about ten degrees to upper left of Venus and to the right of the first-magnitude star Antares. As the month progresses, Venus climbs higher into the sky.

Mars crosses through the southern portion of the Beehive Cluster in Cancer on the morning of October 1. It enters Leo on October 19. By the end of the month, the Red Planet lies six degrees from the first-magnitude star Regulus. Brightening to magnitude 1.1 during October, Mars slightly outshines Regulus at that time but subtends only a modest 5.9 arc seconds.

Jupiter reaches opposition this month, shining at magnitude -2.9 and subtending an unusually large 49.6 arc seconds, on October 29. On that date, the King of the Planets is located 12 degrees north of the celestial equator and is some 594 million kilometers or 33 light minutes from the Earth. See Jupiter for additional information on Jupiter at opposition. Two double Galilean satellite events occur this month but both take place during the daylight for observers in the United States. Click on Transit Times of Jupiter's Great Red Spot - Planets - SkyandTelescope.com to determine transits of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at Jupiter's Moons Javascript Utility - Interactive Observing Tools - SkyandTelescope.com

Saturn is in conjunction with the Sun on October 13. The Ringed Planet reappears in the dawn sky at month’s end. It can be found about ten degrees above the east-southeastern horizon one half-hour before sunrise on October 31. Giovanni Cassini discovered Iapetus on October 25, 1671.

Uranus lies about 15 degrees south of the third-magnitude star Algenib (Gamma Pegasi). It passes south of the celestial equator on October 16. Ariel and Umbriel were discovered by William Lassell on October 24, 1851.

Neptune is located 1.6 degrees northwest of the third-magnitude star Iota Capricorni on October 15. William Lassell discovered Triton on October 10, 1846.

Finder charts for Uranus and Neptune appear on page 53 of the September 2011 issue of Sky & Telescope and are posted online at http://media.skyandtelescope.com/documents/Uranus-Neptune-2011.pdf

The dwarf planet Pluto is visible in western Sagittarius just after nightfall. A finder chart is available on pages 64 and 65 of the July 2011 issue of Sky & Telescope.

Asteroid 1 Ceres shines at eighth-magnitude as it travels westward through Aquarius this month. The first asteroid to be discovered is less than one degree to the north of the binary star 107 Aquarii on the nights of October 4 and October 5 and is immediately south of 106 Aquarii on October 6. For information on asteroid occultation events, browse Asteroid Occultation Predictions (Current)

Comet C/2009 P1 (Garradd) passes slowly through Hercules during October. It lies about one degree to the southwest of 101 Herculis on October 1 and may be somewhat brighter than seventh-magnitude. The periodic comet 45P/Honda-Mrkos-Pajdusakova shines at eighth-magnitude as it glides through southern Leo in the morning sky. Comet C/2010 X1 (Elenin) travels through western Leo. This comet, which has been the subject of a great deal of apocalyptic speculation on the Internet, was disrupted as at it approached perihelion. For more on the demise of Comet Elenin, see

Comet Elenin Self-Destructs - Observing Blog - SkyandTelescope.com

The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on October 3, 6, 8, 11, 14, 17, 20, 23, 26, 29, and 31. Consult The Minima of Algol - Variable Stars - SkyandTelescope.com for the times of the eclipses. For more on Algol, see Algol and Algol / Beta Persei 3

SN 2011fe, a Type Ia supernova in the spiral galaxy M101 in Ursa Major, reached a peak magnitude of 9.9 in September and is still very bright compared to most supernovae. It’s located 59 arc seconds west and 271 arc seconds south of the nucleus of M101. Click on Supernovae 2011fe in M101 and SN 2011fe | AAVSO for additional information, including finder charts, on the brightest supernova in many years.

A free star map for October can be downloaded at Skymaps.com - Publication Quality Sky Maps & Star Charts

Eighty-five binary and multiple stars for October: Struve 2973, Struve 2985, Struve 2992, Struve 3004, Struve 3028, Otto Struve 501, Struve 3034, Otto Struve 513, Struve 3050 (Andromeda); 29 Aquarii, 41 Aquarii, 51 Aquarii, 53 Aquarii, Zeta Aquarii, Struve 2913, Struve 2935, Tau-1 Aquarii, Struve 2944, Struve 2988, Psi-1 Aquarii, 94 Aquarii, 96 Aquarii, h3184, Omega-2 Aquarii, 107 Aquarii (Aquarius); Otto Struve 485, Struve 3037, 6 Cassiopeiae, Otto Struve 512, Sigma Cassiopeiae (Cassiopeia); Xi Cepheii, Struve 2883, Struve 2893, Struve 2903, Krueger 60, Delta Cephei, Struve 2923, Otto Struve 482, Struve 2947, Struve 2948, Struve 2950, Struve 2984, Omicron Cephei, Otto Struve 502 (Cepheus); Otto Struve 459, h1735, Struve 2876, Otto Struve 465, Struve 2886, Struve 2894, h1756, Struve 2902, Struve 2906, 8 Lacertae, Otto Struve 475, 13 Lacertae, h1828, 16 Lacertae (Lacerta); Struve 2857, Struve 2877, 34 Pegasi, Struve 2908, Xi Pegasi, Struve 2958, Struve 2978, 57 Pegasi, Struve 2991, h1859, Struve 3007, Struve 3021, Otto Struve 504, Struve 3044 (Pegasus); Struve 3009, Struve 3019, Struve 3033 (Pisces); Eta Piscis Austrini, Beta Piscis Austrini, Dunlop 241, h5356, Gamma Piscis Austrini, Delta Piscis Austrini, h5371 (Piscis Austrinus); h5417, Delta Sculptoris, h5429 (Sculptor)

Challenge binary star for October: 78 Pegasi

Notable carbon star for October: RZ Pegasi

Seventy-five deep-sky objects for October: NGC 7640, NGC 7662, NGC 7686 (Andromeda); NGC 7180, NGC 7183, NGC 7184, NGC 7293, NGC 7392, NGC 7585, NGC 7606, NGC 7721, NGC 7723, NGC 7727 (Aquarius); Cz43, K12, M52, NGC 7635, NGC 7788, NGC 7789, NGC 7790, St12 (Cassiopeia); B171, B173-4, IC 1454, IC 1470, K10, Mrk50, NGC 7235, NGC 7261, NGC 7354, NGC 7380, NGC 7419, NGC 7510 (Cepheus); IC 1434, IC 5217, NGC 7209, NGC 7223, NGC 7243, NGC 7245 (Lacerta); NGC 7177, NGC 7217, NGC 7320 (the brightest galaxy in Stephan's Quintet), NGC 7331, NGC 7332, NGC 7339, NGC 7448, NGC 7454, NGC 7479, NGC 7619 (the brightest member of Pegasus I), NGC 7626, NGC 7678, NGC 7742, NGC 7769 (Pegasus); NGC 7541, NGC 7562, NGC 7611 (Pisces); IC 5156, IC 5269, IC 5271, NGC 7172, NGC 7173, NGC 7174, NGC 7176, NGC 7201, NGC 7203, NGC 7214, NGC 7221, NGC 7229, NGC 7314, NGC 7361 (Piscis Austrinus); NGC 7507, NGC 7513, NGC 7713, NGC 7755, NGC 7793 (Sculptor)

Top ten binocular deep-sky objects for October: M52, NGC 7209, NGC 7235, NGC 7243, NGC 7293, NGC 7510, NGC 7686, NGC 7789, NGC 7790, St12

Top ten deep-sky objects for October: K12, M52, NGC 7209, NGC 7293, NGC 7331, NGC 7332, NGC 7339, NGC 7640, NGC 7662, NGC 7789

Challenge deep-sky object for October: Jones 1 (PK104-29.1) (Pegasus)

The objects listed above are located between 22:00 and 24:00 hours of right ascension.

[cantab]

"The smallest Full Moon of the year occurs on October 26."

Looks to be an error there, Full Moon is today!