February 2013 Celestial Calendar & Observing Notes c/o Dave Mitsky

[Big Dipper]

February 2013 Celestial Calendar & Observing Notes c/o Dave Mitsky

(calendar data also reproduced in our forum calendar).

*NB: Check out also the resources at the end of Dave's calendar for further reading/information*

All times unless otherwise noted are UT.

2/2 The astronomical cross-quarter day known as Imbolc or Candlemas occurs today; the Moon is 0.3 degree south of the first-magnitude star Spica (Alpha Virginis), with an occultation visible from far eastern Australia, most of Madagascar, and southern and southwest Africa, at 2:00

2/3 Saturn is 3 degrees north of the Moon at 10:00; Last Quarter Moon occurs at 13:56

2/4 The Curtiss Cross, an X-shaped clair-obscure illumination effect located between the craters Parry and Gambart, is predicted to occur at 9:17; Mars is 0.4 degree south of Neptune at 16:00; asteroid 1 Ceres is stationary at 17:00

2/7 The Moon is at perigee, subtending 32 arc minutes from a distance of 365,318 kilometers (226,998 miles), at 12:00

2/8 Mercury is 0.3 degree north of Mars at 21:00

2/10 New Moon (lunation 1115) occurs at 7:20

2/11 Mars is 6 degrees south of the Moon at 14:00; Mercury is 4 degrees south of the Moon at 18:00

2/12 Mercury is at the ascending node today

2/13 Uranus is 4 degrees south of the Moon at 16:00

2/16 Mercury is at greatest eastern elongation (18 degrees) at 21:00

2/17 Mercury is at perihelion today; First Quarter Moon occurs at 20:31; the Lunar X (the Purbach or Werner Cross), an X-shaped clair-obscure illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 22:33

2/18 Jupiter is 0.9 degree north of the Moon, with an occultation visible from Tasmania, southern Australia, and nearby islands, at 12:00; asteroid 4 Vesta is 0.3 degree north of the Moon, with an occultation visible from parts of Africa and central South America, at 21:00

2/19 The Moon is at apogee, subtending 29 arc minutes from a distance of 404,472 kilometers (251,327 miles), at 6:00; Saturn is stationary at 11:00

2/21 Venus is at aphelion at 7:00; Neptune is in conjunction with the Sun at 7:00

2/22 Mercury is stationary at 19:00

2/25 Full Moon (known as the Hunger, Snow, or Storm Moon) occurs at 20:26

2/27 Mercury is at its greatest heliocentric latitude north today

Nicolas Copernicus (1473-1543), Galileo Galilei (1564-1642), and Clyde Tombaugh (1906-1997) were born this month.

Clyde Tombaugh discovered Pluto on February 18, 1930. Gerald Kuiper discovered the Uranian satellite Miranda (magnitude 15.8) on February 16, 1948.

The zodiacal light may be visible in the western sky after sunset from dark locations during the latter part of the month.

The Moon is 20.2 days old and is located in the constellation of Virgo at 0:00 UT on February 1. The Moon is at its greatest northern declination of +20.6 degrees on February 19 and its greatest southern declination of -20.7 degrees on February 6. Latitudinal libration is at a maximum of +6.6 degrees on February 24 and a minimum of -6.6 degrees on February 10. Longitudinal libration is at a maximum of +6.0 degrees on February 13 and a minimum of -5.0 degrees on February 25. Visit http://saberdoesthestars.wordpress.com/2011/07/05/saber-does-the-stars/ for tips on spotting extreme crescent Moons. Times and dates for the lunar light rays predicted to occur this month are available at http://www.lunar-occultations.com/rlo/rays/rays.htm

The Sun is located in the constellation of Capricornus on February 1.

Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on February 1: Mercury (magnitude -1.1, 5.2", 95% illuminated, 1.30 a.u., Capricornus), Venus (magnitude –3.9, 10.1", 97% illuminated, 1.65 a.u., Sagittarius), Mars (magnitude +1.2, 4.1", 99% illuminated, 2.30 a.u., Aquarius), Jupiter (magnitude -2.5, 42.9", 99% illuminated, 4.59 a.u., Taurus), Saturn (magnitude +0.5, 17.1", 100% illuminated, 9.73 a.u., Libra), Uranus (magnitude +5.9, 3.4", 100% illuminated, 20.80 a.u., Pisces), Neptune (magnitude +8.0, 2.2", 100% illuminated, 30.97 a.u., Aquarius), and Pluto (magnitude +14.1, 0.1", 100% illuminated, 33.07 a.u., Sagittarius).

Mercury, Mars, and Uranus can be seen in the west and Jupiter in the south in the evening sky. Jupiter is in the west and Saturn in the east at midnight. Venus lies in the southeast and Saturn in the south in the morning sky.

At midmonth, Mercury is visible during evening twilight, Jupiter transits the meridian at 7:00 p.m. and sets at 2:00 a.m., and Saturn rises at midnight and transits the meridian at 5:00 a.m. local time for observers at latitude 40 degrees north.

The best evening apparition of Mercury of 2013 for mid-latitude northern observers occurs during the first three weeks of the month. Mercury is visible low in the west-southwest during evening twilight. It passes 0.3 degree north of Mars on February 8 and five degrees south of the Moon on January 11. Greatest eastern elongation takes place on February 16, when the planet attains an altitude of 11 degrees one-half hour after sunset. Dichotomy occurs on the same day. Perihelion takes place on February 17.

Venus can be seen very low in the east-southeast just prior to sunrise early in the month. It rises just 40 minutes before sunrise on February 1. Venus is lost in the glare of the Sun by month’s end.

Mars is very low in west-southwest during evening twilight and is no longer visible by the middle of February.

Jupiter drops to magnitude -2.3 and declines in apparent size to 39 arc seconds by month’s end. The First Quarter Moon lies to the west of the planet on the night of February 17. Jupiter is occulted by the waxing gibbous Moon for observers in part of Africa and in central South America on February 18. Eastern quadrature is achieved on February 25. (Shadow transits and eclipses are enhanced by Jupiter’s position in relation to the Sun.) Jupiter sets at 1:00 a.m. local time by the end of the month. All four of the Galilean satellites are to the west of Jupiter on the evenings of February 2 and February 9 and to the east of the planet on February 14. Browse http://skyandtelescope.com/observing/objects/planets/article_107_1.asp in order to determine transit times of Jupiter’s central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://skytonight.com/observing/objects/javascript/3307071.html#

This month Saturn's rings span 40 arc seconds and are inclined 19.3 degrees from edge-on, the maximum for 2013. Saturn rises shortly before midnight by February 15. It commences retrograde (western) motion on February 19. Eight-magnitude Titan is north of Saturn on February 9 and February 25 and south of the planet on February 16. For further information on the satellites of Saturn, browse http://www.skyandtelescope.com/observing/objects/javascript/3308506.html

Uranus sets in the mid-evening. It passes just four arc minutes north of the star 44 Piscium (magnitude 5.8) on the evenings of February 25 and February 26. February is the planet’s last full month of visibility.

Neptune lies 0.5 degree northwest of Mercury during evening twilight on February 6 but is most likely not observable. The eighth planet is in conjunction with the Sun on February 21.

The dwarf planet Pluto is not readily observable during February.

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

During February, Comet C/2011 L4 (PANSTARRS) may brighten from sixth to second magnitude for southern hemisphere observers. The comet travels northeastward through Sagittarius, Grus, and Piscis Austrinus during the course of the month. On February 26 and 27, it passes within three degrees of the first-magnitude star Fomalhaut (Alpha Piscis Austrini). Visit http://cometchasing.skyhound.com/ and http://www.curtrenz.com/comets for additional information on comets visible this month and in the near future.

The dwarf planet/asteroid 1 Ceres turns eastward towards the second-magnitude star Beta Tauri early in the month and passes within one degree of the star at the end of February. Asteroid 4 Vesta lies three degrees north of the first-magnitude star Aldebaran (Alpha Tauri) at the beginning of the month. Both minor planets shine at eighth magnitude.

Free star maps for February can be downloaded at http://www.skymaps.com/downloads.html and http://www.telescope.com/content.jsp?pageName=Monthly-Star-Chart

The famous eclipsing variable star Algol (Beta Persei) is at a minimum, decreasing in magnitude from 2.1 to 3.4, on February 1, 4, 7, 10, 13, 16, 18, 21, 24, and 27. Consult http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algo... for the times of the eclipses. For more on Algol, see http://stars.astro.illinois.edu/sow/Algol.html and http://www.solstation.com/stars2/algol3.htm

Forty binary and multiple stars for February: 41 Aurigae, Struve 872, Otto Struve 147, Struve 929, 56 Aurigae (Auriga); Nu-1 Canis Majoris, 17 Canis Majoris, Pi Canis Majoris, Mu Canis Majoris, h3945, Tau Canis Majoris (Canis Major); Struve 1095, Struve 1103, Struve 1149, 14 Canis Minoris (Canis Minor); 20 Geminorum, 38 Geminorum, Alpha Geminorum (Castor), 15 Geminorum, Lambda Geminorum, Delta Geminorum, Struve 1108, Kappa Geminorum (Gemini); 5 Lyncis, 12 Lyncis, 19 Lyncis, Struve 968, Struve 1025 (Lynx); Epsilon Monocerotis, Beta Monocerotis, 15 (S) Monocerotis (Monoceros); Struve 855 (Orion); Struve 1104, k Puppis, 5 Puppis (Puppis)

Notable carbon star for February: BL Orionis (Orion)

Fifty deep-sky objects for February: NGC 2146, NGC 2403 (Camelopardalis); M41, NGC 2345, NGC 2359, NGC 2360, NGC 2362, NGC 2367, NGC 2383 (Canis Major); M35, NGC 2129, NGC 2158, NGC 2266, NGC 2355, NGC 2371-72, NGC 2392, NGC 2420 (Gemini); NGC 2419 (Lynx); M50, NGC 2232, NGC 2237, NGC 2238, NGC 2244, NGC 2245, NGC 2251, NGC 2261, NGC 2264, NGC 2286, NGC 2301, NGC 2311, NGC 2324, NGC 2335, NGC 2345, NGC 2346, NGC 2353 (Monoceros); NGC 2169, NGC 2174, NGC 2194 (Orion); M46, M47, M93, Mel 71, NGC 2421, NGC 2423, NGC 2438, NGC 2439, NGC 2440, NGC 2467, NGC 2506, NGC 2509 (Puppis)

Top ten binocular deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2244, NGC 2264, NGC 2301, NGC 2360

Top ten deep-sky objects for February: M35, M41, M46, M47, M50, M93, NGC 2261, NGC 2362, NGC 2392, NGC 2403

Challenge deep-sky object for February: IC 443 (Gemini)

The objects listed above are located between 6:00 and 8:00 hours of right ascension.

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*Suggestions for further reading/information:*

Check out the following two sites (both are primarily UK-based) - each of which contain excellent celestial guides for the month ahead:

Astronomical Calendar

Astronomy.co.uk (site includes a short video highlighting some of the main celestial events for the month ahead).