August 2009 Astronomical Data
August 2009 Astronomical Calendar
Dave Mitsky
Note: All times in UTC (EST + 5)
| 8/2 | Mercury is 0.6 degree north of the first-magnitude star Regulus (Alpha Leonis) at 19:00; Venus is 2 degrees south of the bright open cluster M35 in Gemini at 23:00 |
|---|---|
| 8/4 | The Moon is at apogee, subtending 29'37" from a distance of 406,028 km (252,294 miles), at 1:00 |
| 8/5 | The midpoint of a penumbral lunar eclipse occurs at 00:39 |
| 8/6 | Full Moon (known as the Fruit, Grain, Green Corn, or Sturgeon Moon) occurs at 0:55; Jupiter is 3 degrees south of the Moon at 22:00 |
| 8/7 | Neptune is 3 degrees south of the Moon at 2:00 |
| 8/9 | Uranus is 6 degrees south of the Moon at 17:00 |
| 8/11 | Mercury is at the descending node today |
| 8/12 | The peak of the Perseid meteor shower (a zenithal hourly rate of 60-100/hour) occurs at 18:00; a double Galilean shadow transit begins at 21:12 |
| 8/13 | Last Quarter Moon occurs at 18:55 |
| 8/14 | The Curtiss Cross, an X-shaped illumination effect located between the craters Parry and Gambart, is predicted to occur at 9:59; the Moon is 0.5 degree north of the bright open cluster M45 (the Pleiades) in Taurus at 11:00; Jupiter (magnitude -2.9, apparent size 48.95") is at opposition at 18:00 |
| 8/15 | Asteroid 3 Juno is stationary at 18:00 |
| 8/16 | Mars is 3 degrees south of the Moon at 3:00; the Moon is 1.6 degrees north of M35 at 17:00 |
| 8/17 | Neptune (magnitude 7.8, apparent size 2.4") is at opposition at 21:00; Venus is 1.7 degrees south of the Moon at 21:00 |
| 8/18 | Asteroid 7 Vesta is 0.4 degree south of the Moon, with an occultation taking place in southeast Asia, western China, India, the Middle East, western Russia, northern Africa, and Europe, at 7:00; Mercury is 3 degrees south of Saturn at 21:00 |
| 8/19 | The Moon is at perigee, subtending 33'10" from a distance of 359,639 km (223, 469 miles), at 5:00; a double Galilean shadow transit begins at 23:47 |
| 8/20 | Mars is at the ascending node today; New Moon (lunation 1072) occurs at 10:02 |
| 8/21 | Mercury is at aphelion today |
| 8/22 | Venus is 7 degrees south of the second-magnitude star Pollux (Beta Geminorum) at 4:00; Saturn is 7 degrees north of the Moon at 6:00; Mercury is 3 degrees north of the Moon at 12:00 |
| 8/24 | Mercury is at greatest eastern elongation (27 degrees) at 16:00 |
| 8/27 | A double Galilean shadow transit by Europa and Ganymede begins at 2:42; First Quarter Moon occurs at 11:42; the Lunar X, also known as the Werner or Purbach Cross, an X-shaped illumination effect involving various rims and ridges between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 18:45; the Moon is 0.6 degree south of the first-magnitude star Antares (Alpha Scorpii), with an occultation taking place in northwestern Africa, northern South America, and North America with the exception of most of Canada, at 22:00 |
| 8/29 | Mars is 0.8 degrees south of M35 at 3:00 |
| 8/31 | Venus is at the ascending node today; the Moon is at apogee, subtending 29'36" from a distance of 405,269 km (251,822 miles), at 11:00 |
The Perseid meteor shower may exhibit two peaks this year (one at 5:00 a.m. EDT on August 12 and the other, the traditional peak, at 4:00 p.m. EDT on August 12) but is compromised by moonlight.
The Moon occults the first-magnitude star Antares on August 27. Browse http://www.lunar-occultations.com/iota/bstar/0827antares.htm for additional information on this event. The Lunar X occurs on August 27 at approximately 358 degrees co-longitude and the Curtiss Cross on August 14 at approximately 194 degrees co-longitude. The Moon is 9.9 days old and located in Ophiuchus on August 1 at 0:00 UT. It’s at its greatest northern declination on August 15 (+26.4 degrees) and its greatest southern declination on August 1 (-26.5 degrees). Longitudinal libration is at a maximum of +7.3 degrees on August 25 and a minimum of -6.7 degrees on August 12. Latitudinal libration is at a maximum of +6.8 degrees on August 24 and a minimum of -6.8 degrees on August 12. Visit http://www.astronomyblogs.com/member/saberscorpx/?xjMsgID=50821 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 Cancer on August 1.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on August 1: Mercury (-0.4 magnitude, 5.4", 83% illuminated, 1.23 a.u., Leo), Venus (-4.0 magnitude, 14.8", 74% illuminated, 1.13 a.u., Orion), Mars (1.1 magnitude, 5.3", 91% illuminated, 1.76 a.u., Aries), Jupiter (-2.8 magnitude, 48.6", 100% illuminated, 4.06 a.u., Capricornus), Saturn (1.1 magnitude, 16.3", 100% illuminated, 10.18 a.u., Leo), Uranus (5.8 magnitude, 3.7", 100% illuminated, 19.24 a.u., Aquarius), Neptune (7.8 magnitude, 2.3", 100% illuminated, 29.02 a.u., Capricornus), and Pluto (13.9 magnitude, 0.1", 100% illuminated, 31.07 a.u., Sagittarius).
During August evenings, Mercury can be seen in the west, Jupiter in the southeast, and Saturn in the west. Jupiter is in the south and Uranus is the southeast at midnight. Venus and Mars are located in the eastern sky and Jupiter and Uranus in the southwestern sky in the morning.
Mercury is visible during evening twilight but southern hemisphere observers will have more favorable views due to Mercury’s southern declination and the angle of the ecliptic. The speedy planet passes very near the first-magnitude star Regulus on August 2 and close to Saturn on August 18 and the Moon on August 22. Mercury moves into Virgo on August 20. It reaches maximum eastern elongation on August 24. During the course of the month, Mercury decreases in magnitude from -0.4 to 0.4.
Venus is at its highest in early August for observers at latitude 40 degrees north. At the middle of the month, Venus rises by 3:00 a.m. EDT. Venus passes within 0.75 degree of the third-magnitude star Delta Geminorum on August 17. The Moon is seven degrees north of Venus on August 17 and seven degrees south of the planet on August 18. Venus enters Cancer on August 24. On August 25, Venus passes 0.5 degree south of the eighth-magnitude asteroid 4 Vesta. The brightest planet is near the bright open cluster M44 (the Beehive) in Cancer at month’s end.
Mars rises at 1:00 a.m. EDT at mid-month. The Red Planet is 2.1 degrees north of the third-magnitude star Zeta Tauri on August 17. Mars leaves Taurus and enters Gemini on August 26. It passes 0.8 degree south of M35 on August 29 and 1.1 degrees north of third-magnitude star Eta Geminorum on August 31.
During August, the distance between Jupiter and Neptune (which is only one ten-thousandth as bright as Jupiter) increases from two to five degrees. Jupiter occults the sixth-magnitude star 45 Capricorni on August 3, an event that’s visible from the Middle East, Africa, Europe, and the easternmost part of North America. From August 2 to August 5, 45 Capricorni is close enough to Jupiter that it may be appear to be a fifth Galilean satellite. See http://www.iota-es.de/jupiter2009/jupiteroccultation.html for additional information on the occultation. Jupiter will be bigger (48.95 arc seconds) and brighter (magnitude -2.9) than it’s been since October of 1999 when it reaches opposition on August 14. On that date, the giant planet is visible the entire night and culminates in the south at an altitude of about 35 degrees, from latitude 40 degrees north. At opposition, Io, Europa, Ganymede, and Callisto subtend 1.2, 1.1, 1.8, and 1.7 arc seconds and shine at magnitudes 4.8, 5.1, 4.4, and 5.4 respectively. For three hours and eleven minutes on the night of August 26, Callisto is the only one of the Galilean satellites that’s visible. Click on http://skyandtelescope.com/observing/objects/planets/article_107_1.asp to determine transit times of the central meridian by the Great Red Spot. Data on the Galilean satellites is available at http://skytonight.com/observing/objects/javascript/3307071.html
Saturn can still be seen in the evening twilight in early August. It sets around 9:00 p.m. EDT at mid-month and is lost in the glare of the Sun thereafter. Mercury and Saturn are in conjunction on August 18. Saturn’s rings are edge-on to the Sun on August 10 and thus are not illuminated. The ring tilt angle with respect to the Earth is only 0.37 degree on August 29.
During August, Uranus lies about four degrees south of the fourth-magnitude star Lambda Piscium and within one degree of the sixth-magnitude star 20 Piscium.
Neptune is one degree west of the fifth-magnitude star Mu Capricorni and 2.6 degrees north of third-magnitude Delta Capricorni when it reaches opposition on August 17.
Finder charts for Uranus and Neptune are posted at http://www.skyandtelescope.com/observing/highlights/41561382.html
The dwarf planet Pluto is located between the open clusters M18 and M23 in northwestern Sagittarius. It lies to the south of a right triangle of seventh-magnitude field stars. A finder chart is available on page 53 of the June 2009 issue of Sky & Telescope.
Asteroid 7 Iris shines at ninth magnitude as it passes westward through Sagittarius for most of August. During the first week of August, it’s located roughly halfway between the open cluster M25 and the star cloud M24. Near the end of the month, 7 Iris glides across an unnamed dark nebula to the southeast of the dark nebulae B92, B93, B304, and B307. It passes less than two arc minutes south of a seventh-magnitude star during the final nights of August. The following asteroids are at opposition this month: 16 Psyche (magnitude 9.3), 55 Pandora (magnitude 10.9), 88 Thisbe (magnitude 9.8), and 101 Helena (magnitude 10.7).
Comet 22P/Kopff travels southwestward through Aquarius and C/2006 W3 (Christensen) through Vulpecula and Aquila this month. Browse http://www.aerith.net/comet/future-n.html for additional information on these and other visible comets.
Binary and Multiple Stars for August
5 Aquilae, Struve 2404, 11 Aquilae, Struve 2426, 15 Aquilae, Struve 2449, 23 Aquilae, Struve 2532, Pi Aquilae, 57 Aquilae (Aquila); Beta Cygni (Albireo), 16 Cygni, Delta Cygni, 17 Cygni (Cygnus); 41 & 40 Draconis, 39 Draconis, Struve 2348, Sigma Draconis, Struve 2573, Epsilon Draconis (Draco); 95 Herculis, 100 Herculis, Struve 2289, Struve 2411 (Hercules); Struve 2349, Struve 2372, Epsilon-1 & Epsilon-2 Lyrae (the Double-Double), Zeta-2 Lyrae, Beta Lyrae, Otto Struve 525, Struve 2470 & Struve 2474 (the Other Double-Double) (Lyra); 67 Ophiuchi, 69 Ophiuchi, 70 Ophiuchi, Struve 2276, 74 Ophiuchi (Ophiuchus); Mu Sagittarii, Eta Sagittarii, 21 Sagittarii, Zeta Sagittarii, H N 119, 52 Sagittarii, 54 Sagittarii (Sagittarius); Struve 2306, Delta Scuti, Struve 2373 (Scutum); Struve 2296, Struve 2303, 59 Serpentis, Theta Serpentis (Serpens Cauda); Struve 2445, Struve 2455, Struve 2457, 4 Vupeculae, Struve 2521, Struve 2523, Struve 2540, Struve 2586, Otto Struve 388, Struve 2599 (Vulpecula)
Challenge binary star for August: Alvan Clark 11 (ADS 11324) (Serpens Cauda)
| Deep-sky objects for August: | ||||||
|---|---|---|---|---|---|---|
| Aquila: | ||||||
| B 139 | [info] | B 142 | [info] | B 143 | [info] | |
| NGC 6709 | [info] | NGC 6738 | [info] | NGC 6741 | [info] | |
| NGC 6751 | [info] | NGC 6755 | [info] | NGC 6772 | [info] | |
| NGC 6778 | [info] | NGC 6781 | [info] | NGC 6804 | [info] | |
| PK 6451 | [info] | |||||
| Cygnus: | ||||||
| NGC 6819 | [info] | NGC 6826 | [info] | NGC 6834 | [info] | |
| Draco: | ||||||
| NGC 6643 | [info] | NGC 6742 | [info] | |||
| Hercules: | ||||||
| DoDz 9 | [info] | |||||
| Lyra: | ||||||
| M 56 | [info] | M 57 | [info] | NGC 6703 | [info] | |
| NGC 6791 | [info] | Ste 1 | [info] | |||
| Ophiuchus: | ||||||
| NGC 6572 | [info] | NGC 6633 | [info] | |||
| Sagitta: | ||||||
| H 20 | [info] | M 71 | [info] | |||
| Sagittarius: | ||||||
| B 86 | [info] | B 87 | [info] | B 90 | [info] | |
| B 92 | [info] | B 93 | [info] | M 8 | [info] | |
| M 17 | [info] | M 18 | [info] | M 20 | [info] | |
| M 21 | [info] | M 22 | [info] | M 23 | [info] | |
| M 24 | [info] | M 25 | [info] | M 28 | [info] | |
| M 54 | [info] | M 55 | [info] | M 69 | [info] | |
| M 70 | [info] | M 75 | [info] | NGC 6520 | [info] | |
| NGC 6544 | [info] | NGC 6546 | [info] | NGC 6553 | [info] | |
| NGC 6565 | [info] | NGC 6603 | [info] | NGC 6818 | [info] | |
| NGC 6822 | [info] | |||||
| SerpensCauda: | ||||||
| IC 4703 | [info] | IC 4756 | [info] | M 16 | [info] | |
| NGC 6604 | [info] | |||||
| Scutum: | ||||||
| B 100 | [info] | B 101 | [info] | B 103 | [info] | |
| B 104 | [info] | B 110 | [info] | B 111 | [info] | |
| B 113 | [info] | Bas 1 | [info] | IC 1295 | [info] | |
| M 11 | [info] | M 26 | [info] | NGC 6649 | [info] | |
| NGC 6712 | [info] | |||||
| Vulpecula: | ||||||
| Cr 399 (asterism) | [info] | M 27 | [info] | NGC 6802 | [info] | |
| NGC 6823 | [info] | NGC 6834 | [info] | NGC 6940 | [info] | |
| St 1 | [info] | |||||
| Click here for a printable deep sky summary. |
Top ten binocular deep-sky objects for August: Cr 399, IC 4765, M8, M11, M17,
M22, M24, M25, M27, NGC 6633
(IC 4756 and NGC 6633 are collectively known as the Binocular Double Cluster)
Top ten deep-sky objects for August: M8, M11, M16, M17, M20, M22, M24, M27, M55, M57
Challenge deep-sky object for August: Abell 53 (Aquila)
The objects listed above are located between 18:00 and 20:00 hours of right ascension.
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