Post by Dave Mitsky on Aug 1, 2015 7:09:56 GMT
August Celestial Calendar by Dave Mitsky
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
8/1 The astronomical cross-quarter day known as Lammas or Lughnasadh occurs today
8/2 The Moon is at perigee, subtending nearly 33'13'' from a distance of 362,139 kilometers (252,023 miles), at 10:00; Saturn is stationary at 20:00
8/5 Mercury is 8 degrees north of Venus at 9:00; Uranus is 1 degree north of the Moon, with an occultation occurring in the Falkland Islands, southern South America, and Antarctica, at 9:00
8/7 Last Quarter Moon occurs at 2:03; Mercury is 0.6 degree north of Jupiter at 4:00; Mercury is 1.0 degree north of the first-magnitude star Regulus at 15:00
8/8 Venus is at aphelion today; asteroid 2 Pallas is stationary at 12:00; the Curtiss Cross, an X-shaped clair-obscur illumination effect located between the craters Parry and Gambart, is predicted to occur at 16:26
8/9 The Moon is 0.7 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation occurring in northwestern Canada, Alaska, northwestern Asia, Russia, Scandinavia, the Middle East, and eastern Europe, at 0:00
8/10 Jupiter is 0.4 degree north of the first-magnitude star Regulus at 23:00
8/13 Mars is 6 degrees north of the Moon at 5:00; the peak of the Perseid meteor shower (a zenithal hourly rate of 60 to 100 per hour) occurs at 6:00
8/14 New Moon (lunation 1146) occurs at 14:53
8/15 Venus is in inferior conjunction at 19:00; Mercury is 2 degrees north of the Moon at 15:00
8/16 Asteroid 4 Vesta is stationary at 6:00
8/18 The Moon is at apogee, subtending 29'17'' from a distance of 405,848 kilometers (252,182 miles), at 3:00
8/19 Mercury is at the descending node today
8/20 Mars is 0.5 degree south of the bright open cluster M44 (the Beehive or Praesepe) in Cancer at 16:00
8/22 The Lunar X, also known as the Werner or Purbach Cross, an X-shaped clair-obscur illumination effect involving various ridges and crater rims located between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 1:25; Saturn is 3 degrees south of the Moon at 17:00; First Quarter Moon occurs at 19:31
8/26 Jupiter is in conjunction with the Sun at 22:00
8/29 Mercury is at aphelion today; Full Moon (known as the Fruit, Grain, Green Corn, or Sturgeon Moon) occurs at 18:35
8/30 The Moon is at perigee, subtending nearly 32'59'' from a distance of 358,290 kilometers (222,631 miles), at 15:00
8/31 Venus is at its greatest heliocentric latitude south today
John Flamsteed and Maria Mitchell were born this month.
The gibbous phase of Mars was first observed by Francesco Fontana on August 24, 1638. William Herschel discovered Enceladus on August 28, 1789. Asaph Hall discovered Deimos on August 11, 1877 and Phobos on August 17, 1877.
The peak of the Perseid meteor shower is not adversely affected by moonlight this year. Comet 109P/Swift-Tuttle is the source of Perseid meteors. For more on this year’s Perseids, see pages 48-50 of the August issue of Sky & Telescope or click on www.timeanddate.com/astronomy/meteor-shower/perseid.html and earthsky.org/astronomy-essentials/everything-you-need-to-know-perseid-meteor-shower
The Moon is 15.9 days old, is illuminated 99.6%, and is located in Aquarius on August 1st at 0:00 UT. The Moon is at its greatest northern declination on August 10th (+18.3 degrees) and its greatest southern declination on August 25th (-18.2 degrees). Longitudinal libration is at a maximum of +6.2 degrees on August 9th and -7.3 degrees on August 24th. Latitudinal libration is at a maximum of +6.7 degrees on August 10th and a minimum of -6.8 degrees on August 25th. The Moon passes two degrees south of Mars on August 13th, two degrees south of Mercury on August 15th, and three degrees north of Saturn on August 25th. New Moon (i.e., the dark of the Moon) occurs on August 14th. The Moon is at perigee on August 2nd and August 30th and apogee on August 18th. Large tides will take place on August 31st. The Moon occults Uranus on August 5th and Aldebaran on August 9th from certain parts of the world. Browse www.curtrenz.com/occultations and www.lunar-occultations.com/iota/bstar/bstar.htm for information on lunar occultations. Visit 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 in August are available at www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Cancer on August 1st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on August 1: Mercury (magnitude -1.2, 5.1", 95% illuminated, 1.33 a.u., Cancer), Venus (magnitude -4.4, 52.1", 7% illuminated, 0.32 a.u., Gemini), Mars (magnitude +1.7, 3.6", 99% illuminated, 2.58 a.u., Cancer), Jupiter (magnitude -1.7, 31.1", 100% illuminated, 6.33 a.u., Cancer), Saturn (magnitude +0.4, 17.3", 100% illuminated, 9.60 a.u., Libra), Uranus (magnitude +5.8, 3.6", 100% illuminated, 19.42 a.u. on August 16th, Pisces), Neptune (magnitude +7.8, 2.4", 100% illuminated, 28.99 a.u. on August 16th, Aquarius), and Pluto (magnitude +14.1, 0.1", 100% illuminated, 32.14 a.u. on August 16th, Sagittarius).
This month Mercury, Venus, and Jupiter are visible in the west, Saturn in the southwest, and Neptune in the east during the evening. At midnight, Saturn can be found in the southwest, Uranus in the east, and Neptune in the southeast. In the morning, Venus and Mars are in the east, Uranus is in the south, and Neptune is in the southwest.
At midmonth, Mercury is visible in evening twilight, Mars rises at 5:00 a.m. local daylight time, Jupiter is visible in evening twilight, and Saturn sets at midnight for observers at latitude 40 degrees north.
Mercury and Jupiter form a close pair from August 5th through August 8th. The two planets lie within a degree of each other on August 6th and August 7th. On the evening of August 6th, Jupiter (magnitude -1.7) is 0.6 degree to the lower left of Mercury (magnitude -0.7). Mercury is in the process of entering the evening sky this month and Jupiter is in the process of exiting it. Mercury is two degrees north of the waxing crescent Moon on August 15th and is at aphelion on August 29th. As August progresses, Mercury increases its angular separation from the Sun, attaining an altitude of seven degrees above the western horizon 30 minutes after sunset by August 31st.
On the evening of August 1st, Venus is less than 7% illuminated and appears as a very thin crescent 53 arc seconds in size. When Venus reaches aphelion on August 8th, it will be approximately 2.5 light-minutes from the Earth. Venus passes almost eight degrees south of the Sun when it is in inferior conjunction on August 15th. Venus and Mars are nine degrees apart on August 29th, the second of three conjunctions of the two planets this year. Venus rises more than 90 minutes before the Sun by month’s end. By that time, it increases in brightness to magnitude -4.5, decreases in apparent size to 52 arc seconds, and increases in phase to 9% illuminated.
Mars emerges from the glare of the Sun during morning twilight as August progresses. At midmonth, it shines faintly at magnitude +1.7 as it rises 90 minutes before sunrise. By the end of August, Mars rises two hours before the Sun. The Red Planet passes by the open cluster M44 on the mornings of August 20th and August 21st but observing the two objects will be rather difficult.
Jupiter disappears into evening twilight during early August. The gas giant is in conjunction with Mercury on August 7th. On August 10th, Jupiter undergoes the only conjunction with Regulus in this cycle of its 12-year-long orbit. Jupiter is in conjunction with the Sun on August 26th.
During August, Saturn is positioned 13 degrees northwest of the first-magnitude star Antares. The Ringed Planet subtends 17 arc seconds in angular size this month. Its rings are inclined by 24 degrees and span 38 arc seconds. On August 2nd, Saturn ends its retrograde motion through eastern Libra. Saturn is at eastern quadrature (i.e., 90 degrees east of the Sun) on August 21st. It is 9% smaller at that time than at opposition and appears more three dimensional than usual due to the greater angle of the sunlight illuminating the planet. Eighth-magnitude Titan, Saturn’s largest satellite, is due north of the planet on August 7th and August 23rd and due south on August 14th and August 30th. The peculiar satellite Iapetus shines at tenth magnitude as it passes 8.3 arc minutes from Saturn and reaches greatest western elongation on August 6th. It fades to eleventh magnitude by August 25th when it is 2.1 arc minutes north of Saturn. For additional information on Saturn’s satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus rises approximately 90 minutes after Neptune and can be found 0.6 degree from the fifth-magnitude star Zeta Piscium this month. During the course of August, Uranus moves from a position southeast of that star to one that's slightly southwest.
Neptune continues to retrograde through Aquarius. The eighth planet is located 3.4 degrees southwest of Lambda Aquarii at the end of August. It reaches opposition (magnitude +7.8, apparent diameter 2.4 arc seconds) for Western Hemisphere observers on August 31st.
Finder charts for Uranus and Neptune can be found at www.nakedeyeplanets.com/uranus.htm and www.nakedeyeplanets.com/neptune.htm and at www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf
On August 1st, Pluto is positioned approximately midway between the stars Xi-1Sagittarii (magnitude +5.0) and Xi-2 Sagittarii (magnitude +3.5). It is about 35 arc minutes west-northwest of Xi2 Sagittarii by the end of August. Finder charts for Pluto are available on pages 52 and 53 of the July issue of Sky & Telescope and page 47 of the July issue of Astronomy and online at www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf
For more on the planets and how to locate them, see www.nakedeyeplanets.com/
The fragmented periodic comet 141P/Machholz reaches perihelion on August 24th. Assuming the pieces have not completely disintegrated, the comet may be visible as it passes between the bright open clusters M36 and M38 in Auriga on the mornings of August 7th and August 8th. Comet C/2013 US10 (Catalina), which is currently visible from the southern hemisphere, travels northward, passing near the first-magnitude star Alpha Centauri as August ends. For further information on comets visible this month, browse cometchasing.skyhound.com/ and www.aerith.net/comet/future-n.html
Asteroid/dwarf planet 1 Ceres shines at eighth magnitude as it travels southwestward through eastern Sagittarius this month. It passes 0.3 degree north of the fifth-magnitude star SAO 211782 on August 20th and August 21st. Asteroid 100 Hekate (magnitude +10.8) reaches opposition on August 2nd, asteroid 65 Cybele (magnitude +11.1) on August 13th, and asteroid 21 Lutetia (magnitude +9.4) on August 15th. For information on asteroid occultations taking place this month, see www.asteroidoccultation.com/2015_08_si.htm
Free star maps for August can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
Sixty 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)
Notable carbon star for August: V Aquilae
Eighty deep-sky objects for August: B139, B142, B143, NGC 6709, NGC 6738, NGC 6741, NGC 6751, NGC 6755, NGC 6772, NGC 6778, NGC 6781, NGC 6804, PK64+5.1 (Aquila); NGC 6819, NGC 6826, NGC 6834, (Cygnus); NGC 6643, NGC 6742 (Draco); DoDz 9 (Hercules); M56, M57, NGC 6703, NGC 6791, Ste1 (Lyra); NGC 6572, NGC 6633 (Ophiuchus); H20, M71 (Sagitta); B86, B87, B90, B92, B93, M8, M17, M18, M20, M21, M22, M23, M24, M25, M28, M54, M55, M69, M70, M75, NGC 6520, NGC 6544, NGC 6546, NGC 6553, NGC 6565, NGC 6603, NGC 6818, NGC 6822 (Sagittarius); IC 4703, IC 4756, M16, NGC 6604 (Serpens Cauda); B100, B101, B103, B104, B110, B111, B113, Bas 1, IC 1295, M11, M26, NGC 6649, NGC 6712 (Scutum); Cr 399 (asterism), M27, NGC 6802, NGC 6823, NGC 6834, NGC 6940, St 1 (Vulpecula)
Top ten binocular deep-sky objects for August: Cr 399, IC 4756, 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.
All times, unless otherwise noted, are UT (subtract four hours and, when appropriate, one calendar day for EDT)
8/1 The astronomical cross-quarter day known as Lammas or Lughnasadh occurs today
8/2 The Moon is at perigee, subtending nearly 33'13'' from a distance of 362,139 kilometers (252,023 miles), at 10:00; Saturn is stationary at 20:00
8/5 Mercury is 8 degrees north of Venus at 9:00; Uranus is 1 degree north of the Moon, with an occultation occurring in the Falkland Islands, southern South America, and Antarctica, at 9:00
8/7 Last Quarter Moon occurs at 2:03; Mercury is 0.6 degree north of Jupiter at 4:00; Mercury is 1.0 degree north of the first-magnitude star Regulus at 15:00
8/8 Venus is at aphelion today; asteroid 2 Pallas is stationary at 12:00; the Curtiss Cross, an X-shaped clair-obscur illumination effect located between the craters Parry and Gambart, is predicted to occur at 16:26
8/9 The Moon is 0.7 degree north of the first-magnitude star Aldebaran (Alpha Tauri), with an occultation occurring in northwestern Canada, Alaska, northwestern Asia, Russia, Scandinavia, the Middle East, and eastern Europe, at 0:00
8/10 Jupiter is 0.4 degree north of the first-magnitude star Regulus at 23:00
8/13 Mars is 6 degrees north of the Moon at 5:00; the peak of the Perseid meteor shower (a zenithal hourly rate of 60 to 100 per hour) occurs at 6:00
8/14 New Moon (lunation 1146) occurs at 14:53
8/15 Venus is in inferior conjunction at 19:00; Mercury is 2 degrees north of the Moon at 15:00
8/16 Asteroid 4 Vesta is stationary at 6:00
8/18 The Moon is at apogee, subtending 29'17'' from a distance of 405,848 kilometers (252,182 miles), at 3:00
8/19 Mercury is at the descending node today
8/20 Mars is 0.5 degree south of the bright open cluster M44 (the Beehive or Praesepe) in Cancer at 16:00
8/22 The Lunar X, also known as the Werner or Purbach Cross, an X-shaped clair-obscur illumination effect involving various ridges and crater rims located between the craters La Caille, Blanchinus, and Purbach, is predicted to occur at 1:25; Saturn is 3 degrees south of the Moon at 17:00; First Quarter Moon occurs at 19:31
8/26 Jupiter is in conjunction with the Sun at 22:00
8/29 Mercury is at aphelion today; Full Moon (known as the Fruit, Grain, Green Corn, or Sturgeon Moon) occurs at 18:35
8/30 The Moon is at perigee, subtending nearly 32'59'' from a distance of 358,290 kilometers (222,631 miles), at 15:00
8/31 Venus is at its greatest heliocentric latitude south today
John Flamsteed and Maria Mitchell were born this month.
The gibbous phase of Mars was first observed by Francesco Fontana on August 24, 1638. William Herschel discovered Enceladus on August 28, 1789. Asaph Hall discovered Deimos on August 11, 1877 and Phobos on August 17, 1877.
The peak of the Perseid meteor shower is not adversely affected by moonlight this year. Comet 109P/Swift-Tuttle is the source of Perseid meteors. For more on this year’s Perseids, see pages 48-50 of the August issue of Sky & Telescope or click on www.timeanddate.com/astronomy/meteor-shower/perseid.html and earthsky.org/astronomy-essentials/everything-you-need-to-know-perseid-meteor-shower
The Moon is 15.9 days old, is illuminated 99.6%, and is located in Aquarius on August 1st at 0:00 UT. The Moon is at its greatest northern declination on August 10th (+18.3 degrees) and its greatest southern declination on August 25th (-18.2 degrees). Longitudinal libration is at a maximum of +6.2 degrees on August 9th and -7.3 degrees on August 24th. Latitudinal libration is at a maximum of +6.7 degrees on August 10th and a minimum of -6.8 degrees on August 25th. The Moon passes two degrees south of Mars on August 13th, two degrees south of Mercury on August 15th, and three degrees north of Saturn on August 25th. New Moon (i.e., the dark of the Moon) occurs on August 14th. The Moon is at perigee on August 2nd and August 30th and apogee on August 18th. Large tides will take place on August 31st. The Moon occults Uranus on August 5th and Aldebaran on August 9th from certain parts of the world. Browse www.curtrenz.com/occultations and www.lunar-occultations.com/iota/bstar/bstar.htm for information on lunar occultations. Visit 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 in August are available at www.lunar-occultations.com/rlo/rays/rays.htm
The Sun is located in Cancer on August 1st.
Brightness, apparent size, illumination, distance from the Earth in astronomical units, and location data for the planets and Pluto on August 1: Mercury (magnitude -1.2, 5.1", 95% illuminated, 1.33 a.u., Cancer), Venus (magnitude -4.4, 52.1", 7% illuminated, 0.32 a.u., Gemini), Mars (magnitude +1.7, 3.6", 99% illuminated, 2.58 a.u., Cancer), Jupiter (magnitude -1.7, 31.1", 100% illuminated, 6.33 a.u., Cancer), Saturn (magnitude +0.4, 17.3", 100% illuminated, 9.60 a.u., Libra), Uranus (magnitude +5.8, 3.6", 100% illuminated, 19.42 a.u. on August 16th, Pisces), Neptune (magnitude +7.8, 2.4", 100% illuminated, 28.99 a.u. on August 16th, Aquarius), and Pluto (magnitude +14.1, 0.1", 100% illuminated, 32.14 a.u. on August 16th, Sagittarius).
This month Mercury, Venus, and Jupiter are visible in the west, Saturn in the southwest, and Neptune in the east during the evening. At midnight, Saturn can be found in the southwest, Uranus in the east, and Neptune in the southeast. In the morning, Venus and Mars are in the east, Uranus is in the south, and Neptune is in the southwest.
At midmonth, Mercury is visible in evening twilight, Mars rises at 5:00 a.m. local daylight time, Jupiter is visible in evening twilight, and Saturn sets at midnight for observers at latitude 40 degrees north.
Mercury and Jupiter form a close pair from August 5th through August 8th. The two planets lie within a degree of each other on August 6th and August 7th. On the evening of August 6th, Jupiter (magnitude -1.7) is 0.6 degree to the lower left of Mercury (magnitude -0.7). Mercury is in the process of entering the evening sky this month and Jupiter is in the process of exiting it. Mercury is two degrees north of the waxing crescent Moon on August 15th and is at aphelion on August 29th. As August progresses, Mercury increases its angular separation from the Sun, attaining an altitude of seven degrees above the western horizon 30 minutes after sunset by August 31st.
On the evening of August 1st, Venus is less than 7% illuminated and appears as a very thin crescent 53 arc seconds in size. When Venus reaches aphelion on August 8th, it will be approximately 2.5 light-minutes from the Earth. Venus passes almost eight degrees south of the Sun when it is in inferior conjunction on August 15th. Venus and Mars are nine degrees apart on August 29th, the second of three conjunctions of the two planets this year. Venus rises more than 90 minutes before the Sun by month’s end. By that time, it increases in brightness to magnitude -4.5, decreases in apparent size to 52 arc seconds, and increases in phase to 9% illuminated.
Mars emerges from the glare of the Sun during morning twilight as August progresses. At midmonth, it shines faintly at magnitude +1.7 as it rises 90 minutes before sunrise. By the end of August, Mars rises two hours before the Sun. The Red Planet passes by the open cluster M44 on the mornings of August 20th and August 21st but observing the two objects will be rather difficult.
Jupiter disappears into evening twilight during early August. The gas giant is in conjunction with Mercury on August 7th. On August 10th, Jupiter undergoes the only conjunction with Regulus in this cycle of its 12-year-long orbit. Jupiter is in conjunction with the Sun on August 26th.
During August, Saturn is positioned 13 degrees northwest of the first-magnitude star Antares. The Ringed Planet subtends 17 arc seconds in angular size this month. Its rings are inclined by 24 degrees and span 38 arc seconds. On August 2nd, Saturn ends its retrograde motion through eastern Libra. Saturn is at eastern quadrature (i.e., 90 degrees east of the Sun) on August 21st. It is 9% smaller at that time than at opposition and appears more three dimensional than usual due to the greater angle of the sunlight illuminating the planet. Eighth-magnitude Titan, Saturn’s largest satellite, is due north of the planet on August 7th and August 23rd and due south on August 14th and August 30th. The peculiar satellite Iapetus shines at tenth magnitude as it passes 8.3 arc minutes from Saturn and reaches greatest western elongation on August 6th. It fades to eleventh magnitude by August 25th when it is 2.1 arc minutes north of Saturn. For additional information on Saturn’s satellites, browse www.skyandtelescope.com/observing/interactive-sky-watching-tools/
Uranus rises approximately 90 minutes after Neptune and can be found 0.6 degree from the fifth-magnitude star Zeta Piscium this month. During the course of August, Uranus moves from a position southeast of that star to one that's slightly southwest.
Neptune continues to retrograde through Aquarius. The eighth planet is located 3.4 degrees southwest of Lambda Aquarii at the end of August. It reaches opposition (magnitude +7.8, apparent diameter 2.4 arc seconds) for Western Hemisphere observers on August 31st.
Finder charts for Uranus and Neptune can be found at www.nakedeyeplanets.com/uranus.htm and www.nakedeyeplanets.com/neptune.htm and at www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf
On August 1st, Pluto is positioned approximately midway between the stars Xi-1Sagittarii (magnitude +5.0) and Xi-2 Sagittarii (magnitude +3.5). It is about 35 arc minutes west-northwest of Xi2 Sagittarii by the end of August. Finder charts for Pluto are available on pages 52 and 53 of the July issue of Sky & Telescope and page 47 of the July issue of Astronomy and online at www.bluewaterastronomy.info/resources/MapsCharts/planets-2015/22pluto_2015_1.pdf
For more on the planets and how to locate them, see www.nakedeyeplanets.com/
The fragmented periodic comet 141P/Machholz reaches perihelion on August 24th. Assuming the pieces have not completely disintegrated, the comet may be visible as it passes between the bright open clusters M36 and M38 in Auriga on the mornings of August 7th and August 8th. Comet C/2013 US10 (Catalina), which is currently visible from the southern hemisphere, travels northward, passing near the first-magnitude star Alpha Centauri as August ends. For further information on comets visible this month, browse cometchasing.skyhound.com/ and www.aerith.net/comet/future-n.html
Asteroid/dwarf planet 1 Ceres shines at eighth magnitude as it travels southwestward through eastern Sagittarius this month. It passes 0.3 degree north of the fifth-magnitude star SAO 211782 on August 20th and August 21st. Asteroid 100 Hekate (magnitude +10.8) reaches opposition on August 2nd, asteroid 65 Cybele (magnitude +11.1) on August 13th, and asteroid 21 Lutetia (magnitude +9.4) on August 15th. For information on asteroid occultations taking place this month, see www.asteroidoccultation.com/2015_08_si.htm
Free star maps for August can be downloaded at www.skymaps.com/downloads.html and www.telescope.com/content.jsp?pageName=Monthly-Star-Chart
Sixty 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)
Notable carbon star for August: V Aquilae
Eighty deep-sky objects for August: B139, B142, B143, NGC 6709, NGC 6738, NGC 6741, NGC 6751, NGC 6755, NGC 6772, NGC 6778, NGC 6781, NGC 6804, PK64+5.1 (Aquila); NGC 6819, NGC 6826, NGC 6834, (Cygnus); NGC 6643, NGC 6742 (Draco); DoDz 9 (Hercules); M56, M57, NGC 6703, NGC 6791, Ste1 (Lyra); NGC 6572, NGC 6633 (Ophiuchus); H20, M71 (Sagitta); B86, B87, B90, B92, B93, M8, M17, M18, M20, M21, M22, M23, M24, M25, M28, M54, M55, M69, M70, M75, NGC 6520, NGC 6544, NGC 6546, NGC 6553, NGC 6565, NGC 6603, NGC 6818, NGC 6822 (Sagittarius); IC 4703, IC 4756, M16, NGC 6604 (Serpens Cauda); B100, B101, B103, B104, B110, B111, B113, Bas 1, IC 1295, M11, M26, NGC 6649, NGC 6712 (Scutum); Cr 399 (asterism), M27, NGC 6802, NGC 6823, NGC 6834, NGC 6940, St 1 (Vulpecula)
Top ten binocular deep-sky objects for August: Cr 399, IC 4756, 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.