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July + August 09 Observing Guide
- Neill
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14 years 10 months ago #79119
by Neill
July + August 09 Observing Guide was created by Neill
Hello all,
Observing guide for next two months is below. Off to China in a few weeks for the eclipse so thats why you are getting August early!
OBSERVING GUIDE
(Please note all times are BST and are based on an observing location of Belfast and covers the months of July and August)
The Sun
At the start of July the Sun rises at 04:55 and sets at 22:05. By the start of August, it rises at 05:35 and sets at 21:25. By the end of August, it rises at 06:30 and sets at 20:15. There is a total solar eclipse on July 22nd; however it is not visible from Ireland.
The Planets
On the evening of August 17th, Mercury lies close to Saturn, to the West of the ringed planet low in the West after sunset.
Jupiter lies half a degree to the South of Neptune on the morning of July 10th. The two planets then start to drift apart during the rest of July and August with Jupiter heading Westward relative to Neptune. However they do remain relatively close to each other during the above period. The star Mu Capricorni (mag +5.1) lies just to the East of the two planets throughout July and August.
Mercury starts July as a morning object, rising an hour before the Sun at 03:55. It is visible for the first week of July very low in the North-East in the pre dawn skies. It is then too close to the Sun as it at superior conjunction on July 14th. It then becomes an evening object and is visible from about the 24th. At the start of August, it sets less than an hour after the Sun at 22:05 at mag -0.4. It then fades and by the time it is at greatest eastern elongation on August 24th, it is mag +0.3. By the end of August, it sets very shortly after the Sun.
Venus is a morning object during July and August. At the start of July, it rises at 02:40, by month’s end it rises at 02:20 and by the end of August, it rises at 03:20. Its brightness fades during the two months from mag -4.1 to mag -4.0. On the morning of July 27th, it passes less than half a degree South of the Crab Nebula at around 03:00. At the end of August, it lies close to M44 – The Beehive cluster.
Mars rises steadily earlier as July and August progress. At the start of July, it rises at 02:15, by the start of August, it rises at 01:10 and by the end of August, it rises at 00:20. It brightens over the two months from mag +1.1 to mag +1.0. It lies near to M35 in Gemini at the end of August.
Jupiter can be found in Capricornus during July and August. It is well placed for observation during this period. At the start of July, it rises at 23:55 and improves as July and August progress. At the start of August, it rises at 21:50 and by the end of August, it rises at 19:40. It brightens over the two months from mag -2.7 to mag -2.8 and is at opposition on August 14th. The four Galilean moons – Io, Europa, Ganymede and Callisto are visible with 10x50 binoculars or a small telescope and are worth a look.
Saturn is slowly slipping into the evening twilight. It can be located in Leo and sets at 00:45 at the start of July, by the start of August, it sets at 22:45 and by the end of August, it sets at 20:50. It fades over the two months from mag +1.0 to mag +1.1. It will not be visible in dark skies due to the longer evenings and its westward movement.
Uranus can be found in Pisces during July and August. It is well placed for observation during this period. At the start of July, it rises at 00:45 and improves as July and August progress. At the start of August, it rises at 22:40 and by the end of August, it rises at 20:35. It brightens over the two months from mag +5.8 to mag +5.7. It lies South of the circlet asterism with Lambda Piscium (mag +4.5) a good starting point. The planet lies to the South of it.
Neptune can be found in Capricornus during July and August. It is well placed for observation during this period. At the start of July, it rises at 23:50 and improves as July and August progress. At the start of August, it rises at 21:50 and by the end of August, it rises at 19:45. It brightens over the two months from mag +7.9 to mag +7.8 and is at opposition on August 17th.
The Moon
In July, the full moon is on the 7th with the last quarter moon on the 15th and the new moon on the 22nd. The first quarter moon is on the 28th. In August, the full moon is on the 6th with the last quarter moon on the 13th and the new moon on the 20th. The first quarter moon is on the 27th.
In July, on the evening of the 3rd, a 88% illuminated waxing gibbous moon lies to the West of Antares (Alpha Scorpii).
On the evening of the 10th/morning of the 11th, a 88% illuminated waning gibbous moon lies to the North of Jupiter and Neptune.
On the morning of the 13th, a 74% illuminated waning gibbous lies to the West of Uranus.
On the morning of the 18th, a 22% illuminated waning crescent moon occults the Southern part of M45 - The Pleiades. Moonrise is at 00:40. The moon also lies to the West of Mars.
On the morning of the 19th, a 12% illuminated waning crescent moon lies to the North-West of Venus and to the North-East of Mars and M45. Venus lies to the North-East of Mars.
On the evening of the 27th, a 39% illuminated waxing crescent moon lies to the South of Spica (Alpha Virginis).
On the evening of the 31st, a 77% illuminated waxing gibbous moon lies less than three degrees to the East of Antares (Alpha Scorpii) low in the South.
In August, on the evening of the 6th/morning of the 7th, the near full moon lies to the North of Jupiter and Neptune.
On the morning of the 7th, there is a partial penumbral lunar eclipse. The timings are between midnight and around 03:20 with mid eclipse occurring around 01:40. It will be quite faint as less than half the moon enters the outer shadow – the penumbra and a dimming of the Southern limb may be visible at mid eclipse.
On the morning of the 9th, a 91% illuminated waning gibbous moon lies to the West of Uranus.
On the morning of the 16th, a 25% illuminated waning crescent moon lies to the North of Mars.
On the morning of the 18th, a 7% illuminated waning crescent moon lies to the North of Venus.
On the evening of the 27th, a 53% illuminated waxing gibbous moon lies to the West of Antares (Alpha Scorpii).
Meteors
The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky for an observer. The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.
July and August are a busy period for meteors. In July, the first shower is the Capricornids which has three separate peaks on the 8th, 15th and 26th. The shower has a ZHR of 5 and is noted for bright yellow/blue meteors. Its radiant rise at 01:00 on the mornings of the 9th and the 16th and at midnight on the evening of the 26th. The first two peaks are affected by the moon but the third isn’t. A 98% illuminated waning gibbous moon rises at 22:35 in Capricornus on the evening of the 8th. On the evening of the 15th, a 44% illuminated waning crescent rises at 23:55 in Aries. On the evening of the 26th, the moon has set before the radiant rises.
The second shower of July which also has a peak in August is the Alpha Cygnids. The peaks are on the 21st of each month. The shower has a ZHR of 5 and there is no lunar interference for either peak as the moon sets at 21:30 on the evening of July 21st and at 20:35 on the evening of August 21st. The radiant is visible all night.
The next shower in July is the Piscis Australids. It is known for faint meteors and has a ZHR of 5. The moon does not interfere with the shower; however the radiant only rises at 03:00 on the morning of the 29th and is very low on the Southern horizon.
The next shower is the Delta Aquarids which has two peaks on the 29th and also on August 6th. The ZHR for the first peak is 20 and 10 for the second. The shower is known for faint and fast meteors (41 km/s). There is no lunar interference for the first peak with the moonset before the radiant rises at midnight. However for the second peak, the full moon rises at 21:10 in Capricornus with the radiant rising at 23:00.
The next shower is the Alpha Capricornids which peak on July 30th with a ZHR of 5. It is noted for long, slow fireballs. The moon does not interfere with this shower as moonset is roughly at the same time as the radiant rising at midnight.
The first shower of August is the Iota Aquarids which peak on the 6th with a ZHR of 5. The shower is noted for faint meteors. There is lunar interference with the shower as the full moon rises at 21:10 in Capricornus with the radiant rising at 23:00.
The major shower of the two months is the Perseids which peak on August 12th. The peak is during daytime so observing on the nights of the 11th and 12th is advised. The ZHR is 80 with typically fast (34 km/s) meteors and a good proportion of bright meteors leaving trains. However on both nights, the moon interferes with this shower. On the evening of the 11th, a 69% illuminated waning gibbous moon rises at 22:00 in Cetus and on the evening of the 12th, a 60% illuminated waning gibbous moon rises at 22:20 in Aries.
The final shower in August is the Kappa Cygnids which peak on the 17th. It has a ZHR of 3 with possibility of slow fireballs. There is no lunar interference with this shower as the moon sets early on the evening of the 17th.
Asteroids
Asteroid (7) Iris is at opposition on July 4th in Sagittarius with a magnitude of +8.
Comets
Comet 2006 W3 Christensen moves away from its location between the square of Pegasus and Lacerta during July and August. It moves in a Southerly direction, into Cygnus and into Vulpecula by the end of July. During August it continues in the same direction into Sagitta and into Aquila by the end of the month. It passes near to Zeta Cygni (mag +3.2) around mid July and to Gamma Aquilae (mag +2.7) around the end of August. It is predicted to remain around mag +9 through to autumn. It is visible all night throughout July and by the end of August, sets around 05:00.
Comet 22P/Kopff is in Aquarius during July and August. Current predictions estimate it’s brightness at mag +9 with similar long term predictions through to the autumn. At the start of July, it is visible from about 02:00 in the South-East, rising earlier and earlier as the summer goes on. By the start of August, it is visible from about midnight and from about 22:00, by the end of August. Use Lambda Aquarii (mag +3.7) as a starting point and the comet should lie to the South of the star.
Deep Sky
On the deep sky front during July and August, galaxies M81 and M82 can be observed in Ursa Major. Check out the constellation Canes Venatici with the globular cluster - M3 and several galaxies including M51 - the Whirlpool Galaxy and M63 - the Sunflower Galaxy. In Hercules, two globular clusters – M92 and the excellent M13 can be observed and in Lyra – M57 – The Ring Nebula can be observed. In Vulpecula – M27 – The Dumbbell Nebula can be found. In Andromeda, M31 – The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster. Finally in Triangulum, there is the galaxy M33.
For further observing information, check out
www.eaas.co.uk/index.php?option=com_cont...=blog&id=6&Itemid=11
General Notes
Always keep an eye out for Aurorae. Check out www.stronge.org.uk/spaceweather.html for the most up-to-date information on the aurorae. The night sky does not get fully dark in July. Between May and the middle of August, Astronomical twilight is present at night. This is when the sun is between twelve and eighteen degrees below the horizon. We have the return to dark skies in August with Astronomical twilight no longer dominating the night.
Watch out for NLCs - Noctilucent Clouds during July and August. They are also known as Polar Mesospheric Clouds as they are thought to be due to water ice particles up in the mesosphere. They are mostly visible between the Northern latitudes of 50 to 65 degrees, however sightings have been made as far South as Iran – 38 degrees. Look to the North for a white/silvery glow. They can sometimes be faint, sometimes bright. Other interesting naked eye phenomena to look out for include the Zodiacal Light and the Gegenschein. Both are caused by sunlight reflecting off dust particles which are present in the solar system. The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky - it's then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. If you are observing them when the moon has risen, restrict your efforts to the period 4 days either side of the new moon as otherwise the moonlight will be sufficient to drown them out.
Finally check out www.heavens-above.com for the latest passes of the International Space Station and satellites, details of Space Shuttle launches and passes and for details of Iridium Flare activity.
Clear Skies
Neill McKeown
Information Sources Used
www.skyviewcafe.com - Used for the Sun and Planets section. Also partly used for the Moon Section
Sky at Night Magazine Observing Guide and CD
www.aerith.net and cometchasing.skyhound.com – Used for the Comet Section for information and finder charts
BAA Handbook
Stardust Magazine
Sky Guide 2009 – South Dublin Astronomical Society
Observing guide for next two months is below. Off to China in a few weeks for the eclipse so thats why you are getting August early!
OBSERVING GUIDE
(Please note all times are BST and are based on an observing location of Belfast and covers the months of July and August)
The Sun
At the start of July the Sun rises at 04:55 and sets at 22:05. By the start of August, it rises at 05:35 and sets at 21:25. By the end of August, it rises at 06:30 and sets at 20:15. There is a total solar eclipse on July 22nd; however it is not visible from Ireland.
The Planets
On the evening of August 17th, Mercury lies close to Saturn, to the West of the ringed planet low in the West after sunset.
Jupiter lies half a degree to the South of Neptune on the morning of July 10th. The two planets then start to drift apart during the rest of July and August with Jupiter heading Westward relative to Neptune. However they do remain relatively close to each other during the above period. The star Mu Capricorni (mag +5.1) lies just to the East of the two planets throughout July and August.
Mercury starts July as a morning object, rising an hour before the Sun at 03:55. It is visible for the first week of July very low in the North-East in the pre dawn skies. It is then too close to the Sun as it at superior conjunction on July 14th. It then becomes an evening object and is visible from about the 24th. At the start of August, it sets less than an hour after the Sun at 22:05 at mag -0.4. It then fades and by the time it is at greatest eastern elongation on August 24th, it is mag +0.3. By the end of August, it sets very shortly after the Sun.
Venus is a morning object during July and August. At the start of July, it rises at 02:40, by month’s end it rises at 02:20 and by the end of August, it rises at 03:20. Its brightness fades during the two months from mag -4.1 to mag -4.0. On the morning of July 27th, it passes less than half a degree South of the Crab Nebula at around 03:00. At the end of August, it lies close to M44 – The Beehive cluster.
Mars rises steadily earlier as July and August progress. At the start of July, it rises at 02:15, by the start of August, it rises at 01:10 and by the end of August, it rises at 00:20. It brightens over the two months from mag +1.1 to mag +1.0. It lies near to M35 in Gemini at the end of August.
Jupiter can be found in Capricornus during July and August. It is well placed for observation during this period. At the start of July, it rises at 23:55 and improves as July and August progress. At the start of August, it rises at 21:50 and by the end of August, it rises at 19:40. It brightens over the two months from mag -2.7 to mag -2.8 and is at opposition on August 14th. The four Galilean moons – Io, Europa, Ganymede and Callisto are visible with 10x50 binoculars or a small telescope and are worth a look.
Saturn is slowly slipping into the evening twilight. It can be located in Leo and sets at 00:45 at the start of July, by the start of August, it sets at 22:45 and by the end of August, it sets at 20:50. It fades over the two months from mag +1.0 to mag +1.1. It will not be visible in dark skies due to the longer evenings and its westward movement.
Uranus can be found in Pisces during July and August. It is well placed for observation during this period. At the start of July, it rises at 00:45 and improves as July and August progress. At the start of August, it rises at 22:40 and by the end of August, it rises at 20:35. It brightens over the two months from mag +5.8 to mag +5.7. It lies South of the circlet asterism with Lambda Piscium (mag +4.5) a good starting point. The planet lies to the South of it.
Neptune can be found in Capricornus during July and August. It is well placed for observation during this period. At the start of July, it rises at 23:50 and improves as July and August progress. At the start of August, it rises at 21:50 and by the end of August, it rises at 19:45. It brightens over the two months from mag +7.9 to mag +7.8 and is at opposition on August 17th.
The Moon
In July, the full moon is on the 7th with the last quarter moon on the 15th and the new moon on the 22nd. The first quarter moon is on the 28th. In August, the full moon is on the 6th with the last quarter moon on the 13th and the new moon on the 20th. The first quarter moon is on the 27th.
In July, on the evening of the 3rd, a 88% illuminated waxing gibbous moon lies to the West of Antares (Alpha Scorpii).
On the evening of the 10th/morning of the 11th, a 88% illuminated waning gibbous moon lies to the North of Jupiter and Neptune.
On the morning of the 13th, a 74% illuminated waning gibbous lies to the West of Uranus.
On the morning of the 18th, a 22% illuminated waning crescent moon occults the Southern part of M45 - The Pleiades. Moonrise is at 00:40. The moon also lies to the West of Mars.
On the morning of the 19th, a 12% illuminated waning crescent moon lies to the North-West of Venus and to the North-East of Mars and M45. Venus lies to the North-East of Mars.
On the evening of the 27th, a 39% illuminated waxing crescent moon lies to the South of Spica (Alpha Virginis).
On the evening of the 31st, a 77% illuminated waxing gibbous moon lies less than three degrees to the East of Antares (Alpha Scorpii) low in the South.
In August, on the evening of the 6th/morning of the 7th, the near full moon lies to the North of Jupiter and Neptune.
On the morning of the 7th, there is a partial penumbral lunar eclipse. The timings are between midnight and around 03:20 with mid eclipse occurring around 01:40. It will be quite faint as less than half the moon enters the outer shadow – the penumbra and a dimming of the Southern limb may be visible at mid eclipse.
On the morning of the 9th, a 91% illuminated waning gibbous moon lies to the West of Uranus.
On the morning of the 16th, a 25% illuminated waning crescent moon lies to the North of Mars.
On the morning of the 18th, a 7% illuminated waning crescent moon lies to the North of Venus.
On the evening of the 27th, a 53% illuminated waxing gibbous moon lies to the West of Antares (Alpha Scorpii).
Meteors
The ZHR or Zenithal Hourly Rate is the number of meteors an observer would see in one hour under a clear, dark sky with a limiting apparent magnitude of 6.5 and if the radiant of the shower were in the zenith. The rate that can effectively be seen is nearly always lower and decreases as the radiant is closer to the horizon. The Zenith is the overhead point in the sky for an observer. The radiant is the point in the sky, from which (to a planetary observer) meteors appear to originate, i.e. the Perseids, for example, are meteors which appear to come from a point within the constellation of Perseus. A fireball is defined by the International Astronomical Union as a meteor brighter than any of the planets, i.e. magnitude -4 or brighter. The International Meteor Organisation alternatively defines it as a meteor which would have a magnitude of -3 or brighter at the zenith.
July and August are a busy period for meteors. In July, the first shower is the Capricornids which has three separate peaks on the 8th, 15th and 26th. The shower has a ZHR of 5 and is noted for bright yellow/blue meteors. Its radiant rise at 01:00 on the mornings of the 9th and the 16th and at midnight on the evening of the 26th. The first two peaks are affected by the moon but the third isn’t. A 98% illuminated waning gibbous moon rises at 22:35 in Capricornus on the evening of the 8th. On the evening of the 15th, a 44% illuminated waning crescent rises at 23:55 in Aries. On the evening of the 26th, the moon has set before the radiant rises.
The second shower of July which also has a peak in August is the Alpha Cygnids. The peaks are on the 21st of each month. The shower has a ZHR of 5 and there is no lunar interference for either peak as the moon sets at 21:30 on the evening of July 21st and at 20:35 on the evening of August 21st. The radiant is visible all night.
The next shower in July is the Piscis Australids. It is known for faint meteors and has a ZHR of 5. The moon does not interfere with the shower; however the radiant only rises at 03:00 on the morning of the 29th and is very low on the Southern horizon.
The next shower is the Delta Aquarids which has two peaks on the 29th and also on August 6th. The ZHR for the first peak is 20 and 10 for the second. The shower is known for faint and fast meteors (41 km/s). There is no lunar interference for the first peak with the moonset before the radiant rises at midnight. However for the second peak, the full moon rises at 21:10 in Capricornus with the radiant rising at 23:00.
The next shower is the Alpha Capricornids which peak on July 30th with a ZHR of 5. It is noted for long, slow fireballs. The moon does not interfere with this shower as moonset is roughly at the same time as the radiant rising at midnight.
The first shower of August is the Iota Aquarids which peak on the 6th with a ZHR of 5. The shower is noted for faint meteors. There is lunar interference with the shower as the full moon rises at 21:10 in Capricornus with the radiant rising at 23:00.
The major shower of the two months is the Perseids which peak on August 12th. The peak is during daytime so observing on the nights of the 11th and 12th is advised. The ZHR is 80 with typically fast (34 km/s) meteors and a good proportion of bright meteors leaving trains. However on both nights, the moon interferes with this shower. On the evening of the 11th, a 69% illuminated waning gibbous moon rises at 22:00 in Cetus and on the evening of the 12th, a 60% illuminated waning gibbous moon rises at 22:20 in Aries.
The final shower in August is the Kappa Cygnids which peak on the 17th. It has a ZHR of 3 with possibility of slow fireballs. There is no lunar interference with this shower as the moon sets early on the evening of the 17th.
Asteroids
Asteroid (7) Iris is at opposition on July 4th in Sagittarius with a magnitude of +8.
Comets
Comet 2006 W3 Christensen moves away from its location between the square of Pegasus and Lacerta during July and August. It moves in a Southerly direction, into Cygnus and into Vulpecula by the end of July. During August it continues in the same direction into Sagitta and into Aquila by the end of the month. It passes near to Zeta Cygni (mag +3.2) around mid July and to Gamma Aquilae (mag +2.7) around the end of August. It is predicted to remain around mag +9 through to autumn. It is visible all night throughout July and by the end of August, sets around 05:00.
Comet 22P/Kopff is in Aquarius during July and August. Current predictions estimate it’s brightness at mag +9 with similar long term predictions through to the autumn. At the start of July, it is visible from about 02:00 in the South-East, rising earlier and earlier as the summer goes on. By the start of August, it is visible from about midnight and from about 22:00, by the end of August. Use Lambda Aquarii (mag +3.7) as a starting point and the comet should lie to the South of the star.
Deep Sky
On the deep sky front during July and August, galaxies M81 and M82 can be observed in Ursa Major. Check out the constellation Canes Venatici with the globular cluster - M3 and several galaxies including M51 - the Whirlpool Galaxy and M63 - the Sunflower Galaxy. In Hercules, two globular clusters – M92 and the excellent M13 can be observed and in Lyra – M57 – The Ring Nebula can be observed. In Vulpecula – M27 – The Dumbbell Nebula can be found. In Andromeda, M31 – The Andromeda galaxy can be observed along with its satellite galaxies M32 and M110. In Perseus, there is the open cluster M34 and the excellent Double Cluster. Finally in Triangulum, there is the galaxy M33.
For further observing information, check out
www.eaas.co.uk/index.php?option=com_cont...=blog&id=6&Itemid=11
General Notes
Always keep an eye out for Aurorae. Check out www.stronge.org.uk/spaceweather.html for the most up-to-date information on the aurorae. The night sky does not get fully dark in July. Between May and the middle of August, Astronomical twilight is present at night. This is when the sun is between twelve and eighteen degrees below the horizon. We have the return to dark skies in August with Astronomical twilight no longer dominating the night.
Watch out for NLCs - Noctilucent Clouds during July and August. They are also known as Polar Mesospheric Clouds as they are thought to be due to water ice particles up in the mesosphere. They are mostly visible between the Northern latitudes of 50 to 65 degrees, however sightings have been made as far South as Iran – 38 degrees. Look to the North for a white/silvery glow. They can sometimes be faint, sometimes bright. Other interesting naked eye phenomena to look out for include the Zodiacal Light and the Gegenschein. Both are caused by sunlight reflecting off dust particles which are present in the solar system. The Zodiacal Light can be seen in the West after evening twilight has disappeared or in the East before the morning twilight. The best time of year to see the phenomenon is late-Feb to early-April in the evening sky and September/October in the morning sky - it's then that the ecliptic, along which the cone of the zodiacal light lies, is steepest in our skies. The Gegenschein can be seen in the area of the sky opposite the sun. To view either, you must get yourself to a very dark site to cut out the light pollution. When trying to observe either of these phenomena, it is best to do so when the moon is below the horizon. If you are observing them when the moon has risen, restrict your efforts to the period 4 days either side of the new moon as otherwise the moonlight will be sufficient to drown them out.
Finally check out www.heavens-above.com for the latest passes of the International Space Station and satellites, details of Space Shuttle launches and passes and for details of Iridium Flare activity.
Clear Skies
Neill McKeown
Information Sources Used
www.skyviewcafe.com - Used for the Sun and Planets section. Also partly used for the Moon Section
Sky at Night Magazine Observing Guide and CD
www.aerith.net and cometchasing.skyhound.com – Used for the Comet Section for information and finder charts
BAA Handbook
Stardust Magazine
Sky Guide 2009 – South Dublin Astronomical Society
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