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Society News

Programme of Events for September 2009 All meetings are held at Bristol Grammar School.

4th Sep No Meeting - Observatory Maintenance & Observing (if clear)

11th Sep Club Night - Simon Smith

18th Sep No Meeting - Observatory Maintenance & Observing (if clear)

25th Sep Club Night - John Meacham

Solar Observing at Tyntesfield. With promising weather reports (even on the day) a group of us set up telescopes on the croquet lawn at Tyntesfield with the hope of observing the Sun. The weather unfortunately had other ideas and despite an update at around 11am that by 1pm the cloud cover would be just 5%, we had just a few small breaks in the total cloud cover, none of which were near the Sun. During the day we had quite a few of people stop to ask questions and they were all disappointed at not getting to look at the Sun. The next planned date is Sunday 13th September Observatory The observatory and observing area have been kept tidy and usable by a small band of members over the summer period. There are a couple of Friday evenings this month for members to come along to do as much as possible before the start of the new session when we go back to weekly meetings at the beginning of next month. At this time of year the sky gets dark enough to allow some observing after the work is complete, so come along if you can. As the time of writing this (Aug 22) the motor drive on the telescope was still being repaired, however it can still be used.

Don’t forget to check out the BAS website where you can get all the latest info about the society. http://www.bristolastrosoc.org.uk/

Bristol Astronomical Society are a Registered Charity, No. 299649

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Bristol Astronomical Society Information Leaflet September 2009

Constellation of Aquarius by Hevelius

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The Sun The Sun & Moon Sun and Moon Rise and Set times September 2009

Sun Moon Rise Set Rise Set

01 06:23 19:56 18:39 02:41 02 06:25 19:54 18:57 03:52 03 06:26 19:52 19:11 05:03 04 06:28 19:50 19:25 06:14 05 06:29 19:47 19:38 07:25 06 06:31 19:45 19:52 08:38 07 06:33 19:43 20:07 09:52 08 06:34 19:41 20:27 11:09 09 06:36 19:38 20:52 12:27 10 06:37 19:36 21:27 13:46 11 06:39 19:34 22:15 14:58 12 06:41 19:32 23:19 16:00 13 06:42 19:29 16:48 14 06:44 19:27 00:37 17:23 15 06:45 19:25 02:03 17:50 16 06:47 19:22 03:32 18:10 17 06:49 19:20 05:00 18:28 18 06:50 19:18 06:26 18:44 19 06:52 19:15 07:50 19:00 20 06:53 19:13 09:14 19:18 21 06:55 19:11 10:35 19:40 22 06:57 19:08 11:55 20:06 23 06:58 19:06 13:08 20:40 24 07:00 19:04 14:13 21:24 25 07:01 19:02 15:06 22:18 26 07:03 18:59 15:48 23:20 27 07:05 18:57 16:19 28 07:06 18:55 16:43 00:28 29 07:08 18:52 17:02 01:38 30 07:09 18:50 17:17 02:49 31

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AAVSO Chart for AE Aquarii

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AAVSO Chart for R Aquarii

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The Sun This year’s Autumn Equinox occurs on the 22nd at 22:19 at this time the Sun will cross the celestial equator heading south. This marks the official end of summer in the northern hemisphere. The Moon This month’s featured object is the large lunar sea made famous by the Apollo 11 Moon landing, Mare Tranquillitatis (Sea of Tranquillity). The landing area at 0.8° N, 23.5° E is now known as Statio Tranquillitatis, and three small craters to the north of the base have been named Aldrin, Collins, and Armstrong in honour of the Apollo 11 astronauts. These are too small to be seen with amateur instruments. In July, around the time of the 40th anniversary of the Apollo 11 mission, NASA

released pictures of the landing site taken by the Lunar Reconnaissance Orbiter. Image courtesy of NASA/Goddard Space Flight Center/Arizona State University To see pictures of some of the other landing sites check out: http://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/apollosites.html The Mare Tranquillitatis is one of the largest

of the ‘lunar seas’ covering an area of 421,000 km2 (261,000 mile2). It lies in the northeast quadrant of the moon and is easily visible to the naked eye. The borders of the Mare are very irregular due to the fact that it connects with some of the other major seas, Mare Serenitatis (Sea of Serenity), Mare Fecunditatis (Sea of Fertility) and the Mare Nectaris (Sea of Nectar). It can be difficult to tell where one sea ends

The Sun & Moon

Mare Tranquillitatis

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and the other begins. The most prominent crater on the Mare is Plinius which lies on the north-eastern edge close to the border with the Mare Serenitatis Plinius has a diameter of 44km (26 mile), the outer walls are high with steep outer slopes. The floor is flat and there is a large central peak. Other prominent craters on the mare are Ross, 11.7° N, 21.7° E, Arago, 6.2° N 21.4° E and Maskelyne 2.2° N 30.1° E. Ross has a diameter of 27km, with high walls and steep outer slopes. There is a small peak which lies off centre. Arago is also 27km in diameter with high terraced walls. The central mountain is connected to the outer wall by a ridge of hills. Maskelyne is slightly smaller with a diameter of 26km, the crater walls are fairly high with internal terraces. The floor is flat with an off-centre mountain. Around the perimeter of the mare there are a number of named bays including the Sinus Amoris (Bay of Love), Sinus Asperitatis (Bay of Roughness), Sinus Concor-diae (Bay of Harmony) and the Sinus Honoris (Bay of Honour) The best time to look at this area is from around 4 to 5 days after new moon or 3 to 4 days after full moon.

The Sun & Moon

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Pi (π) Aqr is a blue-white B-class dwarf star with an average magnitude of +4.66. It is a Gamma Cas type variable which varies irregularly between magnitude +4.42 to +4.70. Pi is the most northerly star in the Water Jar. Zeta (ζ) Aqr which lies at the fork of the ‘Y’ is a close binary system. The brighter component, ζ² Aquarii, is a magnitude +4.42 yellow F-class dwarf. Its companion, ζ¹ Aquarii, is yellow F-class sub-giant which slightly fainter at magnitude +4.59. The combined magnitude of the system is +3.65. The two stars are separated by just 1.67 arcseconds. Eta (η) Aqr is a magnitude +4.04, blue-white B-class sub-giant with a high surface temperature of 11,400 Kelvin. The star has a very rapid rate of rotation, despite having a diameter 2.5 times that of the sun, it spins on its axis in less than 12 hours. R Aqr is a long period Mira type variable, it varies between magnitude +5.8 and +12.4 every 387 days. The star is a symbiotic star, the main component is an M-class red giant, it companion is a white dwarf. R Aquarii can be found about 15 degrees east of delta (δ) Aqr. Another interesting variable in Aquarius is AE Aqr, a type of binary star known as cataclysmic variable. These systems are composed of a normal star and a white dwarf, whose gravitational field pulls matter from its larger companion. AE Aquarii however does not act like a normal cataclysmic variable. Due to the white dwarf’s rapid rotation and its strong magnetic field it is flinging matter out into space instead of accreting it onto itself. AE Aqr varies between +10.4 and 12.0. AE Aqr can be found close to the border with Aquila about 1 degree north of 71 Aqr. AAVSO chart for R Aqr can be found on page 26 and AE Aqr on page 27. Charts for almost any variable star can be found on the AAVSO website at: http://www.aavso.org/aavso

Constellation of the Month

Objects in Aquarius Object NGC Type Mag RA Dec

M2 7089 Globular cluster +6.4 21h 33.5m -00° 49 '

M72 6981 Globular cluster +9.3 20h 53.5m -12° 32'

M73 6994 Asterism +8.9 20h 59.0m -12° 38'

Saturn Nebula 7009 Planetary Nebula +8.3 21h 04.2m -11° 22'

Helix Nebula 7293 Planetary Nebula +7.3 22h 29.6m -20° 48'

R Aqr Variable Star +5.8 - +12.4 23h 43.8m -15° 17'

AE Aqr Variable Star +10.4 - +12.0 20h 40.1m -00° 52 '

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Mercury passes through inferior conjunction on the 20th and is not visible for the majority of the month. You may catch a glimpse if the innermost planet low in the eastern sky at the end of the month. .

Venus is in morning sky in the east-northeast. During the month the planet’s phase increases from just over 80% to 90% illuminated. The planet is a brilliant beacon in the predawn sky, shining at just under magnitude -4 throughout the month and should be unmistakable. Venus begins the month in the constellation of Cancer; it crosses the border on the 10th and spends the rest of the month making its way through the constellation of Leo.

Mars is a morning object in the constellation of Gemini rising just after midnight at the start of the month and a few minutes before midnight by the end. During the month the apparent diameter of the red planet increases slightly from just under 6 arcseconds to 6.6 arcseconds and brightens by 0.2 of a magnitude to +0.8.

The Planets

Date RA Dec Mag Phase Dia Rise Set 01 06h 17m +23° 34'' +0.96 89% 5.9" 00:23 17:03 15 06h 54m +23° 17'' +0.89 89% 6.2" 00:08 16:43

29/30 07h 32m +22° 30'' +0.78 88% 6.6" 23:52 16:15

Mars Transit 08:43 08:25 08:03

Date RA Dec Mag Phase Dia Rise Set 01 08h 36m +18° 39'' -03.9 83% 23.0" 03:14 18:48 15 09h 44m +14° 21'' -03.9 86% 12.0" 03:54 18:34 30 10h 54m +08° 15'' -03.9 90% 11.0" 04:39 18:12

Venus Transit 11:02 11:15 11:26

Date RA Dec Mag Phase Dia Rise Set 01 12h 11m -05° 01'' +0.60 38% 8.4" 08:59 20:13 15 12h 03m -04° 40'' +2.96 06% 10.0" 07:54 19:10 30 11h 29m +03° 28'' +0.69 25% 8.3" 05:39 18:21

Mercury Transit 14:36 13:32 12:00

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There are a number of faint galaxies scattered throughout the constellation which will require a medium to large telescope to locate. Stars in Aquarius Aquarius is a fairly inconspicuous constellation, none of it’s stars are brighter than magnitude +2.8. The most noticeable part of Aquarius is a ‘Y’ shaped asterism known as the ‘Water Jar’, consisting of four stars, gamma (γ), pi (π), zeta (ζ) and eta (η) Aquarii. Alpha (α) Aqr has the proper name Sadalmalik, it is a G-class, yellow supergiant with a surface temperature of 6000 Kelvin, similar to our Sun. Yellow super-giants are relatively rare and are usually Cepheid type variables, Sadalmalik however is not. Alpha lies just to the west of the water jar and shines at magnitude +2.96. Beta (β) Aqr, is also known as Sadalsuud, this is another yellow, G-class super-giant. Beta is slightly cooler than alpha at 5600 K, however it is just the brighter of the two at magnitude +2.91. Beta Aquarii lies about 8 degrees to the southwest of alpha. These two stars along with Enif, Epsilon (ε) Pegasi all seem to be moving more or less perpendicular to the plane of our Galaxy, an odd motion that implies they were somehow kicked away from their birthplace. Gamma (γ) Aqr, is the westernmost star of the Water Jar, it is a magnitude +3.84 A-class, white star. Gamma is a spectroscopic binary, nothing much is known about it’s companion other than it’s orbital period of 58 days and it’s distance of 0.40 AU, about the distance of Mercury from the Sun. The star has the proper name Sadachbia, which has nothing to do with it’s current constellation, it comes from an old Arabic constellation and means ‘the Lucky Star of the Tents’.

Constellation of the Month

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glance, containing very little nebulosity” M73 can be found 1.5 degrees east of M72. It covers an area of around 3 arcminutes and the group has a combined magnitude of +8.9. There are a couple of very nice planetary nebulae in Aquarius, the Saturn Nebula, NGC7009 and the Helix Nebula NGC7293. The Saturn Nebula is the easiest to locate with small telescopes,

it lies around 5 degrees east-southeast of epsilon (ε) Aquarii. The nebula measures 44 x 26 arcseconds and has an over magnitude of +8.3. It should be visible with a 75mm (3inch) telescope. The nebula was given its name by Lord Rosse in 1850 because of the extensions (ansae) on either side of the main disc giving it a similar appearance to Saturn, as you can see from the image on

the left.

The Helix Nebula is a much more challenging object despite the fact that it has a greater overall brightness, magnitude +7.3. The problem is that the light is spread over a greater area, 13 arcminutes, making it much more difficult to see. The contrast between the nebula and the background sky is also very low and it’s southerly declination means that you are always looking at it through a thick layer of atmosphere which adds to the problem. While the Helix is visible in binoculars on extremely good nights, the addition of an OIII filter on a low power telescope will greatly improve your chances of seeing this object. NGC 7293 lies around 1.5 degrees west of upsilon (υ) Aquarii.

Constellation of the Month

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Jupiter is visible low in the southern sky in Capricornus, setting in the early hours of the morning. Back in July the giant planet was struck by an object which caused a ‘scar’ in the planet’s atmosphere reminiscent of the 1994 Shoemaker-Levy 9 impact. The impact was discovered by

Australian amateur astronomer Anthony Wesley at 13:30 UT on 19 July 2009. This shows that you never know what you might find when you are observing. The image on the left was taken by the Hubble Space Telescope and clearly shows the black scar.

The four largest of Jupiter’s satellites are easily seen with a small telescope, as they orbit their parent planet they transit across the front of Jupiter’s disc, they can disappear behind the planet or into the planet’s shadow. Below is a list of some of the events that are visible this month. 3rd 00:19 Callisto is eclipsed by Jupiter's shadow 4th 02:27 Io begins to cross Jupiter's disk 7th 01:17 Ganymede reappears from behind Jupiter's disk 20th 22:41 Europa's shadow begins to cross Jupiter's disk 21st 00:16 Io reappears from behind Jupiter's disk 21st 00:24 Europa begins to cross Jupiter's disk 22nd 22:09 Europa reappears from behind Jupiter's disk The moons can also undergo mutual events see list below. 1st 03:03 to 03:25 Io passes in front of Europa (81% of Europa is covered) 8th 23:21 to 23:31 Io passes in front of Europa (55% of Europa is covered) 16th 01:42 to 01:50 Io passes in front of Europa (53% of Europa is covered) 21st 01:45 to 01:50 Europa passes in front of Ganymede (48% of Ganymede is covered)

The Planets Date RA Dec Mag Phase Dia Rise Set 01/02 21h 29m -15° 58'' -2.28 99% 48" 19:15 04:31 14/15 21h 24m -16° 24'' -2.75 99% 47" 18:18 03:27 29/30 21h 20m -16° 40'' -2.67 99% 46" 17:20 02:27

Jupiter Transit 23:53 22:52 21:54

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Saturn is in conjunction with the Sun on the 17th so is not observable this month. On the 4th the Earth crosses the ring plane of Saturn so we would see the rings edge.

Uranus reaches opposition on the 17th, it lies in the constellation of Pisces close to the border with Aquarius. At magnitude +5.7 the planet is technically a naked-eye object and easy to locate using even a small pair of binoculars. The chart below shows the position of Uranus at midnight on the 17th. At it closest point to the Earth, Uranus will be at a distance of 2,856 million Km (1,775 million miles). Uranus appears slightly greenish in binoculars or a telescope making it easy to identify.

Date RA Dec Mag Phase Dia Rise Set 01/02 23h 48m -02° 40'' +5.73 100% 3.7" 20:16 07:56 15/16 23h 41m -02° 53'' +5.73 100% 3.7" 19:20 06:57

30 23h 39m -03° 07'' +5.73 100% 3.7" 18:25 05:59

Uranus Transit 02:06 01:09 00:12

The Planets Date RA Dec Mag Phase Dia Rise Set 01 11h 36m +04° 38'' +1.13 100% 16" 07:35 20:28 15 11h 43m +03° 57'' +1.07 100% 16" 06:15 19:36 30 11h 50m +03° 13'' +1.07 100% 16" 06:02 18:39

Saturn Transit 14:02 13:13 12:21

Uranus at Opposition– 17th September 2009

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Aquarius Abbreviation: Aqr. Genitive: Aquarii Aquarius is an ancient constellation which can be traced back over 4000 years to the time of the Babylonians. It is one of the twelve constellations that forms the ‘Zodiac’ a band of constellations along the Ecliptic, the apparent path of the Sun across the sky. The word Zodiac comes from the Greek for ’Circle of Animals’. The Sun passes through Aquarius between mid-February and mid-March. Mythology The stars that form the constellation of Aquarius are linked with water by many cultures, the Babylonians saw them as an overflowing urn, which they associated the heavy rains. The Greeks associate Aquarius with Ganymede, a handsome, young prince of Troy. He was spotted by Zeus, who thought he would make a perfect cup-bearer for the gods. Ganymede was carried off to Mount Olympus by an eagle. When Ganymede realised how much the people on earth needed water he pleaded with Zeus to be allowed to send down rain. Because of this he was placed amongst the stars as Aquarius. Objects in Aquarius There are three objects from Charles Messier’s catalogue in Aquarius, two are globular clusters, the other is just a small group of stars. The constellation is also home to a number of well known NGC objects. M2 is one of the finest globular clusters visible from the UK. At magnitude +6.4 with an apparent diameter of 13 arcminutes, it is an easy object to locate with binoculars. A pair of 10x50’s should show it as a fairly bright fuzzy patch, with a brighter core. Telescopes will resolve the outer regions of the cluster and reveal a large bright core. M2 can be found about 4.5 degrees north of beta (β) Aquarii. M72 is the second of the globular clusters recorded by Messier in Aquarius. The

cluster is almost three magnitudes fainter than M2, at magnitude +9.3 and you will need a telescope to see it. M72 has an apparent diameter of 6 arcminutes, the core of the cluster is very compact and appears almost star like in small telescopes. Larger instru-ments are needed to resolve the cluster. M72 can be found just over 3 degrees southeast of epsilon (ε) Aquarii.

The last of the Messier objects, M73, is one of the oddities in Messier's catalogue, as it is just a Y shaped asterism formed by 4 unrelated stars. Messier described it as a “Cluster of three or four small stars, which resembles a nebula at first

Constellation of the Month

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Neptune can be found in the constellation Capricornus about 5 degrees to the east of Jupiter, which should help you locate the outermost planet. At magnitude +7.8 it should be visible in binoculars but a telescope is required see the planet as anything other than another star. 3 Juno reaches opposition on the 22nd in the constellation of Pisces just to the south of 27 Piscium. The minor planet will be around magnitude +7.4 so well within the range of binoculars and small telescopes. The chart below shows the position of Juno at midnight on the 22nd/23rd. The circle represent the view in a pair of 7x50 binoculars.

The Planets Date RA Dec Mag Phase Dia Rise Set 01 21h 47m -13° 44'' +7.83 100% 2.4" 19:25 05:05

15/16 21h 46m -13° 51'' +7.83 100% 2.3" 18:42 04:05 29/30 21h 45m -13° 57'' +7.84 100% 2.3" 17:29 03:08

Neptune Transit 00:15 23:15 22:18

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As we move into the autumn the nights are getting noticeably longer giving you more time to observe the night sky, darkness also arrives at a more sociable hour. The southern part of the sky is populated by the faint constellations which are known collectively as ‘The Water’, Capricornus, Aquarius, Pisces and Cetus. Our featured constellation, Aquarius lies due south around midnight mid month (see pages 21 to 27 for details). Low in the southern sky you will find the constellation of Capricornus, currently home to two of the gas giants, Jupiter and Neptune, which should help you identify the constellation. There is only one Messier object in Capricornus, M30; a globular cluster. M30 is quite a dense cluster, it has an apparent diameter of 12 arcminutes and an overall magnitude of +7.7. It should be visible with binoculars and is a very nice object with a small telescope. M30 can be found to the east of zeta (ζ) Cap, close to the magnitude +5.2 star 41 Cap.

To the northeast of Aquarius lies the constellation of Pisces, the most obvious part of the Pisces, which lies at the western end of the constellation is the asterism known as the ‘Circlet of Pisces’. It is made up of seven stars, iota (ι), theta (θ), 7 Piscium, gamma (γ), kappa (κ), lambda (λ) and the variable star TX Piscium which lies between iota and lambda. Pisces is currently home to Uranus, you will find the planet to the south of the circlet close to the border with Aquarius. At the eastern end of Pisces you will find the constellation’s only Messier object, the lovely face-on spiral galaxy M74. You can

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find M74 about 1.5 degrees east-northeast of eta (η) Piscium. Although the galaxy is recorded as magnitude +9.4, due to its low surface brightness it is one of the more difficult Messier objects to locate. Below Pisces you will find Cetus, home to one of the most famous stars in the sky, Mira; omicron (ο) Ceti. Hevelius gave the star its name which means ‘the Wonderful One’. Mira is the prototype of a class of long period variables all of which are red giants who’s outer layers pulsate, increasing and decreasing the star’s brightness. Mira is normally around magnitude +9, however when it brightens it can reach magnitude +2. The average period between maxima is 330 days. Mira is visible

with 10x50 binoculars throughout its brightness range, the next maximum is due on November 18th. You can find Mira at RA 02h 19.3m Dec -02° 59'. Like Pisces, there is just one Messier object in Cetus, M77, a face on spiral, which can be found just over 1 degree southeast of delta (δ) Ceti. M77 is famous for being the prototype of Seyfert Galaxies,

the nuclei which are very active and are the sources of strong radio emissions. M77 can be quite a tricky object to locate despite it’s overall magnitude of +8.9. The galaxy has an apparent diameter of 8 arcminutes and is slightly elongated to the north, the bright central core is surrounded by a misty halo. Above Pisces lies the large constellation of Pegasus, the north-eastern star of the ‘Square of Pegasus’ has since 1930 belonged to the neighbouring constellation of Andromeda and is known as alpha (α) Andromedae (formally delta (δ) Pegasi). In the far west of the constellation close to the border with Equuleus, lies the lovely globular cluster M15. Through binoculars and small telescopes the cluster

The Sky this Month

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appears as a small hazy patch. Larger instruments will resolve some of the outer regions of the cluster, however the central core is too densely packed to be re-solved. The cluster is easy to lo-cate, it lies 3.5 degrees west and 2.5 degrees north of Enif; epsilon (ε) Pegasi. M15 has an apparent diameter of 18 arcseconds and shines at magnitude +6.2. You can use the two stars on the western side of the Square of Pegasus to locate Fomalhaut; alpha (α) Piscis Austrini, the brightest star in the constellation of Piscis Austrinus (Southern Fish). Fomalhaut is the most southerly first magnitude star visible form the UK. Draw a line from beta Pegasi through alpha and extend to the horizon, the bright star just above the horizon is Fomalhaut. Low in the western sky lies the constellation of Hercules home to a couple of the best globular clusters in the northern hemisphere, M13 which lies between eta (η) and zeta (ζ) Her and M92 north of pi (π) Her. Lower down is the small circlet of stars which form the northern crown, Corona Borealis. The famous variable R Coronae Borealis lies at the centre of the circlet. At present R CrB is undergoing a very deep minimum with the star below magnitude +15, beyond the reach of most amateurs. Check to see if you can see R Crb, you may be the first person to catch a glimpse of it as it returns to it’s normal brightness of around magnitude +6. Above Hercules lies the small constellation of Lyra, it’s brightest star Vega is the western point of the summer triangle. Lyra is home to the lovely planetary neb-ula M57 the Ring Nebula. M57 lies midway between beta (β) and gamma (γ) Lyrae. Overhead you will find the constel-lation of Cygnus, the tail of the swan in marked by Deneb; alpha (α) Cygni, another of the stars in the Summer Triangle. The star at the southern end of Cygnus mark-ing the beak is the famous double star Albireo, beta (β) Cygni. The

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contrasting colours of yellow/orange and blue /green make this one of the most pleasing double stars in the sky. Cygnus seem to be flying south along the Milky Way and scanning this area of the sky with a pair of binoculars can occupy you for many hours on a warm autumn night. To the east of Cygnus you will find the house shaped constellation of Cepheus. At the south-eastern corner lies a triangle of stars, zeta (ζ), epsilon (ε) and delta (δ). Delta Cephei is the prototype of the Cepheid class of variable stars. Delta varies between magnitude +3.5 and + 4.4 with a period of 5 days 8 hours 48 minutes. The stars epsilon (ε) +4.19 and zeta (ζ) + 3.35 are good comparison stars. Delta is also a binary star, its companion is a magnitude +6.3 blue star, the two are separated by 41 arcseconds. The ‘W’ shape of Cassiopeia can also be found high in the sky at this time of the year. The middle star of the W is another naked-eye variable, gamma (γ) Cassiopeiae. The star varies at irregular intervals between magnitude +2.20 and +3.40. It is the prototype of the Gamma Cassiopeiae type variable stars. You cabn download an observing programme from our website. The open cluster M103 lies close to delta (δ) Cas. Perseus lies just below the Cassiopeia, between these two constellations lies the famous ‘Double Cluster’ h and chi (χ) Persei also know as NGC 884 and NCG 896. The double cluster is a glorious sight in binoculars. The northern part sky is fairly blank this month, Ursa Major and its well known asterism ‘The Plough’ is likely to be the only recognisable constellation in the lower part of the sky. Polaris, the pole star lies midway between the horizon and the zenith and marks the tip of the tail of Ursa Minor. In the eastern sky we have the tradition autumn constellations of Andromeda, Perseus, Triangulum and Aries. Andromeda runs in a north-easterly direction from the northeast corner of the ‘Square of Pegasus’ towards Perseus. Midway along this line of stars lies our closest large galactic neighbour the stunning galaxy M31, the Andromeda Galaxy. M31 has a couple of close neighbours of it’s own M32 and M110. M31 is a naked-eye object from a dark location and an easy binocular object. A telescope is required to see it’s companions. Another of our local group

The Sky this Month

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Chart Produced by Chris Peat http://www.heavens-above.co

01 Sep 01:00 16 Sep 00:00 30 Sep 23:00 of galaxies lies in the small neighbouring constellation

of Triangulum. M33, is a large spiral galaxy, similar to our own Milky Way and M31, however when it comes to locating it, it is an entirely different proposition. Due to it’s low surface brightness M33 can be extremely difficult to see and requires dark transparent nights and a lot of patience in order to locate it.

Below Perseus just above the eastern horizon you will find Auriga. Like Cepheus, Auriga is basically ‘House’ shaped. The bright yellow first magnitude star Capella makes the constellation easily identifiable. There are three Messier objects in Auriga, all open clusters M36, M37 and M38. All three clusters are visible as hazy patches in binoculars and small telescopes will reveal the individual stars. M37 which lies just outside of the ‘House’ shape is the brightest of the three at magnitude +5.6 and it is also richest of the three. The sight of the Pleiades (M45) low in the east is a sign that winter is not far away.

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