Society News. Bristol Astronomical Society Information Leaflet February 2009

Transcription

1 Society News AGM This year s AGM takes place on the 13th of February. At the AGM the entire committee resign, and any fully paid up member over the age of 18 is entitled to stand for any position on the committee. There are posts for 3 named officers, Chairman, Secretary and Treasurer plus a further 9 positions for committee members. There are also two posts for junior members (under 18). If you that you have something to offer the society and would like to stand for any of the positions on the committee, nomination forms will be available at all meetings up to the AGM. You can also download one from the documents section of the website. Both the nominee and the person nominating them must sign the form. Bristol Astronomical Society Information Leaflet February 2009 IYA 2009 During 2009, the International Year of Astronomy, there will be lots of events to celebrate the 400th anniversary of the first telescopic observations of the sky. The BAS will be organising some events of our own throughout the year, more details will be available soon. There are some events that are planned to be nationwide, such as MoonWatch where societies hold observing sessions to allow the public to observe the moon through telescopes. MoonWatch dates are 28th Mar to 5th Apr and 10th to 24th Oct to 1st Nov. There is also Schools MoonWatch, 19th to 29th Nov and a Jupiter/Sky watch week 10th 23rd Oct. If you want to organise something for any of these events and need any help please contact a member of the committee. Programme of Events for February 2009 All meetings are held at Bristol Grammar School. 6th Feb Club Night - 13th Feb 20th Feb AGM Club Night - Nigel Tasker 27th Feb Johannes & Elizabetha Hevelius: Frontline Astronomy in the 17th century. - Prof Mark Birkinshaw Don t forget to check out the BAS website where you can get all the latest info about the society. Bristol Astronomical Society are a Registered Charity, No NGC 2683 in the constellation of Lynx 1

2 Cliff Martin Clifford William Martin. It is with very great sadness that we have to report the death of Clifford Martin. Cliff, as he was always known was one of the society s longest serving members and without doubt, the longest serving committee member. Cliff was the society s treasurer for 43 years, a feat I am sure will never be surpassed, and only gave up the job when illness forced him to move away from Bristol in During his time as treasurer Cliff, saw the society through some tough financial times, juggling the funds to make sure all our guest speakers were paid on time even when the society was almost broke. In recognition of his long service and commitment to the society, Cliff was given the honour of becoming one of our vice presidents. Cliff will always be affectionately remembered for his rustling carrier bags, which he regularly used to keep his records and cash in. During meetings he would go through the records and check the funds rustling his bag while he did so. Lynx A rare meeting of the society s Vice presidents in 2002 (left to right) Rodney Hillier Retired Lecturer in Astrophysics, Bristol University Mark Birkinshaw Professor and Chair of Astronomy, Bristol University Gordon Taylor One of the founding members of the Society Cliff Martin Society Treasurer for 41 years Cliff will be sadly missed by everyone who knew him. 2 23

3 Constellation of the Month Stars in Lynx Only one of the stars that make up the constellation of lynx has a proper name, Alsciaukat; (31 Lyncis), which come from the Arabic and refers to a Thorn. The star is a K-class (K7) orange giant with an apparent magnitude of It lies about 2/3 of the way along a line drawn for Castor (α Geminorum) to Talitha (ι Ursa Majoris). Alpha (α) Lyncis lies at the eastern end of the constellation, it is the only star in Lynx to carry a Bayer letter. Alpha is another K-class (K5) orange giant with an apparent magnitude of Around 3 degrees north of alpha lies 38 Lyncis, a very nice visual double star for small telescopes. The primary is magnitude +3.82, the secondary is magnitude +6.6 the pair are separated by 2.7 arcseconds (PA 229 ). Take a look at this star and see what colours you think they are. Some reports state that the primary looks green others that it appears white with the secondary being blue or red. The primary star is itself a spectroscopic binary, the two visual components are sometimes referred to as A and C or AB and C. There is fourth component 88 arcseconds away at PA 212, which is around magnitude Lyncis is a triple star with components of magnitude A +5.4, B +6.0 and C Components A and B are both blue/white A-class stars and are separated by just 1.8 arcseconds (70 ). A and C are separated by 8.5 arcseconds (PA 308 ). Small instrument should split the A and C pair while larger telescopes will be needed to split the A-B pair. 19 Lyncis is another multiple star the primary (A) is another spectroscopic binary, magnitude It s magnitude +6.5, visual companion (C) lies 15 arcseconds away at PA 315. Both A and C components are B-class stars. Now is a good time to observe Lynx as it is high in the sky which should help you locate this faint constellation. Objects in Lynx Object NGC Type Mag RA Dec Intergalactic Wanderer 2419 Globular Cluster h 38.1m ' UFO Galaxy 2683 Spiral Galaxy h 52.7m ' 12 Lyncis Multiple Star +5.4 & +6.0 & h 46.2m ' 19 Lyncis Multiple Star +5.6 & h 22.8m ' 38 Lyncis Multiple Star +3.8 & h 18.8m ' 22 The The Sun & Sun Moon Sun Rise and Set times February 2009 Date Sun Moon Rise Set Rise Set 01 07:48 17:00 09: :47 17:02 09:50 00: :45 17:04 10:15 02: :44 17:06 10:52 03: :42 17:07 11:45 04: :40 17:09 12:56 05: :39 17:11 14:21 06: :37 17:13 15:52 07: :35 17:15 17:23 07: :33 17:17 18:50 07: :31 17:18 20:14 08: :30 17:20 21:35 08: :28 17:22 22:54 08: :26 17:24 08: :24 17:26 00:11 09: :22 17:28 01:26 09: :20 17:29 02:37 09: :18 17:31 03:40 10: :16 17:33 04:34 11: :14 17:35 05:15 12: :12 17:37 05:47 13: :10 17:38 06:11 14: :08 17:40 06:29 16: :06 17:42 06:45 17: :04 17:44 06:58 18: :02 17:46 07:11 19: :00 17:47 07:24 21: :57 17:49 07:39 22:27 3

4 The Sun & Moon The Sun The Sun is still very quiet at the moment with very few reports of sunspots being visible. Hopefully as the year progresses there will be more to see on the Sun s disc. IYA 2009 As you know 2009 is the International Year of Astronomy and the society hope to run a number of events to show the public the wonders of the sky. The Sun is an ideal object for this as it is out in the daytime and easy to find. It is very important when observing the Sun to make everyone aware that looking directly at the Sun is dangerous even without optical aid. Here is a couple of basic ways to view our nearest star safely. One of the easiest and safest ways to observe is by projecting an image of the Sun using a pinhole camera. The simplest form of pinhole projector uses just 2 sheets of card. With a pin, make a small hole in the centre of one of the sheets, hold the card up and aim the hole at the Sun. (Don t look at the Sun through the hole!). Hold the second sheet directly behind the first and you should find that the image of the Sun is projected onto it. You will need to move the second sheet of paper back and forth until the image is in focus. Another simple method, is to use a long box or tube, cover one end entirely with tin foil or cut a hole in the end and cover this with foil (tin foil will give a sharper edge to the hole). Cover the other end of the tube with tracing paper so that you can see the projected image through it. A sheet of card can be used at the screen end of the tube to create more shadow and give better contrast. A further refinement is to stick a sheet of ordinary white paper on the inside at the screen end instead of a sheet of see through paper and cut a viewing hole in the side of the tube to allow you to see the image. Using different lengths tube will produce different sized images. 4 Constellation of the Month Lynx Abbreviation: Lyn - Genitive: Lyncis Lynx is a fairly modern constellation, one of seven introduced by Johannes Hevelius in his catalogue Prodromus Astronomiae which was published by his wife in 1690, three years after his death. The other new constellations were Canes Venatici, Lacerta, Leo Minor, Scutum, Sextans, and Vulpecula. Lynx lies in a very sparse region of the northern sky and is bounded by Camelopardalis to the north, Auriga to the east, Gemini and Cancer to the south and Leo Minor and the Ursa Major to the west. Hevelius acknowledged the faintness of its stars when he wrote that to see this constellation, observers would have to be lynx-eyed to see it. Objects in Lynx There are no Messier objects that lie within the boundaries of Lynx. NGC 2419 is a globular cluster that also goes by the name of the Intergalactic Wanderer due to its distance from the galactic centre. The cluster lies almost 300,000 lightyears from the Earth almost twice the distance of the Large Magellanic Cloud. For a time it was thought that the cluster was not associated with our galaxy, however recent studies show that it is gravitationally bound to the Milky Way, following an elliptical orbit around the galaxy. NGC 2419 was discovered by William Herschel on December 31st The cluster is also known as Caldwell 25. The Caldwell catalogue is a list of Patrick Moore s 109 favourite deep-sky objects. As M numbers had already been used by Messier, he used one of his middle names Caldwell to refer to objects in his list. NGC 2683 was also discovered by William Herschel, this one on February 5th This is an almost edge on spiral galaxy (Sb Type) which lies in the south the constellation close to the border with Cancer. NGC 2683 has an apparent diameter of 9.3 x 2.2 arcminutes and is magnitude Medium to large instruments are required for this object. NGC 2683 is sometimes known as the UFO galaxy. 21

5 Path of Comet 2007 N3 Lulin During February 2009 The Sun and Moon The Moon This month we take a look at the one of the most well known craters on the Moon, Eratosthenes. The crater lies just to the west of the central meridian of the Moon, at the south-western end of the lunar Apennines, Latitude 14.5 north, Longitude 11.3 west. Eratosthenes is 60km (35 miles) in diameter, the crater walls rise to over 2,400 m (8,000ft) above the surrounding area, with steep outer slopes which are very rugged with many hills and valleys. The inner walls are lightly terraced. The floor of Eratosthenes lies around 2,400m (8,00ft) below the surrounding area and contains a central mountain with several peaks. There are also a number low hills and wrinkle ridges with in the crater. The best time to observe Eratosthenes is 1 day after First Quarter or Last Quarter Mons Hadley Mons Bradley Eratosthenes Mons Ampère Mons Huygens Mons Wolff The Apennine Mountains are a magnificent range of peaks that form part of the south-eastern rim of the Mare Serenitatis (sea of serenity). The range is around 650 Km (400 miles) in length and contain a number of the highest mountain peaks on the Moon, including the highest, Mons Huygens; Lat 20.0 N, Lon 3.0 W at 5400m (16400ft) A number of the other Apennine peaks have been individually named including: 20 5

6 The Sky this Month Mons Ampère:- Lat 19.0 N, Lon 4.0 W. Height 3000m (9100ft) Mons Bradley:- Lat 22.0 N, Lon 1.0 E. Height 4200m (12700ft) Mons Hadley:- Lat 27.0 N, Lon 5.0 E. Height 4800m (14500ft) Mons Wolff:- Lat 17.0 N, Lon 7.0 W. Height 3500m (10600ft) If you observe the mountain range at sunrise or sunset the sight can be spectacular as the sun illuminates the very tops of the mountains while the surrounding area is still in deep shadow. Deep within the Apennines you will find Rima Hadley (Hadley Rille), Lat 25.0 N, Lon 3.0 E, an 82Km (48 mile) long sinuous canyon that runs in a Southwest- Northeast direction. About midway along the rille it passes close to the craterlet Hadley C, Lat 25.5 N, Lon 2.8 E. It was in this area that the Apollo 15 mission was based, during the mission the astronauts visited Hadley Rille. Apollo 15 was launched on 26 July 1971, the crew were David Scott (Commander) James Irwin (LM pilot) Alfred Worden (CSM pilot). The lunar module landed on the Moon at 22:16 on July 30th During the mission Scott showed that a feather and a hammer fall at the same rate because of the atmosphere lack. Apollo 15 left the Moon on August 2nd and splashed down on August 7th at 20:45. The best time to observe the Apennines is around First Quarter or 6 days after Full Moon. 6 25th 01:35 2nd 23:13 9th 14:49 16th 21:37 Comet 2007 N3 Lulin During the next couple of months Comet 2007 N3 Lulin should be visible in the southern sky. At the beginning of February it will be visible in the early hours of the morning, but by the end of the month it will be visible during the late evening. The comet visible in binoculars and may even be visible with the naked-eye from dark sites. At the beginning of the month, Lulin is predicted to be magnitude +7.4, on the 1st the comet can be found approximately midway between beta (β) and sigma (σ) Librae. The path of the comet follows the Ecliptic quite closely. On the February 5th it will pass less than 1 degree of north of Alpha (α) Librae, a nice the binocular double, the comet will be around magnitude +7.1 by this time. The comet will initially be moving against the background stars at about 1 degree per day, but as it comes closer to the Earth its speed will increase. By the 11th when it crosses into Virgo it will be moving at a rate of 2 degrees per day. On the 11th it will pass within 90 arcminutes of lambda (λ) Virginis, on the 16th it will be about 3 degrees north of Spica, alpha (α) Virginis, and the comet s speed will have increased to 3 degrees per day. By this time the comet will rise around 22:30 and will be around magnitude Lulin is expected to reach peak brightness sometime between the 21st and the 25th when it could reach On the 23rd the comet crosses into Leo and passes 2 degrees southwest of Saturn. Comet Lulin s closest approach to Earth, 0.41 AU. (61 million km), occurs on February 24th. At this time the comet will be covering over 5 degrees of the sky per day. On the 27th Lulin will pass just 40 arcminutes south of Regulus; alpha (α) Leonis. As the comet moves away from the Earth it will fade quite quickly. Date RA Dec Mag Date RA Dec 01 15h 14m h 43m h 10m h 31m h 06m h 19m h 02m h 05m h 57m h 50m h 53m h 34m h 47m h 17m h 42m h 59m h 35m h 40m h 28m h 21m h 21m h 02m h 13m h 43m h 04m h 24m h 54m h 06m Mag

7 The Sky looking East around midnight mid February 2009 The Planets Mercury 01 19h 31m '' % 8.8" 06:32 15: h 11m '' % 6.7" 06:22 14: h 20m '' % 5.7" 06:22 15:31 Mercury maybe be visible very low in the south-eastern sky for the first two weeks of the month. The planet reaches greatest western elongation on the 13th.. Venus 01 23h 52m '' % 30" 09:06 21: h 27m '' % 37" 08:14 21: h 44m '' % 45" 07:19 21:21 Venus is visible in the western sky in the early evening. The planet is a brilliant object and easily visible in twilight. Venus reaches greatest brilliance on the 19th reaching magnitude 4.6. It was Edmund Halley that first recorded that Venus Venus 01/02/09 was at its brightest when the phase was around 30%. Venus 28/02/09 During February the phase of Venus decreases from 40% to just under 20%. The apparent size however, increases from 30 arcseconds to over 45 arcseconds. The phase should be visible in binoculars and small telescopes. On the 27th and 28th the Moon will be close by. Mars 01 19h 58m '' % 4.0" 07:17 15: h 43m '' % 4.1" 06:51 15: h 24m '' % 4.1" 06:23 15:36 Mars maybe visible for a short time before sunrise, however you will need a very good eastern horizon to spot the red planet. Jupiter will pass 0.6 degrees to the north of Mars on the 17th. Jupiter 01 20h 34m '' % 32" 07:35 16: h 48m '' % 33" 06:49 15: h 00m '' % 33" 06:06 15:

8 The Planets Jupiter is slowly reappearing after last month s solar conjunction, you may catch a glimpse of the planet in the eastern sky shortly before sunrise. As it will be very low in the sky it will be very difficult to pick out any real detail on the disc. Take care when observing as the Sun will rise soon after the planet. Saturn 01/02 11h 29m '' % 19" 20:15 09:20 14/15 11h 26m '' % 20" 19:20 08:27 27/28 11h 22m '' % 20" 18:24 07:34 Saturn reaches opposition next month and is ideally placed for observation this month. The famous rings are tilted just 2 degrees to the south as seen form Earth at present and details in the rings will be very difficult to see. Uranus 01 23h 25m '' % 3.4" 09:06 20: h 28m '' % 3.4" 08:12 19: h 30m '' % 3.3" 07:22 18:48 Uranus is visible for a short time in the western sky after sunset. At the beginning of the month the planet sets over 3 hours after sun but by the end of the month it sets just 1 hour after sunset. Neptune 01 21h 43m '' % 2.2" 08:15 17: h 45m '' % 2.2" 07:22 17: h 47m 13 43'' % 2.2" 06:31 16:12 Neptune passes through solar conjunction on the 13th and is therefore not observable this month. 1 Ceres The dwarf planet (1) Ceres reaches opposition on the 25th in the constellation of Leo. Ceres will be magnitude +6.9 and lies to the north of delta (δ) Leonis (see chart on page 9). To check you have the right object make careful plots of the field over a few nights, one of the stars will have shifted its position, that will be Ceres. Astro-imagers can follow the same procedure by taking images at intervals which should reveal Ceres moving against the background stars. The Sky looking West around midnight mid February

9 16 9 The Sky looking North around midnight mid February Ceres at opposition 25th February 2009

10 The Sky this Month Overhead High overhead at around midnight is this month s featured constellation, Lynx. This is a very faint group of stars and you may have trouble locating it from light polluted areas. To the west of Lynx lies the familiar shape of Auriga with its three lovely open clusters M36, M37 and M38. South lies Gemini the two bright stars Castor (α Gem) and Pollux (β Gem) marking the head of the twins. Near the feet of the twins lies the open cluster M35 a group of around 500 stars within an area about the size of the full Moon. M35 should be visible to the naked-eye from a very dark location and is a wonderful sight in binoculars. East of Lynx lies another small faint constellation Leo Minor. To the northeast you will find Ursa Major, the familiar asterism of the Plough forming the Bear s rear end and it s tail. Ursa Major has numerous deepsky objects which lie within its boundaries, including M40 a double star, M81 a spiral galaxy, M82 an irregular galaxy, M97 a planetary nebula, M101, M108 and M109 all spiral galaxies. To the north of Lynx is yet another very faint constellation, Camelopardalis. The outstanding object in Camelopardalis is Kemble s Cascade; a string of stars that leads to NGC To locate this delightful asterism in binoculars, first find Cassiopeia and draw an imaginary line from β Cas to ε Cas (the two end stars of the W ) and extend the line by the same distance again, Kemble s Kemble s Cascade Cascade should be in your field of view. The Sky looking South around midnight mid February

11 The Sky looking overhead around midnight mid February The Sky this Month Looking South The bright constellations of winter are still prominent in the southern sky during February, Orion is outstanding with its many bright stars and multitude of deep sky objects. There is always plenty to keep both serious and casual observers coming back for more. High in the south is the faint constellation of Cancer, you will need a dark sky to see the stars that form this zodiacal constellation. There are a couple of Messier objects in Cancer; M44 and M67 both open clusters. M44, which is visible to the naked-eye from a dark site, is also known as Praesepe (Latin for "manger"), or the Beehive cluster. M44 is a spectacular sight in binoculars' and small telescopes. This cluster has been known since ancient times, it was recorded by Aratos in 260 BC as the "Little Mist". M67 is one of the oldest known open clusters at around at 3.2 billion years, it lies just top the west of alpha (α) Cnc. Just below Cancer, and meandering to the southeastern you will find Hydra, another fairly inconspicuous constellation. There are three Messier objects in Hydra, M83, a spiral galaxy located close to the border with Centaurus, M68, a globular cluster near M83, and M48 an open cluster which lies at the western end the constellation. Looking North Low in the north you will find the house shaped constellation of Cepheus, delta (δ) Cep is the prototype of the Cepheid class of variables, noted for the correlation between their period of variability and absolute luminosity. Due to this correlation, discovered by Henrietta Swan Leavitt in 1908, Cepheid s can be used as standard candles to determine the distance of the cluster or galaxy the star belongs to. Mu (μ) Cephei is another variable star, noted for being the reddest star visible to the naked-eye. William Herschel named it the Garnet Star. The colour is even more noticeable when seen through binoculars. 11

12 The Sky This Month West of Cepheus lies the W shaped Cassiopeia, home to the open cluster M103, which lies not far from delta (δ) Cas. To the east lies Draco which seems to wrap itself around Ursa Minor. 01 Feb 01:00 16 Feb 00:00 30 Feb 23:00 Looking West The western sky is dominated by the constellation of Taurus, the two famous open cluster s, the V shaped Hyades and the beautiful Pleiades (M45) are excellent binocular objects. For those with a access to a medium to large telescope, M1, the Crab Nebula; can be found near the tip of the southern horn of the Bull. Higher in the sky you will Auriga, home to three open clusters, M36, M37 and M38 all easy binoculars objects. In the northwest lies Perseus, midway between Perseus and Cassiopeia you will find a pair of open clusters, NGC 869 and NCG 884 known as the double cluster. There are also a couple of Messier objects in Perseus; M34, an open cluster and M76 a planetary nebula, also known as the Little Dumbbell Double Cluster Looking East Over in the east the spring constellations are beginning to make their presence known. The galaxy rich area of Virgo and Coma Berenices can be found low in the southeast. This region is a deep-sky observers paradise with literally hundreds of galaxies visible in amateur telescopes. Further around to the east you will find the Kite shaped constellation of Boötes. Chart Produced by Chris Peat