* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Society News - Bristol Astronomical Society
Tropical year wikipedia , lookup
Definition of planet wikipedia , lookup
History of astronomy wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Archaeoastronomy wikipedia , lookup
Formation and evolution of the Solar System wikipedia , lookup
Orion (constellation) wikipedia , lookup
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
International Ultraviolet Explorer wikipedia , lookup
Chinese astronomy wikipedia , lookup
Star formation wikipedia , lookup
Open cluster wikipedia , lookup
H II region wikipedia , lookup
Corona Borealis wikipedia , lookup
Stellar kinematics wikipedia , lookup
Astrophotography wikipedia , lookup
Hubble Deep Field wikipedia , lookup
Auriga (constellation) wikipedia , lookup
Cosmic distance ladder wikipedia , lookup
Coma Berenices wikipedia , lookup
Canis Minor wikipedia , lookup
Malmquist bias wikipedia , lookup
Aries (constellation) wikipedia , lookup
Canis Major wikipedia , lookup
Extraterrestrial skies wikipedia , lookup
Cassiopeia (constellation) wikipedia , lookup
Astronomical spectroscopy wikipedia , lookup
Astronomical naming conventions wikipedia , lookup
Corona Australis wikipedia , lookup
Observational astronomy wikipedia , lookup
Cygnus (constellation) wikipedia , lookup
Constellation wikipedia , lookup
Perseus (constellation) wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Corvus (constellation) wikipedia , lookup
Society News At last month's AGM the following people were elected as the committee for the coming year. Chairman Secretary Treasurer Bristol Astronomical Society Information Leaflet Richard Mansfield Fiona Lambert Stephen Lloyd March 2013 British Sumer Time begins 31st March All times are UT Committee Chris Lee Jane Clark Andrew Hounsom Allan McCarthy John Meacham Ryan Parle Steve Plenty Mel Rigby Trevor Taylor John Willis At the AGM it was agreed that the subscriptions would remain the same as last year . Subscription rates are as follows Adult £37.00 Concession £18.50 Family £47.00 Youth £7.00 Programme of Events for March 2013 All meetings are held at Bristol Grammar School, University Road BS8 1SR 1st Mar Club Night - Jane Clark 8th Mar Certain types of Variables - Melvyn Taylor 15th Mar Club Night - Richard Mansfield 25th Mar Small Bodies inn the Solar System - Jerry Workman FRAS. 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/ Drawing of M44 by Chris Lee Bristol Astronomical Society are a Registered Charity, No. 299649 24 1 TheSun&Moon The Sun Date 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 Sun and Moon Rise and Set times for March 2013 Sun Moon Rise Set Rise 06:55 17:51 22:45 06:53 17:53 06:51 17:54 00:00 06:49 17:56 01:11 06:47 17:58 02:16 06:44 18:00 03:11 06:42 18:01 03:58 06:40 18:03 04:35 06:38 18:05 05:07 06:35 18:07 05:34 06:33 18:08 05:58 06:31 18:10 06:22 06:29 18:12 06:45 06:26 06:24 06:22 06:20 06:17 06:15 06:13 06:11 06:08 06:06 06:04 06:01 05:59 05:57 05:55 05:52 05:50 05:48 18:13 18:15 18:17 18:19 18:20 18:22 18:24 18:25 18:27 18:29 18:30 18:32 18:34 18:35 18:37 18:39 18:40 18:42 2 07:10 07:37 08:08 08:44 09:26 10:14 11:08 12:08 13:12 14:18 15:28 16:40 17:54 19:10 20:28 21:45 23:00 Failand Open Observing March 2013 Set 08:01 08:32 09:09 09:55 10:51 11:55 13:07 14:23 15:40 16:56 18:10 19:23 20:34 21:43 22:48 23:50 00:47 01:37 02:21 02:58 03:31 03:59 04:25 04:48 05:12 05:36 06:02 06:33 07:09 07:53 For names of the members opening the observatory this month, please check the ‘Open Observing Page’ on the website:http://www.bristolastrosoc.org.uk/wb/pages/open-observing-sessions.php All welcome Including Family, Friends, Neighbours, with or without telescopes binoculars etc. No Astronomical knowledge or skill required. Please: Contact the opener by email if you want to bring more than 4 visitors or to ask if it appropriate to run an activity on the night. Use the status message on www.bristolastrosoc.org.uk to check if the session is running. Email [email protected] if you want to join the rota. See the charts on open observing page on the website to see what objects are visible that weekend. 23 The Sun & Moon British Summer Time (BST) begins on March 25th so please remember to put your clocks forward by 1 hour. All times in this issue are UT even those between 25th and 31st of March. The Sun Comet C/2011 L4 (PANNSTARS) The Vernal (Spring) Equinox occurs at 11:02 on March 20th at this time the Sun will lie directly above the Earth’s equator and day and night will be equal length across most of the world. The word Equinox is derived from the Latin words ‘aequus’ (equal) and ‘nox’ (night). The name Equinox is often used to refer to the whole day but to astronomers it refers to the actual time the Sun is directly over the equator. Equinox also refers to the points on the celestial sphere where the Ecliptic (the apparent path of the sun across the sky) and Celestial Equator (a projection of the Earth’s equator on to the sky) cross, the Vernal Equinox is used as the zero point for Right Ascension (RA) on the celestial grid. This point in the sky was previously in Aries, which accounts for another of its names ‘the 1st point of Aries’, however due to the wobble of the Earth’s axis (Precession) the Vernal Equinox now occurs when the Sun is in the constellation of Pisces. In the northern hemisphere the Vernal Equinox marks the first day of spring. The diagram above shows celestial sphere and the location of Vernal and Autumnal equinoxes and the Summer and Winter solstices. The Moon 11th 19:44 19th 17:27 27th 09:28 4th 21:53 Apogee - 19th 03:14 (404,261 km) Perigee - 5th 23:21 (369,9563 km) 25 Day Old Moon At 25 days old the moon is a wide crescent, it doesn't rise until the early hours of the morning so its in the sky in daylight and as its so bright it can be viewed in 22 3 TheSun&Moon daylight. On the terminator in the northern half of the Moon you will find the Sinus Iridium or Bay of Rainbows which lies on the north-western edge of the Mare Imbrium. The northern walls of the bay is formed by the Montes Jura (Jura mountains) with some of its peaks rising to over 18,000m. On the north-western rim of the bay lies the 39km diameter crater Bianchini. Near the western limb of the Moon just south of the lunar equator lies the 228km diameter crater Grimaldi. This dark floored crater is easy to spot against the bright surrounding. The floor of Grimaldi is very flat, the rim of the crater is damaged in a number of places by later impacts. Comet C/2011 L4 (PANSTARRS) Comet C/2011 L4 PANSTARRS will be visible low in the north-western sky after sunset from around the middle of the month. It was discovered in June 2011 using the PanStarrs telescope. It is not a periodic comet so will not return to our skies again so make the most of any clear nights and try to spot this one time visitor The comet is expected to reach magnitude +1 when it passes through perihelion (closest point to the sun) on March 10th, making it a very easy naked-eye object, however the brightness of comets is notoriously difficult to predict. Comet C/2011 L4 will be at its closest point to the Earth on the 5th at a distance of 1.09AU, just slightly further away form us than the Sun. On the 17th it will lie just to the northeast of Algenib (gamma (γ) Pegasi) and heads in the general direction of the Andromeda galaxy (M31) which it passes early next month. On the 23rd the comet will lie east-southeast of Alpheratz (alpha (α) Andromedae) and by march 30th it will be to the northwest of pi (π) Andromedae. Below is a table showing the position of the comet each night from March 15th Date RA Dec Mag 15th 0h 34.0m 09.30º +3.4 16th 0h 34.7m 11.43º +3.5 17th 0h 35.1m 13.51º +3.6 18th 0h 35.3m 15.54º +3.7 19th 0h 35.3m 17.51º +3.9 20th 0h 35.2m 19.44º +4.0 21st 0h 35.1m 21.33º +4.1 22nd 0h 34.8m 23.17º +4.2 23rd 0h 34.5m 24.57º +4.3 24th 0h 34.2m 26.34º +4.4 25th 0h 33.8m 28.08º +4.5 26th 0h 33.4m 29.39º +4.6 27th 0h 33.0m 31.06º +4.7 28th 0h 32.6m 32.32º +4.8 29th 0h 32.1m 33.55º +4.9 30th 0h 31.7m 35.15º +5.0 4 21 The Planets Double Star of the Month Iota (ι) Cancri - RA 08h 46m 41s - Dec +28° 45′ 36′′ Iota (ι) Cancri is a double star that lies in the constellation Cancer. The brighter of the two stars (iota A) is a yellow G-class (G5.7) bright giant with an apparent magnitude of +4.02. Its companion (iota B) is a white A-class (A3) main sequence dwarf star with an apparent magnitude of +6.57. The pair are separated by 30.5 arcseconds and can be split with a small telescope. Iota Cancri lies just over 9 degrees north of the open cluster M44 and marks the northern tip of the inverted Y shape of the constellation of Cancer. Although the stars are yellow and white, many reports, including historic and more recent ones quote the stars as blue and yellow/orange and describing it as being very similar to Albireo (beta Cygni). Take a look at this double star and see what colours you think the stars are. Mercury Date 01 15 30 RA Dec Mag Phase Dia 23h 04m -01° 58' +3.89 2% 10" 22h 27m -07° 59' +1.45 19% 10" 22h 57m -08° 14' +0.33 49% 7.7" Rise 06:45 05:39 05:12 Transit 12:38 11:01 10:34 Set 18:31 16:23 15:57 Mercury is not visible from the UK this month. The innermost planet passes through ‘Inferior Conjunction’ (between the Earth and the Sun) on March 4th. Venus Date RA Dec Mag Phase Dia 01 22h 28m -11° 02' -3.90 99% 9.8" 15 23h 33m -04° 25' -3.90 100% 9.7" 30 00h 41m +03° 05' -3.91 100% 9.7" Venus passes through ‘Superior Conjunction’ (on March 28th and is not visible this month. Rise Transit 06:51 12.00 06:29 12:09 06.00 12.18 the far side of the Set 17.09 17:50 18.37 Sun) on Mars Date 01 15 30 RA Dec Mag 23h 31m -04° 01' +1.17 00h 11m +00° 25' +1.17 00h 53m +05° 05' +1.18 Phase Dia 100% 4.7" 100% 3.9" 100% 3.9" Rise 07.20 06:42 06:02 Transit 13.03 12:47 12:31 Set 18:46 18:53 18:59 Mars is not visible this month as it will be too close too the Sun. Jupiter Date 01/02 15/16 30/31 RA Dec Mag Phase 04h 23m +21° 06' -2.29 99% 04h 30m +21° 24' -2.20 99% 04h 40m +21° 46' -2.11 99% Dia 39" 37" 36" Rise 09:56 09:06 08:14 Transit 17:56 17:07 16:18 Set 01:55 01:09 00:22 Jupiter is visible in the southern sky as soon as it starts getting dark. The giant planet can be found in the constellation of Taurus not far from the bright red giant Aldebaran. By the end of the month Jupiter will set less than 30 minutes after midnight so you will need to start observing as early as possible. On the 17th the waxing crescent moon will lie close to Jupiter in the evening sky giving imagers a nice opportunity for a good picture with the Moon, Jupiter, the Hyades and the Pleiades all in the same field. 20 5 The Planets Messier of the Month M44 (NGC 2635) Praesepe - RA 08h 40m 22s - Dec +19° 41′ 19′′ M44, Praesepe or Beehive Cluster is one of the few objects in Messier's catalogue of nebulous objects that is visible to the naked eye. This large open cluster lies at the heart of the faint zodiacal constellation of Cancer (the Crab), it has been known since ancient times when it was seen as a manger. Hipparchus included it in his star catalogue of 130bc and Ptolemy mentions it as one of seven nebulae in the Almagest. Due to its large size, 95 arcminutes across, the best way to observe M44 is using binoculars. Any binoculars will resolve this beautiful cluster into a multitude of individual stars, more than 300 stars have been confirmed as members of M44. The chart below shows location of M44. In September 2012 two planets were discovered orbiting separate sun-like stars in the Beehive Cluster. Next time the sky is clear take a look at M44, and if you are into imaging why not take a picture of it, we need images for the gallery on the new website and also for Eclipse magazine. The chart above shows the position of Jupiter and the Moon art 21:00 on the 17th. Jupiter is the largest and most dynamic of the planets and there is always plenty to see on the disc of the planet. The most famous feature is the Great Red Spot (GRS) which is visible in small telescopes, the table on page 6 shows the times when the GRS crosses the central meridian of the Jupiter (which are visible from the UK) March 2nd 00:13, 20:04; 4th 21:43; 6th 23:22; 7th 19:14; 9th 20:53; 11th 22:32; 14th 00:11, 20:03; 16th 21:42; 18th 23:21; 19th 19:13; 21st 20:52; 23rd 22:31; 26th 20:02; 28th 21:41; 30th 23:20. The Galilean Moons (Jupiter’s 4 largest and brightest moons) can be seen with binoculars if they are held steady on a tripod or other binocular mount. As these four moons orbit their parent planet they undergo a number of events such as eclipses, occultations and transits, below is a list of just a few of these events:4th Transit of Io start 21:28 end 23:47 12th Shadow Transit of Europa start 21:27 end 00:01 (13th) 19th Occultation of Ganymede start 19:21 end 22:10 21st Eclipse of Io - start 18:24 end 20:40. 6 19 The Sky this Month The Sky looking East around midnight mid March 2012 Saturn Date 01/02 15/16 30/31 RA Dec Mag 14h 38m -12° 45' +0.41 14h 36m -12° 34' +0.33 14h 33m -12° 17' +0.25 Phase 100% 100% 100% Dia 18" 18" 19" Rise 23:12 22:14 21:11 Transit 04:09 03:12 02:10 Set 09:05 08:10 07:09 Saturn lies in the constellation of Libra and now rises before midnight and lies due south in the early hours of the morning. Even a relatively small telescope will show Saturn’s rings which are currently tilted at an angle of around 19 degrees providing us with a spectacular view of this beautiful object. The moon will appear close to Saturn on the morning of the 2nd and the evening of the 29th. Uranus Date 01 15 30 RA Dec Mag 00h 26m +02° 04' +5.92 00h 28m +02° 23' +5.93 00h 31m +02° 43' +5.93 Phase Dia 100% 3.4" 100% 3.4" 100% 3.3" Rise 07:45 06:51 05:54 Transit 13:58 13:06 12:10 Set 20:12 19:21 18:27 Uranus lies in the constellation of Cetus, it may be visible for a short time after sunset at the beginning of the month but will rapidly be lost in the evening twilight. Neptune Date 01 15 30 RA Dec Mag 22h 20m -10° 59' +7.96 22h 22m -10° 48' +7.96 22h 24m -10° 37' +7.95 Phase Dia 100% 2.2" 100% 2.2" 100% 2.2" Rise 06:46 05:52 04:54 Transit 11:53 11:00 10:03 Set 17:00 16:08 15:12 Neptune lies in the constellation of Aquarius, due to its apparent proximity to the Sun it s not visible this month. 18 7 On March 25th Spring officially begins in the northern hemisphere, this is the date of the Vernal (Spring) Equinox. Probably the most recognisable of the ‘Spring’ constellations is Leo, there are a number of galaxies that are located with its boundaries including 5 that made it into Messiers list of nebulous objects. The bright stars form a reasonable outline of a prone lion, the brightest member of Leo, alpha (α) Leonis, has the proper name Regulus and shines at magnitude +1.35. it marks one of the lion’s front paws and lies at the base of the asterism known as ‘the Sickle’ (a backwards ?) which forms the head and mane and chest of the celestial lion. The other stars that form the ‘Sickle’ are eta (η), gamma (γ), zeta (ζ), mu (μ) and epsilon (ε). Gamma Leonis is a very nice double star which is suitable for observers with small telescopes, the primary is a magnitude +2.2 K-class yellow-orange giant, it’s companion is a magnitude +2.5 yellow G-class star. The two stars are separated by 4.4 arcseconds. The rear and tail of the lion is formed by a trio of stars consisting of beta (β) (Denebola), delta (δ) (Zosma) and theta (θ) (Chertan). Lying 3 degrees south of theta lie the a group of three spiral galaxies, M65, M66, and NGC 3628, which are known collectively as the ‘Leo Triplet’. A second group consisting of M95, M96 and M105 can be found below the midway point between alpha and theta Leonis. M95 and M96 are spiral galaxies, M105 is an elliptical galaxy, these three are the brightest members of a larger group of galaxies with at least 5 other members. Stretching across south-western horizon you will find the constellation Hydra, the largest constellation in the entire sky, covering an area of 1303 square degrees. There are 3 Messier objects that lie with the boundaries of Hydra, M48 an open star cluster, M68 a globular cluster and M83 a spiral galaxy. Along the back of Hydra lie the three small constellations of Sextans, Crater and Corvus. These constellations are faint and can be difficult to make out due to their low altitude which means you will be looking through a thick layer of atmosphere. There are no Messier objects in any of these constellations, but there is one very interesting object in Corvus, the ‘Antennae Galaxy’ pair of interacting galaxies NGC 4038 and NGC 4039. At magnitude +10.3 you will need a reasonable size telescope to see this object. To the east of Leo is the faint constellation of Coma Berenices, another galaxy rich constellation which is also popular with deep-sky observers. To the south of Coma Berenices is Virgo, within the boundaries of these two constellations is an huge cluster of galaxies with well over 2000 members. No fewer than 19 of these objects appear in Charles Messier’s catalogue of nebulous objects, 11 in Virgo, 8 The Sky looking North around midnight mid March 2012 The Sky this Month 17 16 9 Leo The Sky looking West around midnight mid March 2012 M49, M58, M59, M60, M61, M84, M86, M87, M89, M90 and M104 and 8 in Coma Berenices, M53, M64, M85, M88, M91, M98, M99 and M100. All these objects are galaxies with the exception of M53, which is a globular cluster. In the west the winter constellations of Orion and Taurus are disappearing below the western horizon, only Gemini remains above the horizon beyond midnight. Gemini is rectangular in shape with the long sides representing the bodies of the celestial twins. Their heads are represented by the two bright stars named after the twins Castor and Pollux. Lying at the feet of ‘Castor’ you will find the lovely open cluster M35. Low in the northwest you will find Auriga with its three lovely open clusters M36, M37 and M38, all visible with binoculars and small telescopes. High in the west around midnight you will find the constellation of Cancer, at its heart lies the large open cluster M44, ‘the Beehive Cluster’ or Praesepe. M44 is just visible to the naked-eye and is a spectacular sight in binoculars and widefield telescopes. In the eastern sky you will find the constellation of Boötes, at the base of this kite shaped constellation lies the bright red super-giant Arcturus, which at magnitude –0.04 is the fourth brightest star in the sky and the brightest in the northern half of the sky. Lower down near the eastern horizon lies Hercules, at its centre lies the wellknown asterism the ‘Keystone’. On the western side of the ‘Keystone’ around 1/3 of the way from eta (η) to zeta (ζ) lies M13, the best example of a globular cluster visible from the northern hemisphere. Around 6 degrees north of pi (π) (at the north-eastern corner) lies another globular cluster, M92 which is a lovely sight in a small telescope. Tucked between the constellations of Boötes and Hercules lies the small semicircular constellation of Corona Borealis, which is home to the famous variable star R Coronae Borealis (R CrB). At its normal brightness R CrB is magnitude +6, and consequently visible in binoculars, when it drops in brightness it can be as dim as magnitude +15. Keep an eye on R Coronae when you’re out observing and check its brightness as it can fade at any time. Charts for R CrB are available from the AAVSO website at http://www.aavso.org/vsp High overhead you will find the constellation of Ursa Major, its seven brightest stars form the familiar asterism known as the ‘Plough’, or ‘Saucepan’ making one of the most recognisable constellations in the sky. The two end stars of the ‘Bowl’ alpha (α) and beta (β) Ursae Majoris are collectively known as the pointers as 10 The Sky looking South around midnight mid March 2012 The Sky this Month 15 14 11 Coma Berenices & Virgo The Sky looking Overhead around midnight mid march 2012 The Sky This Month they point the way to Polaris, the ‘Pole’ or ‘Northern Star’. Within the boundaries of Ursa Major there are eight Messier objects, M40, M81, M82, M97, M101, M102, M108 and M109. M40 is a double star which is also known as Winecke 4, M81, M82, M101, M108 and M109 are all galaxies, M97 is a Planetary Nebula known as the ‘Owl Nebula’. M102 is generally recorded as a duplicate of M101. All of these objects are visible with medium to large telescopes, although some like the M97 need very dark clear skies. 01 Mar 01:00 16 Mar 00:00 30 Mar 23:00 The area surrounding Ursa Major is fairly blank with hardly any bright stars in it. To the northwest lies the faint constellation of Camelopardalis, which is home to one of the best binocular objects in the northern sky ‘Kemble’s Cascade’ a string of around 20 stars which lie in an almost straight line. The constellation of Perseus lies close to the northwestern horizon, it is home to another of the northern sky’s great binocular sight, the famous ’Double Cluster’ NGC 884, and NGC 869. Low in the north is the ‘W’ shape of Cassiopeia, the central star of the ‘W’, gamma (γ) Cassiopeiae is a naked-eye variable which varies between magnitude +1.6 and +3.0 at irregular intervals. To the east of Cassiopeia you will fine the crooked house shape of Cepheus, at the south-eastern corner you will find a triangle of stars zeta (ζ), epsilon (ε) and delta (δ). Delta is another naked-eye variable star, it’s famous as the type star of the Cepheid class of variable stars which are ‘standard candles’ used in the measurement of distances in the universe. Delta Cep varies between magnitude +3.5 and +4.4 every 5 days 8 hours 48 minutes. These variations are extremely regular with a rapid rise followed by a much slower fall. Epsilon (ε) Cep +4.19 and zeta (ζ) Cep +3.35 are good comparison stars. 12 Chart Produced by Chris Peat http://www.heavens-above.coom 13