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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
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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
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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.
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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.
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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
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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