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Society News
On the evening of the 19th of August we held our second annual summer picnic
at the national Trust’s Tyntesfield Estate. The evening started with a quiz, those
attending split in to groups of four to six people to answer a series of astronomy
related questions set by Tricia. Drinks were served while we were answering the
questions, some of which were quite tricky. The winning team will be announced
as soon as Tricia has had time to go through the answer sheets.
After the question papers were collected it was time for the food, which as always
was excellent with plenty of choice. The puddings were especially good
After everyone had had enough to eat the plan had been that we would do some
observing, however the weather had other plans. Other than small, short breaks in
the clouds, the sky was completely obscured.
People started to pack up and leave at around 11pm, all in all despite the poor
weather the evening was a great success.
BristolAstronomicalSocietyInformationLea let
All times are BST (UT +1hr) unless stated otherwise
Astronomy Course
Rodney Hillier’s long running astronomy course begins again on October 17th, it
will be held in Room J16 above the 6th form common room.
Further details will be published in next months’ issue.
Observatory
We have now been given the go ahead to install the 18” telescope at Failand, we
now need people to help carry out the work needed. If you are willing to help
please contact John Willis.
Programme of Events for September 2011
All meetings are held at Bristol Grammar School, University Road BS8 1SR
2nd
Sep
Club Night - Eddie Carpenter
9th
Sep
Observatory Maintenance & Observing (if clear)
16th Sep
Club Night - John Willis
23rd Sep
Observatory Maintenance & Observing (if clear)
30th Sep
Club Night - Roger Steer
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/
Sunspots 16/08/11 - Image from SOHO
Bristol Astronomical Society are a Registered Charity, No. 299649
24
September2011
1
The The
Sun &
Moon
Sun
Sun and Moon Rise and Set times for September 2011
Sun
Moon
Date
Rise
Set
Rise
01
06:22
19:57
11:05
02
06:24
19:55
12:29
03
06:25
19:53
13:47
04
06:27
19:51
14:57
05
06:29
19:49
15:55
06
06:30
19:46
16:42
07
06:32
19:44
17:18
08
06:33
19:42
17:46
09
06:35
19:39
18:09
10
06:37
19:37
18:29
11
06:38
19:35
18:47
12
06:40
19:33
19:04
13
06:41
19:30
19:21
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
06:43
06:45
06:46
06:48
06:49
06:51
06:53
06:54
06:56
06:57
06:59
07:01
07:02
07:04
07:05
07:07
07:09
19:28
19:26
19:23
19:21
19:19
19:16
19:14
19:12
19:10
19:07
19:05
19:03
19:00
18:58
18:56
18:54
18:51
2
19:40
20:01
20:26
20:56
21:34
22:21
23:18
00:24
01:38
02:56
04:18
05:42
07:08
08:35
10:02
11:26
Failand Open Observing Rota September 2011
Month Day
Set
20:55
21:28
22:08
22:57
23:57
Opener
Email
Assistant
Terry Blake
[email protected]
Roger Sykes
Sep
3rd
Sep
10th Terry Flower
[email protected]
James Nelis
Sep
17th Terry Blake
[email protected]
Dave Smales
Sep
24th Roger Sykes
[email protected]
Alison
Camacho
All welcome
01:03
02:13
03:24
04:34
05:43
06:51
07:57
09:04
10:10
11:16
12:20
13:22
14:18
15:08
15:50
16:25
16:54
17:19
17:43
18:05
18:29
18:55
19:26
20:04
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
The Autumn Equinox occurs on the 23rd of this month. At 10.05 the Sun will
cross the celestial equator heading south. This marks the end of the northern hemisphere summer and the start of autumn. Equinox mean equal night and at this
time of the year the length of day and night are approximately the same length.
The Sun
Observers of the Sun have had plenty to look at over the
past few months with lots of active regions visible. The
image on the right was taken by the SOHO satellite on
the 16th August and shows the large sunspot group
1271 just appearing round the eastern limb. To get the
latest news and images of our nearest star check out the
SOHO website at:- http://sohowww.nascom.nasa.gov
Pegasus
The Moon
27th
12:09
4th
18:39
12th
07:04
The Seven Day Old (First Quarter) Moon
The First Quarter Moon is one of the most
spectacular lunar phases, in the northern half of
the moon the following interesting features are
visible on or near the terminator, the Alpine
Valley, the Lunar Alps, Aristillus, Archimedes
and the Apennine Mountains.
The Alpine Valley (Vallis Alpes) is one of the
most popular features on the moon, this 166km
long scar runs in an east-northeast direction
from the edge of the Mare Imbrium and slices
through the Lunar Alps.
The Lunar Alps (Montes Alpes) form part of
the north-western rim of the Mare Imbrium, the
range is around 260 km in length and contains
some stunning peaks. Two of the most notable
peaks are Mons Blanc which rises to 3.6km in
height and Mons Piton which reaches 2.3km in
height.
22
3
20th
14:39
The Sun & Moon
Aristillus is a 50km wide crater with a central peak which is over 900m high.
Archimedes is 85km in diameter, its inner walls are terraced and the floor is flat
with no central peak.
The Apennine Mountains (Montes Apenninus) run for almost 1000km around the
south-western rim of the Mare Imbrium. Like the Lunar alps it has some notable
peaks including Mons Huygens which at 5.4km in height is listed as the highest
mountain on the Moon. Mons Bradley 4.2km and Mons Hadley 3.5km.
In the southern half of the Moon you will find Ptolemaeus, Alphonsus, Arzachel,
in a line running from north to south. Ptolemaeus is the largest with a diameter of
158km, it has high walls and a flat floor riddles with craterlets. Alphonsus is the
next in size with a diameter of 121km. Its high walls are terraced and the crater
floor is fairly flat with a central peak. The last of the trio is Arzachel, which with
a diameter of 100km is the smallest. Arzachel has high terraced internal walls and
a central peak which rises to over 1.5km.
Constellation of the Month
AG Pegasi is a Z Andromedae type variable, a group of symbiotic stars which
exchange of mass between the two components which causes the variations in
brightness. The star brightened by about 3 magnitudes from 9th to 6th magnitude
over a 20 year period (1850 –1870) then very slowly faded back to 9th magnitude
by 1960. AG Peg can be found around 3 degrees north-northwest of epsilon Pegasi.
The chart on the right is
produced by the AAVSO .
As the Sun rises the high points of mountains and crater walls are illuminated
while the surrounding area is still in shadow providing you with some spectacular
sights. First Quarter occurs on the 4th of the month at around 18:30 so get out that
evening and have a look at our nearest neighbour during this lovely phase.
Objects in Pegasus
Object
M15
Stephan’s
Quintet
AG Pegasi
R Pegasi
4
NGC
Type
Mag
7078 Globular Cluster
+6.0
7331
Spiral Galaxy
+9.5
7317 7320
Galaxy Group
RA
Dec
21h 30.0m +12° 10'
22h 37m
+34° 25'
+12.6 to +13.6 22h 35.9m +33° 57'
Variable Star
+6.0 to +9.4
21h 51.0m +12° 38'
Variable Star
+6.9 to +13.8
22h 06.6m +10° 33'
21
The Planets
Constellation of the Month
in the constellation of Pegasus. This small group of five galaxies lies just to the
south on NGC 7331. The group is very popular with imagers but can be difficult
to spot visually.
Stars in Pegasus
Alpha (α) Pegasi has the proper name Markab which comes from an Arabic
phrase meaning "the horse's shoulder". Markab lies at the south-western corner of
the square of Pegasus. The star is a hot B-class (B9) dwarf which, at magnitude
+2.49 ranks as the third brightest star in the constellation.
Beta (β) Pegasi has the proper name Scheat from the Arabic for ‘foreleg’. Beta is
an M-class (M2.5) red giant that is classed as a semi-regular variable, it ranges in
brightness from +2.1 to +3.0. Scheat marks the north-western corner of the
‘Square’.
Mercury
Date
01
15
30
RA
Dec
Mag
09h 32m +14° 05' +0.03
10h 54m +08° 55' -1.24
12h 54m -02° 28' -1.44
Phase Dia
39% 7.6"
90% 5.4"
100% 4.8"
Rise
04:44
05:32
07:12
Transit
12:01
12:24
13:06
Set
19:18
19:15
18:59
Mercury reaches greatest western elongation on September 3rd when it will be
18 degrees from the Sun. The innermost planet will be visible in the eastern sky
before sunrise until the middle of the month. The planet rapidly moves in towards
the Sun and it passes through superior conjunction on the 28th. Mercury is at its
brightest around mid-month when it will be magnitude –1.2. The chart below
shows the position of Mercury at 05:30 on morning of September 3rd.
Gamma (γ) Pegasi lies at the south-eastern corner of the ‘Square of Pegasus’, the
star has the proper name Algenib; Arabic for ’the side’. Gamma is a magnitude
+2.83 B-class (B2) hot white star.
Epsilon (ε) Pegasi has the proper name Enif, meaning ‘the nose’. Enif is a Kclass (K2) orange super-giant which shines at magnitude +2.39.
Zeta (ζ) Pegasi is a magnitude +3.40 B-class (B8) dwarf
Eta (η) Pegasi has the proper name Matar which comes from an Arabic phrase
meaning ‘fortunate rain’. Eta is a double star (possibly quadruple), the brighter of
the two is a G-class (G2) giant which shines at +2.9. Its companion is an A-class
(A5) dwarf star.
There are a couple of well known variable stars in Pegasus, R Pegasi and AG
Pegasi.
R Pegasi is a
long period
Mira type variable which
ranges
in
brightness
from +6.9 to
13.8 over a
period of 378
days.
Venus
Date
01
15
30
RA
Dec
Mag Phase Dia
11h 01m +07° 47' -3.92 100% 9.7"
12h 05m +00° 49' -3.91 99% 9.8"
13h 13m -06° 46' -3.90 98% 10.0"
Rise
06:44
07:28
08:15
Transit
13:28
13:37
13:46
Set
20:12
19:45
19:16
Venus is recovering from last month’s superior conjunction and is not visible this
month.
Mars
Date
01
15
30
20
RA
Dec
Mag
07h 20m +22° 50' +1.39
07h 58m +21° 34' +1.36
08h 36m +19° 44' +1.30
Phase Dia
93% 4.7"
93% 4.9"
92% 5.1"
5
Rise
01:40
01:31
01:22
Transit
09:52
09:34
09:13
Set
18:03
17:36
17:03
The Planets
Constellation of the Month
Mars is visible in the early hours of the morning, the planet begins the month in
the constellation of Gemini just under 1 degree north of delta (δ) Geminorum.
The red planet moves fairly rapidly against the background stars and crosses the
border into Cancer on the 16th ending the month less that a degree from the lovely open cluster M44, the Beehive cluster. The chart below shows the position of
Mars at 04:00 on September 30th.
Pegasus
Abbreviation: Peg, Genitive: Pegasi
Pegasus is one of the 48 classical constellations named in Ptolemy's Almagest. It
is the seventh largest constellation covering an area of 1121 square degrees of the
sky. The most recognisable part of the constellation is the asterism known as the
‘Square of Pegasus’ which is formed by the stars alpha, beta and gamma Pegasi
and alpha Andromedae (which was previously known as delta Pegasi).
Mythology
In Greek mythology, Pegasus is the winged
horse that sprang from the body of Medusa
when Perseus cut of her head.
Jupiter
Date
RA
Dec
Mag Phase Dia
Rise
Transit
Set
01/02 02h 32m +13° 32' -2.65 99% 45"
21:46
04:59
12:13
15/15 02h 31m +12° 22' -2.75 99% 47"
20:50
04:03
11:15
29/30 02h 27m +12° 59' -2.83 100% 48"
19:53
03:04
10:14
Jupiter rises in the early evening and is visible for most of the night. The giant
planet is currently moving in a retrograde direction (east to west) through Aries.
During the month Jupiter brightens slightly from magnitude –2.6 to –2.8. The
chart on page 7 shows the position of Jupiter at midnight on 16th September.
Saturn
Date
01
15
30
RA
Dec
Mag
12h 54m -03° 50' +0.89
12h 04m -04° 27' +0.84
13h 11m -05° 08' +0.77
Phase
100%
100%
100%
Dia
16"
16"
16"
Rise
09:45
08:58
08:09
Transit
15:28
14:38
13:46
Saturn sets in the early evening and is not visible from the UK this month.
Set
21:11
20:19
19:23
When the horse was drinking from a well
Bellerophon, the Corinthian hero captured it
using a golden bridle given to him by Athena. He was later presented Pegasus as a reward for killing Chimera. However when he
attempted to mount the horse it threw him
off and rose to the heavens, where it became
the constellation we know today.
Objects in Pegasus
There is just one object from Charles Messier’s catalogue in Pegasus, M15. This
lovely example of a globular cluster can be found approximately
4 degrees west-northwest of the double star epsilon (ε) Pegasi.
M15 shines at magnitude +6.0 and is an easy object to locate in
binoculars. Through a telescope the outer regions can easily be
resolved into individual stars. This image of M15 is from a
drawing by Chris Lee.
There are plenty of galaxies that lie within the boundaries of Pegasus but most are
faint. The brightest of these is NGC 7331 which can be found
approximately 4 degrees north of eta (η) Pegasi. You will
need a reasonable sized telescope to locate this magnitude
+9.5 spiral galaxy, which appears as an elongated faint patch
which is slightly brighter in the centre.
Probably one of the best known galaxy groups in the sky ‘Stephan’s Quintet’ lies
6
19
Thelooking
Sky looking
East around
midnight
mid 2011 2011
The Sky
west around
midnight
mid September
The Planets
Uranus
Date
01/02
15/16
29/30
RA
Dec
Mag
00h 13m +00° 37' +5.73
00h 11m +00° 24' +5.72
00h 09m +00° 11' +5.72
Phase Dia
100% 3.7"
100% 3.7"
100% 3.7"
Rise
20:34
19:38
18:42
Transit
02:40
01:43
00:46
Set
08:46
07:48
06:50
Uranus reaches opposition on the 26th in the constellation of Pisces. Although
the planet is technically a naked-eye object in reality you will need at least a pair
of binoculars to spot it. Uranus can be found around 7 degrees south of omega (ω)
Piscium. The chart on page 8 shows the location of the planet and the chart below
shows a closer view with the field of view of 10x50 and 7x30 binoculars marked
on the chart.
Neptune
Date
01/02
15/16
29/30
RA
Dec
Mag
22h 05m -12° 18' +7.82
22h 04m -12° 26' +7.83
22h 03m -12° 33' +7.84
Phase Dia
100% 2.4"
100% 2.3"
100% 2.3"
Rise
19:33
18:37
17:42
Transit
00:33
23:37
22:40
Set
05:33
04:36
03:39
Neptune can be found in the constellation of Aquarius just under 1.5 degrees
northwest of iota (ι) Aquarii. At magnitude +7.8 Neptune should be visible with
binoculars. The chart on page 8 shows the position of Neptune at midnight on the
16th.
18
7
Ceres
Date
01/02
15/16
29/30
RA
00h 12m
00h 02m
23h 50m
Dec
-15° 46'
-17° 09'
-18° 07'
Mag
Dia
+7.23 0.65"
+7.19 0.66"
+7.22 0.65"
Rise
21:59
21:01
20:01
Transit
02:39
01:34
00:27
Set
07:20
06:06
04:54
Minor planet 1 Ceres reaches opposition on September 16th in the constellation
Cetus. At the time of opposition Ceres will be magnitude 7.2 so should be visible
in binoculars and small telescopes. Check out the area a few nights before the
date of opposition and
mark the positions of
the stars in the field of
view, then check the
field on the 16th and
the ‘star’ that has
moved will be Ceres.
The charts show the
position of Ceres at
midnight on the 16th.
8
Thelooking
Sky looking
around
midnight
mid 2011 2011
The Sky
NorthNorth
around
midnight
mid September
The Sky this Month
17
The looking
Sky looking
West around
midnight
mid 2011 2011
The Sky
East around
midnight
mid September
The Sky this Month
As we move into the autumn season, the longer nights become more noticeable,
allowing observing to take place at a more sociable time.
This month, low in the southern sky you will find a faint group of constellations
which are collectively known as ‘The Water’. The members of this group are Cetus, Capricornus, Aquarius and Pisces and all have a mythological connection
with water.
Capricornus lies furthest west and is therefore the first of the four to rise in the
evening, there is just one Messier object in Capricornus the globular cluster M30.
The cluster is visible in binoculars and small telescopes. M30 lies a little over 3
degrees east of zeta (ζ) Capricorni.
Lying to the east Capricorn is Aquarius currently home to the planet Neptune.
Aquarius is also home to three objects from Charles Messier’s catalogue plus a
couple of NGC objects you might like to try to locate. M2 is one of the finest
globular clusters visible from the UK. With an apparent magnitude of +6.4 and a
diameter of 13 arcminutes, it is an easy binocular object. M2 can be found about
4.5 degrees north of beta (β) Aquarii. M72 is another globular cluster, it is much
fainter at magnitude +9.3 and with a diameter of 6 arcseconds its much trickier
for observers with small instruments. M72 can be found just over 3 degrees southeast of epsilon (ε) Aquarii. M73 is the last of the Messier objects, it is one of the
oddities in the catalogue, it is a Y shaped asterism formed by 4 unrelated stars.
M73 can be found 1.5 degrees east of M72.
The NGC objects are both planetary nebulae, NGC7009 is known as the ‘Saturn
Nebula’ it is the easiest of the pair to locate with a small telescope. The nebula
measures 44 x 26 arcseconds and has an over magnitude of +8.3, it can be found
around 5 degrees east-southeast of epsilon (ε) Aquarii. The Helix Nebula; NGC
7293 is a more challenging object despite being listed as the brighter of the two at
magnitude +7.3. NGC 7293 lies around 1.5 degrees west of upsilon (υ) Aquarii.
Pisces lies to the northeast of Aquarius, the most obvious part of the constellation
is the asterism known as the ‘Circlet of Pisces’ which lies at its western end. The
planet Uranus can currently be found with the constellation. There is just one
Messier object in Pisces, M74. This lovely face-on spiral galaxy can be found at
the eastern end of Pisces around 1.5 degrees east-northeast of eta (η) Piscium.
M74 has an apparent magnitude of +9.4 and 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 the well known variable star Mira;
omicron (ο) Ceti. Mira is the type star of a class of long period variables whose
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9
brightness varies due to pulsation in the star. Mira is normally around magnitude
+9, however when it brightens it can reach magnitude +2. Mira is visible with
binoculars throughout its brightness range, the next maximum is due between 21st
and 30th of this month. Mira is visible to the naked eye for around 6 weeks before
and 3 months after maximum. You can find Mira at RA 02h 19.3m Dec -02° 59'.
There is just one Messier object in Cetus, M77. This face on spiral galaxy can be
found just over 1 degree southeast of delta (δ) Ceti. M77 has an apparent diameter
of 8 arcminutes and an overall magnitude of +8.9.
High in the southern sky you will find this months featured constellation Pegasus
(see pages 19 to 22)
Running in a north-easterly direction from Pegasus you will find the constellation
of Andromeda. Approximately midway along this line of stars you will find our
closest large galactic neighbour M31, the Andromeda Galaxy. M31 can be seen
with the naked-eye from a dark location and is a very easy object to locate with
binoculars. The galaxy has a couple of close neighbours of it’s own M32 and
M110. You will need a telescope to spot these two companion galaxies.
To the East of Andromeda you will find the small constellation of Triangulum,
home to another of our galactic neighbours, M33. Like M31 this is a large spiral
galaxy similar to our own Milky Way. M33 is a much more challenging object
due to it’s low surface brightness and requires dark skies and very good seeing
conditions.
If you follow the line of stars that forms the body of Andromeda it will lead you
to the constellation of Perseus. Beta (β) Persei; Algol is an Eclipsing Binary type
variable which is normally magnitude +2.1, but during an eclipse the star dims to
10
Thelooking
Sky looking
around
midnight
mid 2011 2011
The Sky
SouthSouth
around
midnight
mid September
The Sky this Month
15
The Sky looking Overhead around midnight mid September 2011
The Sky this Month
magnitude +3.4. This happens every two days, 20 hours and 49 minutes. Good
comparison stars are α Andromedae +2.06 and κ Persei +3.78. You can find the
date and time of the minima of Algol from the Sky & Telescope website at
http://www.skyandtelescope.com/observing/objects/variablestars/Minima_of_Algol.html
There are a couple of Messier object in Perseus, M34 is an open cluster which lies
approximately midway between κ Persei and γ Andromedae. M76 is a planetary
nebula which is also known as the ‘Little Dumbbell’. M76 can be found around
one degree north of phi (φ) Andromedae.
To the north of Perseus lies the ‘W’ shape of Cassiopeia. The centre star of the
‘W’, is gamma (γ) Cassiopeiae, this is a naked-eye variable, which ranges in
brightness at irregular intervals between magnitude +2.20 and +3.40. There is just
one Messier object in Cassiopeia, the open cluster M103, which can be found
close to delta (δ) Cassiopeiae.
Between Perseus and Cassiopeia, lies the famous ‘Double Cluster’ h and chi (χ)
Persei also know as NGC 884 and NCG 896. The double cluster is a lovely sight
in binoculars.
Below Perseus you will find Auriga. The bright yellow star Capella; alpha (α)
Aurigae; makes the constellation easy to identify. 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.
Around midnight the northern part sky is fairly blank, 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.
High overhead you will find one of the signature constellations of the summer
sky, Cygnus. The tail of the swan (northern end) is marked by the constellation’s
brightest star Deneb; alpha (α) Cygni, one of the trio stars that form the ‘Summer
Triangle’, the other two are Vega; α Lyrae and Altair α Aquilae. The star at the
southern end of Cygnus, marking the swan’s beak, is the well known double star
Albireo, β Cygni. The contrasting colours of yellow/orange and blue /green make
this one of the most pleasing double stars in the sky. Cygnus seems to be flying
south along the Milky Way and scanning this area of the sky with binoculars can
occupy you for many hours on a warm autumn night.
To the west of Cygnus lies the small constellation of Lyra which is home to one
of the finest examples of a planetary nebula in the sky, M57, the Ring Nebula.
M57 can be found midway between beta (β) and gamma (γ) Lyrae.
14
11
The Sky This Month
To the east of Cygnus you will find the ‘crooked house’
shaped constellation of Cepheus. At the south-eastern
01 Sep 01:00
16 Sep 00:00
30 Sep 23:00
corner lies a small 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 every 5 days 8 hours 48 minutes.
The stars epsilon +4.19 and zeta + 3.35 are good comparison stars. Delta is also a binary star, its companion
is a magnitude +6.3 blue star, the pair are separated by
41 arcseconds .
The constellation of Hercules lies in the western sky, it
is 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.
Chart Produced by
Chris Peat
http://www.heavens-above.coom
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