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Transcript
The Volume 125 No. 4 April 2016 Bulle n Monthly newsle er of the
Astronomical Society of South Australia Inc
The new Turret at Stockport was officially opened on 5 March, 2016. More on page 6 In this issue:  New Members’ Night at Stockport Observatory  The variable star L2 Puppis  The blue necklace of NGC 3081 in Hydra  A possible new meteor shower in Columba Gravita onal Wave Detec on Heralds New Era "With this discovery, we humans are embarking on a
marvelous new quest: the quest to explore the warped
side of the universe”‐ Kip Thorne. More on pages 7‐9
Registered by Australia Post Bulle n of the ASSA Inc
Print Post Approved PP 100000605 1
Visit us on the web: April 2016
www.assa.org.au In this issue: ASSA Ac vi es Details of general mee ngs, viewing nights etc ASTRONOMICAL SOCIETY of SOUTH AUSTRALIA Inc GPO Box 199, Adelaide SA 5001
The Society (ASSA) can be contacted by post to the
address above, or by e‐mail to [email protected] Membership of the Society is open to all, with the only
prerequisite being an interest in Astronomy.
Membership fees are: Full Member
Concessional Member
Subscribe e‐Bulle n only; discount
$75
$60
$20
Concession informa on and membership brochures can
be obtained from the ASSA web site at:
h p://www.assa.org.au
or by contac ng The Secretary (see contacts page).
3‐5
Telescope Clinic A successful telescope clinic was held on February 21 5
The new Stockport Turret The new turret was opened on March 5, 2016 6
Gravita onal Waves discovered 100 years a er Einstein’s predic on One of the biggest discoveries in physics The Sky this month Solar System, Comets, Variable Stars, Deep Sky 7‐9
10‐14
ASSA Contact Informa on 15
Members’ Image Gallery A gallery of members’ astrophotos 16
Sister Society rela onships with: Member Submissions Submissions for inclusion in The Bulle n are welcome
from all members; submissions may be held over for later
edi ons.
Orange County Astronomers www.ocastronomers.org
Colorado Springs Astronomical Society www.csastro.org
Central Arkansas Astronomical Society www.caasastro.org
Wherever possible, text submissions should be sent via e‐
mail or posted on CD‐ROM in almost any word processing
format and may s ll be submi ed handwri en or typed.
Your name may be withheld only if requested at the me
of submi ng. Images should be high resolu on and
uncompressed, e.g. TIFF file formats, although high
resolu on JPEGs are acceptable. Your full name and
object designa on must be provided with each image and
will be published. Equipment/exposure etc details are
welcome but op onal.
Adver sing & Classifieds Small adverts and classifieds are free for members (space
permi ng). Commercial adver sing is available at a cost
of $50.00 per quarter page per issue.
HAVE YOU GOT YOUR COPY YET? Available at the General Mee ngs, or by mail order All enquiries and submissions should be addressed to The
Editor and preferably sent by e‐mail to:
[email protected]
$25 + $4 p&h Email: [email protected] For large files (e.g. on CD) or
hardcopy items, post to:
Joe Grida Editor, The Bulle n PO Box 682, Mylor SA 5153 Contribu ons should reach the Editor no later than the 7th of each month, for publica on in the following month’s issue of The Bulle n
Cover photo: The nebula, Gum 15, imaged by Paul Haese at
Clayton Bay, SA. Takahashi FSQ106ED scope with QSI683‐8
CCD camera. Guiding ‐ QSI OAG and SBIG ST‐i. So ware ‐
MaximDL, Focusmax, Pinpoint, CCDautopilot 5. LRGB 14.3
hours. Darks, flats and biases applied. Processed in CCD stack
and Photoshop CS6
Bulle n of the ASSA Inc
2
April 2016
Ac vi es April 2016 ‐ the month at a glance
General Mee ng Wednesday, 6 April 2016 @ 8:00pm Kerr Grant Lecture Theatre 2nd Floor, Physics Blg University of Adelaide North Terrace, Adelaide Guest Speaker Professor Ray Norris Australia Telescope Na onal Facility (See speaker bio on page 4) WTF? Planning for Unexpected Discoveries with the Evolu onary Map of the Universe Australia is building a new $165m telescope in Western Australia, called
the Australian Square Kilometre Array Pathfinder (ASKAP). Two key
science projects are driving the design of ASKAP, one of which is the
Evolu onary Map of the Universe (EMU), led by Norris, which is set to
discover 70 million radio sources, compared to the 2.5 million discovered
in the en re history of radio astronomy.
Even more importantly, history shows that such large projects tend to
make unexpected discoveries (e.g. pulsars, quasars, dark energy) that we
cannot easily plan for.
But since these are probably going to be the most important discoveries
made with ASKAP, we have to be ready to make them, and have created
a project called WTF (Widefield ouTlier Finder) with the goal of
iden fying the unexpected. April 2016 Calendar Planning on going observing? Save yourself unnecessary travel and me. If the weather looks doub ul where you are, check with the following people to see if the event is s ll on (or see www.assa.org.au a er 5pm). Stockport Observatory (DO 3‐13)
Observatory 8528 2284
Lyn Grida 8391 5377
Tony Beresford 8338 1231
Heights Observatory (DO 3‐34)
Robert Bronca 8266 7504
Day Sat
Sat
Wed
Wed
Thurs
Fri
Sat
Sat
Fri
Tue
Fri
Time 8:00pm
8.00pm
7:00pm
8:00pm
7:30pm
8:00pm
8:00pm
8:00pm
8:00pm
7:30pm
7:30pm
2
2
6
6
7
8
9
9
15
26
29
Ac vity Members’ Viewing Night – Stockport
Member’s Viewing Night ‐ Riverland
Beginners’ Mee ng, Adelaide
General Mee ng, Adelaide
Whyalla Members’ Meetng
Public & Members’ Viewing – NYP
Members’ Viewing Night – Tooperang
Members’ Viewing Night – Stockport
Public Viewing Night – The Heights
ASSA Council Mee ng
Astro‐Imaging Group mee ng
Note: Times shown above and throughout this document are: 4 Oct 2015 to 3 Apr 2016 : South Australia Summer Time (UTC+10:30)
4 Apr 2016 to 2 Oct 2016 : South Australia Standard Time (UTC+ 9:30)
3 Oct 2016 to 1 Apr 2017 : South Australia Summer Time (UTC+10:30)
Whyalla Peter Mayfield 0408 410 895
Astronomy Educa on ‐ Beginners’ Talks Tooperang Wednesday, 6 April, 2016 @ 7:00pm Kerr Grant Lecture Theatre Jeff Lowrey 0429 690 610
Northern Yorke Peninsula
Tony “Hendy” Henderson 0429 352 382
Riverland Tim Vivian 0407 800 225
Bulle n of the ASSA Inc
The Sun This month we take a close look at our
local star, The Sun. How did it form?
What keeps it shining for billions of
years and what will be it’s ul mate fate
in far distant future? These and other
aspects of the Sun will be discussed.
3
April 2016
Reports and No ces Reports on recent ASSA ac vi es, and no ces of upcoming events
Have you got your copy of the ASSA 2016 Calendar yet? Guest Speaker Biography Professor Ray Norris is a Bri sh/Australian astronomer
Full of beau ful sky photos taken by ASSA members, as well as details of mee ngs, observing nights, and other special events in the 2016 calendar. with CSIRO Astronomy & Space Science who researches
how galaxies formed and evolved a er the Big Bang, and
also researches the astronomy of Aboriginal Australians.
He was educated at Cambridge
University,
and
University
of
Manchester, UK, and moved to
Australia to join CSIRO, where he
became Head of Astrophysics in
1994, and then Deputy Director of
the Australia Telescope, and Director
of the Australian Astronomy Major
Na onal Research Facility, before
returning in 2005 to ac ve research.
Special Price He currently leads an interna onal project (EMU, or
Evolu onary Map of the Universe) to image the faintest
radio galaxies in the Universe, using the new Australian SKA
Pathfinder radio‐telescope nearing comple on in Western
Australia.
Get your copy at mee ngs, or email [email protected] $15 + $5 postage/handling the Society’s telescopes or any of the other scopes that will
be available on the night.
New Members’ Night @ Stockport Observatory So if you are new to ASSA and want to experience Stockport
for the first me, then come along to a night dedicated to
you and get to know your society and the people who make
it what it is.
April 2, 2016 If you have joined ASSA for the first me or perhaps you
have been a member for a while and have never been to
Stockport, then here is your chance.
It is important to let me know if you intend to come to this
event, so we can cater for the BBQ. Send an email to
[email protected] or ring (08) 8523 0211 a/h.
A night for new members is to be held at Stockport
Observatory on the 2nd of April, which is a regular members’
Colin Hill night, so that you can meet the more experienced
observers as well as other new members.
The night will commence at 4:00pm with a tour of the
facility followed by a mini telescope clinic, so bring along
your scopes and we will help with ques ons you may have
regarding se ng up and using them.
At the BBQ that follows, you will have the opportunity to
mingle with your fellow members and get the chance to see
some of the equipment others have brought along before it
gets too dark.
Later, you will get the chance to view the heavens through
Bulle n of the ASSA Inc
4
April 2016
Reports and No ces Reports on recent ASSA ac vi es, and no ces of upcoming events
2017 ASSA Calendar Compe on Have you got your Na onal Police Check? As part of the fund raising program, the
Council has decided to again produce a
calendar for 2017. The images to populate
the calendar will come from photographs
supplied by members in a competition which will close on 30 June, 2016. The calendars will be on sale by the August
2016 Winter Star Party.
 New legisla on applies from 11 April 2015
 Impacts on all ASSA members who volunteer at ASSA
sanc oned public events
 i.e. public viewing nights, school visits, Na onal Science
Week, private booked nights
The only criteria for the images are that they must be taken
by a member and have an astronomical theme. This means
they could be planetary, solar, deep sky, wide field or it
could even be an image from an ASSA event. They can be
old images or ones that have previously been submitted in
the imaging awards. There will be only 1 image per member
included and unless at least 12 members submit, there will
be no calendar.
From the 11th April 2015, all members who a end ASSA sanc oned public events MUST have a current NPC clearance cer ficate, or equivalent clearance le er from their employer, and MUST have provided ASSA with these details. Non‐compliance is a $10,000 fine to ASSA.
Please submit your entries to me at [email protected]
including a title to be included with the image on the
calendar. Images should be no larger than 2000 pixels wide.
Full details available here:
h ps://www.assa.org.au/members/policies
Trish Ellin Honorary Life member Telescope Clinic held on February 21 at The Heights Observatory Instrument Officer, Paul Haese and Life Member, Ian
Anderson, with assistance from other members, had a look
at a number of telescopes, from small refractors to larger
equatorial mounted Schmidt telescopes.
The first telescope clinic of 2016 was held on Sunday
a ernoon, February 21 at The Heights Observatory,
Modbury.
The day was well a ended, with about 12 “pa ents”.
The next clinic will be held on
October 29, 2016 at the Tooperang
Observing Site.
Many thanks to The Heights School
for allowing the use of the
observatory classroom, and to
Andrew Cool for opening up for us
and playing the perfect host.
Far le : Paul Haese, in the background assists Andrew Collings to setup his Celestron SCT on an equatorial mount for the first me. Le : Paul Haese and Ian Anderson collimate a short focus Newtonian. Ge ng the secondary offset right proved quite a challenge.
Bulle n of the ASSA Inc
5
April 2016
Official Opening of new Stockport Turret The new turret over the Charles Todd Observatory was opened on 5 March, 2016
A er years of work and planning, the new Turret over the
Charles Todd Observatory at Stockport was officially opened
the State Minister for Regional Development and Local
Government, Mr Geoff Brock, MP, (pictured at right).
Apart for the very hot weather, which threatened to rain on
us a couple of mes, the planning put into the event by Lyn
Grida, Robert & Bonnie Jenkins and Dean Davidson ensured
that the whole a ernoon went without incident.
Credit: Stephen Scheer
In his welcome speech, President, Joe Grida, especially
thanked those members who had worked relessly to make
the Dome Replacement Project a success. Special men on to
Dean Davidson as Project Manager, Paul Haese as
Construc on Manager, and Stephen Scheer, Ian Anderson,
Lyn Grida, Robert Jenkins and Blair Lade.
Now that the construc on phase has completed, we move
into the automa on part of the project.
Credit: John Hisco
Credit: John Hisco
Credit: John Hisco
Bulle n of the ASSA Inc
6
April 2016
Astro News Interes ng news stories sourced around the world
Gravita onal waves detected 100 years a er Einstein's predic on LIGO opens new window on the universe with observa on of gravita onal waves from colliding
black holes
For the first me, scien sts have observed ripples in the
fabric of space me called gravita onal waves, arriving at
Earth from a cataclysmic event in the distant universe. This
confirms a major predic on of Albert Einstein's 1915 general
theory of rela vity and opens an unprecedented new
window onto the cosmos.
detector in Livingston recorded the event 7 milliseconds
before the detector in Hanford ‐‐ scien sts can say that the
source was located in the Southern Hemisphere.
According to general rela vity, a pair of black holes orbi ng
around each other lose energy through the emission of
gravita onal waves, causing them to gradually approach
each other over billions of years, and then much more
Gravita onal waves carry informa on about their drama c quickly in the final minutes. During the final frac on of a
origins and about the nature of gravity that cannot
second, the two black holes collide into each other at nearly
otherwise be obtained. Physicists have concluded that the
one‐half the speed of light and form a single more massive
detected gravita onal waves were produced during the final black hole, conver ng a por on of the combined black holes'
frac on of a second of the merger of two black holes to
mass to energy, according to Einstein's formula E=mc2. This
produce a single, more massive spinning black hole. This
energy is emi ed as a final strong burst of gravita onal
collision of two black holes had been predicted but never
waves. It is these gravita onal waves that LIGO has
observed.
observed.
The gravita onal waves were detected on September 14,
The existence of gravita onal waves was first demonstrated
2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both in the 1970s and 80s by Joseph Taylor, Jr., and colleagues.
of the twin Laser Interferometer Gravita onal‐wave
Taylor and Russell Hulse discovered in 1974 a binary system
Observatory (LIGO) detectors, located in Livingston,
composed of a pulsar in orbit around a neutron star. Taylor
Louisiana, and Hanford, Washington, USA. The LIGO
and Joel M. Weisberg in 1982 found that the orbit of the
Observatories are funded by the Na onal Science
pulsar was slowly shrinking over me because of the release
Founda on (NSF), and were conceived, built, and are
of energy in the form of gravita onal waves. For discovering
operated by Caltech and MIT. The discovery, accepted for
the pulsar and showing that it would make possible this
publica on in the journal Physical Review Le ers, was made par cular gravita onal wave measurement, Hulse and Taylor
by the LIGO Scien fic Collabora on (which includes the GEO were awarded the Nobel Prize in Physics in 1993.
Collabora on and the Australian Consor um for
The new LIGO discovery is the first observa on of
Interferometric Gravita onal Astronomy) and the Virgo
gravita onal waves themselves, made by measuring the ny
Collabora on using data from the two LIGO detectors.
disturbances the waves make to space and me as they pass
Based on the observed signals, LIGO scien sts es mate that through Earth.
the black holes for this event were about 29 and 36 mes
"Our observa on of gravita onal waves accomplishes an
the mass of the sun, and the event took place 1.3 billion
years ago. About 3 mes the mass of the sun was converted ambi ous goal set out over 5 decades ago to directly detect
this elusive phenomenon and be er understand the
into gravita onal waves in a frac on of a second ‐‐ with a
peak power output about 50 mes that of the whole visible universe, and, fi ngly, fulfills Einstein's legacy on the 100th
universe. By looking at the me of arrival of the signals ‐‐ the anniversary of his general theory of rela vity," says Caltech's
David H. Reitze, execu ve director of
the LIGO Laboratory.
The discovery was made possible by
the enhanced capabili es of Advanced
LIGO, a major upgrade that increases
Le : Two black holes coalesce in a s ll from a numerical simula on. Such predic ons, based on Einstein's theory of general rela vity match exactly what LIGO scien sts discovered on September 14, 2015. MPI for Gravitaonal Physics / Werner Benger / ZIB / Louisiana State University Bulle n of the ASSA Inc
7
April 2016
Astro News Interes ng news stories sourced around the world
the sensi vity of the instruments compared to the first
genera on LIGO detectors, enabling a large increase in the
volume of the universe probed ‐‐ and the discovery of
gravita onal waves during its first observa on run. The US
Na onal Science Founda on leads in financial support for
Advanced LIGO. Funding organiza ons in Germany (Max
Planck Society), the U.K. (Science and Technology Facili es
Council, STFC) and Australia (Australian Research Council)
also have made significant commitments to the project.
Several of the key technologies that made Advanced LIGO so
much more sensi ve have been developed and tested by the
German UK GEO collabora on. Significant computer
resources have been contributed by the AEI Hannover Atlas
Cluster, the LIGO Laboratory, Syracuse University, and the
University of Wisconsin‐ Milwaukee. Several universi es
designed, built, and tested key components for Advanced
LIGO: The Australian Na onal University, the University of
Adelaide, the University of Florida, Stanford University,
Columbia University of the City of New York, and Louisiana
State University.
"In 1992, when LIGO's ini al funding was approved, it
represented the biggest investment the NSF had ever
made," says France Córdova, NSF director. "It was a big risk.
But the Na onal Science Founda on is the agency that takes
these kinds of risks. We support fundamental science and
engineering at a point in the road to discovery where that
path is anything but clear. We fund trailblazers. It's why the
U.S. con nues to be a global leader in advancing
knowledge."
LIGO research is carried out by the LIGO Scien fic
Collabora on (LSC), a group of more than 1000 scien sts
from universi es around the United States and in 14 other
countries. More than 90 universi es and research ins tutes
in the LSC develop detector technology and analyze data;
approximately 250 students are strong contribu ng
members of the collabora on. The LSC detector network
includes the LIGO interferometers and the GEO600 detector.
The GEO team includes scien sts at the Max Planck Ins tute
for Gravita onal Physics (Albert Einstein Ins tute, AEI),
Leibniz Universität Hannover, along with partners at the
University of Glasgow, Cardiff University, the University of
Birmingham, other universi es in the United Kingdom, and
the University of the Balearic Islands in Spain.
"This detec on is the beginning of a new era: The field of
gravita onal wave astronomy is now a reality," says Gabriela
González, LSC spokesperson and professor of physics and
astronomy at Louisiana State University.
LIGO was originally proposed as a means of detec ng these
gravita onal waves in the 1980s by Rainer Weiss, professor
of physics, emeritus, from MIT; Kip Thorne, Caltech's Richard
P. Feynman Professor of Theore cal Physics, emeritus; and
Ronald Drever, professor of physics, emeritus, also from
Caltech.
"The descrip on of this observa on is beau fully described
in the Einstein theory of general rela vity formulated 100
years ago and comprises the first test of the theory in strong
gravita on. It would have been wonderful to watch
Einstein's face had we been able to tell him," says Weiss.
"With this discovery, we humans are embarking on a
marvelous new quest: the quest to explore the warped side
of the universe ‐‐ objects and phenomena that are made
from warped space me. Colliding black holes and
gravita onal waves are our first beau ful examples," says
Thorne.
Above: The plots show signals of gravita onal waves detected by the twin LIGO observatories. The signals came from two merging black holes 1.3 billion light-years away. The top two plots show data received at each detector, along with waveforms predicted by general rela vity. The Xaxis plots me, the Y-axis strain--the frac onal amount by which distances are distorted. The LIGO data match the predic ons very closely. The final plot compares data from both facili es, confirming the detec on. Credit: LIGO
Bulle n of the ASSA Inc
Virgo research is carried out by the Virgo Collabora on,
consis ng of more than 250 physicists and engineers
belonging to 19 different European research groups: 6 from
Centre Na onal de la Recherche Scien fique (CNRS) in
France; 8 from the Is tuto Nazionale di Fisica Nucleare
(INFN) in Italy; 2 in The Netherlands with Nikhef; the Wigner
RCP in Hungary; the POLGRAW group in Poland; and the
European Gravita onal Observatory (EGO), the laboratory
hos ng the Virgo detector near Pisa in Italy.
8
April 2016
Astro News Interes ng news stories sourced around the world
Fulvio Ricci, Virgo Spokesperson, notes that, "This is a
significant milestone for physics, but more importantly
merely the start of many new and exci ng astrophysical
discoveries to come with LIGO and Virgo."
Bruce Allen, managing director of the Max Planck Ins tute
for Gravita onal Physics (Albert Einstein Ins tute), adds,
"Einstein thought gravita onal waves were too weak to
detect, and didn't believe in black holes. But I don't think
he'd have minded being wrong!"
"The Advanced LIGO detectors are a tour de force of science
and technology, made possible by a truly excep onal
interna onal team of technicians, engineers, and scien sts,"
says David Shoemaker of MIT, the project leader for
Advanced LIGO. "We are very proud that we finished this
NSF‐funded project on me and on budget."
At each observatory, the two‐and‐a‐half‐mile (4‐km) long L‐
shaped LIGO interferometer uses laser light split into two
beams that travel back and forth down the arms (four‐foot
diameter tubes kept under a near‐perfect vacuum). The
beams are used to monitor the distance between mirrors
precisely posi oned at the ends of the arms. According to
Einstein's theory, the distance between the mirrors will
change by an infinitesimal amount when a gravita onal
wave passes by the detector. A change in the lengths of the
arms smaller than one‐ten‐thousandth the diameter of a
proton (10‐19 meter) can be detected.
Above: In this schema c of LIGO, a beamspli er sends light along two paths perpendicular to each other. Each beam bounces between two mirrors, one of which allows a frac on of the light through. When the two transmi ed beams meet and interfere, they’ll cancel each other out — if the length of the path they’ve each traveled has remained constant. But if a gravita onal wave passes through, it’ll warp space me and change that distance, crea ng an interference pa ern. S&T: Leah Tiscione
"To make this fantas c milestone possible took a global
collabora on of scien sts ‐‐ laser and suspension technology
developed for our GEO600 detector was used to help make
Advanced LIGO the most sophis cated gravita onal wave
detector ever created," says Sheila Rowan, professor of
physics and astronomy at the University of Glasgow.
Independent and widely separated observatories are
necessary to determine the direc on of the event causing
the gravita onal waves, and also to verify that the signals
come from space and are not from some other local
phenomenon. Toward this end, the LIGO Laboratory is
working closely with scien sts in India to establish a third
Advanced LIGO detector on the Indian subcon nent.
Awai ng approval by the government of India, it could be
opera onal early in the next decade. The addi onal detector
will greatly improve the ability of the global detector
network to localize gravita onal‐wave sources.
"Hopefully this first observa on will accelerate the
construc on of a global network of detectors to enable
accurate source loca on in the era of mul ‐messenger
astronomy," says David McClelland, professor of physics and
director of the Centre for Gravita onal Physics at the
Australian Na onal University.
Above: LIGO didn't watch the whole many-year-long dance of the black hole duo, but it did see the last few cycles of the death spiral, the merger itself, and the "ringing" effect as the merged black hole se led into its new form. B. P. Abbo & others, "Observa on of Gravita onal Waves from a Binary Black Hole", Physical Review Le ers
Story Source: LIGO Laboratory. "LIGO opens new window on the universe with observa on of gravita onal waves from colliding black holes." ScienceDaily. ScienceDaily, 11 February 2016. <www.sciencedaily.com/
releases/2016/02/160211103935.htm>.
Bulle n of the ASSA Inc
9
April 2016
Solar System Highlights by Joe Grida
The major planets during April 2016
Mercury makes a poor showing in the western evening
twilight sky this month. At the start of the month, the
diminu ve planet shines brightly at ‐1.5 mag, and displays a
disk of 5.6”. It reaches greatest elonga on east on the 18th
April, by which me it has dimmed to magnitude 0, but its
disk has grown to 7.5”. By April 25th, it has dimmed to mag
+1.5, and ge ng lost in the glare of the Sun as it heads
towards inferior conjunc on.
Having reached opposi on of March 8th, the largest of the
planets commands a en on all night. Shining like a celes al
lighthouse at mag ‐2.4, Jupiter shows a massive face of 43.6”
at the beginning of the month, as it hovers above the hind
legs of Leo, the lion. On the 8th of April, it passes just 7’ from
4.7 magnitude Chi Leonis. Of course, its only a line of sight
view, as Chi is 94.5 light years away! Then, just a er
midnight on the evening of April 12th, Jupiter occults the 7th
magnitude star HD95848. See the graphic below, generated
Bid farewell to Venus, which has been domina ng the
with Cartes du Ciel so ware. The star is at the le limb of
morning sky for so long. It remain hidden from our view un l Jupiter. The shadow of Europa is also visible on Jupiter’s disk.
mid‐July, when it then reappears in our evening western sky.
Saturn, comfortable in its home in Ophiuchus, contrasts its
Get ready for Mars. It’ going to put up a great show over the golden‐white colour with that of orange‐gold Mars and
next few months. It starts the month in Scorpius, but crosses Antares. These 3 bodies will form striking triangular shapes
the border into Ophiuchus just a couple of days later. On the throughout Autumn.
night of the 2nd of April, you can find it 5o to the north‐east of
Antares, albeit 2 magnitudes brighter. Mid‐month, Mars
Uranus is in conjunc on with the Sun this month, and
displays a face of 13.8” from a distance of 102 million
therefore not observable, whilst Neptune, in Aquarius, rises
kilometres. By the end of April, the apparent diameter will
around 3am in mid‐April.
have grown to 15.9” as the distance decreases to 88 million
kilometres. At opposi on, on May 22nd, the disk will be
18.6”. Bring on the clear skies! I’m sure there will be lots of
Mars par es.
Diary of phenomena April 2016 d
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7
7
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10
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h(UT)
2 Pluto 3.3oS of Moon
23 Neptune 1.8oS of Moon
7 Venus 0.6oS of Moon
11 NEW MOON
14 Uranus 1.9oN of Moon
17 Moon at perigee
13 Mercury 5.0oN of Moon
21 Uranus at conjunction
22 Aldebaran 0.4oS of Moon
12 Moon furthest North (18.3o)
4 FIRST QUARTER
23 Regulus 2.4oN of Moon
1 Mars stationary
3 Jupiter 2.1oN of Moon
12 Mercury greatest elong E(20o)
12 Spica 4.8oS of Moon
15 Moon at apogee
5 FULL MOON
20 Venus 0.8oS of Uranus
5 Mars 4.8oS of Moon
19 Saturn 3.3oS of Moon
4 Moon furthest South (-18.4o)
9 Pluto 3.1oS of Moon
3 LAST QUARTER
Bulle n of the ASSA Inc
Moon Phases ‐ April 2016 10
April 2016
Southern Hemisphere Comets by Michael Ma azzo
A roundup of bright and telescopic comets visible for southern hemisphere observers
252P LINEAR, P/2016 BA14 PANSTARRS and a possible new meteor shower in Columba 252P LINEAR is a short period comet (5.3 year orbit) which The two comets are obviously related, with 2016 BA14 a
small fragment breaking off the larger 252P centuries ago.
This opened up the prospect of a poten al meteor shower
during March, as there is likely to be a debris field near the
Earth's vicinity.
had an excep onally close passage to the Earth, only 13.9
Lunar distances on March 21. This is one of the closest
approaches of a comet to the Earth on record.
Despite this, the intrinsically faint comet was only expected
to reach a maximum magnitude of 10!
On February 10th, NASA's "fireball" network detected a
cluster of very slow, low inclina on meteors that appeared
to be linked to the comets.
In late January, the PANSTARRS survey team in Hawaii
discovered an asteroid, 2016 BA14, the orbit of which has
been shown to be remarkably similar to 252P.
Southern Meteor observers should be on the lookout for any
poten al ac vity, arising from the constella on of Columba
or thereabouts, during evening skies.
On closer inspec on, the asteroid had a small hint of a tail
and was rebadged comet P/2016 BA14 PANSTARRS. In fact,
2016 BA14 passed the Earth even closer than 252P, 9.2 lunar The meteors will be recognizable by their very slow speed.
distances on March 22!
Above: Comets 252P/LINEAR and P/2016 BA14 (PANSTARRS) imaged on March 2nd 2016 by Jose J. Chambo using a remotely controlled Takahashi FSQ ED 106mm f/5.0 telescope & SBIG STL-11000M CCD camera. The 2 comets, separated by 1.5o seem very different; 252P with an enormous and greenish gassy envelope, while 2016-BA14 is just a ny mote between stars. Nevertheless, the similarity of their orbits reveal that they really are fragments of a unique comet. Between the comets can be viewed the spiral galaxy NGC 2090.
Bulle n of the ASSA Inc
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April 2016
Southern Hemisphere Comets by Michael Ma azzo
A roundup of bright and telescopic comets visible for southern hemisphere observers
The shower is predicted to last for quite some me, February
through to May, due to the low inclina on of the shower
Viewing circumstances won't be ideal un l moonlight
orbit.
disappears around May 5th. By then the comet has
brightened half a magnitude.
I'll post an update on what eventuates in next month’s issue
of The Bulle n.
VOLANTIDS C/2013 X1 PANSTARRS Will be closest to the Sun this month on April 20th at a
distance of 1.31AU. Despite the rela vely large perihelion
distance, it has the poten al to reach faint naked eye
brightness when it approaches Earth to within 0.64AU on
June 21st.
At this me, it will be well situated for southern observers.
Around early January 2016, the comet underwent a small
outburst, when it was seen to rise 1.5 magnitudes in a 24hr
period.
The comet is emerging from solar conjunc on and will
reappear in morning skies around mid April. Assuming there
were no further outbursts, you will find the 7th magnitude
comet in the constella on of Pisces, low in the east before
dawn.
Surprise meteor shower on new Years Eve. P Jenniskens
reports on CBET 4261 that the New Zealand video based
meteor survey detected 21 meteors of naked eye brightness
arising from the southern constella on of Volans. More
informa on at:
h p://www.cbat.eps.harvard.edu/iau/cbet/004200/
CBET004261.txt
The parent body is that of a Jupiter family comet, as yet
undiscovered, and now poten ally hazardous to the Earth!
Check my Southern Comets website for more up to date
informa on:
h p://members.westnet.com.au/mma /sc.htm
It climbs steadily higher each morning, but moonlight starts
to interfere from April 21.
Bulle n of the ASSA Inc
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April 2016
Variable Vagaries by David Benn This regular column will cover happenings in the ever‐changing world of variable stars.
One of the pulsa ng variable subclasses I men oned in the
January bulle n is semi-regular or SR. As the name suggests,
variables of this kind exhibit regularity that is some mes
interrupted. Semi‐regulars are named for their behaviour
rather than their prototype star. They are giants or super‐
giants of late or intermediate spectral class. SR periods range
from 20 days to more than 2000 days and amplitudes are
usually 1 to 2 magnitudes in V, but specialisa ons of SR —
SRA, SRB, SRC, SRD, SRS — modify these ranges.
I want to highlight one of these specialisa ons: SRB (and no,
it’s not short for solid rocket booster; rather, the more
prosaic: semi-regular type B). SRB stars show poorly defined
periodicity with mean cycles in the range 20 to 2300 days. L2
Puppis (or just L2 Pup) is one such star. It has a period of
around 140 days and a magnitude range of about 2.5 to 8. Its
light curve for the last few years is shown below.
Looking back to around the me Einstein published his
General Theory of Rela vity (1915) to the present day, the
varia on in amplitude and period over me is obvious, as
shown by the following light curve, consis ng of almost
28,000 observa ons (see top right) A second plot of change
in period over me (using a Weighted Wavelet Z‐Transform I
carried out with VStar) highlights the meandering period
over the last hundred years (see right).
Andrew Pearce of Variable Stars South is currently
encouraging visual and DSLR observa ons of this star. In the
few years preceding mid‐2015 (see cross hairs in first light
curve), L2 Pup had a magnitude range of 6 to 8.5 and a
period of around 136 days. It remains to be seen what the
new period will be. Since then, the magnitude range has
reduced. By inspec on of the light curve, similar behaviour
can be seen to have occurred in the 1920s and 1930s.
From a VSS ar cle by Andrew (updated March 6): “Recent
observa ons with the VLT have revealed that L2 Pup is
actually a close binary and surrounded by a circumstellar
dust disk seen almost edge on from the Earth.” He remarks
that varia on in the past has been explained in terms of
variable density in a dust disc surrounding the star” and goes
on to say that “…it appears that the current event may be
caused by a very dense sec on of the dust disc which is
almost completely masking the stellar pulsa on. Long term
varia ons in the light curve can then provide us with a
density map of the dust in the disc.”
A paper submi ed to arXiv.org on February 16 (revised on
March 1) by Zhuo Chen et al, Three-dimensional hydrodynamic simula ons of L2 Puppis proposes that L2 Pup
may be in the process of forming a bi‐polar planetary nebula.
The authors say: “As one of nearest and brightest AGB stars,
and due to its status as a binary, L2 Puppis serves as a
benchmark object for studying the late‐
stages of stellar evolu on.”
We can talk about other SR subclasses in
future instalments. In the mean me, see
the AAVSO Variable Star Index (VSX)
variability types page for more about the
SR subclasses SRA, SRB, SRC, SRD, and
SRS.
In the last month I’ve only had me to
make visual es mates of eta Carinae.
Over the next few weeks, I intend to do
photometry for L2 Puppis, R and eta
Carinae, and possibly the mid‐March
eclipse of V777 Sagi arii.
Bulle n of the ASSA Inc
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April 2016
Alone in the dark A guide to observing faint fuzzies in our night sky
by Joe Grida
The blue necklace of NGC 3081 in Hydra Hydra, the biggest constella on in the sky, is filled with many
wonderful extragalac c objects. Galaxies abound within its
borders, and one of the most interes ng objects is the face
on spiral galaxy, NGC 3081.
These rings form in par cular loca ons known as
resonances, where gravita onal effects throughout a galaxy
cause gas to pile up and accumulate in certain posi ons.
These can be caused by the presence of a "bar" within the
galaxy, as with NGC 3081, or by interac ons with other
NGC 3081 was discovered by Sir William Herschel on
nearby objects. It is not unusual for rings like this to be seen
December 21, 1786 and recorded it as "very faint, small, li le in barred galaxies, as the bars are very effec ve at gathering
brighter in the middle. South of a triangle of unequal small
gas into these resonance regions, causing pile‐ups which
stars." Of course, he was already famous a er his discovery lead to ac ve and very well‐organised star forma on.
of the planet Uranus in March 1781. He was the first
Located at R.A.: 09 59 29.5, Dec: ‐22 49 35, this mag 12
President of the Royal Astronomical Society, when it was
galaxy is not far from the border with Antlia. It is fairly small,
founded in 1820.
at 2.1’ x 1.6’, so you want the light gathering ability of a large
scope, as well as a high magnifica on, say 300x + to tease
NGC 3081 is located over 86 million light‐years from us. It is
out as much detail as you can.
known as a type II Seyfert galaxy, characterised by its
dazzling ac ve nucleus.
When viewed through my 16” Dob at 208x it was very
NGC 3081 is seen in the Hubble photo below, nearly face‐on. sharply concentrated with a very bright, roundish nucleus.
Compared to other spiral galaxies, it looks a li le different.
The inner halo was visible, but the dis nc ve blue necklace
The galaxy's barred spiral centre is surrounded by a bright
shown in the Hubble image was not seen. I was observing
loop known as a resonance ring.
from Mount Barker, with a DeepSky filter, so I can
This ring is full of bright clusters and bursts of new star
understand the difficulty.
forma on, and frames the supermassive black hole thought
to be lurking within NGC 3081 — which glows brightly as it
This will be a target for me in the Flinders Ranges during one
hungrily gobbles up infalling material.
of our camps.
Above: The galaxy NGC 3081 in Hydra, as imaged by the Hubble Space Telescope. The bright nucleus is home to a very hungry supermassive black hole. Bulle n of the ASSA Inc
14
April 2016
Contact informa on Here’s how to contact various members of Council, Regional Co‐ordinators and SIG’s
2016 COUNCIL President & Public Officer Vice President Secretary Assistant Secretary Treasurer Editor Publicity Officer Observatories Director Technical Informa on Officer Instrument Officer Librarian Beginners’ Councillor Councillors Joe Grida
Paul Curnow
Peter McKeough
Rob Jenkins
Lyne e O’Born
Joe Grida
Paul Curnow
Lyn Grida
Dr Tony Beresford
Paul Haese
Susan Baker
Colin Hill
Greg Weaver
David Benne
Phil Stephen
Philip Pudney
Stephen Scheer
(08) 8391 5377
0402 079 578
0418 688 654
(08) 8258 0204
(08) 8268 3352
(08) 8391 5377
0402 079 578
(08) 8391 5377
(08) 8338 1231
0408 808 390
0415 655 378
(08) 8523 0211
(08) 8293 2341
0419 419 552
(08) 8356 6936
0418 818 839
0423 702 975
[email protected]
vice‐[email protected]
[email protected]
assistant‐[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
[email protected]
david.benne @assa.org.au
[email protected]
[email protected]
[email protected]
Honorary Life Members: Ian Anderson, Ian Bedford, Dr Tony Beresford, Trish Ellin, Joe Grida, Lyn Grida, Colin Hill, Blair
Lade, Paul Rogers, Michael Williams.
Note: To address all members of the ASSA Council, send email to: [email protected] REGIONAL GROUPS Whyalla The group meets on the first
Thursday of the month.
Coordinator: Peter Mayfield
Ph: 0408 410 895
Email: [email protected] SPECIAL INTEREST GROUPS Astro Imaging Neil Walter
0418 805 182
Variable Stars David Benn
0407 261163
Radio Astronomy Peter Gray
0418 829 632
Light Pollu on Mar n Lewicki
0413 494 366
OTHER CONTACTS Aboriginal & Ethno Astronomy Paul Curnow
0402 079 578
Northern Yorke Peninsula Comets & Meteors Michael Ma azzo
0420 959 664
Planetarium Paul Curnow
0402 079 578
Society Historian Terry Wardle [email protected] The NYP’pers hold combined
members’ and public viewing
nights monthly.
Coordinator: Tony Henderson
Ph: 0429 352 382
Email: [email protected] Riverland The Riverland group hold
combined members’ and public
viewing nights monthly.
Co‐ordinator: Tim Vivian
Ph: 0417 800 225
Email: [email protected] Bulle n of the ASSA Inc
Schools Viewing Nights Coordinator TBA
Webmaster Phillip Pudney
0408 818 839
[email protected] Awards Commi ee [email protected] South Australia Telescope (36”) [email protected] Na onal Police Check Coordinator Paul Rogers
[email protected]
15
08 8263 7666 April 2016
Members’ Gallery Highligh ng members’ astrophotos
Above: The Helix Nebula, NGC7293, in Aquarius. Imaged by Kym Anthony, at the November 2015 VicSouth Desert Spring
Star Party, using an Orion ED80T telescope, Full modded Canon 450D, 15 x 7 minutes ISO400 exposures, Darks & Flats.
Below: A crop of the Eta Carina Nebula, NGC 3372, by Jarrod Koh. This single frame image was taken at Monarto
Conserva on Park, on 7 January 2016. Nikon DSLR, ISO 1600, 30 seconds. Nikon 400mm/F2.8 on an Astrotrac tracking
mount.
Bulle n of the ASSA Inc
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April 2016