RASNZ E-Newsletter

RASNZ E-Newsletter

From Alan Gilmore RASNZ

=================================================. Royal Astronomical Society of
New Zealand
Email Newsletter Number 85, 23 September 2007
=================================================Affiliated Societies are welcome to
reproduce any item in this email
newsletter or on the RASNZ website
in their own newsletters provided an acknowledgement of the source is
also included.

1. Total Lunar Eclipse
2. 2008 RASNZ Conference
3. The Solar System in October
4. Stargazers Getaway Summary
5. Waharua Report
6. Harley Wood Winter School Report
7. Astrophotography Camp 2007
8. Council Nominations Sought
9. 2007 AGM Minutes Available
10. Stardate North Island 2008
11. Stardate South Island 2008
12. NZ IYA Website - Biographies Needed
13. Comet Gilmore P/2007 Q2
14. K-T Extinctions Due to Asteroid Collision Debris?
15. Giant Hole in the Universe
16. Nearest Neutron Star?
17. Stars v. Sand Recounted
18. How to Join the RASNZ
19. The Biggest Dob in the World

==============================================================1. Total Lunar Eclipse
The total lunar eclipse was widely observed in New Zealand with numerous
pictures displayed to the nzastronomers group. The moon went as dark as
expected. In rural locations the reappearance of the Milky Way and faint
stars was dramatic.

The Editor, with thick eyeglasses removed, estimated the eclipsed moon's
total magnitude at around magnitude -1, a bit fainter than Jupiter. Thus
the eclipsed moon was around 1/30 000th of the full moon's brightness; an
estimate confirmed by Fraser Gunn from the ratios of photographic
exposures required.

==============================================================2. 2008 RASNZ
The Conference Hosts, Canterbury Astronomical Society and the RASNZ
Standing Conference Committee are now planning for the 2008 RASNZ
Conference and we look forward to seeing many of you at Lake Tekapo next
year. If you have a 2008 Diary or Planner please note the dates now 23 -
25 May. This is a few weeks earlier in the year than recent conferences
and it will be necessary to book early. Registrations forms will be posted
on the RASNZ website
http://www.rasnz.org.nz/ as soon as they are
available. The conference will be focussing on the dark skies of the
region and the proposal to form a Dark Sky Heritage Park of the Mackenzie

Special conference workshop - CCD Photometry
A special workshop will be held on Friday 23rd May 2008 for those
interested in CCD Photometry. This workshop introduces you to the
principles and practice of CCD photometry as applied to brightness
measurements of variable stars and asteroids. The technique to be studied
is unfiltered differential time-series photometry, the simplest of all CCD
photometric methods yet the one most widely used by amateurs. For further
details go to the RASNZ website
http://www.rasnz.org.nz/ and follow the
2008Conference link. The workshop is strictly limited to 20 persons so
you are advised to pre-register your interested in this workshop by
sending an email to Pauline Loader at
varstar@rasnz.org.nz to have a place
reserved for you.

Call for Papers
Now is the time to start thinking about your presentation at the RASNZ
Conference. We would particularly like to hear from you if you have
worked or observed at Mt John but presentations from others will also be
welcome. Conference paper submission forms are available on the RASNZ
website. Send your submission to

-- Pauline Loader

==============================================================3. The Solar System in
The usual notes on the visibility of the Planets for October 2007 have
been placed on the RASNZ web site:
http://www.rasnz.org.nz/SolarSys/Oct_07.htm. Notes for November 2007 will
be in place in a few days.


MERCURY will start the month readily visible as the sky darkens following
sunset. On October 1 the planet at magnitude 0.1 will be about 16 degrees
up and to the west, 45 minutes after sunset.

Mercury will be in Virgo moving towards Libra. On October 12 the planet
will be on the border of the constellation, but on the 12th it is also
stationary after which it will move back into Virgo and towards the Sun.
As a result it will rapidly get lower from night to night in the evening
sky and rapidly get fainter. On the 15th of October it will be about 10
degrees up 45 minutes after sunset at magnitude 1.3. 2 nights later the
corresponding figures are 7 degrees and magnitude 1.9 and by October 19,
1.5 degrees and magnitude 2.7

The Moon, a very thin crescent less than 4% lit, will be 2.8 degrees
directly above Mercury on October 13.

Mercury reaches inferior conjunction on October 24 after which it will
move into the morning sky.

JUPITER is the only other naked eye planet visible in the evening,
although by the end of the month it will set shortly before midnight
(NZDT). As a result the planet will be low later in the evening. Jupiter
remains in Ophiuchus in October. Its distance from Antares will slowly
increase during the month.

VENUS will be a brilliant but rather low object in the dawn sky throughout
October. It will rise a little under 2 hours before the Sun and be nearly
round to the northeast shortly before sunrise. It reaches its greatest
elongation east of the Sun on October 29.

The planet will be in Leo and move past the brightest star, Regulus. The
two are closest on October 8 and 9 when Venus will be less than 3degrees
above the star. The crescent waning Moon also joins them on the morning of
October 8, some 7 degrees to the left of Venus and Regulus. After passing
Regulus, Venus will move towards Saturn. The two are closest on the
morning of October 14, when Venus will be 3 degrees above Saturn.

Venus reaches its maximum elongation, 46 degrees west of the Sun on
October 29, NZDT.

MARS will continue to be a morning object throughout October, rising about
2.30 am NZDT at the beginning of the month, and just over an hour earlier
at the end. It will brighten a little from magnitude -0.1 to -0.6. Half an
hour before sunrise, Mars will be to the north and fairly low, with an
altitude ranging from about 30° at Auckland to 20°at Invercargill.
At the end of September Mars moved from Taurus into Gemini. Throughout
October it will be moving to the east through the latter constellation.
The Moon will pass Mars twice during the month. On the morning of October
3 the 58% lit Moon will be 6° below the planet. On October 31 the Moon,
73% lit, will be 4.5° below it.

SATURN will be a low object to the east and difficult to see in the dawn
sky early in the month. But finding the planet should be made easier as
Venus and Saturn close in on one another. On the morning of October 13
Venus will be just over 3° above Saturn with the star Regulus (magnitude
1.4) some 4° to the left of Venus. Over the next few mornings, Venus will
move to the right of Saturn and gradually get a little lower compared to
Saturn, until on the morning of October 22 will be about level and just
over 6° apart.

Earlier in the month, on the morning of October 8, the thin crescent Moon
will be only 1.5° to the right of Saturn, but the two will be very low
about half way between northeast and east 45 minutes before sunrise.
By the end of October, Saturn will rise more than 2 hours before the Sun,
so will become a little easier to find. It will be about 15° up 40 minutes
before sunrise.


Both Uranus and Neptune set well after midnight throughout October and so
are well placed in the evening sky. Uranus is in Aquarius between phi and
lambda, slowly moving towards the latter. Neptune is in Capricornus,
just under 2 degrees from iota, magnitude 4.3


(1) Ceres will be a late evening object, rising about 11 pm NZDT on
October 1 and 8:40 pm on the 31st. During the month the asteroid
brightens from magnitude 8.0 to 7.4, so will become the brightest asteroid
visible during October. Ceres starts the month in Taurus and will be
less than half a degree south of omicron Tau, magnitude 3.6, on October
19. It moves on into Cetus on the 21st.

(4) Vesta starts October in Ophiuchus at magnitude 7.6, some 24' from the
magnitude 4.16 star 44 Oph. On October 4 it passes 1.24' north of the
4.80 star 51 Oph. This is so close the relative movement of Vesta should
be detectable within a few minutes. The asteroid moves on into
Sagittarius on October 11 and ends the month at magnitude 7.8. By then it
will set just after 1 am NZDT.

-- Brian Loader

==============================================================4. Stargazers Getaway
Late afternoon, Friday 7th September saw the first arrivals at Camp Iona,
Herbert, a few kilometres south of Oamaru. Some set up telescopes on the
grassed areas before sunset, hoping that the remaining clouds would
disperse for a fine evening. After tea Phil Barker welcomed those present
and discussed the programme for the weekend. As by now the clouds had
completely dispersed most opted for a fine evening's viewing of the
magnificent dark skies, while a few not so hardy souls chatted round the
log file in the main hall.

Saturday morning after a late breakfast we gathered in the hall. Euan
Mason started the morning's talks by answering the question "Why do I have
so many eyepieces?" Euan discussed a number of different types of
eyepieces, their characteristics and features. The type of eyepiece to
use depends on many factors including not only the telescope and intended
target but factors such as eye relief, exit pupil, coatings and the size
of one's wallet all needing to be taken into account when choosing an

Paul Rodmell then gave us an overview of his trip to Egypt, Turkey and
Europe last year. This included viewing the Solar Eclipse and also
visiting historic places in Turkey and Europe. As Paul had also visited
the USA he treated us to shots of the Viking Lander at the Kennedy Space
centre and Discovery being moved to the launching pad.

After lunch was free time. Some took the opportunity to visit the vintage
farm machinery at Maheno a few kilometres away while others visited
friends and relatives in Dunedin.

Saturday evening we again assembled in the hall. To start with we observed
a few moments of silence to pay our respects for George Patterson who died
a few months ago. A few people remembered how he had started running
Stardate South Island. He had been a familiar figure at the Herbert
weekends for a number of years.

A number of people took the opportunity of a "soapbox" session to give
brief talks on items of interest. Robert Rea demonstrated the Seeker
Software he had recently acquired as his Murray Geddes prize. Pauline
Loader mentioned the 2008 RASNZ conference to be held in Tekapo Village.
A CCD Photometry workshop will be held during the day prior to the start
of the conference. Marilyn Head spoke about the International Year of
Astronomy in 2009. She is collecting information about NZ astronomers,
past and present, amateur and professional to go on the New Zealand IYA
website. Malcolm Flain talked about what was up or down, left or
right. Star charts can be very confusing, particularly for beginners.

As, by now, the sky had cleared again about half those present opted to
make the most of the good conditions to put in some more stargazing. The
remainder stayed in the warm to hear Steve Butler's presentation on light
pollution. Steve has added various quotes from both our Prime Minister
and policy documents showing that some bodies are beginning to take into
account the need for appropriate lighting and consider the effects of
excessive artificial light on the environment.

On Sunday morning after another late breakfast we again gathered in the
hall, this time to hear Brian Loader present and demonstrate various
software programmes for the Occult. This was a follow up to the
Occultation Symposium following this year's RASNZ conference. Brian
demonstrated some of the capabilities of Dave Herald's "Occult"
program. He also showed LI Movie to analyse and produce graph of a minor
planet occultation from a video of the event. Finally he showed how
Hristo Pavlov's Occult Watcher can be used to ensure observers receive
updated information about forthcoming events and where intending observers
are located.

After all this technology Lyn Taylor gave us a talk about the work of
Jeremiah Horrocks, the father of British Astronomy. Horrocks lived on the
17th century and observed the Transit of Venus in 1639. While at Cambridge
he became familiar with the works of Kepler and Tycho Brahe. Using his own
observations of the Sun he was able to determine that the astronomical
table produce by Lansberg were not accurate and correctly predicted the
transit. Horrocks also determined that the Moon's orbit is elliptical and
suggested that the Sun as well as the earth influenced the moons orbit.

At the end of the morning thanks were given to the organisers, Phil Barker
and Ross Dickie for organising another very enjoyable weekend.

-- Pauline Loader

==============================================================5. Waharua Report
Dave Brock reported briefly to nzastronomers on the gathering at
Auckland's dark sky site:

Well, the Waharau weekend [September 7-9] was not quite as good, weather-
wise, as the Herbert one it seems, but Friday night was clear for a few
hours and then the clouds came and went continuously until I finally
called it quits around 4 a.m. Saturday was overcast and with no obvious
signs of clearing a lot of people left late afternoon.

========================================================6. Harley Wood Winter School
Robyn Woollands, University Canterbury astronomy MSc student, reports on
her attendance at the Harely Wood Winter School:

The Harley Wood Winter School (HWWS) and the Astronomical Society of
Australia (ASA) meeting were hosted by Sydney's Macquarie University, and
took place from 28th June to 5th July 2007. The HWWS is a series of
lectures for honours and postgraduate astronomy and astrophysics students,
which preceeds the annual ASA meeting. This year the HWWS was held at
Potters Hotel and Brewery in Cessnock, Hunter Valley. The theme was "Ideas
to Answers", and focussed on astronomical tools and techniques. 59
participants attended the two-day conference which consisted of several
interesting lectures and discussion sessions. Some of the social events
included a pre-conference trivia night and dinner, as well as an observing

The ASA meeting was held on the Macquarie University campus and started
with a pre-conference drinks and registration on the Sunday evening which
gave the 155 participants a chance to get to know each other and discuss
ideas. Over the four days, 90 talks were presented and 63 posters were up
on display. The conference dinner and the presentation of prizes were held
on the Wednesday night at Curzon Hall. This is a magnificent 19th Century
Manor, set on three acres of manicured gardens.

Attending the HWWS and the ASA meeting was an excellent opportunity to
meet new people and learn more about the different fields of astronomy
research being done in Australia. Presenting a poster at the ASA meeting
also allowed people to see what type of work we are doing in New Zealand.
I am grateful for the funding I received from the Royal Astronomical
Society of New Zealand's, Kingdon-Tomlinson Grant, which contributed to
covering my travel expenses to this informative and interesting

========================================================7. Astrophotography Camp
Friday 5th - Sunday/Monday 7th/8th October 2007, Possum Observatory,

A gathering of astrophotographers at a dark site near Gisborne

* The third annual RASNZ Astrophotography Section camp will be held at a
dark sky site about 11 km from Gisborne (NZ) from Friday 5th until Sunday
7th October 2007 (people are welcome to stay Thursday, Friday, Saturday,
Sunday nights if they wish though - it's the last weekend of the school

* The focus of the weekend will be astrophotography - where we image at
night and discuss imaging and processing techniques during the day (but
people are more than welcome to just come and observe the celestial
splendours overhead - I have two 41cm scopes, a 20cm, etc).

* It will be held on a small farm near the little township of Patutahi.
The site offers a dark sky. The weather in Gisborne is often fine and so
we're hoping for a clear weekend.

* The weekend costs $15 per person, per night to cover power and water -
and a nightly BBQ. Accommodation is either tents, caravans (bring your
own), or sleeping communally in John's house (space is also available in a
8 x 6m shed ). If you want a fun observing weekend you're welcome to

If you are keen on coming please contact John Drummond
john_drummond@xtra.co.nz). My home number is (06) 8627 557, my mobile is
0275 609 287.
For more information go to:
Please note that directions and maps are on the webpage.

-- John Drummond, Director, RASNZ Astrophotography Section

==============================================================8. Council Nominations
At the Annual General Meeting in 2008, the term of the present council
comes to an end. It is therefore necessary to call upon members to
consider who they wish to nominate to Council for the next two years. We
need to elect the president, a vice-president (who will by custom be
nominated for president in two years' time), the secretary, the treasurer,
and five councillors. Two more councillors will be appointed by the
Affiliated Societies Committee, and the council may co-opt others if they
are needed.

Nominations in all categories must be made by two currently financial
members of the RASNZ, and must contain a signed statement by the nominee
that he/she is willing to be nominated. A short (200 words) biographical
note can also be included.

A nomination form is available at
Please use this as a guide if you wish, but it is also possible to send in
the nomination without using the form, as long as all the necessary
information is included. The form cannot be used online, as there must be
signatures from the nominee and the two nominators.

Nominations should be sent to the Executive Secretary, Pam Kilmartin, P.O.
Box 57, Lake Tekapo 7945, to be received before 24 February 2008. An
election may be held during April 2008.

-- Pam Kilmartin, Executive Secretary

Nominations for Newsletter Editor would also be welcomed. -Ed

==============================================================9. 2007 AGM Minutes
Brian Loader advises that the minutes of the AGM held on 30 June 2007 at
Manukau are now available on the RASNZ website as a pdf
file at <

==============================================================10. Stardate North
Island 2008
Stardate will be held at Tukituki, near Havelock North from Thursday
January 10 - Monday January 14 2008
For details see

-- Edwin Rod in a note to the nzastronomers group

========================================================11. Stardate South Island
Stardate South Island will be held at Staveley, inland from Christchurch
(a long way inland!), on Feb 15-17, Friday to Sunday. Stavely is a
dark-sky site with cabins, kitchen, lecture theatre and camping ground.
More details in the next Newsletter.

==============================================================12. NZ IYA Website -
Biographies Needed
Marilyn head, RASNZ Publicity officer, writes:

The NZ International Year of Astronomy (IYA) site is up and running thanks
to the sterling efforts of Roland Idacsyk at

To make it as useful as possible we'd like it to be comprehensive so
please let me know if you want any events - and that includes any from now
until the end of 2009 - to be posted.

A critical part is the section that deals with NZ astronomers - past,
present and overseas. We would like to include as many active astronomers
as we can - it should end up being the Who's Who of NZ astronomy. So we
would like all individuals and societies to send me (not Roland) names and
very short profiles with any relevant links to be posted. Hopefully this
will encourage societies to dig up some information about older members so
that it is an accurate historical record too. We'd also be very grateful
if you could pass this message on to people you know overseas to
contribute too. Don't be shy!!!! Do add any links to articles other sites
and references.

I've given an example below. You can write it in sentences, note form
however you like. There will just be a short paragraph for most people but
for the likes of Albert Jones, etc, more is fine. Photos are good. If you
have a website with all the info just the link will be fine.

Head, Marilyn. b 1953 - Wellington Astronomical Society; RASNZ, Publicity
officer; Coordinator Galactic Circle Kids Space and Astronomy Club;
Editor Galaxy- Te Korurangi astronomy magazine for kids downunder 1999
-2004; Restoration of Gifford Observatory.
http://www.gifford-observatory.wellington.net.nz/; Astronomy
columnist Dominion Post.

========================================================13. Comet Gilmore P/2007 Q2
The Editor discovered a very faint periodic comet in August. It orbits the
sun in 13 years, ranging from just outside the orbit of Mars, where
it is now, to near the orbit of Saturn.

The comet was first noticed on images taken with Mt John's one-metre
McLellan telescope on August 22, during follow-up work on near-Earth
asteroids. The comet was first thought to be an asteroid as it
appeared as a small star-like spot on CCD images. It was observed again
on the 24th. From these measurements the Minor Planet Center in Cambridge,
Massachusetts determined that it was in an orbit more usual for short-
period comets. Astronomers at Guangzhou in China and Siding Spring in
Australia saw a very tiny coma and short faint tail, confirming its
cometary nature. Though at its brightest now, the comet is very faint,
19th magnitude: around one-millionth the brightness of the faintest stars
visible to the naked eye. The comet is designated P/2007 Q2 Gilmore.

More details are in the upcoming issue of Southern Stars.

-- Alan Gilmore

========================================================14. K-T Extinctions Due to
Asteroid Collision Debris?
That the collision of two asteroids 160 million years ago led to the
demise of the dinosaurs is a suggestion made in the September 6th issue of
Nature by William Bottke and his colleagues at the Southwest Research
Institute in Boulder, Colorado.

Asteroids or minor planets, most of which are located between the orbits
of Mars and Jupiter, often come in families. Members share both chemical
composition (which can be deduced from the spectrum of the light they
reflect) and orbital characteristics. The assumption is that such families
are the daughters of single, larger bodies that have been hit by other
asteroids and smashed into pieces. Dr Bottke thinks he has traced
one such family back to its original collision.

The largest member of the family in question is called Baptistina, and is
some 40km across. In addition to her, the team identified many more than
2,000 smaller objects as belonging to the same family. They were able to
do this by looking at those asteroids' orbits in detail.

The orbits of asteroids are slowly changed by sunlight due to the
Yarkovsky effect. Heat radiation from the hotter 'afternoon' side of an
asteroid provides a tiny push that gradually distorts the asteroid's
orbit. The smaller the asteroid in question, the faster that distortion
happens. The result is that the daughters of Baptistina have become
scattered farther and farther away from their mother. From the pattern of
this scattering, and from the sizes of the asteroids (which tells you how
fast they will scatter), it is possible to calculate the date of the
original collision. That turns out to be 160m years ago, give or take
about 20m years.

That the dinosaurs were killed off 65 million years ago by an asteroid
impact is now widely accepted. The impact ended the Cretaceous geological
era and began the Tertiary period: it produced the K-T boundary. Dr
Bottke's contention is that the deed was done by one of Baptistina's
daughters. His evidence is twofold. First, the surviving debris from the
devastating impact has the same composition as Baptistina and her
offspring. That is a necessary but not a sufficient condition, as the type
of rock involved, called carbonaceous chondrite, is found in other
asteroids, too.

The second line of evidence is the "case of the missing daughters".
The cluster of Baptistina's young has a gap in it. This corresponds to a
place where the gravitational pulls of Mars and Jupiter have conspired to
change the orbits of any asteroids much faster than the Yarkovsky effect
could manage alone. Such asteroids would rapidly have adopted orbits that
cut across those of the inner planets, including Earth. Many of the larger
ones would have started arriving about 100m years ago. Sooner or later,
collisions would have been inevitable.

Those collisions are why the asteroids that ought to be in the space are
missing. They are probably also the explanation for the fact that, over
the past 100m years or so, the number of asteroids that have hit the Earth
is about twice that which would have been expected. Taking into account
the circumstances that pertained 65m years ago, Dr Bottke reckons it more
than 90% probable that the dinosaur killer was one of Baptistina's

The hole made by that collision, in what is now the Yucatan Peninsula in
southern Mexico, has long since been buried in thick layers of sediment
under the sea. But anyone with a pair of field glasses can see for
themselves what Baptistina's daughters are capable of.

The lunar crater Tycho, near the moon's south pole, is 85km across. It is
surrounded by rays of ejecta that stretch across much of the southern
lunar hemisphere, indicating the violence of the impact that formed it. It
is thought to be just over 100m years old (Apollo 17 brought back material
from the site, which allowed it to be dated), and it is reckoned by Dr
Bottke to be the result of the moon encountering one of the first
of Baptistina's progeny to arrive in the inner solar system. It is a
beautiful sight. But you would not have wanted to witness, at close
quarters, its creation.

-- abridged from The Economist, 2007 September 8, p. 85-6.
See the full story at

==============================================================15. Giant Hole in the
A void in space nearly a billion light-years across has been found by a
team of radio astronomers. The "hole" is located in the direction of
Eridanus. Previous sky surveys that have traced the large-scale structure
of the nearby Universe have long shown how the clustering of galaxies is
strung into vast filaments and sheets that are separated by great gaps.
But the void discovered by a University of Minnesota team is about 1,000
times the volume of what would be expected in typical cosmic gaps. The
void is roughly 6-10 billion light-years away and takes a sizeable chunk
out of the visible Universe in its direction.

The team used data from the US National Radio Astronomy Observatory's VLA
Sky Survey (NVSS) to make its discovery. The Very Large Array (VLA) is a
collection of 27 radio telescopes in New Mexico.

The finding is said to fit neatly with observations of the Universe's
"oldest light" - the famous Cosmic Microwave Background (CMB) radiation,
the study of which has earned several scientists the Nobel Prize.
This is the radiation that comes from just 380,000 years after the Big
Bang when the Universe had cooled to such a degree that hydrogen atoms
could exist. Before that time the Universe would have been so hot that
matter and light would have been "coupled" - the cosmos would have been

Today, this light shines at microwave wavelengths at a frigid -270C; and
observations of the CMB made by NASA's Wilkinson Microwave Anisotropy
Probe show a particular "cold spot" in the direction of the newly
identified void. The explanation for this may lie in the enigmatic "dark
energy" that scientists know so little about but which is said to be
accelerating the expansion of the Universe.

Light particles passing through the void would be expected to lose a
little more energy than those passing through space cluttered with matter
- if dark energy is stretching the Universe apart at a faster and faster
rate. Scientists refer to this as the Integrated Sachs-Wolfe Effect and a
corresponding "warm spot" in the CMB associated with an area of space
dominated by a supercluster of galaxies was identified some years ago.
"In essence, this latest study gives us a very elegant demonstration of
the existence of dark energy in a way which is very convincing," commented
Professor Carlos Frenk, the director of the Institute for Computational
Cosmology at Durham University, UK. "We keep getting evidence for dark
energy, this component of the Universe which is so dominant, and yet we
still have only a tiny glimmer of what it could be."

The reason the void exists is not known. "That's going to be a challenge
for people that work on the development of structure in the Universe. It's
a very hot topic in the cosmology right now," said Minnesota's Professor
Lawrence Rudnick, lead author of the Astrophysical Journal paper.

Abridged from a BBC News item:

==============================================================16. Nearest Neutron
Using NASA's Swift satellite, McGill University and Penn State
University astronomers have identified an object that is likely one
of the closest neutron stars to Earth -- and possibly the closest.

The object was noted in a comparison of a catalogue of 18,000 X-ray
sources from the German-American ROSAT satellite, which operated from 1990
to 1999, with catalogues of objects that appear in visible light, infrared
light, and radio waves. The ROSAT source known as 1RXS J141256.0+792204
did not appear to have a counterpart at any other wavelength.

The group aimed Swift at the object in August 2006. Swift's X-ray
telescope showed that the source was still there, and emitting about
the same amount of X-ray energy as it had during the ROSAT era. Swift
enabled the group to pinpoint the object's position more accurately, and
confirmed that it was not associated with any known object.

Further observations with the 8.1-meter Gemini North Telescope in Hawaii,
and NASA's Chandra X-ray Observatory, showed that the object was not
visible down to a very faint magnitude. Chandra's sharper X-ray vision
sees the object as point-like, consistent with the neutron-star

According to Robert Rutledge of McGill University there are no widely
accepted alternative theories for objects that are bright in X-rays and
faint in visible light. Exactly which type of neutron star it is,
however, remains a mystery. It is either an unusual example of a known
type of neutron star, or it is some new type of neutron star, the first of
its kind.

In all likelihood, the neutron star is the remnant of a star that lived in
our galaxy's starry disk before exploding as a supernova. In order to
reach its current position, it had to wander some distance out of the
disk. But exactly how far? "The best guess is that it is still close to
its birthplace, and therefore close to Earth," says Rutledge. If this
interpretation is correct, the object is 250 to 1,000 light-years away.
This would make it one of the closest known neutron stars -- possibly the
closest. If so then it could represent the tip of the iceberg for isolated
neutron stars.

-- adapted from a Pennsylvania Stat University press release forwarded by
Karen Pollard.

==============================================================17. Stars v. Sand
Last month's note about the number of grains of sand on all the world's
beaches versus the number of stars in the universe generated an
informative debate.

Lloyd Esler of Southland Museum begged to differ:
"Can I take issue with your stars versus grains of sand estimate?
10,000 grains in a handful is a gross underestimate. 10,000 grains
of sand will cling to a wet fingertip. The figure is more like 10
million. Here is the Esler Sand Grain Counting Technique - open for
1) Measure a cubic centimetre of sand and put it in a jar.
2) Wind a length of sellotape, sticky side out, around a piece of
card and put it in the jar as well.
3) Shake the jar until no more sand clings to the sellotape.
4) Remove the sellotape and replace it and keep doing this until
there is no more sand.
5) Measure the length and area of the sellotape needed to hold the
6) Under a microscope, count the grains of sand in representative
1mm squares of sellotape."

Using this method with Oreti Beach sand Lloyd initially estimated 500
million grains per litre. The beach being 26km x 100m x say 60 metres
deep, so the number of grains is 78 sextillion, more than the number of
stars. [78 sextillion = 78 x 10^21.] Earth has 450,000 km of coastline,
perhaps a quarter of it sandy, so the sand grains win easily!

Further measurements gave 650 million grains per litre or 15,000 grains on
a wet fingertip for Oreti sand. A sample of coarser sand from Northland
had about half that number suggesting perhaps 250 million per litre but
this doesn't significantly alter the magnitude of the number.

To this Jay GaBany replied:
"Thanks for this feedback. Actually, before writing my introductory
essay, I did a lot of research. Following are links you can review or pass
along to Lloyd for his digestion:

Number of stars in the Universe:

Number of sand grains on the Earth's beaches:

The actual calculation for sand grains:

Other references:

Significantly, at least for me, NASA supports the notion that there are
10 times the number of stars compared to sand grains on the Earth's
I suppose all of this is debatable since both numbers are based on
estimates but, intuitively, I do not agree with the vast numbers Lloyd
is quoting for sand on a fingertip, much less held in a two litre milk

==============================================================18. How to Join the
A membership application form and details can be found on the RASNZ
Alternatively please send an email to the membership secretary
members@rasnz.org.nz for further information.

The annual subscription rate is $75. For overseas rates please check with
the membership secretary.

==============================================================19. The Biggest Dob in
the World
A minor typo in a note from Ashley to nzastronomers "... friend of mine
wants to buy a telescope, for terrestrial and night use. Wanting around
70-100m aperture, doesn't have to be top of range..."

Got a response from Rod "70-100m ????!! He's a bit optimistic isn't he?"

And a helpful suggestion from Bill "One of these for a backyard Dob

Project OWL is a 100-m telescope. OWL = Overwhelmingly Large Telescope
=============================================================Alan Gilmore
Phone: 03 680 6000
P.O. Box 57
Lake Tekapo 7945
New Zealand


Popular posts from this blog

September Astro Events

Childrens Yoga