The RASNZ Email newsletter is distributed by email on or near the 20th of each month. If you would like to be on the circulation list This email address is being protected from spambots. You need JavaScript enabled to view it. for a copy.

Affiliated Societies are welcome to reproduce any item in this email newsletter or on the RASNZ website http://www.rasnz.org.nz/ in their own newsletters provided an acknowledgement of the source is also included.

Contents

1. 2014 Beatrice Hill Tinsley Lectures
2. The Solar System in September
3. Comet C/2013 A1 (Siding Spring)
4. Herbert Astronomy Weekend, August 22-25
5. Space Camp NZ, September 19-21
6. AAO Student Fellowship Program - Applications Invited (Quickly!)
7. 2015 RASNZ Conference
8. Variable Stars South Symposium Report
9. Gaia 'Go' for Science
10. More Notes from the Conference
11. Rosetta Rendezvous with Comet Nucleus
12. How to Join RASNZ
13. Gifford-Eiby Lecture Fund
14. Kingdon-Tomlinson Fund
15. Correction to Thorne-Zytkow
16. Here and There

1. 2014 Beatrice Hill Tinsley Lectures

Presented by the RASNZ Lecture Trust.

This year's lectures are by Dr Tamara Davis who is the Future Fellow of the School of Mathematics and Physical Sciences, University of Queensland, Australia.

She is a cosmologist who spends her time investigating why the expansion of the universe is accelerating. She was part of the WiggleZ Dark Energy Survey, which made one of the largest ever maps of the distribution of galaxies in the universe, and uses supernovae to measure the properties of "dark energy". She´s an avid science communicator and has a knack for turning complex concepts into everyday language.

She is offering one of two lectures at each of six venues this year. Updates will be posted on the RASNZ website.

NEW PLYMOUTH Sunday September 21st, 7:30 pm, Ryder Hall, New Plymouth Boys´ HS. "Cosmological Confusion"

LEVIN Monday September 22nd, 7:00 pm, School Hall, Waiopehu College, Levin. "Cosmological Confusion"

NAPIER Tuesday September 23rd, 7:00 pm, Holt Planetarium, Chambers St, Napier. "The Dark Side"

INVERCARGILL Wednesday September 24th, 7:30 pm, Ascot Park Hotel, Invercargill. "The Dark Side"

DUNEDIN Thursday September 25th, 5:30 pm, Hutton Lecture Theatre, Otago Museum. "Cosmological Confusion"

CHRISTCHURCH Friday September 26th

She is also giving three special student lectures in New Plymouth, Levin and Invercargill. Contact Bob Evans, Lecture Trust secretary, for more information. <This email address is being protected from spambots. You need JavaScript enabled to view it.>

2. The Solar System in September

Up to September 27 dates and times are NZST (UT +12 hours) unless otherwise specified. NZDT starts September 28. Rise and set times are for Wellington. They will vary by a few minutes elsewhere in NZ.

The Sun rises at 6.44 am and sets at 5.58 pm on September 1. On September 30 the times are 6.55 am NZDT and 7.27 pm NZDT respectively.

Phases of the moon (times as shown by guide)

First quarter: September  2 at 11.11 pm (11:11 UT)
Full moon:     September  9 at  1.38 pm (01:38 UT)
Last quarter   September 16 at  2.05 pm (02:05 UT)
New moon:      September 24 at  6.14 pm (06:14 UT)

The planets in september

Mercury has its best evening appearance of the year for southern hemisphere viewers this month. Mars and Saturn are also early evening objects

Jupiter rises further into the morning sky but Venus is too close to the Sun to observe.

PLANETS IN THE EVENING SKY. Best viewed as the sky darkens following sunset.

Mercury is an evening object throughout September. It reaches its maximum elongation 26° east of the Sun on September 21. It will then set more than 2 hours after the Sun. With a magnitude 0.1 it will be readily visible fairly low to the west as the sky darkens especially later in the month. It will be the brightest star like object in that region of the sky.

On the 20th and 21st Mercury will be only 45 arc minutes from the Spica, magnitude 1.1 thus an obvious pair in the western sky. Mercury will be noticeably brighter.

Mercury is in Virgo all month. It will be brightest early in September, on the 1st magnitude -0.2, when it sets about 100 minutes after the Sun. By the end of September the planet will be a little less bright, magnitude 0.4. It will still be setting over 2 hours later than the Sun.

On the 26th a very thin crescent moon will be 5.5° below and to the right of Mercury with Spica just over 3° left of the moon.

Mars remains an evening object setting just after midnight all month; when NZDT starts at the end of September the planet will set close to 1am.

Mars starts September in Libra. It moves across the narrow part of Scorpius between the 13th and 25th and then on into Ophiuchus. While in Scorpius, Mars will move through the head of the Scorpion passing just over half a degree from the 2.3 magnitude star delta Sco on the 18th. After entering Ophiuchus, Mars will move past Antares, being closest on the 28th when the two will be just over 3° apart. Planet and star will be almost identical in brightness, thus they will make a notable pair of reddish objects in the evening sky.

The Moon passes Mars twice in September. On the 1st the 38% lit moon will be some 5.5° from Mars (but much closer to Saturn). On the 29th the 24% lit moon will 8° from Mars, the next evening the two will be 9° apart with the moon 34% lit.

Saturn, like Mars remains an early evening object throughout September. But as Saturn's motion to the east is less than that of Mars, it will drop behind the red planet and steadily set earlier. On the 1st it will set about half an hour before Mars, by the 30th almost two hours earlier at about 11 pm NZDT. So the planet is best viewed early evening as the sky darkens.

Saturn is in Libra during September. The moon joins Saturn on September 28, with the 16% moon 2° to the right of Saturn. Earlier, at about 5 pm NZDT, the moon will occult Saturn, an event visible from Hawaii and the western parts of Alaska.

By the end of September the two asteroids Ceres and Vesta will be close to Saturn. In fact Vesta is closest to Saturn on the 14th, with the asteroid, magnitude 7.8, just over a degree to the right of, and slightly lower than Saturn. On the 30th Ceres, magnitude 9.0, will be 1.5° below Saturn.

Planets in the morning sky.

Jupiter rises a little over an hour before the Sun on September 1, two hours before it on the 30th. So, unlike Venus it will become more visible in the morning sky as the month progresses. Jupiter is in Cancer all month. On the mornings of the 20th and 21st the crescent moon will be a few degrees from the planet.

The equatorial plane of Jupiter is now nearly edge-on to the Earth. The four major satellites of Jupiter orbit close to the plane of Jupiter's equator. As a result eclipses, transits and occultations of Callisto, as well as the other three, are now taking place. Also a series of mutual events of the moon's are about to start. The first, on September 10, involves a very slight penumbral eclipse of Ganymede by Callisto. At this event the change in brightness is too slight to detect. Some events later this year and in 2015 will be easier to see.

Venus is also a morning object but not readily visible. It rises only half an hour before the Sun at the beginning of September, and only 7 minutes earlier than the Sun by the 30th. The planet is in Leo much of the month but moves into Virgo on the 24th. On the 6th it will be less than 1° from Regulus, but with an altitude only 4° at sunrise, the conjunction will not be visible.

Outer planets

Uranus rises just before 9 pm on September 1st and close to sunset on the 30th. The planet is in Pisces with a magnitude 5.7.

Neptune rises more than an hour before sunset the 1st and is highest just after midnight. The times get earlier by about 2 hours during the month, but start of NZDT drops it to only one hours earlier on the 30th. The planet is in Aquarius, magnitude 7.8.

Pluto is in Sagittarius at magnitude 14.3, about 6° from Nunki, sigma Sgr. Nunki, at magnitude 2.1, is the brightest star in the handle of the teapot.

Brighter asteroids:

(1) Ceres and (4) Vesta are in Libra during September in the vicinity of Saturn. As noted above Vesta is in conjunction with Saturn on the 14th, Ceres' conjunction is early October. Their magnitudes change little in September at 9 and 7.8 respectively.

(6) Hebe brightens from magnitude 9.1 to 8.6 in the month. The asteroid starts September in Taurus but it moves into Eridanus on the 7th.

-- Brian Loader

3. Comet C/2013 A1 (Siding Spring)

C/2013 A1 (Siding Spring) will be at its brightest when it makes its closest approach to Earth in September. It will then be 0.891 AU or 134 million km from us. It passes Mars in October then sinks into the evening twilight in November as it moves to the far side of the sun. The ephemeris below is for 8 pm NZST.

         R.A.(2000) Dec.                    R.A.(2000) Dec.
         h  m  s    °  '   m1             h  m  s   °  '   m1
Aug. 20  02 35 47  -59 25   8.3    Sep. 9  19 53 35  -69 50   7.7
     21  02 29 34  -60 48   8.3        10  19 36 46  -68 26   7.7 
     22  02 22 27  -62 12   8.2        11  19 22 17  -66 57   7.7 
     23  02 14 18  -63 37   8.2        12  19 09 47  -65 25   7.7 
     24  02 04 54  -65 02   8.1        13  18 59 00  -63 51   7.7 
     25  01 54 03  -66 27   8.1        14  18 49 38  -62 16   7.7 
     26  01 41 29  -67 50   8.0        15  18 41 30  -60 40   7.7 
     27  01 26 53  -69 11   8.0        16  18 34 24  -59 06   7.7 
     28  01 09 56  -70 27   8.0        17  18 28 10  -57 32   7.7 
     29  00 50 19  -71 38   7.9        18  18 22 40  -56 00   7.7 
     30  00 27 45  -72 40   7.9        19  18 17 49  -54 29   7.8 
     31  00 02 11  -73 32   7.8        20  18 13 31  -53 00   7.8 
Sep.  1  23 33 48  -74 11   7.8        21  18 09 41  -51 34   7.8 
      2  23 03 11  -74 34   7.8        22  18 06 16  -50 10   7.8 
      3  22 31 21  -74 40   7.8        23  18 03 13  -48 48   7.8 
      4  21 59 33  -74 29   7.7        24  18 00 29  -47 28   7.9 
      5  21 29 03  -74 00   7.7        25  17 58 01  -46 11   7.9 
      6  21 00 49  -73 15   7.7        26  17 55 49  -44 56   7.9 
      7  20 35 26  -72 17   7.7        27  17 53 49  -43 43   7.9 
      8  20 13 03  -71 08   7.7        28  17 52 01  -42 33   8.0

m1 is the comet's total magnitude, the brightness of a star defocused to the size of the comet's head. The comet is 'new' in the sense that it has not passed close to the sun before. It came from a distance of 52,f600 AU from the sun. (1 AU 'astronomical unit' is the Earth's distance from the sun, 150 million km.) The gravity pull of the planets will shrunk its orbit. It will go out to a maximum distance of 15,600 AU some 700,000 years from now.

Orbit data from Minor Planet Electronic Circular 2014-P53. The ephemeris is from Minor Planet Center.


Tony Barry points out that the comet will cross the globular cluster NGC 362 on the morning of August 29. NGC 362 is just off the edge of the Small Magellanic Cloud.


C/2013 A1 will pass just 130,000 km from Mars on October 19. That is one- third the Earth-Moon distance. The closest comets known to have passed Earth have been at least ten times more distant.

Such a close encounter means the dust tail left in Siding Spring´s wake might graze Mars´s upper atmosphere. The smallest particles are only about half a mm across, but careening through space at 56 km per second, even these could severely damage a spacecraft. The time of greatest danger for the spacecraft orbiting Mars will occur about 90 minutes after Siding Spring´s closest approach, and will last about 20 minutes.

To avoid the threat of Siding Spring´s debris, NASA engineers will manipulate the trajectories of the Mars orbiters so that all three will end up on the opposite side of the planet during the flyby. The MRO team executed one manoeuvre at the beginning of July, with another planned for the end of August. The Mars Odyssey team took similar steps on August 5th, and the MAVEN team will perform a precautionary manoeuvre shortly after the spacecraft enters orbit around Mars.

-- The above from Sky & Telescope. Read more at http://www.skyandtelescope.com/astronomy-news/mars-orbiters-duck-cover-comet- siding-spring-081420142/?et_mid=687221&rid=246399573

4. Herbert Astronomy Weekend, August 22-25

The Herbert Astronomy Weekend will be on the weekend of August 22nd to 25th at Camp Iona, 2km to the west of Herbert in North Otago, beginning from this Friday afternoon.

The overnight fees are now $34 per adult for two nights and $17 for one night. For secondary school teenagers, they are $15 and $30 for one and two night per teenager, and for primary schoolchildren they are $12 and $24 for one and two nights. For those staying the full three nights at Camp Iona, the charge is only $35 for three nights. There is also a daytime or evening visitor charge of $5 per person for those who wish to come to our Herbert Astronomy Weekend without the need to stay overnights at Camp Iona. Those fees are payable in cash or cheque at Camp Iona.

Confirmed speaker are Steve Butler on "The Colours of the Night" and Martin Unwin on the upcoming "2014/2015 Mutual Phenomenas of Jovian satellites". Other speakers are welcome at our Herbert Astronomy Weekend, and a data projector is available for those who wish to speak.

The Herbert Astronomy Weekend´s website is http://www.treesandstars.com/herbert/ where online registrations are encouraged for those attending the Weekend.

-- Ross Dickie

5. Space Camp NZ, September 19-21

Date: 19th to 21st September 214 Location: Raincliff Youth camp South Canterbury Contact: Robert Ph 03-6883735 Website: http://spacecampnz.scastro.org.nz/

This astronomy event is packed with activities, seven speakers, three overseas speakers who will present remotely, there presentations will be interactive with the audience. Speakers: Dr Joe Liske (European Southern Observatory), Dr Pamela Gay (USA, professional astronomer, citizen science), Warren Keller (USA, renowned astro imager), John Whitby (NZ, video astronomy), Stephen Chadwick (NZ author, astro imager), Peter Aldous (NZ, Hyperstar Photoraphy), Robert McTague (NZ, Hyperstar Photography).

Registrations are flowing in, its possible that we will have to limit numbers because of the facility, so register as soon as possible.

-- Robert McTague, South Canterbury Astronomers Group

6. AAO Student Fellowship Program - Applications Invited (Quickly!)

The Australian Astronomical Observatory provides opportunities for undergraduate students to participate in research projects. Students will spend 10-12 weeks in the period Dec 2014 - Feb 2015 working at the Australian Astronomical Observatory in Sydney on research projects under the supervision of AAO staff astronomers and engineers. Students will have the opportunity to participate in a field trip to visit the telescopes at Siding Spring Observatory.

Please encourage your undergraduate students to apply.

The deadline for applications is: 31 August 2014.

Details are available here: http://www.aao.gov.au/science/research/students/fellowships The stipend is A$700 per week.

How to Apply

Applications are required to be sent by e-mail. Please send your application as a single Word or PDF document attachment to the AAO Student Fellowship Coordinator, A.Prof. Andrew Hopkins (This email address is being protected from spambots. You need JavaScript enabled to view it.). The application should include the following: - Full name and contact address (it is essential to include an e-mail address). - Full details of university studies, including a transcript of academic record (if your university supplies only hardcopy transcripts, please scan it and send us the JPEG or PDF file). - Names and e-mail addresses of TWO academic referees who have been asked to e-mail letters to A.Prof. Hopkins by the application deadline, outlining the applicant's suitability for this scholarship program. The AAO does not chase up late referees, and missing references can hinder your chances of selection. - A one page statement giving the applicant's reasons for applying and their interests in Astronomy/Astrophysics/Instrumentation. If you have prior research experience, computing skills, or other skills associated with astronomy or research, please emphasise these. - A short resume (2-3 pages) is optional, but often helpful, to provide as well.

Please contact Andrew Hopkins with any queries about the program or the application process.

-- Andrew Hopkins, Associate Prof. Andrew Hopkins, Head of AAT Science Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670, Australia. ph: +61 2 9372 4849 fax: +61 2 9372 4880

7. 2015 RASNZ Conference

The 2015 RASNZ Conference will be held in Lake Tekapo village From Friday May 8 to Sunday 10th. It will be followed by the 9th Trans-Tasman Occultation Meeting on the Monday and Tuesday, May 11-12.

Preceding the RASNZ Conference will be a two-day meeting celebrating Mt John Observatory's 50th Anniversary. The meeting will be held in Lake Tekapo village on the Thursday and Friday, May 7-8. The theme is `Celebrating 50 years of Mt John´. Past Pennsylvania and Canterbury students will contribute papers but anyone is welcome. About 80 participants are expected. Details are available at www.mjuo50.org.nz.

8. Variable Stars South Symposium Report

Variable Stars South (VSS) held a very successful Symposium in Whakatane associated with the 2014 RASNZ Conference. The papers covered instrumental techniques, current observing projects and astrophysics. Transcriptions of most of the papers and the associated discussion have now been placed on the VSS website (www.variablestarssouth.org). PowerPoint presentations with associated captions are available for a paper on visual observing and on a discussion of the early stage light curve of nova 1369 Centauri and nova ejecta phenomena. The material is open to all who visit the site.

A feature of the Symposium was a Workshop on DSLR photometry. This was a comprehensive coverage of the topic presented by Mark Blackford and participants benefited greatly from his practical experience. The information is available through both the original PowerPoint and a transcript and will be of particular benefit to anyone wanting to start out in this field.

If you are interested in any of the observing projects described - Short Period Eclipsing Binary, Southern Eclipsing Binary (CCD) Cepheid, Semi- regulars - you are invited to contact the appropriate Project Leader. Some programmes utilise CCD devices; others involving brighter stars are more suited to DSLR and some projects can accommodate visual observing.

Finding Symposium 3 Content: Symposium Programme and Transcripts: Tab Community > Events > RASNZ Conference and VSS 3 Symposium 2014 Link http://www.variablestarssouth.org/community/events/category/4-rasnz- conference-and-vss-3-symposium-2014

PowerPoint Presentations Tab Community > Community Publications > Presentations > VSS Symposium

You are encouraged to explore aspects of the programme which interest you.

Also carrying coverage of the VSS Symposium 3 is the latest Newsletter, issued July 2104. Again look under the "Community" tab.

-- Alan Baldwin

9. Gaia 'Go' for Science

Following extensive in-orbit commissioning and several unexpected challenges, the European Space Agency´s billion-star surveyor, Gaia, is now ready to begin its science mission. The satellite was launched on 19 December 2013, and is orbiting a virtual location in space 1.5 million km from Earth.

Gaia´s goal is to create the most accurate map yet of the Milky Way. It will make extremely accurate measurements of the positions and motions of about 1% of the total population of roughly 100 billion stars in our home galaxy to help answer questions about its origin and evolution.

Repeatedly scanning the sky, Gaia will observe each of its billion stars an average of 70 times each over five years. Small shifts in the positions of the stars will allow astronomers to determine their distances and movements through the Milky Way. In addition, Gaia will also measure key physical properties of each star, including its brightness, temperature and chemical composition.

Gaia spins slowly once every six hours, sweeping its two telescopes across the sky and focusing the light from their separate fields simultaneously onto a single focal plane -- the largest digital camera ever flown in space, with nearly a billion pixels. As the stars drift across the camera, the relative positions of all detected stars are measured and downlinked to Earth. Over time, a complete network of positions of stars covering the whole sky is built up, before being analyzed to yield a highly accurate 3D map.

The accuracy required is astonishing: Gaia must be able to measure positions to a level equivalent to the width of a human hair seen at 2,000 km. In turn, these measurements demand a very rigorous calibration of the satellite and its instruments, a painstaking procedure that has taken the first part of the year to complete.

Gaia is now ready to begin its five-year science phase, but the commissioning also uncovered some unexpected anomalies.

One problem detected early in the commissioning was associated with water freezing on some parts of the optics, causing a temporary reduction in transmission of the telescopes. This water was likely trapped in the spacecraft before launch and emerged once it was in a vacuum. Heating the affected optics to remove the ice has now largely solved this problem, but it is likely that one or two more `decontamination´ cycles will be required during the mission to keep it in check.

Another problem is associated with `stray light´ reaching Gaia´s focal plane at a level higher than predicted before launch. This appears to be a mixture of light from the Sun finding its way past Gaia´s 10-m-diameter sunshield and light from other astronomical objects, both making their way to the focal plane as a diffuse background. The effect on Gaia´s performance is negligible for brighter objects at magnitude 15 and above, and a slight degradation in the positional accuracy is seen for fainter stars, reaching 50% for stars at Gaia´s nominal faint limit of magnitude 20. There is also some effect on the accuracy to which stellar brightnesses will be measured.

The impact of the stray light should, in principle, be more significant for faint stars seen by Gaia´s Radial Velocity Spectrometer (RVS). "However, we are optimizing the onboard software to mitigate as much as possible the impact caused by these higher background levels of light, and we are confident that we will not be far off our initial and somewhat conservative estimate of studying 150 million stars with RVS, as planned," says Giuseppe Sarri, ESA´s Gaia project manager. "We will still be able to analyze one billion -- if not more -- stars with the astrometry and photometry instruments, measuring each star´s position and motion up to 100 times more accurately than Gaia´s predecessor Hipparcos and for a far larger number of stars."

The commissioning has not only focused on the spacecraft performance, but also on the flow of data on the ground, testing procedures that will be used to process and analyze the vast amount of data that will be transmitted to Earth on a daily basis for the next five years. Thus, after extensive testing and analysis of systems both in space and on the ground, Gaia is now in a position to begin routine operations.

It is anticipate that the first intermediate catalogue of science data will be released in summer 2016. However, if rapidly-changing objects such as supernovas are detected, open alerts will be made as soon as possible -- a service the Gaia scientists hope to have up and running before the end of this year.

For more see http://www.esa.int/Our_Activities/Space_Science/Gaia/Gaia_Go_for_science

-- From a European Space Agency press release forwarded by Karen Pollard.

10. More Notes from the Conference

Featured speaker Jocelyn Bell-Burnell´s talk about `Transient astronomy - Bursts, bangs and things that go bump in the night´. Transients, short bursts have been an interest of Jocelyn´s for 40 years. Now others are taking notice of them too, and not only at radio wavelengths. Optical telescopes like Panstarrs are taking four 30s exposures 10 minutes apart and seeing if anything changes. They find a lot of NEOs that way. Results are announced quickly to allow follow-up. The Catalina Real Time Transient Survey sweeps 3/4ths of the sky. It has found 9000 transients since 2004. Most are active galactic nuclei, supernovae and cataclysmic variables. We need more supernova examples; there are now many types. Objects disrupted by tidal forces fall into black holes in separate pieces, the way Comet Shoemaker-Levy 9 met Jupiter. Gamma ray bursts mostly come from distant supernovae, we think, but the Crab pulsar produces gamma ray emissions lasting several days.

Radio transients have been discovered accidentally by pulsar astronomers. The distance to a radio source can be estimated by the dispersion of the signal. Electrons in space slow low frequencies more than the high. `Whistlers´, pulses from lightning, travelling along Earth´s magnetic field, are prime examples of this effect. The effect is seen with pulsar signals. Fast Radio Bursts (FRBs) have dispersions showing that they come from far beyond the galaxy. Some have red shifts greater than 1, indicating they are from billions of light-years away, yet they are strong signals.

Oxford University, Dame Jocelyn´s home institution, is involved with the Large Synoptic Telescope (LSST). It will have an 8.4-metre mirror and wide field of view. It is likely to find a million transient events per night. Pipelining of events will be required: variable stars, supernovae, cataclysmic variables and asteroids. The Square Kilometre Array radio telescope has a transient programme as does LOFAR, a European network of low- frequency radio antennas. The `Lorimer Burst´, six years ago, has drawn attention to these phenomena.

Norman Izett gave a history of the Whakatane Astronomical Society. Playing in the background was an old video of the removal of an historic shed from what is now the WAS´s observatory site. Action in this, particularly some frighteningly non-OSH chainsaw work, rather distracted this scribe from Norman´s talk. However, Norman kindly provided a draft of the history.

Pam Kilmartin gave the eighth in her long-running series on asteroid names. Among the gems, asteroid 327512 Biro is named for Lazlo Jozsef Biro (1899-1985), the Hungarian inventor of the ubiquitous ballpoint. He wasn´t the first to think of the ballpoint but having a printer brother enabled him to get the ink mix right. Argentina, where he later emigrated, celebrates him on Inventors´ Day, 29 September. Asteroid 11425 Wearydunlop commemorates Colonel Sir Ernest Edward Dunlop 1907-93, an Australian Army surgeon who was a prisoner-of-war on the infamous Thai-Burma railway. There he was "a lighthouse of sanity in a universe of madness and suffering". He was Australian of the year in 1976.

11. Rosetta Rendezvous with Comet Nucleus

After a decade-long chase, the European Space Agency's Rosetta spacecraft rendezvoused with the nucleus of Comet 67P/Churyumov-Gerasimenko (67P) on August 6. 67P and Rosetta were then 405 million km from Earth, about halfway between the orbits of Jupiter and Mars, rushing towards the inner solar system at nearly 55,000 km per hour.

The comet is in an elliptical 6.5-year orbit that takes it from beyond Jupiter at its furthest point, to between the orbits of Mars and Earth at its closest to the Sun. Rosetta will accompany it for over a year as they swing around the Sun and back out towards Jupiter again.

Comets are considered to be primitive building blocks of the solar system and may have helped to 'seed' Earth with water, perhaps even the ingredients for life. But many fundamental questions about these enigmatic objects remain, and through a comprehensive, in situ study of the comet, Rosetta aims to unlock the secrets within.

The comet began to reveal its personality while Rosetta was on its approach. Images taken by the OSIRIS camera between late April and early June showed that its activity was variable. The comet's 'coma' -- the extended envelope of gas and dust around the nucleus -- became rapidly brighter and then died down again over the course of those six weeks. Microwave measurements suggested that the comet was emitting water vapour into space at about 300 mls per second.

Meanwhile, the Visible and Infrared Thermal Imaging Spectrometer, VIRTIS, measured the comet¹s average temperature to be about -70°C, indicating that the surface is predominantly dark and dusty rather than clean and icy. Images taken by Rosetta reveal that the nucleus comprises two distinct segments joined by a 'neck', giving it a duck-like appearance.

Till late September Rosetta will describe two triangular-shaped trajectories in front of the comet, first at a distance of 100 km and then at 50 km. At the same time, more of the suite of instruments will provide a detailed scientific study of the comet, scrutinizing the surface for a target site for the Philae lander. Eventually, Rosetta will attempt a close, near-circular orbit at 30 km and, depending on the activity of the comet, perhaps come even closer.

The primary landing site will be identified in mid-September. The final timeline for the sequence of events for deploying Philae -- currently expected for 11 November -- will be confirmed by the middle of October. After landing, Rosetta will continue to accompany the comet until its closest approach to the Sun in August 2015 and beyond.

-- From a European Space Agency press release forwarded by Karen Pollard.

12. How to Join RASNZ

RASNZ membership is open to all individuals with an interest in astronomy in New Zealand. Information about the society and its objects can be found at http://rasnz.org.nz/RASNZInfo/MemberBenefits.shtml

A membership form can be either obtained from This email address is being protected from spambots. You need JavaScript enabled to view it. or by completing the online application form found at http://rasnz.org.nz/RASNZInfo/Membership/

Basic membership for the 2015 year starts at $40 for an ordinary member, which includes an electronic subscription to our journal 'Southern Stars'.

13. Gifford-Eiby Lecture Fund

The RASNZ administers the Gifford-Eiby Memorial Lectureship Fund to assist Affiliated Societies with travel costs of getting a lecturer or instructor to their meetings. Details are in RASNZ By-Laws Section H.

For an application form contact the Executive Secretary This email address is being protected from spambots. You need JavaScript enabled to view it., R O'Keeffe, 662 Onewhero-Tuakau Bridge Rd, RD 2, TUAKAU 2697

14. Kingdon-Tomlinson Fund

The RASNZ is responsible for recommending to the trustees of the Kingdon Tomlinson Fund that grants be made for astronomical projects. The grants may be to any person or persons, or organisations, requiring funding for any projects or ventures that promote the progress of astronomy in New Zealand. Full details are set down in the RASNZ By-Laws, Section J.

For an application form contact the RASNZ Executive Secretary, This email address is being protected from spambots. You need JavaScript enabled to view it. R O'Keeffe, 662 Onewhero-Tuakau Bridge Rd, RD 2, TUAKAU 2697

15. Correction to Thorne-Zytkow

Last month's Newsletter had an item about a possible Thorne-Zytkow object. The plain-text spelling should have been Thorne-Zytkow. Formally, the Z has a dot over it.

-- Ed.

16. Here and There

From The Observatory, 2014 June.

A SENSIBLE PRECAUTION Before diving into black holes, you should make sure you have a solid understanding of the concepts and equations related to density and escape speed.

-- A Student's Guide to the Mathematics of Astronomy (CUP), 2013.

LIGHT ON ACCURACY Early measurements showed that the galaxy had a mass of 1bn suns, which is 40bn to 50bn times lighter than the Milky Way.

-- The Guardian, 2013 October 24.

THE SHRINKING MOON The cluster is 95 arc-seconds across, meaning it is three times the size of the full moon...

-- Journal of the British Astronomical Association, v123, 372, 2013.


Newsletter editor:

Alan Gilmore   Phone: 03 680 6000
P.O. Box 57   Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Lake Tekapo 7945
New Zealand