COTM: Hydra - Part 2 (East of RA 10h 56m)

Peter Ogilvie

As Ross Gould mentioned last month, Hydra is a large and long constellation. The eastern half is a fairly narrow strip of sky running east-west, bordered on its southern side by Centaurus, and on its northern side Crater, Corvus, Virgo and Libra. As with the western half, there are no bright stars, clusters or nebulae – the primary attraction for observers are the numerous galaxies and double stars.

The objects listed here were mostly observed with a 25 cm (10 inch) telescope under a suburban sky illuminated by a fat gibbous moon (not exactly ideal), however a few of my galaxy observations were made three or four years earlier using the Society's 14-inch at Mt Stromlo.

Variable star

R Hya (13 29.7, -23 17) Irregular variable with a period of about 387 days, changing from magnitude 4 down to 10. Hartung describes it as crimson-red, but I think this is an exaggeration – to me it appears orange. Magnitude was about 7.

Double stars

Beta Hya (11 52.9, -33 55) Magnitudes 4.7 and 5.5 separated by only 0.7 arcseconds. Hartung's (1995) says that at least 20 cm (8 inches) is needed to split them. I couldn't to do it with the 10-inch at 278x but also the seeing was a bit unsteady. Described as pale yellow, I see it as white.

h 4455 (11 36.6, -33 34) Mag. 5.9 and 7.8, separation 3.3 arcsec. At 278x the primary is orange but the secondary (supposedly yellow) is a bit too dim to distinguish the colour easily.

H III 96 (11 32.3, -29 16) Mag. 5.7 and 5.8, separation 9.3 arcsec. This equal pair of yellow-white stars should be quite easy in any telescope, but the clouds beat me to it.

HN 69 (13 36.8, -26 30) Mag. 5.8 and 6.7, with a generous separation of 10 arcsec this slightly uneven pair (both white) is easy at 100x.

54 Hya (14 46.0, -25 27) Mag. 5.1 and 7.1, separation an easy 8.9 arcsec. Averted vision made the secondary markedly brighter.

59 Hya (14 58.7, -27 39) A fairly even mag. 6.3 and 6.6 at a tight 0.8 arcsec. The seeing was not good enough for me to have any chance of splitting it.

Galaxies

NGC 3261 (11 18.3, -32 49) A moderate-sized elongated oval haze, dim in the bright moonlight.

NGC 4105-4106 (12 06.7, -29 46) Two small round galaxies only 1.5 arcmin apart, both with conspicuous, sharp nuclei.

NGC 5061 (13 18.1, -26 50) Small circular haze with an obvious nucleus. It is close to a mag. 8 star.

NGC 5236 (M83) (13 37.0, -29 52) This famous galaxy is a moderately large ellipse which really suffers in moonlight or badly light polluted skies, making it difficult to see except for its nucleus. This is due to its face-on aspect giving it a low surface brightness. Under dark skies however, the 10-inch will show its extent and also reveal some subtle structure. It is a favourite with astro photographers.

NGC 3585 (11 13.3, -26 45) Obvious elongated oval with a conspicuous nucleus.

NCG 3923 (11 51.0, -28 48) Conspicuous roundish haze with a brighter centre.

NGC 5101 (13 21.8, -27 26) Very faint but still visible in the moonlight as a oval haze.

The following fainter galaxies were observed under a darker moonless sky with the 14-inch at Mt Stromlo:

NGC 5182 (13 30.7, -28 08) Very faint small oval with faint stellar nucleus.

NGC 5135 (13 25.7, -29 50) Faint, very small oval with dim stellar nucleus.

NGC 5150-5153-5152 ( 13 28, -29 37) Three fairly faint systems close together, all with a dim stellar nucleus. 5150 and 5153 are extremely close together.

IC 4252-4254-4555 (13 27.5, -27 19) Another three very close together, these galaxies are very faint with tiny stellar nuclei.

IC 4249 (13 27.2, -27 56) Quite a challenge, this one is an extremely faint, very small elongated oval haze. What makes it more difficult is the extreme proximity (touching) of a mag. 10 star which is very bright by comparison.

Globular clusters

NGC 4590 (12 39.5, -26 45) A soft, broadly condensed haze, partially resolved in the 10 inch.

NGC 5694 (14 39.6, -26 32) This globular is quite remote at nearly 100,000 light years. It appears as a small dim hazy spot.

21st NACAA – HOBART

Albert Brakel

Imagine about two years worth of CAS monthly meeting guest speakers, rolled together into an Easter long weekend, and held in Hobart's Wrest Point Convention Centre – would this be a good description of the 21st National Australian Convention of Amateur Astronomers held on 9-12 April 2004? Well, almost. There were some differences – only two presentations lasted an hour, the rest were 40, 30, and down to 10 minutes long, and most of the speakers were amateur astronomers talking about their projects, or other topics dear to their hearts. NACAA is a Convention held every two years in a different city or town, and hosted by the local astro society, with participants coming from every state, and sometimes from overseas as well. After the talk fest, the last day is given over for visits to professional and/or amateur observatories.

As attendees walked into Wrest Point on Good Friday for the registration and cocktail reception, they might have been forgiven for wondering if they had come to the right place, with so many signs directing people to a Psychic Expo. It turned out that the psychics were holding their expo in the area right next door to us.

First up on Saturday morning was the keynote address by Fred Watson of the Anglo-Australian Observatory, Siding Spring, on "Star Wars – Astronomy with attitude". Fred gave an hour-long and very lively account of disputes and competition in astronomy, including astronomers behaving badly. Starring prominently were the vituperative and public 19th-century dispute between South and Sheepshanks, the attacks of bad guy Hubble on mild-mannered van Maanen, and currently the heat that is being generated between normally rational people over what is the definition of a planet.

To give an idea of the range and flavor of the rest of the program of 16 talks, we had: Bright comets of 2004; The star of Bethlehem (an entertaining presentation by Ray Johnston of Hamilton Island); Diamond star Lucy and Hoyle's problem (on how carbon is synthesized in stars); Organizing eclipse expeditions; two on video techniques; The Venus transit of 1874; work by Colin Bembrick on modelling eclipsing binary stars; The solar eclipse of 2006 by Byron Soulsby; and of course the perennial talk on the history of NACAA by John Perdrix.

These days most of the presentations are via PowerPoint – only a few old fogies were still cranking up steam-powered overhead and slide projectors.

The numbers attending (63) were down from previous NACAAs, not because mainlanders were reluctant to cross Bass Strait (the Victorians especially were out in force), but because local registrants were fewer than normal. Lucy Merlino, Byron Soulsby and myself formed the contingent from CAS.

There were two delegates meetings, where astro society representatives discussed things related to holding NACAA, and things of common concern like public liability insurance. It turned out that the Tasmanian organizers had never themselves been to a NACAA, and received no advice on how to hold the Convention. They did well nevertheless, and the communication problem will be solved in future by the formation of a NACAA Secretariate. It was confirmed that the 2006 NACAA will be hosted by the Mornington Peninsula Astronomical Society (formerly the Frankston Astronomical Society) in Victoria. I won't bore you with further details; a full report on the delegates meetings has been given to the CAS Committee.

The Dinner on Sunday night was accompanied by the usual trivia quiz, and the presentation of the Berenice Page Medal by the professional Astronomical Society of Australia to the Australian amateur who is judged to have made the greatest scientific contribution to astronomy. Last time, you will recall, it went to our own RAPT team. This time it was awarded to Colin Bembrick, mainly for his extensive work on asteroid light curves, among other things. To obtain such a light curve, an asteroid has to be monitored throughout at least a full rotation, and this requires input from observers situated at different longitudes around the world. Colin had played a leading part in setting up such an international team.

Monday's observatories visits took us first to Mt Canopus, where the University of Tasmania has three telescopes – a 40-inch, a 16-inch, and a 14-inch SCT. The 14" has been handed over to the custody of the Astronomical Society of Tasmania, in much the same way as we used to have custody of the Oddie on Mt Stromlo, and they are also allowed some use of the 16". The AST has also put up its own 10" reflector in a roll-off-roof shed. The main observing complaint is of course the Tasmanian weather (how lucky we are in Canberra to have only 50% of our nights wiped out). The other complaint is all those auroras that keep degrading the view of deep sky objects! The buildings on Mt Canopus contain a meeting room seating about two dozen people, where the AST holds its summer meetings (the AST is a small society of 76 people at present). Winter AST meetings are held in Hobart.

Next stop was Mt Pleasant, NE of Hobart between Mt Canopus and Richmond, where the University of Tasmania has a 26-metre radio telescope, that was originally one of the NASA dishes located at Orroral Valley south of Canberra. Unusual for a radio telescope, it has an X-Y mount instead of the normal alt-az mount, because it was originally designed to follow rapidly-moving satellites overhead. It is used for observing natural masers (the microwave equivalent of lasers), pulsars, the strength of a collection of radio sources including gravitational lens candidates, very long baseline interferometry (VLBI) including with the VSOP orbiting radio telescope, and measurement of tectonic plate movement and Earth rotational parameters through geodesic VLBI.

Just down the hill from it is a smaller 14-metre chicken-wire dish that continuously monitors the Vela pulsar whenever it is above the horizon (18 hours/day). It is the only telescope in the world dedicated to monitoring a single pulsar. Why does it do this? Because pulsars, as they very slowly slow down their spin (and their pulses), every few years undergo a sudden speeding up, called a glitch, thought to be due to a restructuring of the neutron star forming the pulsar. If a glitch can be observed as it happens, the time it takes can be found, and this places constraints on the properties of neutron matter. The trouble is, glitches are unpredictable, so the monitoring has to be continuous.

The 14-m dish has been monitoring the Vela pulsar since 1983, and glitches have been observed in 1988, 1991, 1996, 2000 and 2002. As the pulses are extremely weak, initially they had to be integrated over a two-minute period. This showed that the 1988 and 1991 glitches took place in less than 2 minutes. After improvements were made so that individual pulses could be recorded, it was found that the 2002 glitch took less than 10 seconds. A further upgrade in sensitivity has since been made, and it will be possible to measure the next glitch with 1 second accuracy (provided the pulsar is above the horizon at the time, of course!).

Our tour was completed with lunch at historic Richmond.

The Convention was a great success, with all those attending enjoying it immensely. Despite the organizers never having run something like this before, they aquitted themselves with honors. If you are interested in attending the next NACAA, I can recommend the experience.

Autumn Planetary Nebulae With The Bedford 30-Inch

Jenni Kay FRAS

There is a small group of us here in the Adelaide Hills who are very fortunate to be invited each month to a night's observing with a very fine 30-inch f/5 Newtonian telescope, owned by Ian Bedford, that is housed in his observatory at Riverton, SA. Riverton is about 100 km north of Adelaide. Even at this distance from Adelaide, the sky suffers from the city light pollution, and typically, the sky here has a limiting naked eye magnitude of 6.5 mag. Very soon, the telescope will be moving to a new location where the sky will be at least 0.5 mag. darker. But even so, the views through this telescope are spectacular, and there have been many occasions where I have nearly had to be dragged away from the eyepiece to give someone else a turn.

On this particular night, 17 April 2004, before we began observing from our list of mostly planetary nebulae, we just had to have a look at Comet NEAT, through 7x50 mm and 16x60 mm binoculars. The unanimous reaction was "WOW!" It showed a very bright, large round coma, intense nucleus, and a long, relatively faint tail. Now this is what a comet should look like! And, the forecast is that it will improve by next month. (My April view of it is appended to this article).

Those present this night included Ian Bedford, Bruce Aldam, Rob Scott and myself, with Peter Andrews joining us between setting up his astro-photos on his own telescope in Ian's second observatory. Most of the time our observing lists include very faint, 15th mag. targets, but for a change, I thought we'd spend our time enjoying some brighter sights, and many of the following objects can be reached with much smaller telescopes.

IC 2448 : 09 07.1 –69 58 (CAR)

120X: This 10.4v mag. planetary was easily seen as a very bright, relatively small, round, blue coloured disc, with soft edges, with a size of 30". The OIII filter really boosted the view.

IC 2501 : 09 38.8 –60 05 (CAR)

360X: At 10.4v mag, the PN was very bright, very small, round disc, with a uniform brightness, and soft edges.

IC 2553 : 10 09.3 –62 37 (CAR)

360X: Very bright, 10.3v mag, very small with a size of 4", blue in colour, and set off by a bright, red star nearby. A most attractive view!

IC 2621 : 11 00.3 –65 15 (CAR)

360X: Very bright, at 11.3v mag, very small, almost stellar in size, with a size of 5".

NGC 2792 : 09 12.4 –42 25 (VEL)

360X: Very bright at 11.6v mag, relatively small, 24" in size, round disc, with soft edges. Appears a little larger in size with the OIII filter in place.

NGC 2867 : 09 21.4 –58 19 (CAR)

360X: Very bright, 9.7v mag, small, round disc, 10" in size, with a smooth glow throughout.

NGC 2899 : 09 27.0 –56 06 (VEL)

120X: Bright, round to oval shaped glow, large, and with the OIII filter there is some interesting structure. There seem to be two brighter spots on the planetary. 360X: The central star at 15.9 mag. can be easily seen, and the two spots seen earlier at the lower power are still present. Overall, the planetary is 2.0' x 1.25' in size.

NGC 3195 : 10 09.5 –80 52 (CHA)

360X: Another interesting sight! This 11.6v mag. planetary is bright, large and round, with a hint of a hole in the middle. With the OIII filter, it seems the dark central region is shaped more like a lens rather than round, and the view looks like a cat's eye.

NGC 3211 : 10 17.8 –62 40 (CAR)

360X: Very bright, small, round disc, where averted vision catches a hint of a very slight, dark spot in the centre. The planetary is 10.7 v mag, with a size of 12".

IC 2631 : 11 09.9 –76 37 (CHA) Bright Nebula

240X: Here there is a bright, yellow star within a relatively bright, relatively large round halo. There is a very good response from the OIII and UHC filters.

NGC 4361 : 12 24.5 –18 48 (CRV)

120X: Rather bright, large, irregularly round glow, with the central star at 13.18v easily seen.

M68 : 12 53.6 –22 52 (HYA) GC

120X: A highlight for the night – very bright, large, round, peppery glow, with stars resolved across and beyond the cluster edge. There is a three dimensional sensation here, with the resolved stars across the cluster glow seeming to lie way in front of the background glow. At 240X the views is breathtaking – the many stars look like a splendid firecracker exploding.

In between views at the eyepiece, while waiting my turn, I slowly swept in views of the Milky Way with the 16x60 mm binoculars. NGC 6231 was looking superb! This cluster is part of a long stream of stars, nebulae, and clusters in the tail of the Scorpion. While each section offers a great view through the telescope eyepiece, in my opinion, it is best seen with binoculars. Also through binoculars of breathtaking status here, are the Sagittarian starclouds, M24 in particular; the nebulae M16 and M17; and back south for Omega Centauri and the Carina Nebula. There's a lot to be said for binocular observing!

Comet NEAT update

8 May 2004. 16x60 mm binoculars. Can easily see it now with the naked eye from Lobethal, where the limiting naked-eye mag. is 6.1, as a very bright, small, round, fuzzy patch, and a hint of a tail. But through the binoculars – My Goodness... The comet has a very bright, large, green coma, with an intensely bright nucleus showing a blue colour. The tail is long and straight and extends well past the edge of the 3- degree view. With averted vision, the tail is fan-shaped close to the coma.