Tähtitieteellinen yhdistys Ursa

Syvä taivas

Deep Sky in the Seventh Heaven

Australia is a dear country to me. My father had lived there for almost 50 years until he passed away in 2006. Me and my brothers inherited his terrace house apartment by the Indian Ocean in the city of Geraldton on Australia's west coast. I visited my dad about every second year since 1988 and since I had already then been an active amateur astronomer for 10 years, it was very exciting to see the southern skies for the first time. Thirteen trips south of the equator have I made so far and I have soon logged every southern deep-sky object that is visible in large binoculars, in fact, more than a thousand objects. Therefore, it felt tempting to buy a midsize telescope which I would keep on-site and I had not to lug instruments from Sweden next time.

Those who have studied Pierantonio Cinzano's global light pollution maps have certainly noticed that most of Australia is colored black. The colors tell how dark the night skies are. Black means that the sky is <1 % brighter than the unspoiled, natural night sky. Red color means that the sky is >900% brighter than the natural level. It corresponds to an increase of the sky's surface brightness by <0.01 and >2.4 magnitudes per square arc-second, respectively. Europe, eastern USA, Japan etc baths in yellow, green and red on the map. I knew by experience how dark the night skies are in Western Australia, so I wanted to quantify it with a newly purchased Unihedron Sky Quality Meter - Lens. A sky with the surface brightness of 20.0 magnitudes per square arc-second can normally show stars down to magnitude 6.0 to the unaided eye. A SQM 21.5 sky is considered true-dark and is usually sufficiently dark for the most demanding observations. A pristine sky totally devoid of anthropic light pollution can reach the surface brightness of 22.0 magnitudes per square arc-second (in clear skies). Much darker than that is not achieved anywhere on Earth because our atmosphere glows faintly with its own light, the so called airglow, more about it below. The Milky Way, zodiacal light and northern (or southern) lights also contribute and these light-sources are inevitable.

Since my apartment in Geraldton is most of the time unoccupied, the southern sky is an argument for interested amateur astronomers from the northern hemisphere to stay there. The Finnish amateur, the deep-sky observer Iiro Sairanen, asked me in the autumn 2008 if the apartment was rentable in December-January 2009-2010. I knew this talented, young amateur since a couple of years. He would bring his 4.5-inch light-weight Dobsonian and another Finnish amateur amateur astronomer, Esko Luukkonen, would acccompany him and they would stay in my flat for about six weeks. I offered them me to travel to Oz in advance and arrange for their living, buy an air-conditioning system etc.

Arriving to Geraldton

At the end of November 2009, I flew to Perth via Singapore and next morning I caught a Greyhound bus for a continued 430 km travel north along the west coast. I would stay at the neighbour, my father's friend and coincidently (!), the amateur astronomer Pauli Jeronen. In the last minute, I happened to recall that it is forbidden to bring in fresh, untreated wooden material into Australia without permission and Iiro's Dobsonian mount was made of veneer and plywood! He was prepared to let the telescope be confiscated in a worst case scenario should the customer officer consider that there was a risk that the wood was containing foreign insect eggs. Australia tries to avoid spreading plant diseases and they are very keen on preserving their endemic fauna. Fortunatelly, the telescope went through the customs satisfactorily.

Iiro and Esko arrived a week after me to Geraldton. They had not experienced the southern skies before, so despite some acquainting themselves with the skies with planetarium software, they had initially some problems identifying the brightest stars under the real sky. Iiro had also brought a Sky Quality Meter. From my backyard, the SQM-apparatus showed the value 20.2 and the limiting naked eye magnitude was close to 6.2 after midnight. Yet, we regarded the sky as being way too bright, so we decided to regularly drive out from the city with a rental car. The nearest city outside Geraldton is Perth (430 kms south), towards north there are no larger towns and to the east there are only some minor villages, farms and desert practically all the way to the east coast of Australia, some 3500 kms distant! To avoid all the light pollution from a metropolian area, one has to drive a few hundred kms. Even minor villages brightens up the sky as seen from tens of kilometres distance even when the light domes from the villages can be seen mostly near the horizon. Western Australia has an area of 2.5 million square kilometres (like western Europe) and has a population of only 2.2 million, whereof 85 % of them lives in the southwest corner of the state. Thus, it is a simple matter to find light pollution free regions in this part of the world.

I knew of an emigrated Swedish farmer who has a remote farm 130 kms east of Geraldton. I had already in Sweden corresponded with him and asked if we could visit his ranch during the new-moon period and study the starry skies. No worries, we could use his facilities as we wished, because it had been abandoned for a few years. The very same morning as my Finnish friends would arrive with the bus, the farmer drove me to his ranch, Nangerwalla, for my inspection. The entire farm, including 1074 acres of land (mostly wheat and vineyards), were for sale. The site was a little bit tumbledown and there was no electricity present anymore since the farmer currently lived in Geraldton. The population density is a quite good measure of the amount of light pollution and in this region there were less than 1000 people living within a radius of 100 kms, i.e. <0.03 inhabitants per square kilometre! There were no places with more than 500 people within >100 kms in any direction as the crow flies.

Nangerwalla farm

We drove here around New moon on December 16 when the sky would be at its darkest. We noted that some parts of the sky, especially the southwestern horizon were covered by smoke from bush fires. The border from where the smoke barrier could be seen went approximately at the farm. The sunset were therefore red and one could look directly at the sun. We hoped that the smoke would disappear for the night, which it did! The horizon was practically 360° free from obstacles since the landscape was quite flat. Even if this site was completely free of man-made light pollution, there was one problem at this open space, the wind. It was constantly blowing from south, so not to let it shake the telescope tube and not to let my star charts flap in the gales, we found that some larger bushes reduced the wind greatly and scattered it. Standing behind our car made quite the opposite effect due to the vehicle's aerodynamic shape!

In the twilight, we saw the zodiacal light with Jupiter in the middle, shining stronger and stronger. The origin of the light is microscopic dust in the ecliptic plane. Finally it became annoyingly bright. The zodiacal cone in the west was pyramid shaped, stretching upwards, getting thinner and the band continued along the ecliptic all the way to the eastern horizon. Just before crossing the Milky Way, the zodiacal band grew somewhat brighter and formed a 10-15 degrees wide, roundish glow. This is the counterglow (Gegenschein) and shows the antisolar point on the ecliptic. One could use the Gegenschein as a kind of a nocturnal sundial! Despite being close to the Milky Way in Taurus, and having rather low contrast to the Galaxy, the counterglow was still relatively obvious. The counterglow and the Milky Way had a different texture in their light. The light from the Galaxy was unevenly distributed while the Gegenschein was smooth and very diffuse. As seen through binoculars, the entire Milky Way was marbled, that is, all the fields were peppered with small, black spots between the stars. They looked like tiny dark nebulae in the midst of brighter nebulae.

I found the short-periodic comet 88P/Howell smack in the bright zodiacal light in Capricornus. The light did not hinder me to see comet Howell well. With my 25x100 binoculars on a Saxon tripod, I estimated the comet as magnitude 9.5, coma diameter 4' and he degree of condensation (DC) as about 3 (rather diffuse).

My new magnitude record

The darkness fell swiftly upon us and my guests saw the grandest starry skies that they had ever experienced! Iiro had observed from 2280 metres altitude in Tenerife on the Canary Islands but these skies were more overwhelming. It took about ten seconds for the apparatuses to collect enough light since our SQM-meters showed up to 22.01 magnitudes per square arcsecond tonight and our devices did not differ by many hundredths, so the values were convincing. It does not get substantially darker than this anywere on Earth, not even at the professional observatories in Chile, Hawaii, Canary Islands etc. We performed naked eye limiting magnitude tests. Iiro was able to glimpse stars of magnitude 7.8 in Lepus. I concentrated instead my vision towards the relatively star poor region in Fornax which was nearly overhead. I used my -0.5 diopters over-corrected glasses which make every star, even the brightest ones, to appear as a pinpoint. For solely this purpose had I printed out charts but with the magnitudes omitted. I marked those stars I could detect on the map, going progressively fainter. Stars of magnitude 7.4 could I perceive nearly continuously, but with difficulty. Stars of magnitude 7.6 was seen only part of the time, with effort. The dimmest star that I could discern, maybe 10% or less of the time, with occasional glimpses and averted vision during about 20 minutes of concentration, was of V-magnitude 7.9! It broke my previous personal record from the Peruvian Andes at 3780 metres of altitude in June 1996 which was magnitude 7.7. Nangerwalla is only at 250 metres altitude but the extinction difference at zenith between sea-level and 4000 metres is only about 0.1 magnitudes.

With my 25x100-binoculars I took the opportunity to observe two dwarf spheroids and an irregular galaxy in our Local Group of galaxies. These are the dwarf systems in Sculptor and Fornax and these galaxies lack NGC-numbers. They were discovered on photographs exposed for almost 24 hours in the beginning of the last century and were initially regarded as plate faults. Sculptor Dwarf has the incredibly low surface brightness of 26.0 magnitudes per square arc-second! The third galaxy was IC1613 in Cetus. IC1613 is without doubt the most difficult target in Patrick Moore's Caldwell list of 109 DS-objects outside the Messier-catalog. All these three galaxies appeared as very large, ghostly, diffuse glows without brighter central parts and they were best noticed when I swept the fields back and forth with the binocular. Fornax Dwarf harbours a number of globular clusters orbiting it. The brightest of these, NGC1049 of magnitude 12.6, were seen as a stellar object. I do not know of anyone else who has reported this 460 000 light years distant globular with binoculars. Up to now, I had logged 16 galaxies in our Local Group.

From here I also found comet 217P/LINEAR in Orion. I had failed to see it from Sweden with my Celestron-8 telescope earlier in the autumn but from here it was even evident with binoculars. Comet LINEAR was faint, of magnitude 10.8, coma diameter 5' and DC 2.

I observed a couple of lesser known open starclusters in the southern Milky Way and these are catalogued by the Swedish astronomer Lars-Olof Lodén. These clusters were Lodén 1409 in Circinus, Lodén 1378, Lodén 1289, Lodén 894 and Lodén 1002 in Centaurus. Lodén's starclusters are usually not remarkable and often it is even difficult to see any increased concentration of stars in the field. The finest of these were Lodén 1378.

A curious detail I accidentally happened to notice were stars reflected on the rental car's plate. I recognized the constellation Orion's mirrored reflexion and even the Orion nebula could clearly be seen on the paintwork!

Herschel 400

After you have gone through the entire Messier catalog, which I have done with, for example 50 mm binoculars, the next natural step is the Herschel 400 list. It is a selection of DS-objects which William Herschel discovered at the end of the 18th century. I had logged each of the 400 objects so far, except the most southern one, the galaxy NGC3621 in Hydra, which has the declination -32°49'. It was plainly visible from here with 25x100 binoculars. The galaxy reminded me of M108 in Ursa Major which is also cigar shaped and has several (Milky Way) stars superposed or close nearby.

We observed all night long in these fantastic conditions. Just before sunrise we tested for how long we could hold Sirius in vison naked eye. It got dimmer and dimmer when the Sun crept nearer the horizon. One careless blink with the eye and the star could be lost. I did that in fact once, but luckily I could find Sirius again against the blue sky. At the same time when the sun's first rays illuminated the landscape, I lost Sirius from sight for good this morning. By the way, the SQM-meter showed the value 7.0 magnitudes per square arc-second in zenith at sunrise.

Venomous spiders

We tried to get some sleep in the middle of the morning but the growing heat made it impossible. A flock of parrots had gathered around a large water tank just outside the slide-door and their cackle sounded like they were indoors. We even got some visitors who were prospective buyers of the farm Some of them warned us for snakes which could easily wind in through the door openings. We actually saw curling marks of snakes outside the house. The evening before, I took out a chair from the corner of the room and happened to bump against a spider web beneath the table-top. Today we found out whose net it was. The owner was a Redback spider which is a cousin to the American black widow. The Redback is about as poisonous as a Swedish black adder snake and the spider usually bites when it gets provoked and when its net is touched, like I did! A much larger spider's dry remnants were hanging there. My father got bitten by a Redback a number of years ago in his backyard and his foot swelled up and he had to be hospitalized a few weeks. In the afternoon, an irritating blowfly flew around our room and we got to witness when it finally ended up in another spider's net, the Daddy longleg spider. We studied closely how the arachnid very rapidly spinned the fly in a cocoon and bit it several times. The blowfly tried in vain to get loose, buzzed maybe a minute before it went silent. It was fascinating to study nature in action from extremely close range.

Next night looked even more promising because the sun was dazzlingly bright at sunset. Even prior to sunset, I managed to find Jupiter naked eye quite easily. The sky towards WSW, above the sun, was purple colored before the end of civil twilight and this feature has its own name, the so called Purple light. Now we found the 23 hours 34 minutes young lunar crescent and Mercury 10° above it. The length of the arc was not much longer than about 90°. The crescent was particularly difficult to view since it was in apogeum a few days earlier and it had not receded so far away from the sun during this time. The crescent had a topocentric elongation of 10°.2, phase 0.795% and its width was just 14.2 seconds of arc.

Crickets (nocturnal grasshoppers) commenced their chirping and the atmosphere was like in the wild west, and it certainly was, the wild Western Australia! A bat had gone astray into our house but we managed to shoot it out again. Even when it was still a bit over +30° C hot, it was safest to wear long trousers in case of snakes and spiders outdoors. We brought out our instruments behind the same bushes where we observed the night before. The irritating swarms of small flies which plagued us in daytime were gone like magic in the darkness. Apparently, they have a lousy night vision or they are evening tired / afraid of the dark!

The Caveman and airglow

Esko had with his 10x50 Bresser binocular (puchased from Lidl department store) found a funny asterism somewhere in the Milky Way in Puppis or Vela. The interesting detail with it was the fact that the stars made up a raging caveman figure brandishing his club with his hand. An orange star was the troglodyte's navel. Under his feet was a nebula or a starcluster with very faint members. I forgot to look up their more exact positions but I suspect they were the open starcluster NGC2467 and the nebula Sharpless 311 in Puppis.

It was still +28° C when the astronomical twilight ended. It felt marvellous to be able to observe in short sleeves all night long. Actually, I got thirsty in this dry air, so I had to wet my whistle with water regularly. The dry semidesert air is of course a contributory factor for the exceptionally good transparency.

Tonight was even slightly darker than the night before. We measured the sky brightness as SQM 22.09 (when not pointing the device towards the Milky Way or the zodiacal band)! According to the Bortle scale, a Bortle class 9 sky is a metropolitan night sky while Bortle 1 is a site completely devoid of artificial light pollution and where no trace or just minor light domes can be glimpsed somewhere at the horizon. Nangerwalla had naturally a clear Bortle class 1 sky. He describes that under these conditions, it is so dark that you have problems to discern the surroundings, the telescope etc. This is utter nonsense! When your eyes have been fully dark adapted, all people, instruments, white charts, eyepieces etc are seen with the aid of starlight only. We were observing quite close to each other and walking around the place and not a single time in two nights did we bump into each other or other instruments since they were all visible, at least with averted vison! Our eyes were not exposed to white light during the entire night so we were dark adapted for some 10 hours.

Airglow is a phenomenon which I had not paid much attention to before. It was actually discovered by the Swedish physicist Anders Ångström in 1868. It manifests itself as a slightly brighter band 10°-20° above the horizon. It has nothing to do with twilight or light pollution but is an intrinsic property of our atmosphere. Air molecules in the upper atmosphere which were photoionized by the sun during the day are recombined at night. This process emits visible light. Luminescence from cosmic radiation also cause airglow. That is why the sky never gets totally black anywhere on Earth. Airglow is everywhere but is readily visible to the naked eye only in the best of skies. The phenomenon is dynamic and varies during the night and with the solar activity. We noticed that the airglow was brightest to the north and possibly its brightness varied over the night. Airglow did not extinguish starlight so much to speak of, since we could follow the dark Coalsack nebula grazing the southern horizon in the middle of the airglow band. In fact, airglow should have been in its faintest phase now since we were still in a solar minimum.

The Coalsack makes up the Australian Emu bird's black head. According to the aboriginal mythology, is the Emu a huge dark bird figure in the Milky Way, which body begins in Ophiuchus / Scorpius, the long neck consisting of numerous dark nebulae along the Galaxy and ending with the Coalsack in Crux. The brightest star in it is a 5.4 magnitude star which can be considered as the Emu's eye One can enjoy this majestic black Milky Way feature best in the winter in June-August when it can be seen in its entirety high up.

The zodiacal band and the Milky Way formed a heavenly cross in the sky. It looked like as if the Galaxy was divided in two lanes in Taurus where the Gegenschein shone. Not too many have seen the Milky Way cast shadows. To really see this, I simply move my hand over my starcharts and follow the diffuse shadow beneath my hand. It does not necessarily have to be our Galaxy which casts a shadow since the integrated light from the whole night sky exceeds the Milky Way's.

The light bridge of the Large Magellanic Cloud

The journey's most exciting and unexpected sky phenomenon that we observed, was without a doubt, the light or materia bridge (as I call it) of the Large Magellanic Cloud, LMC. It is not even scientifically studied yet and only a handful of people have reported it in the literature! Lowell astronomer, Brian Skiff, confirmed my description of the 'thing' and he had seen the bridge from Las Campanas observatory in Chile. US amateur, David Riddle, had noticed this bridge while being in Namibia. Apparently, the first who reported this light bridge in the astronomical literature was the Russian born astronomer Sirgay Gaposchkin in his article The Visual Milky Way in Vistas in Astronomy, vol. 3. He had sketched the object from Mt. Stromlo observatory while he scrutinized the southern Milky Way during the years 1956-57. Isn't it strange that only northern observers have reported this phenomenon when they have visited the southern hemisphere?

With our unaided eyes, we noted how the light band reached from the LMC, went due south, passed the south celestial pole and continued along a great circle towards the Norma starcloud in the Milky Way. The materia bridge was nearly as wide as LMC itself and more than 40° long. In surface brightness it was comparable to the faintest part of the zodiacal band and maybe half of the gegenschein's. In the beginning of the night, it reminded me of a waterfall that disappeared into the airglow near the horizon. Later in the night, this phenomenon had rotated clock-wise around the south celestial pole which proved that this was indeed an astronomical feature and followed the earth's rotation. The materia bridge disappeared in Triangulum Australe, near its alpha star, Atria. It is most remarkable that nobody (as far as I know) has taken photographs of the light bridge! It is neither visible on Axel Mellinger's panorama of the Milky Way which reaches the surface brightness level of about 24 magnitudes per square arc-second. This phenomenon shall not be confused with the Magellanic Stream which is only visible in radio wavelengths and goes in other direction. My theory is that our observed light bridge is the combined light from millions of faint stars or gas that Milky Way has ripped off from our satellite galaxy due to tidal effects at an earlier close passage. The light can also originate from intergalactic cirrus, like those clouds that can be seen near M81 in extremely deep photographical exposures. Spectroscopic analyses of the light should settle this matter. Curiously enough, the southern celestial pole is involved in a faint band of light while the northern pole, near Polaris, is the starting point of a dark lane in the Milky Way (have you seen it?).

NGC 3372, Eta Carinae Nebula. © Timo Karhula.
Coalsack, a dark nebula in the southern Milky Way. © Timo Karhula.

A selection of DS-objects in the dawn

NGC 2442 in Volans is a beautiful S-shaped spiral galaxy on photographs. It is sometimes called the 'Meat-hook Galaxy' due to its appearance. With my 25x100, I could not really discern its spiral arms. NGC625 is the brightest galaxy in the constellation Phoenix. Now, I had logged at least one Deep-Sky object in every constellation so far except Microscopium.

The Eta Carinae nebula (NGC 3372) in Carina shares with the Orion nebula the title of being the heaven's grandest. I peeked with Iiro's 110mm Dob equipped with an O-III nebula filter and the view was indescribable. The nebula was so bright and detailed and was so sharply delineated that it looked like a painting. Since it is two degrees in diameter, I had to sweep with the telescope in order to frame the whole nebula. The central star Eta Carinae is a supernova candidate and will within tens of thousands of years illuminate the southern skies.

Southeast of the Coalsack lies the emission nebula Cederblad 122. It is so big, 2°.5 in diameter, that it stretches over two constellations, Centaurus and Musca. First I believed it was not a visual object but with the 25x100 binocular, and no nebula filters, I could actually follow the nebula's borders over the very rich star regions. It was not round but had several bulges on its edges. Ced 122 is relatively unknown and is not included in the standard observation guides and is seldom mentioned in the literature as a visual object.

The planetary nebula NGC5315 in Circinus could I identify in a funny way. There was a star of 10-11th magnitude on its position. When I placed a Baader O-III filter in front of one of the 25x100 oculars, this star suddenly shone as bright as a star of 7th magnitude in the same field of view according to the Uranometria atlas. When I moved the nebula filter back and forth, all the stars blinked, except the planetary. It meant that the stellar nebula kept its brightness while the stars were dimmed by more than three magnitudes.

The Southern Pleiades, IC2602 in Carina, is a competitor to our northern original. With naked eyes, I was able to count seven stars here within 1°.2. The lucida, theta Carinae, is a tad brighter than the Seven Sisters' brightest star, Alcyone. M45 wins only by a small marginal over IC2602 in total brightness.

In the dawn, I noticed that the globular cluster omega Centauri (NGC5139), was situated 2° north of a perfect 1°.3 wide semi-circle of eight 6-8 magnitude stars that reminded me of the constellation Corona Borealis. I had not seen or heard about this prominent asterism before. The radio galaxy Centaurus A (NGC5128) nearby looked like a hamburger where the steak consisted of the central, dark dustlane.

The last objects in the dawn had to be of Saturn and Mars. With Iiro's 110mm Dobsonian telescope and 165x magnification we saw easily Saturn's thin ring and Mars' northern polar cap and some darker markings on its surface when the red planet's diameter was only 11 arc-seconds.

After two all-nighters, >19 hours of effective observation time and 51 hours without sleep, I was quite exhausted. Esko had slept a few hours in the rental car after midnight, so it was safest that he drove us back to civilization at sunrise. Already after a few kilometres, we finally got to see kangaroos and it was a whole flock with a dozen of Red Kangaroos leaping in front of and alongside our car. They are hard to spot in daytime since they are resting in the shades and the 'Roos are typically nocturnal or crepuscular.

A 10 inch telescope ordered

I placed an order for a 10 inch (25cm) f/4.7 SkyWatcher Dobsonian telescope on Internet from Sydney and which arrived to the front-door a few days before Christmas, on December 21. It was an early present from Santa Claus and we tested its performance from Pauli's backyard the very first night. With my Baader Hyperion 8-24mm zoom ocular's highest magnification, 150x, we could resolve the Trapezium, the multiple star in the heart of the Orion nebula, into six components. It was a good sign.

Neptune had a triple conjunction with Jupiter in 2009 and now at Xmas they would have their last mutual conjunction for more than 12 years. Both planets were simultaneously seen in the field of view, separated by 32'. This observation reminded me of Galileo Galilei's who accidentally plotted Neptune near Jupiter on 28 December 1612, without knowing that the 'star' was a new planet. The tiny disc of Neptune could be seen comfortably with 150x power.

Next evening we wanted to use the new scope under dark skies. Alas, it was varying cloudiness but we hoped that the clouds would disperse further in the inland. We drove for several hours and more than 200 kms on rough, wash-board roads, and the clouds did not dispel, on the contrary. Here ran hundreds of small wild rabbits across the roads and I do not know how many we ran over during the night.

The night before Xmas Eve would be all clear so we packed all our stuff in the rental car. It was impressive seeing that there was room enough for two telescopes, several binoculars, three observing chairs and three astronomers in the compact Hyundai. We drove some 50 kms due east to a place called Wicherina, where Iiro and Esko had observed a few times so far during their stay in W.A. The site was just by the main road but still behind bushes, so that the searchlights from the up to 56 metre long road-trains were blocked. It was nearly as dark here as in Nangerwalla. I could quite quickly find a star of magnitude 7.4 in the Lepus rectangle and after moonset, the SQM-meter showed the sky brightness as 21.93 magnitudes per square arc-second. Even from here could we glimpse the mysterious light bridge of the Large Magellanic Cloud since we knew what to expect.

The Large Magellanic Cloud (LMC). © Timo Karhula.
The Tarantula Nebula, located within the LMC. © Timo Karhula.

Starcluster hopping in the LMC

I wanted to study deep-sky objects in LMC, so I employed only one eyepiece the whole night, the high quality Baader Hyperion 8-24 mm zoom. It gives magnification between 50 and 150x. Tarantula-nebula (NGC2070) is considered by many as the most beautiful nebula in the heavens and indeed looks like its namesake, the bird spider, with its curved nebula arcs as its legs. The whole area was full of bright and dark spots of nebulosity and surprisingly detailed while being at the distance of 170 000 light years.

From the Tarantula, I starCLUSTERhopped to every Deep-Sky object in the Large Magellanic Cloud that are plotted on Uranometria (2nd edition) detailed chart A25. In 6 hours, I saw about 130 DS-objects within 2° from the Tarantula, of which 20 of them were not plotted on the chart and therefore anonymous and lack any NGC/IC-designations. Back home in Sweden, it was a detective work to identify my anonymous fuzzies. Mati Morel in NSW also kindly provided me with his LMC Visual Atlas and Selected Areas of cluttered regions. These obscure DS-objects have I found in very special catalogs or what do you think about Shapley-Lindsay (designation SL), Henize (Hen), Lucke-Hodge (LH), Hodge-Sexton (HS), Kontizas-Morgan-Evangelos-Kontizas (KMKH), Bica-Schmitt-Dutra-L. Oliveira (BSDL), OGLE (starclusters catalogued during the project Optical Gravitational Lensing Experiment), Bica-Claria-Dottori (BCD) and Bhatia-Read-Hatzidimitriou-Tritton (BRHT)?! Not even the second edition of Uranometria atlas (the southern volume) was error-free and I discovered many clusters being more or less plotted in a somewhat wrong position. The emission nebula NGC2052 was too large depicted on the map and some sources give a grossly oversized dimension. I had brought the third volume in the series The Night Sky Observer's Guide and the book describes visual observations of most NGC-objects in the Cloud. In LMC, there were still a few globular clusters (actually, most of them have been reclassified as open clusters) that I had not yet seen. I finished my project by finding the V=13.5 magnitude NGC2257 (a bona-fide globular) and now I had observed every globular cluster, both galactic and extragalactic, in the entire NGC-catalog! NGC2257 is the dimmest globular cluster of them all. I estimated that I could reach to magnitude 16 visually tonight with the 25cm telescope.

The brightest globular in the sky, omega Centauri, was fabulously beautiful in the light of the dawn. It looked like someone had poured a handful of salt in the whole field of view. Close to its centre, there were a few darker spots and especially a 'footprint' was conspicious. Omega's closest rival, 47 Tucanae, was somewhat smaller but possessed a considerably more compact core. It was so brilliant that the centre was yellowish.

NGC 5139 (Omega Centauri). © Timo Karhula.

An unusual Christmas spirit

This was the first time I celebrated Christmas in Australia. In the Xmas day morning, I swam in the turquoise Indian Ocean. I did not feel any normal Christmas spirit since it was +39° C in the shade (and no snow!) and we ate Christmas smorgasbord outdoors. No ham but instead lamb, prawns, potatoes au gratin etc. From Pauli's family I got an akubra as a present. It is a brush hat worn by Australian cowboys.

The gibbous moon grew brighter each night after Xmas, so I had to wait until the small hours to get darkness. I had my last observing session on Boxing Day morning with the 10-inch in Geraldton. I continued viewing starclusters and nebulae in the northern part of LMC. My tally so far is 271 DS objects in the Clouds and there may be a thousand more objects to study with larger apertures for many years to come.

The most exotic object tonight was the newly discovered starcluster ESO 92-18. It is situated in the southern part of Carina, 3° west of the Southern Pleiades and is plotted only on the most recent and detailed star atlases. Here I saw a faint, large, hazy glow with some faint stars in it. I was a little bit surprised to know that the brightest of the approximately 1100 stars are only of magnitude 15.7. The distance is a whopping 31 000 light years. In the image from the Digitized Sky Survey it looks like the brightest stars are just foreground stars and the faint cluster is globular-like. I have not been able to find any other visual sightings of ESO 92-18 despite some inquiries on astronomy communities, so my observation can have been a 'First visual'.

My flight back home to Sweden was on December 29. My Finnish friends stayed another two weeks in my apartment. Luckily, I managed to install an aircondition system before my departure since there came some heatwaves in January. I had experienced four days with at least +40° C in December but after New Year the highest official temperature was one day +46° C in the shade! The summer in Western Australia became the hottest ever recorded and Perth did not get one millimetre of precipitation. It was naturally a minor shock for me arriving to Stockholm in thin summer clothes when it was almost -20° C the day before New Year's Eve.

Iiro and Esko got to use my 10-inch telescope and Iiro told me afterwards that he had observed deep-sky for about 100 hours, the double amount that I managed to. He was more than satisfied with his trip to Western Australia and highly recommends it to every DS-observer and photographer. For you who wants to experience the relaxed lifestyle Down-Under, especially that in W.A., and marvel at the darkest night sky in the world, can rent my apartment. The terrace house is visible on Google Earth at the coordinates: latitude -28°45′40″.8, longitude +114°37′08″.1. Please contact me for further details. Maybe you will be the first who images the Large Magellanic Cloud's mysterious and virtually unknown light bridge?

Clear and Dark Skies!

© Timo Karhula / Webb Society 2011-. Republished with the permission of the author.

RSS Zeniitti

RSS Taivaanvahti

  • Syvä avaruus NGC 5128 IV 24.5.2020 klo 21.00, Hakos Farm, Tapio Lahtinen 4
  • Syvä avaruus Supernova SN2020jfo IV 23.5.2020 klo 1.22-1.44, Orimattila, Kari Laihia (ryhmä)
  • Syvä avaruus M81, M82 IV 21.5.2020 klo 1.00, Fregenal de la Sierra, Tapio Lahtinen
  • Syvä avaruus Supernova 2020hvf II 18.5.2020 klo 22.00, Fregenal de la Sierra, Tapio Lahtinen
  • Syvä avaruus Supernova 2020jfo II 18.5.2020 klo 21.20, Fregenal de la Sierra, Tapio Lahtinen
  • Syvä avaruus M61 III 9.5.2020 klo 1.00, Jyväskylä, Petri Tikkanen 1
  • Syvä avaruus NGC 7000 V 1.5.2020 klo 0.00-0.00, Lahti, Jussi Saarivirta 1

RSS Avaruus.fi-foorumi