MARE NEAR RIMA HYGINUS
THE RADIAL STRUCTURE OF MARE NEAR RIMA HYGINUS
By Ivor Clarke
This drawing shows the rill Rima Ariadaeus passing the 13 km crater Silberschlag top left and running parallel to the Rima Hyginus for a while before it disappears. A faint rill, Rima Hyginus I joins them both at an acute angle. Both rills are shallow, flat bottom surface features about 100 to 300 m deep and up to 2 to 5 km wide and up to 220 km long. The processes which caused these formations is unknown, possible lava flows. The large crater at the top right is Agrippa (46 km), filled with shadow with only its west wall lit. At the start of this observation the terminator was close to this crater but by the time of completion had moved another 50 km or so, revealing the faint linear ridges across the mare: this was the final area to be drawn. To the south a faint set of high-lighted hills could be seen, very dull, these must be rough bolder strewn areas for most mountain peaks show as bright spots of light when catching the sun. Hyginus W, is the elongated crater like feature just in view. All of this area is part of the outward gradation of Imbrium ejecta deposits and is classed as part of the Fra Mauro Formation in the Lower Imbrian Series, this gives a time of 3.85 aeons ago. All of this area has very subtle landforms, the gentle undulating surface only shows features under a very low sun angle with early morning or late evening lighting. The drawing is mixture of crayon and ink on cartridge paper, then reduced in copying.
TIME: 1994 / 4 / 17 at 20.40 UT to 21.50 UT
MOON : 6 days old, Colong 353.1 Lunation: 882
CONDITIONS : Good, cold and clear, seeing 9/10, shimmer 7/10
INSTRUMENT : 102mm Refractor at x135 & x180
The Rhythms of Life
by Ivor Clarke
We all enjoy the rhythms of music, the rhythms of the day and night. The rise and set of the sun and moon. The seasons and the years. All this change we take for granted as the way our planet and nature works, we hope it will continue without too much alteration. From the earliest days of mankind we have recorded the passing of time and have observed the heavens filled with stars and planets and our Moon.We know each day brings a small change in the length of time the sun stays above the horizon, longer each day in spring and shorter in autumn. We also know that each year repeats itself, even if the weather is different, and that the same stars will rise and fall at the same time every year. As far as we humans are concerned, the only change belongs to the planets in the solar system. These travel along their orbits and are forever in a different spot in the sky every day. Or are they? The Earth completes an orbit of the sun in a year of 365.256 days and the Moon goes round the Earth in 27·3 days. Mercury orbits in 88 days and Venus in 224·7, Mars 687 days, Jupiter 11·86 years and Saturn 29·45 years, Uranus in 84 years, Neptune in 164·8 years and distant Pluto in 248·5 years. This arrangement has gone on like this for maybe nearly a third of the life of our universe!
An amazing thought. So let us start at the beginning and look at the length of our day. It was not always 24 hours long. Very early in the history of planet Earth, it was about half what it is now, something less then 12 hours. This fast spin may have been caused by the body which crashed into the early Earth, causing the Moon to form in low orbit from the splash of its impact smashing into our planet. This impactor is suspected of being a body larger in size than Mars. Luckily this happened about 60m years, after the formation of the Earth, so the consequences weren't as dire to any life forms as they might have been! This crash could also have given our planet its inclination of 23.5°. However this tilt alters over eons as the Earths core moves slightly differently to the rocks above it. At the present time the core spins a quarter of an hour quicker per year than the surface! The Moon is also responsible for holding the axis of the Earth in an upright position and not allowing it to tilt to far over, such as the planet Uranus giving us month long days twice a year. The effect of the Moon on the oceans is slowly slowing down the length of the day by friction of the tides on the land masses. The transfer of angular momentum is pushing the Moon further out so its effect will lesson as its orbital distance increases. The Sun too has its rhythms with the well known sunspot cycle of 11·1 years, although this is known to vary between 8 and 16 years. The magnetic fields of the sun have a period of twice the sunspot cycle at around 22 years. The magnetic fields inside the sunspots exchange polarity in successive cycles with a preceding spot first having northern polarity and the following spot southern polarity, then reversing for the next cycle. While all the planets orbit the sun in the same direction (anti-clockwise from a position above the north pole) and roughly in the same orbital plane. They also interact with each other through the small gravitational pulls each makes on the other as they pass by. Most of these interactions will, over the life time of our solar system, cause a small shift in the position of a neighbouring body until it balances with the other forces acting on it. So most of the planets orbit the sun in a resonance with other bodies which keeps them locked in position. These are small but significant over time, for instance, the mass of Jupiter is 1/1000 that of the sun. This causes the sun to move in a small circular motion around a point opposite to were Jupiter is in its orbit. All the other planets pull on the sun too, but because of their lower mass their effect is much smaller. Venus and the Earth repeat their positions in respect to each other after 211 years when a double transit of Venus will occur with a gap of 8 years. There will also be a double transit after 105·5 years after the last transit but this takes place on the other side of the sun, either in June or 6 months later in December. Likewise the Moon returns to the exact position it was in, in its orbit after 18 years, 111/3 days, (for a 4 leap year span). This is the Saros cycle of 223 lunations or 6585·32 days. This was known to the Chaldeans more than 2,000 years ago. They discovered this cycle by observing solar eclipses, and noting that they returned to the same longitude after 54 years, a triple Saros. The Sun of cause holds its grip most of all on Mercury as it speeds on its 88 day orbit. It was expected that it would have a gravitational locked rotation to the sun with one side hot and the other freezing. So it was a surprise to find in 1968 that it rotated in 58·7 days, exactly two-thirds of its orbital period. Mercury transits the sun at intervals of 7, 13, and 46 years, according to circumstances, when it either transits in November (more common) or May. This cycle will then repeat itself. What we are seeing is that all of nature is governed by rhythms caused by the interaction with other objects. All the bodies in the solar system effect each other, the larger obversely having a greater effect on the smaller. Don't forget that the Earth is the fifth largest body in the solar system, so has a large influence on all the inner planets. Further out the asteroid belt between Mars and Jupiter is not a smooth spread of objects. It has groups of concentrated material at resonance points. Other resonances points in the asteroid belt are marked by gaps called the Kirkwood gaps which are caused by Jupiter's gravity. This has, over time, cleaned out areas by the slight tugging caused by Jupiter's gravity on the smaller bodies orbiting faster than Jupiter. Asteroids orbit in exact fractions, 3/4 and 2/3, of Jupiter's orbit safely, but other fractions 1/2, 1/3, 3/5 etc. cause gaps and holes. This is not the same mechanism which forms the fine ring structure in the rings of Saturn as seen by Voyager; the F-ring shepherd satellites Prometheos and Pandora exchange orbits when passing each other. Most of these rings are caused by small bodies in orbit clearing out particles in their orbit. With Jupiter it is resonances of the orbital times which cause the groupings and the gaps. One of the more remarkable orbits concerns the minor planet 1986 TO, asteroid number 3753. Its orbit takes it just out side of Mercury's orbit to a little beyond Mars! This makes it one of the numerous Apollo family of bodies which come within Earth's orbit, but the strange thing about its orbit is that the semimajor axis (which means its orbital time) varies from being just under 1 a.u. to just over 1 a.u. every 770 years. It is not quite a 1 : 1 resonance with Earth. What happens is that it spends 385 years slowly catching up with the Earth's position in space and then swops energy with the Earth to spend the next 385 years slowly dropping behind again until the Earth catches it up and gives it a little push to help it complete the cycle! Its orbital period varies between 363.67 and 366.85 days in each half of its cycle. Other moons in our system are in resonance with their planet, for instance the three inner Galilean moons of Jupiter, Io, Europa and Ganymede follow a 2 : 1 resonance with each other. Io orbits Jupiter in 42.5 hours, twice to Europa's once and Europa orbits twice to each orbit of Ganyamede. This forms a very stable relationship as the bodies can never come close to each other with the gravity of each slightly pushing and pulling the other, so keeping the balance with each orbit. At Saturn the same 2:1 relationship exists between Mimas and Tethys as well as between Enceladus and Dione. At Neptune a 4:1 resonance between Titan and Hyperion exists. Further out the small body of Pluto has an orbital resonance of 2:3 with much larger Neptune. Neptune controls the smaller Pluto and also most likely, thousands of other icy worlds in the Kuiper Belt. I suspect this will be found to have gaps and holes the same as the asteroid belt has from the pull of Jupiter, but in this case from the pull of Neptune. Other rhythms effect the Earth on much longer time scales, at present we are about 33 light years above the plane of our galaxy which the sun orbits around in 250 million years. During each orbit the sun bobs up and down several times each side of the plane of the galaxy, sometimes passing through dust clouds which may dim the suns light for a time. These and others forces acting on us have made life on our Earth possible by creating the right amount of variation and change to stimulate life to progress but not so much that it has killed it off. If change is too rapid, ie. by a big rock dropping out of the sky!, it will damage life. The environment may change to quickly before the evolution process can fit and adapt the fauna and flora into the new mode.
Luckily for us this change in rhythm happens at a smooth pace in our bit of the universe.
The Astronomy of Tidal Bores
by Mike Frost
"The enormous wave which marches at the head of the tide swells, rises,
stands up; it bursts of a sudden, and its summit falls with a crash; an
immense roll is formed and unfolds itself, sometimes from one end to the
other; it is a cascade which moves, which runs and remounts the river with
the speed of a galloping horse. The wall runs along like a wall of
foam, overthrowing all obstacles and rearing itself up each instant like
a gigantic plume, to fall again quivering on the bank, which it deluges.
The ground sometimes trembles under the feet of the spectators, who see,
in less time than it takes to describe it, the boiling mass passing on
and pursuing its ungovernable course."
— Camille Flammarion, quoted in 'The Romance of Modern Astronomy' (1919)
Stand by the riverbank at Minsterworth, Gloucestershire, at around 10pm on October 7th
, and, weather permitting, you will witness one of the most imposing natural sights in Britain — the tidal bore on the river Severn. Without warning, the stately flow of the river downstream toward the Bristol Channel will be interrupted by the arrival of a wall of water, a metre or more in height, moving rapidly upstream toward Gloucester. What causes this strange phenomenon? What factors affect it's magnitude and the time of its arrival? And why does it favour the River Severn? A comprehensive discussion of these questions involves consideration of many sciences — not least hydrology, fluid dynamics and meteorology. Yet a surprising number of the factors involved in the formation of the largest tidal bores turn out to be astronomical in origin. To answer one question — although the bore on the River Severn is the largest in Britain, it is by no means the only one; indeed, most tidal rivers exhibit some sort of bore, although usually only centimetres in height. Most rivers draining into the Bristol Channel, particularly the Parrett, have a bore similar to that on the Severn, and there are similar systems associated with the River Humber and the Wash. The tidal bore on the River Trent, better known as the Aegir, can be best seen from around Gainsborough. And the rapid arrival of the tide in the Solway Firth features in Redgauntlet, Sir Walter Scott's tale of Jacobean rebellion in Border country. "...for the tide advances with such rapidity on these fatal sands that well-mounted horsemen lay aside hopes of safety if they see its white surge advancing as they are yet at a distance from the beach." So what causes tidal bores? In essence, the tidal bore can be thought of as the abrupt commencement of the flood tide. Ordinarily, the level of the sea rises and falls in a regular oscillatory manner. At most seaside locations, the tide comes in and out gradually, with an interval of approximately 12 hours 25 minutes between high tides. A tidal bore forms when this sinusoidal behaviour is distorted by the geometry of the river bed. When tides flow into an estuary or inlet where the depth rises steeply upwards, the profile of the incoming tide is modified. Instead of the tide turning half way between high tides, the river level continues to drop. When the incoming tide does arrive, the level rises rapidly, taking perhaps one or two hours to reach high tide. The tidal bore is the most extreme case of this, where the first hint of a rising tide is the arrival of a wall of water. Even if the river bed is a favourable shape, a tidal bore may still not form. On the Severn, for example, bores only occur perhaps 130 days a year. Tidal bores are generally likeliest and most impressive when the tides are highest. To predict when the highest tides occur, we need to understand the effects which modify the tidal range — and, of course, these are mostly astronomical. The tides are caused by the gravitational attraction of the Moon and (to a lesser extent) the Sun. Because one side of the Earth is approximately 8000 miles closer to the Moon than the other side, the Moon's gravitational force on the near side is approximately 7% more than on the far side. The average force exerted by the Moon on the Earth is required to give the centripetal acceleration of the Earth as it rotates around the centre of gravity of the Earth — Moon system. Locally subtracting off this centripetal acceleration from the Moon's gravity gives a differential force field which tries to deform the Earth into something like a rugby ball, with its longest axis pointing toward the Moon. Because the Earth is essentially a rigid body, the deformation does not take place and the planet remains spherical. However the waters of the oceans are free to respond to the differential force field. If the Earth were completely covered with oceans, they would be pulled into two bulges, one beneath and one directly opposite the Moon, into which the solid Earth would rotate — the time between bulges would be slightly more than half a day because of the Moon's progression around its orbit. The distribution of land mass complicates this simple picture considerably, but the dominant tidal oscillation remains one of 12.4 hrs, with a lag behind the Moon's passage overhead which varies considerably from place to place.The gravitational force due to the Sun on the Earth is much larger the Moon's, so you might think that the corresponding tidal force was greater. You would be mistaken; the size of the gravitational force is greater, but it's variation across the Earth is much less; consequently tidal effects due to the Sun are only a half of those due to the Moon. Clearly, however, the combined effects of these two tides are greatest when Sun and Moon are pulling together. These are spring tides, which occur at New Moon and Full Moon, although for the Severn there is a lag of two days because of the landmass complications detailed above. Whether the tide is highest at New or Full Moon depends on whether the Moon is closest to perigee at New or Full Moon. The perigee, the point where the Moon is closest to Earth (and the gravitational attraction strongest), moves gradually around the Moon's orbit, and consequently the highest tides will occur first for a run of Full Moons, then a similar run of New Moons. During 1998 tidal bores on the Severn are best shortly after the New Moon in the first half of the year, and after the Full Moon in the second half. If Full or New Moon co-incides with perigee tides are particularly high. The Earth's orbit around the Sun is itself elliptical, although not as eccentric as the Moon's around Earth. Consequently there is a bias of the height of tides towards January, when the Earth is closest to the Sun. Of greater importance to the formation of tides, however, are the declinations of Sun and Moon. Tides are greatest when Sun or Moon is on the celestial equator. The Moon's crossings of the equator wander through the calendar, but the Sun's appearance on the equator is more straightforward — at the spring and vernal equinoxes (March 21st and September 21st). The size of tidal bores gradually increase as an equinox approaches, then start to reduce toward midsummer or midwinter. Which goes some way toward explaining a curious piece of folklore — that the Severn bore only ever occurs on Good Friday. For Easter Sunday is supposed to coincide with Passover, the closest full Moon to the spring equinox. So Good Friday will usually be an excellent day to observe the Severn bore. The ecumenical and astronomical calenders do not always coincide; however, up until recent years, Good Friday was often the only holiday anywhere close to the equinoxes — the one chance for most people to observe the bore. Apart from Good Friday, however, the best river bores are to be seen at the Full and New Moons closest to the equinoxes — in 1998, these will be around March 1st, March 29th, and October 7th. On the Severn, at these times of the year, the high tide will arrive at Minsterworth at around 10 in the morning and 10 in the evening. Indeed, because of the phase lag of the tides, the highest bores on the Severn are to be found between 7 and 12 in the morning and 7 and 12 in the evening. Whether morning bores are better than evening depends on whether the Moon is above or beneath the Celestial equator (and whether or not it is full, and don't forget the phase lag!) — in early October the bores are best in the evening. Note however that the size of the bore is also dependent on several non-astronomical considerations, such as the wind speed and direction, and the barometric pressure, all of which can spoil or enhance the bore. Finally, the presence of boats, canoes or surfers riding the bore, whilst providing scale and spectacle, can "break the wave" and reduce its size. Worldwide, many river systems exhibit bores greater in size than that on the Severn. The Seine in northern France used to exhibit a sizeable bore called the "Mascaret". Camille Flammarion, the notable French astronomer, wrote a vivid description which I have used to open this article; unfortunately, work on the river banks has now reduced the size of the Seine bore. The Bay of Fundy, in Nova Scotia, Canada, has the world's largest tides, which give rise to a substantial tidal bore. The mouth of the Amazon and the Cook inlet in Alaska boast notable bores. The biggest of all tidal bores, the guan chao or "wonder tide", is on the Qiantang Kiang, in Southern China. The bore is also known as the "black dragon" because of the river silt it carries. It can reach up to 4.5m in height and has been known to wash away unwary cattle grazing on its banks. The Chinese long ago built backwaters on the Qiantang Kiang in which river traffic could ride out the bore. Which leads to one final intriguing event. When are the tidal attractions of Moon and Sun most closely aligned? At an eclipse, of course, when Earth, Moon and Sun lie in a straight line (not necessarily in that order). And on July 22nd 2009, the path of a total solar eclipse passes directly across the Qiantang Kiang. At 9:37am local time there is an eclipse of the Sun, and around two hours later, an unseasonably large bore on the world's most boring river. Quite a day!
The author would like to thank Mike Feist of Foredown Tower, Portslade,
for historical sources, Eric Jones of the Proudman Oceanographic Laboratory
for scientific assistance, and the Environment Agency for information on
the Severn and Trent bores.
'The Severn Bore' — Fred Rowbotham (David and Charles, 1983)
'The Severn Bore and Trent Aegir 1998' — Environment Agency
'The Romance of Modern Astronomy' — Hector MacPherson, Jnr (1919)
'The Revolving Heavens' - Astronomy for Observers with the Naked Eye' — Reginald L. Waterfield (Duckworth, 1944)
'McGraw Hill Encyclopaedia of Science and Technology' — entries on
tides and river bores (V12,18 1992)
'Redgauntlet' - Sir Walter Scott (P33, OUP 1995)
Severn Bores for October 1998 (approx times at Minsterworth)
Mon 5th Oct 08.19, 20.40
Tue 6th Oct 09.02, 21.23
Wed 7th Oct 09.45, 22.05
Thu 8th Oct 10.26, 22.47
Fri 9th Oct 11.06, 23.27
Evening bores are predicted to be better than morning bores, and bores
towards the middle of the week are best — but nothing is guaranteed!
Notable Tidal Bores of Britain:
Bristol Channel Severn, Parrett and others
Morecambe Bay Lune
Humber Trent (Aegir) and others
Notable Tidal Bores of the world:
River Country Name
Amazon Brazil Porocora
Cook Inlet, Alaska USA
Gulf of California USA
Bay of Fundy (Petitcodiac) Canada
Ganges (Hooghly,Brahmaputra) India
Seine France Mascaret
Qiantang Kiang China Guan Chao,
Diamond Rings and Golden Orioles
by Mike Frost
On February 26th
1998, a total eclipse of the Sun was visible along a track from north of the Galapagos Islands to west of the Canary Isles, passing over parts of Colombia, Venezuela and the Caribbean. I travelled to Curacao in the Netherlands Antilles, 100 km north of the Venezuelan coast, with a party from Explorers Tours. The centre line of totality passed just to the north of the island, but from our chosen observing site we could still expect to see 3 min 26 seconds of total eclipse, weather permitting. As the 26th dawned, conditions did not look good from Willemstad, the chief town of Curacao. There was heavy cloud cover and even a dispiriting sprinkle of rain. However, local opinion was that the sun would burn off cloud cover during the morning. Even as we made our way north by minibus convoy, their predictions seemed to be coming true. The appearance of the Sun from behind a cloud was greeted with delight. Our observing site was called Knip Bay, a few miles south of the tip of the island. It was a beautiful cove carved into limestone cliffs, a sandy valley with shady tree cover surrounded by formidable cactus fields. A pair of orioles, black apart from golden wings and a streak of "suntan lotion" beneath the eyes, watched the proceedings nervously from the periphery of the beach. Knip bay was packed! Half the bay had been cordoned off for our party, the rest was full of locals who had taken the day off and were swimming and splashing prior to viewing the eclipse. An impressive variety of craft, from jet skis to cabin cruisers, were moored offshore. First contact of Moon on Sun was at 11:40am local time, and many of the party began observing the Sun through eclipse shades and filters, or via projection. Other astronomers (me included) went for a dip! Two collections of sunspots were visible. As the Moon's disk began to progress gradually across the Sun, the cloud cover began thinning — perhaps now the decreasing flux of heat was preventing further cloud formation. In the shadow of the trees, the pinhole gaps began to take on the appearance of multiple crescents, and shadows began to sharpen perpendicular to the direction of the remaining crescent of sunlight. By 2pm, eleven minutes before totality, things were really cooling down. The light thinned and silvered, lending an oddly wintry feel to the tropical surroundings. The orioles began to fly around skittishly, seeking a roost. Now the sky was almost completely clear, so despite the cues for twilight, the entire horizon remained resolutely blue. Final checks were made to equipment settings — we were going to see the eclipse! The final countdown to totality was thrilling. The skylight dimmed perceptibly before our eyes — Venus popped into sight, as if by magic, low to the west. Now the crescent of remaining sunlight was beginning to break up as the serrated edge of the moon bit into the last uncovered edge of the Sun's photosphere. The lines of light dwindled to beads, and flickered out relentlessly one by one. I looked away and out to sea. The sky to the west darkened to near night and the wall of darkness rose upwards and towards us. The last brilliant bead flicked out and totality was under way. Above us was a jet black disk surrounded by the gorgeous soft white glow of the solar corona. I rattled off a quick series of photographs, then switched to observing through my binoculars. The corona was four-horned, with streamers flowing between the pairs of horns. There was one bright red prominence, with hints of several others. Mercury and Jupiter shone bright within a few solar diameters of the eclipsed Sun. The horizon was a dull deep blue in all directions, confirming the circular shape of the moon's shadow. The audience were animated, emitting whoops of joy and expressions of glee. The blustery offshore breeze had dropped completely, so that the only other sounds were of the frantic clicking of cameras. "Three minutes" someone yelled, and I prepared for a final batch of photographs. One more run through the exposure settings in preparation for the end of totality; then the pink glow of the chromosphere appeared on the lower limb. And then the end of totality — a beautiful, persistent, diamond ring of light on the pearly ring of the corona, as first of the Sun's rays found their way through a valley on the lunar rim. For a few hushed seconds the photographers snapped and snapped and snapped — then as the beads began to reappear and the skylight level rose, a round of jubilant applause echoed round the bay. Those of us with our wits still intact turned round to watch the shadow sweeping away to the north east. I looked down to my feet and to my immense delight saw shadow bands rippling across the sand — alternate light and dark patches, perhaps 20cm apart, flitting along the beach at running speed, seemingly in pursuit of the Moon's shadow. Shadow bands are caused by atmospheric turbulence causing rippling of the Sun's first light, and the narrowness of the banding suggested a very turbulent layer somewhere above us — probably the one our incoming plane had shuddered through on the way in. Dedicated observers continued to photograph the outgoing partial phases of the eclipse, recording the re-appearance of sunspots as the Moon's disk moved on. This observer went for another swim before enjoying several celebratory beers. As we swapped stories and drank toasts, a flying boat from the north made a low pass across the bay, and a cruise ship appeared from beyond the headland on its way south. And for one party, aboard the plushest of the yachts in the bay, celebrations were only beginning. Minutes after the end of totality, the strains of the wedding march rang out across Knip Bay, to applause from the shore. We hope one lucky lady saw her third diamond ring of the day!
by Mike Frost
(As usual, I have made every attempt to stick to known astrophysics in this story.
I make no claims for the validity of the human psychology)
You may recall that the last time I met my friend Clive from the Dangerous Sports Club, he was planning on surfing the shock wave from an exploding supernova. This would take him beyond the edge of the observable universe and occupy approximately eighty days of his life. However, due to the effects of relativistic time dilation, twenty billion years would elapse back on Earth.
So it was a surprise when I bumped into him six months later, in the queue for the delicatessen in Sainsbury's. It was even more of a surprise when I took a second look. Clive had changed. His battered old trainers were replaced with shiny new shoes, his ragged jeans by smart trousers. And was that a collar and tie he was wearing? There could only be one explanation.
"Clive, darling," came a voice from the dairy products, "have you bought the guacamole yet?"
She was certainly good looking. And when Clive turned round to answer her, you could see he was smitten with her. Then he caught sight of me, and another expression crossed his face. Pure fear.
"Still waiting, dear," he said strangledly, and then, as offhand as he could manage, "Oh hi Frosty." But it wasn't offhand enough; his girlfriend marched across to the deli counter.
"Aren't you going to introduce us?" she said, sweetly, and turned to me, "Clive is a darling but he's so impolite sometimes."
"Sorry dear," said Clive, "Frosty, this is my girlfriend, Clarissa. Clarissa, this is Frosty, a friend from university."
Clarissa shook my hand and eyed me suspiciously. "You're not one of those ridiculous dangerous sports people, are you?"
"Oh no," I said, reassuringly, "that was never my cup of tea."
"Good," Clarissa said firmly, and smiled at Clive," I'm glad to say we're beyond that kind of thing these days, aren't we darling." She looked at me again, "Clive's a changed man these days. You'd never guess, but he's taking his first accountancy exams next week. So we'd better hurry. Get that guacamole, darling, and I'll see you in the fancy pastries aisle."
She strode off purposefully. Clive collected his tub of guacamole, and made to follow her. As he brushed past me he whispered "Black Horse, seven o'clock" very quietly. Then he was off in pursuit of his girlfriend.
It took me several minutes to compose myself. Clive, domesticated. Who'd have thought? But one thing the lovely Clarissa had said puzzled me. "We're beyond that kind of thing these days." Was that a royal we or was Clarissa also a veteran of the dangerous sports club? There was only one way to find out.
* * * * * * * * * * * * *
Clive joined me in the pub with a worried look on his face. "Oh thank goodness you're here, Frosty. I don't have much time. Clarissa thinks I'm in Ikea, looking at futon covers."
I was horrified. "Doesn't she let you out?"
Clive was miffed. "Of course she does! I get one night a month all to myself. She's just not very keen on me associating with my old university friends. Especially the dangerous sports club."
"Why ever not?"
"She thinks we were a bunch of reckless, immature maniacs." He sighed into his pint. "I told her that was what attracted me to the club, but she didn't understand. Especially after our little accident."
He'd said "our" again - so maybe I was onto something. Best not to ask directly. "I thought you were going supernova surfing, anyway."
"Yes," Clive said sadly, "that was where it all began. I was just setting off for final preparatory trials, when I met Clarissa..."
"What, at the hyperspace check-in?"
"No, the hypermarket check-out. I was behind her in the queue, trying to work out what hummus was. Then she turned round. Frosty, it was love at first sight!" I could swear his eyes went misty at the memory.
Unfortunately, it wasn't getting me any closer to any answers. "So what about the supernova surfing?" But Clive wasn't easily deflected.
"At first, you see, she took an interest. She said 'dangerous sports - that sounds exciting! What sort of dangerous sports?' So I told her I was going jet ski-ing and she said 'that sounds fun! Can I come along?' What could I say?"
He paused and sipped his beer. "If only I'd told her it was a galactic jet we were ski-ing."
I wanted to scream at him "Yes, but what about the supernova!?" Fortunately, he began to answer my question.
"You see, Frosty, you forgot to tell me some things about surfing a supernova" (Why am I expected to tell him everything?) "The biggest problem about being blown out of a supernova is that you might hit something!"
"Well, space is quite empty" I said, unconvincingly, but I knew he was ready for that.
"It's not very empty when you're travelling close to the speed of light. When you cross the universe in forty days, stars and galaxies and things tend to come at you pretty fast! You don't have very much time to swerve. It's not so much like surfing as snowboarding - dodging round the obstacles as fast as you can. And I was a bit rusty on my ski technique. So I thought I'd practice on something a teeny bit slower than an exploding supernova."
It was beginning to make sense now "So you thought you'd try and ride a galactic jet!"
"Exactly," said Clive, pleased he had someone he could talk astrophysics to. "When we made our bungee jump on to the black hole in the active galaxy M87, we saw the jets erupting from the poles of the hole. Even then, I fancied trying to surf one."
I was desperately trying to recall my astrophysics. "But the jets can't erupt from inside a black hole because nothing can escape a black hole. So...."
Clive was perking up, back in his element. "Well I'm not sure, either - you're the physicist, after all. But big black holes like M87 are surrounded by an accretion disc of matter, which is being sucked onto the hole. It looks a bit like the rings of Saturn, only rather thicker, and a lot hotter! When stuff reaches the inside of the accretion disc, it has almost reached the event horizon of the black hole, and is travelling very, very fast in orbit. The point is, not all of the matter in the accretion disk actually falls onto the black hole. Some of it gets caught by the magnetic field of the black hole. It can't escape out the way in came in because the accretion disc gets in the way. Instead, streams of matter are flung towards the poles of the black hole - and at the poles synchrotron acceleration spits out two jets of matter, in opposite directions, at half the speed of light."
He paused for another drink. "When we bungee jumped on the black hole, we had to pick our spot very carefully, to avoid being hit by the streams of matter on their way to the poles. But for jet ski-ing, things were a lot simpler. We put our ship into an orbit taking us close to one of the poles. I had strapped my surfboard to our spaceship. Before we reached the jet, I was to leave the ship and get on my board. There was a rocket attached to the surfboard, which I would fire to launch myself deep into the jet. Inside the jet, the stream of matter would shoot me out on the surfboard at half the speed of light, dodging stars and planets and things as I cleared the galaxy. Clarissa would leave the black hole system under ship's power, and we would meet up a few thousand light years outside M87. It was a beautiful surfboard, it really was, all sorts of attachments and boosters to get me round obstacles."
"So what was the problem?"
He looked at me. "Clarissa was the problem! I didn't have enough time to train her up on piloting the spacecraft. She kept asking questions and making suggestions and trying to help.." He winced at memory, "Anyway, I made a mistake.."
I began to suspect that the problem had not been Clarissa. "What did you do?"
He looked sheepish, "I switched off one of the engines. It was a mistake, Frosty, she'd got me all confused. And we couldn't switch the engine back on again - the plutonium fuel line was vapourlocked, or so she thought."
It suddenly dawned on me that what Clive really needed in life was someone to keep him out of trouble. And then it occurred to me that Clarissa had probably realised exactly the same thing somewhere in the vicinity of M87.
Clive clasped his fingers, "You have to realise the seriousness of the situation, Frosty. There we were, headed towards the event horizon of a black hole. We didn't have a rope to pull us up out of trouble this time - we only had two rocket engines, and one of those wasn't working. With only one engine, we didn't have enough thrust to keep us in orbit round the black hole. Pretty soon we'd reach the zone where orbiting was impossible, shortly after that we'd cross the event horizon, and then there would be nothing we could do but wait to perish in the singularity."
"So what did you do?"
Clive looked shifty, "I went through the airlock and hid on my surfboard. Well, I had to prepare for my launch into the jet..."
"Oh, I left her to vent the plutonium fuel-line by hand. Anyway, she didn't say anything, but after a few minutes, my belongings started flying out of the airlock...."
"You see, she figured out that our only way out was to jettison weight. If we could fire stuff in the direction of the black hole, the equal and opposite reaction might just push us away from the event horizon. So she began firing stuff out of the waste disposal lock, in the direction of the black hole. Everything we jettisoned would be lost forever once it crossed the event horizon. All our provisions, manuals, everything. Until there were only three things left on the spaceship that weren't nailed down. Me, Clarissa .... and my beautiful surfboard."
I realised that Clive was about to describe a watershed in his life. Tears welled in his eyes. "Finally she said, 'Clive, Either that surfboard goes or I do'."
As he was confessing, I looked over Clive's shoulder and noticed Clarissa walking into the bar. "Clive, I really think you ought to..."
"No Frosty, let me finish... You see, Clarissa had just reminded me that there were two possibilities. Either I could rejoin Clarissa on the ship, and we could blast the surfboard into the black hole, pushing us to safety."
Clarissa spotted us and walked over towards where we were sitting. "Clive...", I said urgently. "... or I could launch myself on the surfboard, blasting out towards the jet and completing my jet-skiing stunt."
Clarissa stood behind Clive, arms on her hips. I was speechless. Clive took a contemplative sip of beer.
"... of course, that would have meant dumping my new girlfriend. Into a black hole..."
"CLIVE!!!!" Clarissa shrieked. The bar went silent. If Clive's hand trembled I didn't notice.
"... and that was when I found out I truly loved her. Oh hello dear! How nice of you to join us..."
Clarissa gave Clive a deeply withering look. Then she turned to me.
"He hasn't been telling you about our so-called trip to the Black Hole, has he? Don't tell me you believed it?... Clive and I spent our holiday in Majorca, and when we DID go jet skiing, he was sea-sick... Clive, why do you feel you have to do this? Don't you want to spend the evening with me?"
"Yes dear," muttered Clive, "Just finishing, dear."
I was open-mouthed. Because if Clive was lying about the jet-skiing, then how many of the rest of his exploits were true? And if they were all made up, how did he know all about the astrophysics he claimed to have experienced? And if he actually knew all about astrophysics, why did he keep protesting his ignorance?
Unless he was winding me up...
Clive and Clarissa walked out of the bar. And as he left, Clive turned back towards me - and winked.
The MIRA Catalogue
by Vaughan Cooper and Ivor Clarke
Many years ago, during a cleanout of the observatory on the Coventry
Technical College roof, a rather interesting item was uncovered. "A Catalogue
of I85 Celestial Objects suitable for a Two-Inch Object Glass Astronomical
Telescope!" had been diligently compiled, from observation, by a past member
of the Society. The format is ingenious. A little 1919 edition
of Maunder's 'The Stars - and how to identify them', has the catalogue
entries and remarks pasted onto the pages facing the constellation charts
- but these may be lifted so that the text underneath can still be read.
Who compiled this very useful list (of double stars mainly) is not certain,
but it was obviously done a long time ago. A pencil note indicates
the year 1926. Whoever it was who compiled this list originally must
have had an interest in mainly double stars only as many nebula and star
clusters have not been listed which are well within range of a small 2" refractor telescope. At any rate, it is high time that the catalogue
saw the light of day once more again. It was started off in MIRA
number 4 (September 1984) and continued up to issue number 28, May 1990.
So with the help of Vaughan Cooper (who was the editor of MIRA for most
of these listings), here is the listing of all of the catalogue we have
at present, brought up-to-date and corrected with Vaughan's help.
As most of the list contains double stars which by their very nature
are revolving around each other, so can move position and distance quite
a lot in the intervening years in some cases, Vaughan has corrected the
separation and PA (Position Angle, measured in degrees from north via east,
south and west) where ever possible to give modern figures. I hope
this new improved list will provide an ongoing project for someone to re-observe.
We start with the prominent Summer constellation of Lyra. Exact
positions may be easily looked up in any good star atlas such as Phillips,
Sky Atlas 2000 or Norton's 2000.0. Editors notes are in brackets,
these include Vaughan Cooper, Rob Moseley, Richard Barrett and Ivor Clarke.
Cat. No. and Constellation
001 α Alpha, (Vega) mags. 1 & 10; sep. 60". (A
severe test to start with! Distance increasing, the companion
is hard to see against the blaze of the primary. A 3" shows many
other stars in a low power field.)
002 β Beta, mags. 4, 7, 8 & 11; seps. 45", 65", 85";
PA's 150°, 320°, 20°. (It is interesting that the author
has included two fainter stars in this system to form a wide quadruple.
Webb does not mention them. Can anyone confirm? The bright
star is an eclipsing binary, mag. 3·4 - 4·4, period 12·9
003 e Epsilon "Double Double", mags. 5 & 6, 5 &
6; seps. 2", 3". (The two pairs are separated by 208". Some
can see this with the naked eye. Splitting the two close pairs is
a stiff test for a 2" inch.)
004 ζ Zeta, mags. 4 & 6; sep. 44", PA 150°. Colours
topaz and green. (Most star colours from this time contain strange
colours, tints and tones which bare no resemblance to any type of star
known today. I suspect that what a lot of old observers were seeing
was poor chromatic correction in their 'scopes and eyepieces.)
005 η Eta, mags. 4 & 8; sep. 28", PA 85°.
A fine field containing another double. (A wide separation easily
visible in small telescopes.)
006 θ Theta, mags. 4 & 9; sep. 101", PA 70°.
Yellow and blue.
007 M57 "The Ring Nebula". (Quite easy to find, lying a
third the way between β Beta and γ Gamma. Difficult in a 2 inch though.)
Note the field around δ Delta.
008 α Alpha (Castor) mags. 2 & 3, both white.
(When the catalogue was compiled the separation was 6". It is now
2·51" and slowly widening once more. Technically it is beyond
a 2" at present. A good test for a 3" though. This is the brightest
binary pair in the northern hemisphere and will be at their widest, 6·5",
in approx. 60 years time.)
009 ζ Zeta, mags. 3 & 7; sep. 90", PA 360°.
Yellow & purple. (Purple???) ζ Zeta is both a variable
star and a binocular double. A yellow supergiant star of the Cepheid
class fluctuating between mags. 3·7 and 4·1 every 10·2
days. Binoculars or a small scope reveals a wide 8th mag. companion
which is unrelated.)
010 ε Epsilon, mags. 3 & 9; sep. 110", PA 94°.
011 δ Delta, mags. 3 & 8; sep. 7", PA 197°.
Yellow & purple. (Delicate object with a 3" scope, at 59 light
years away with a 1200 year orbit.)
012 λ Lambda, mags. 3 & 10; sep. 10", PA 31°.
Colours green & blue. (A good light test for a 3" scope)
013 β Beta, (Pollux, mag. 1·16), Note its rosy-orange
014 M35, A fine cluster near η Eta.
Note the field around η Eta. γ Gamma has a remarkable
array of stars round it.
As Spring progresses we see the constellation of Bootes, the Herdsman,
rising steadily earlier in the Eastern sky. It contains the magnificent
Arcturus, the brightest star in the Northern hemisphere - so bright that
Schmidt once saw it with the naked eye 24 minutes before sunset!
015 ε Epsilon, mags. 3 & 6; sep. 3", PA 326°. Orange
& green. (A gorgeous double, Struve's "Pulcherrima". Well
seen with John Graham's 3" refractor, xI56. Separation slowly increasing.)
016 π Pi, mags. 4 & 6; sep. 6", PA 99°. Both
white. (Separation slowly increasing.)
017 ι Iota, mags. 4 & 7; sep. 38", PA 33°.
Yellow and white. (In an attractive field.)
018 κ Kappa, mags. 5 & 8; sep. 12", PA 237°.
White and blue. (Attractive contrast.)
019 δ Delta, mags. 3 & 8; sep. 110", PA 75°.
Yellow and blue. (Visible in steady binoculars.)
020 μ Mu, mags. 4 & 7; sep. 108", PA 172°.
(Another binocular double)
021 Struve 1850, mags. 6 & 7; sep. 26", PA 262°.
Yellow & blue.
022 Arcturus, (mag. ?0·06). Fine orange colour.
Lilac companion? (The last entry is intriguing, Arcturus is not a
double and the entry must refer to a field star at some distance.
What do you make of it?)
Hercules is a distinctive configuration well placed in the evening sky
during Summer. It occupies most of the area between Arcturus and
Vega, and contains many fine coloured doubles - and a very famous globular
023 α Alpha, mags. 3 & 6; sep. 5", PA 118°.
Orange & green. ("Ras Algethi" a glorious colour contrast.
The orange/red primary is variable.)
024 γ Gamma, mags. 3 & 9; sep. 38", PA 242°.
White & lilac.
025 δ Delta, mags. 3 & 8; sep. 19", PA 175°.
Green & purple. (These colours can't exist on stars!)
026 ζ Zeta, mags. 3 & 6. (This is an odd inclusion -
as it is well beyond a 2 inch telescope. A fast moving binary with
a period of only 30 years and a maximum sep. of 1·6". At the
moment it is 1·4" and widening. A stiff test for a 4 inch.)
027 κ Kappa, mags. 5 & 7; sep. 31". PA 10°.
Yellow & pink. (Pink? In a fine field.)
028 ρ Rho, mags. 4 & 6; sep. 4", PA 309°.
Green. (A fine object. Webb describes the companion as also
029 μ Mu, mags. 4 & 9; sep. 30", PA 241°.
(The companion is a very rapid close binary - revolving in just 18 years!)
030 Cluster between ζ Zeta and η Eta. (This is the famous M13
globular, the brightest globular cluster in Northern skies. On a
good night a 3 inch refractor at x100 will resolve its outer stars.)
The autumn groups of Andromeda and Aries are featured in this section.
031 γ Gamma, mags. 3 & 6; sep. 10", PA 62°. Yellow
& blue. (Webb calls it "One of the most beautiful pairs in the
heavens." Discovered by Mayer in 1788)
032 π Pi, mags. 4 & 8; sep. 36", PA 173°.
Yellow & blue.
033 M31, The Great Galaxy. (Visible to the naked eye, use
a very low power on a moonless night.)
034 γ Gamma, mags. 4 & 4; sep. 8", PA 360°.
White & yellow. (Most observers see both stars of this fine equal
pair as pure white - although Webb gives "Violet-white & yellow-white".)
035 λ Lambda, mags. 5 & 6; sep. 37", PA 45°.
White & lilac.
036 α Alpha, a fine yellow star. (Called Hamal, it is mag.
A look at the Zodiacal constellations of Leo, Cancer, Virgo and
037 ι Iota, mags. 4 & 6; sep. 30", PA 308°.
Both yellow. (Some say beautiful contrast yellow and blue.)
038 Praesope cluster. (Magnificent "Beehive" cluster, very large,
1°, bright, naked eye cluster.)
039 γ Gamma, mags. 2 & 4; sep. 4", PA 118°. Orange
& Green. (A famous double, sep. and PA slowly increasing.
Difficult for a 2". Try to observe this star against a twilight sky
as this helps the colours to stand out.)
040 τ Tau, mags. 5 & 7; sep. 95", PA 170°.
Lemon & blue.
041 54, mags. 4 & 7; sep. 6", PA 102°. (Both
white. PA increasing)
042 93, mags. 5 & 8; sep. 74", PA 356°.
043 Regulus, mag. 1·3; star 176" away. "steeped in indigo". (PA 86°, quoted remark is not supported by observers today. Regulus
is a double with a mag. 10·8 companion.)
044 R Leonis. (One of brightest 'Mira' type variables,
mags. 5·9 at max. to 10·1 at min. with a period of 370 days
045 γ Gamma, mags. 3·6 and 3·7; sep. 6*, PA
150°. Both yellow. (A famous double, PA decreasing as well
as distance between stars, period 171 years, so that this is now a difficult
object even in larger telescopes.)
046 τ Tau, mags. 4 & 8; sep. 79", PA 290°.
047 θ Theta, mags. 4 & 9; sep. 7", PA 345°.
(White primary. Test for a 3" scope)
048 ι Iota, mags. 4·5 & 9; sep. 57", PA 110°.
049 α Alpha, mags. 2·8 & 5·2. Yellow & gray.
(Sep. 231", PA 314°, a wide pair.)
050 β Beta. Note green colour. (Mag. 2·61.
Is this is a mistake? The green colour is apparent on the secondary
of α Alpha, the binary listed above is some books. There has always
been great controversy over the existence of this green hue. Only
the observer themselves can decide whether it is there, but if it is a
real effect then it is the only single star to appear green).
051 λ Lambda, mags. 5 & 9; sep. 121", PA 13°.
052 41, mags. 5 & 6; sep. 8", PA 335°. (Webb
refers to the colours as tawny or violet.)
053 14, mags. 5 & 7·5; sep. 14", PA 225°.
(Cream and dull blue.)
054 α Alpha, mags. 2 & 9; sep. 62", PA 280°
055 η Eta, mags. 4 & 7; sep. 5", PA 200°.
White & purple. (Long period binary.)
056 ι Iota, mags. 5 & 8; sep. 7", PA 112°.
(In larger telescopes a third member can be seen.)
057 163, mags. 6 & 8; sep. 35", PA 33°. Gold & blue. (A fine contrast.)
Note field between π and ο.
Note field between υ and κ.
Cassiopeia affords fine sweeping.
Two circumpolar constellations, Draco which occupies a good 180" of the sky, so any part can be seen overhead during the night at any time of the year, and also Ursa Minor.
058 ν Nu, mags. 5 & 5; sep. 62", PA 312°.
059 ψ Psi, mags. 4 & 9; sep. 20", PA 120°. (Yellow and lilac.)
060 40 ≠ 41, mags. 5 & 6; sep. 20", PA 235°. (Yellow and pale yellow.)
061 α Alpha, (Polaris), mags. 2 & 9; sep. 18", PA 210°. Yellow blue. (Easy with a 3" under good conditions. The primary is a yellow supergiant star of the Cepheid type with a small amplitude varying in brightness mags. 2.1 to 2.2 every 4 days.)
062 β Beta, mags. 3 & 6; sep. 34", PA 55°. Yellow blue. (A real show piece, being an easy pair that can be split in any scope.)
063 52, mags. 4 & 9; sep. 6", PA 60°. Yellow blue.
064 61, mags. 6 & 6; sep. 28", PA 140°. (First star to have it's parallax measured by Bessel in 1838.)
Note, a fine field about γ Gamma, whole region very rich.
065 α Alpha, mags. 4 & 9; sep. 35", PA 278°. (A wide pair; pale yellow and pale blue.)
066 γ Gamma, mags. 4 & 5; sep. 11", PA 273°. Gold and blue. (In the same field of view appears Σ2725 consisting of stars of 7th and 8th mag.)
067 θ Theta, in a fine field.
068 α Alpha, (Sirius, mag. -1.43) note colour and scintillation, brightest star in the heavens.
069 ε Epsilon, mags. 2 & 9; sep, 7", PA 160°
070 Clusters 1454, 1479 and Nebula 1511. (Not sure where these numbers originated from, however No. 1454 refers to M41 - No. 1479 refers to NGC 2318, they are both star clusters and stated as such in the original notes, but No. 1511 is referred to as a nebula and this is causing a bit of a problem as the only two candidates which fit the approximate positions on the original maps are NGC 2343 or NGC 2353 but they are both star clusters, any ideas on this point please.)
071 α Alpha, (Procyon, mag. 0.37), Yellowish-orange colour.
072 14, mags. 6, 7 & 8; sep. 115" & 75", PA's 154° & 65°
073 β Beta, (Rigal), mags. 1 & 7; sep. 9", PA 200°. White and deep blue. (Norton says a test for a two inch.)
074 δ Delta, mags. 2 & 7; sep. 53", PA 0°. White blue.
075 ι Iota, mags. 3 & 7; sep. 11", PA 142°. (Ye!low-white and bluish.)
076 λ Lambda, mags 3 & 6; sep. 5", PA 43°. Yellow red. (Set in a very fine region.)
077 ρ Rho, mags. 5 & 8.5; sep. 7", PA 62°. Yellow blue. (Not easy to see with a 3" telescope.)
078 ζ Zeta, mags. 2 & 5; sep. 3", PA 159°.
079 σ Sigma, multiple, note grape red star. (Norton's calls this a fine group with striking colours. This group of two pairs, mags. 4 & 10; sep 11", PA 236°, and mags. 7 & 7.5; sep 13", PA 56°. The faint star is rather difficult in a 3" scope.)
080 23, mags. 5 & 7; sep. 31", PA 284°. Green white.
Colours α Betelgeuse Orange red
γ Bellatrix Yellowish
ε Alnilam White
ζ Alnitak Yellow
081 ζ Zeta, mags. 4 & 5; sep. 6", PA 300°. White blue. (Norton's calls this a beautiful object.)
082 γ Gamma, mags. 4 & 7
083 Σ1964, mags. 7 & 7; sep. 15", PA 86°
084 ζ Zeta, mags. 2 & 4; sep. 14", PA 148°. White and green. (Mizar and Alcor a naked eye double.)
085 23, mags. 4 & 9; sep. 23", PA 272°. A fine contrast. (White and lilac.)
086 Σ1495, mags. 6 & 8; sep. 35", PA 38°. Pale yellow and blue.)
087 1520, mags. 6.5 & 8; sep. 13", PA 345°. (White and bluish.)
Spiral Nebula M51, 4° SSW of η Eta
Owl, M97 (planetary) 2½° SE of β Beta
Colours α Alpha (Dubhe) Yellow
γ Gamma (Phad) Yellow this star lies in a fine field
β Beta (Merak) Greenish
089 ε Epsilon, mags. 2 & 8; sep. 138", PA 324°. Yellow violet. (The primary is a suspect variable star, with an average mag. of 2.5.)
090 Ι, mags. 4 & 8; sep. 37", PA 310°. (Deep yellow and bluish.)
Colours α (Markab), White
β (Scheat), Deep yellow
091 η Eta, mags. 4 & 8; sep. 28", PA 300°. White blue. (Others say intense yellow and deep blue form a fine contrast.)
092 ε Epsilon, mags. 3 & 8; sep. 9", PA 9°.
093 ζ Zeta, mags. 3 & 9; sep. 13", PA 207°. (Primary white.)
094 ο Omicron, mags. 4 & 9; sep. 20", PA 237°.
095 331, mags. 5 & 7; sep. 12", PA 85°. (Bluish and white.)
Colours α Alpha (Mirphak) yellowish.
β Beta (Algol eclipsing variable) yellowish.
The whole region affords fine sweeping.
And there I'm afraid the list ends, with all the rest missing at this moment. Vaughan has made attempts to track down the original book but has drawn a blank. If any member of the Society has any knowledge of the missing part of this list or the book, please let Vaughan Cooper or myself know. What we can do with this list is expand it to cover all the objects say visible through a 4" (Newtonian, Refractors, Cassegrain). This will include many Messier and NGC objects as well as double stars and other clusters, galaxies, and nebula. If any member would like to help with this task please contact Vaughan or myself.
Ivor Clarke, Editor