MIRA 4
September 1983


EDITORIAL

It seems pointless for a local society magazine to try and compete with the likes of 'Sky & Telescope' or 'Astronomy'.  Its function should be to provide communication between members - especially by the publication of observations.
Observing is the sharp end of Astronomy as a hobby - where the real thrills and satisfactions lie.  Some people take their observing very seriously, others observe for the sheer fun of it.  Both approaches are equally valid.  It remains a fascinating and rewarding activity... once you get started… and even when the bug has bitten it can be lonely.  This is where sharing your observations with other amateurs becomes a crucial need - in providing necessary motivation.
A lot of societies spend a great deal of time talking about what they are going to observe.  This often involves a grandiose, never-ending observatory project.
I think that this issue of 'MIRA' proves that the C&WAS is something more than the usual collection of "armchair astronomers".  I am delighted that several members have already sent in observational reports — and I hope this will encourage others to contribute.  The illustrated observing notes in 'MIRA' are expanding with each issue - and this month they range over most of the major areas.  Any recent observations, at whatever level, will be warmly welcomed. All contributions will appear in the following issue.  Do have a go!

May saw two excellent evenings for the C&WAS.  On the 6th Harry Brierley cane over from Northampton to give a first rate talk on the Circumpolar Constellations (did you realise that M 31 never sets?), accompanied by some of his own astrophotography.  Harry is pledged to return next year.
May 20th was, of course, the surprise presentation evening for Howard Miles - and featured Patrick Moore as the special guest speaker.  A full account of the evening will be found in the August edition of the BAA Journal.
June 10th was the AGM - an internal affair really, with plenty of time for a good natter. Finances turned out to be in reasonable shape - with the membership voting overwhelmingly not to increase the subs!  Surprise, surprise...  The following were confirmed in office:-

RA Arculus (Hon. President)
HG Miles (Hon. Vice-President)
Ted Nicholls (Chairman)
Keith Jennings (Vice-Chairman)
Alan Hancocks (Secretary)
Tony Sturgess (Treasurer)
Committee Members - John Richards, Reg Nobbs, John Graham, Martin Wein, Richard Willis and Rob Moseley.  Richard Barrett and Bob Marriott were elected onto the Committee at the AGM, Ivor Penrose having retired from it.

After weighty deliberation the Committee recently decided that it might be a good idea to introduce a coffee break halfway through meetings.  The aim is to give more opportunity for informal conversation - as this was felt to be lacking.
The programme for next year will also feature two "home-grown" meetings, where again we will be able to talk more amongst ourselves.
Proceeds from the sale of duplicated and unwanted material from the Library at the May meeting and the F.A.S. Convention caae to well over £20.  This has mainly been used to help in restoring the College Observatory.
The Observatory should be operational at any time now.  When it is, the telescope will be available for any member to use (with help and guidance if required) on Thursday evenings - weather permitting.  The Library will also be open then, and for ½ hour before normal Friday night meetings.  More details in due course.
The Society has recently re-affiliated to the BAA.





The Number of Stars in the Square of Pegasus
By Geoff Johnstone

There is no definite cut-off to the number of stars visible to the naked eye.  Much depends on how dark the sky is and the transparency of the atmosphere - as well as eyesight.
The Square of Pegasus covers 200 square degrees.  The two brightest stars within it are Upsilon and Tau Pegasi of Magnitude 4.4 and 4.6 respectively.  Even under poor skies it should be possible to see a few more.
FWA Argelander (1799 - 1875) of Bonn Observatory catalogued 50 naked eye stars.  The 1955 'Handbook of the Heavens' commented that under ideal conditions as many as 80 stars have been identified with the naked eye.  Even 80 stars is not apparently the final word, for Julius Schmidt, the great 19th century selenographer once counted 102 stars from his observing site in Athens.
Using the table below an observer can immediately tell his or her naked eye limit... to the nearest tenth of a magnitude.  The country observer will obviously be able to work farther through the table than the "townie" - but a lot will depend on sky transparency at the time.

No. of stars   Mag.             No. of stars   Mag.

1                 4.4               18                6.1
2                 4.6               23                6.2
3                 4.7               25                6.3
4                 4.8               30                6.4
5                 5.1               37                6.5
6                 5.3               47                6.6
7                 5.4               55                6.7
8                 5.5               59                6.8
10               5.7               63                6.9
12               5.9               70                7.0
13               6.0    

Why not try this out and let me know how you get on?
(Observation by "townie" : Thurs Aug 4th 1985.  Exceptionally transparent sky.  Six stars within the Square.  Limiting mag. - 5.5.  Just over a mile from the city centre ~ not bad! Ed.)





Building, Large Telescopes  (Part 2)
By John Wall   FSAS

A large telescope must be correctly designed, so some drawing board work is in order.  Once the basic philosophy has been decided upon one must resort to hand sketches, and then a series of design layouts to hammer out all the important features pertaining to shape, points of balance, centre of gravity, observer positions etc.
The main difficulty is usually in obtaining heavy bearings for the axes, so a visit to the scrapyard will be needed in order to pick up a heavy back axle from a truck - and perhaps a couple of front stub axles as well.  These will be a valuable source of bearings and support structure.
The most important thing is to obtain the' bearings first, even before the design work begins - and when obtained the mounting should be designed around the material at hand.  Usually the scrap parts can be purchased by scrap metal weight, rather than as a spare part.
Great use can be made of slotted angle sections - used widely these days for industrial racking and light structural work.  The angle cones in various shapes and weights, depending on the stress that will be placed on the framing members.  Slotted angle is easily available through mail order, and can be purchased in 100 foot packs.  The whole telescope can be made from this material - including the mirror cell fittings and flotation system - and it will be found that very little alternative material will be required.  All framing should be carefully designed using structural engineering techniques.  The telescope will be a large one - and the loadings will be quite high on some parts of the structure.
The tube must be of the 'Surrier' A frame truss system.  There is no other way of efficiently designing a large telescope tube.  Most large professional telescopes use this system.
The telescope should never be made of wood.  This is alright for small instruments, but taboo for a large one.  Wood has high structural strength but has no stability.  It warps and shrinks in hot weather, and it will swell when damp - the worst possible system for maintaining collimation of large optics.  As wood is now highly expensive, why not buy steel?
To conclude.  A large telescope built on a budget by amateurs will never be in the same league as a comparable aperture in the professional world, but the optical performance can approach that of a professional instrument.  Because tho discs of glass will be thin, due to the non-availability of professional size blanks, one is forced to settle for a lesser optical performance.  This means that the instrument should only be used for medium power work... deep sky observations of extended objects, comet seeking, variable star work etc.
For serious scientific observations beyond tho visual, photoelectric work should be considered. Here the thin mirror telescope comes into its own - fully justifying building such an instrument.
Finally, a huge expensive observatory building is not required, as adequate weather-proof, roll-off cabins can be built from slotted angle, and skinned in a variety of the excellent corrugated plastic roofing sheets now available.





OBSERVATION NOTES

Comet Notes
The observational event of the year so far was undoubtedly the appearance of Comet IRAS-Araki-Alcock, visible in early May.  A little disappointing to the casual observer, the object nevertheless had many points of interest.  I know that many members had a look, but only a few actual reports have reached me.
Geoff Johnstone took one of the most successful exposures of tho comet that I have seen.  A shot was published in the June edition of "The Astronomer" after being enhanced by slide copier from a sensitised 2415 negative.  He comments that "this shows the coma extending to at least 8 degrees with a suspicion of a tail."  Geoff showed some other views of the comet at tho special May 20th meeting.
Paul Porter was a little loss successful in capturing a difficult photographic object - but was spectacularly rewarded for his effort with a remarkable meteor shot.  The meteor (of around mag 0.5) passed close to Polaris, heading duo South, right through tho centre of his field.  Paul didn't notice the meteor while making the exposure, so a precise timing is unavailable.  Unfortunately reproduction doesn't do any justice to the beautiful slide original.  Meteor activity associated with this comet has been a great point of interest and on learning that Rob McNaught of the RGO had calculated the position of the radiant, I chocked the photograph at once.  Alas. . . its a sporadic.
Bob Marriott and I examined the comet nucleus, using 8½" and 6" reflectors, on the nights of May 9 and 10.  We both recorded a starlike nucleus of mag 8 surrounded by bright condensation between 3 - 5' across.  In addition Bob could see a fan shaped inner coma on the 10th.  I saw that with a power of 60 the comet was moving almost visibly among the field stars.  At 00.00 UT May 10 I estimated a proper notion of ¾ degree per hour!  At its closest the comet later speeded up to an incredible 2 degrees per hour.  We may wait centuries before another comet comes as close as this one did.

Meteor Notes
For sheer entertainment value the summer Perseids always provide the meteor highlight of the year.  Alex Thomas reports considerable activity around predicted maximum on the 15th August.  At one point 8 bright meteors were seen within 10 minutes.
Fine, warn, moonless nights were enough to induce me to get the deck-chair out.  A watch on Aug 10/11 yielded just 8 Perseids and 4 sporadics.  Next night was bettor with 12 Perseids, including a -4 fireball which flared brilliant orange on extinction near the Head of Draco.
Maximum, on Aug 12/15th, produced 41 Perseids and 5 sporadics in just over 2 hours.  The distribution table below incorporated the results from the three separate watches.

Magnitude distribution   Aug. 10 - 15    Total duration - 5hr 45m.

                -4   -5   -2   -1   0   1   2   3   4

Perseids      1    2    4    4   6   13  22  8   1      Total 61
Sporadics     0    0    1    0   0   0   5   2   1          "   9

Most Perseids were blue/white and swift - brighter specimens leaving short, smokey trails.  The minus magnitude objects were generally slower moving with several showing green and yellow/orange colouration.  (RM)


Planetary Notes
Tim Gouldstone has supplied a recent drawing of Jupiter and the following notes ~ made with his new Astrosysteas 8½" reflector, which he was kind enough to bring along to the June AGM meeting and show us.


Jupiter 1983 June 15  20.30 UT  216mm spec. x155 - x216
Long. CM  System I - 303   System II - 312
Sat. II (Europa) was observed emerging from eclipse, but not timed, its notion was quite noticeable over a period of 1 hr.
Disc of planet :   N. Polar region observed uniform / NEB darker to E side and also generally darker on S margin.  Disturbance noticed near central meridian on S side of NEB / SEB broad, darker on S margin / STB clear, homogeneous and darker to E margin.  Signs that it is divided into 2 units. / SPR variable dark N margin, otherwise uniform.
Seeing - Moderate/Poor.

My own efforts have been rather sparse due to the low altitude of the planet and the consequent poor seeing.  I was able to record the Great Red Spot on June 27, and again on July 4.
Perhaps inspired by the notes on Saturn's moons in last issue's Sky Diary, one of our junior members, Mr. S Lea, has sent me a sketch of the planet he made with his 2.4" refractor on May 16, Titan, Saturn's largest moon is well shown.



Deep Sky Notes
(...continuing a survey of Planetary Nebulae)
By Richard Barrett

NGG 7662 in Andromeda (see also 'MIRA' Dec 82) is a fairly small planetary.  Despite its brightness it is rarely described in text-books.  This nay be something to do with its size, and perhaps its lack of unusual features.  At mag 8.5 and with a diameter of 50" it is roughly equivalent to the 'Saturn' nebula.  It is visible even in binocular (although it cannot be recognised as nebulous, but appears stellar.)  It is easily located using the flattened triangle of 4th mag stars (Iota, Kappa and Lanbda And.) in the north-west of the constellation.  Note that Norton lists it by its Herschel number (18/4).  Once located, high powers can be used to bring out its nebulous properties.
In the constellation of Draco there is a bright (mag 8.6) but small (22x16") planetary - NGC 6543, sometimes called the "Cat's Eye" nebula.  It lies very close to the N. pole of the ecliptic.  I have not seen this planetary, and this is largely because of a distinct lack of field stars to aid location.  It can be found about halfway between Delta and Zeta Draconis.
The faintest object in Messier's catalogue is a planetary nebula - M 76 or NGC 6501.  It is often called the "Bar-bell" or "Little Dumbbell" nebula, as it looks like a smaller version of M 27 in Vulpecula.  It has a magnitude of 11, a size of 140x70" - and is really beyond the reach of small amateur telescopes.  However, the more advanced observer, with a 6" telescope or larger, should be able to pick it up a little less than a degree NNW of Phi Persei (8 degrees SW of the Perseus double cluster.)

Solar Notes
Both Paul Porter and Alex Thomas have been observing the Sun recently, (there has been plenty of opportunity this Summer).  Alex has supplied a sketch of the disc made on Aug 15.  It shows a scattered North Hemisphere group, rather typical of recent sunspot activity.  The usual words of warning to anyone contemplating observation of the Sun for the first time...  Always use the projection method, NEVER directly or with so-called "solar filters" through a telescope or binocular.  This will blind you.  Even when the Sun looks harmless as it rises or sets its focussed light will burn out the retina in a second or two.

Lunar Notes
The great flooded basin of the Mare Imbrium is bounded by some of the Moon's most impressive mountain ranges.  The Juras, Alps, Appenines and Carpathians encircle from NW to SW - but to the W there is a vast gap, filled only by the minor Harbinger Range.
On June 21, this small but interesting range was well placed just E of the terminator.  The mountains are so named because they herald the dawn for Aristarchus, the brightest formation on the Moon, which lies just to the SW.  They are divided into five main masses running roughly N - S, the highest peak rising 8000 feet above the mare.  To the S the drawing shows part of the incomplete ring Prinz, and to the W the walls of Krieger are appearing out of the darkness.  To the N is the small crater Angstrom.
Note also the ridges in the area.  Under higher lighting they vanish almost completely - being in reality very gentle features.  Clefts abound in this area, and there are several domes near Prinz. Very good conditions and an adequate telescope are needed to see these delicate features though.

Possible TLP activity has been recorded by the BAA network during July, consisting of obscurations in and around Plato.


The Harbinger Mountains
6" Spec  x60
Obs R Moseley




ASTRONOMICAL NEWS ROUND UP

IRAS-Araki-Alcock... A Confused Discovery
MJ Hendrie gave an account of the discovery at a recent BAA meeting which has cleared up the confusion surrounding its circumstance.
The object was first picked up by John Davies and Simon Green at Leicester University, being responsible for 'quick look' examination of IRAS data.  Thinking that the stranger was a fast moving minor planet they did not inform the IAU Bureau, but instead contacted various observing groups directly.  Optical confirmation was made by a Swedish observatory — but these results were held up by a postal delay.
On the night of May 3 - 4 George Alcock, (observing from his landing through a double glazed window) saw what he took to be a bright comet - and received immediate confirmation from Guy Hurst and Roy Panther.  Hurst immediately informed the IAU.  Araki's earlier observation was reported subsequently.
Without the unfortunate delay in issuing the news it is quite possible that at least a week's more observation might have been obtained.

Antarctic Meteorites
In recent years some 5000 meteorites have been found in Antarctica, concentrated at two main sites - the Yamato Mts and South Victoria Land - by ice movements.
Two finds are particularly unusual.  One is suspected as having come from the Moon.  It appears to be a mixture of particles typical of the lunar soils, no more shocked than Apollo samples.  It is thought the an impact on the Moon could eject mildly shocked fragments of considerable size if they lay near the surface.
The second find is a 'Sherottite'.  Only three other examples are known.  Mars seems the most likely source for these igneous meteorites - though there is considerable difficulty in explaining their escape from the planet.

Low Light Detection Systems
Astronomers and electronics engineers at the Australian National University at Canberra have co-operated to produce their own photon counter.  The device counts electrons emitted from a single photon when it strikes a photoelectric surface.  The resulting electron beam then forms an image, after intensification on a cathode ray tube.
Computer processing of the results gives a two-dimensional picture formed from the single photons. The sensitivity of the device is said to be 1O,OOO times greater than that of the average commercial film.  It also has applications in medicine.

The Next Supernova?
The last supernova in our galaxy occurred in 1604, but as astronomers estimate that supernovae erupt every fifty years or so, we are long overdue for one.  Ian Ridpath recently described the next possible candidate.
The star concerned is Eta Carinae, which sits in a gas cloud in the southern Milky Way.  It has a history of instability.  By examining the gas thrown off by the star astronomers have come to the conclusion that Eta Carinae is nearing the end of its life.
Eta Carinae is the heaviest and most luminous star known - about 100 times the mass of the Sun and giving out the energy of millions of suns.  It lies about 9,000 light years away.  Stars of such mass have short lives, probably not exceeding 2 million years.
Latest observations suggest that Eta Carinae will become a supernova between 1,000 and 10,000 years from now.  When it does explode it could rival the crescent moon in brightness - sufficient to light up the night sky.

Farewell, Viking!
The last of the Viking craft on Mars has fallen silent - almost certainly for good.  Until last November Viking Lander I, its activities reduced to stationkeeping, was sending back a small but steady stream of data, mainly meteorological.  Recently, as part of the normal monitoring routine, a new set of commands was radioed to the craft.  It failed to acknowledge then, and engineers began to worry.
The most likely causes of breakdown have all been eliminated, and there is a remote chance that transmission might resume spontaneously.  But NASA won't be listening.  The returns would not justify the expense of building up a large staff in an attempt to revive the mission.




Historical Note
By Reg Nobbs

This is an eye-witness account of the great Leonid meteor shower of 1866
(November 15 / 14) by Robert S Ball.

"I shall never forget that night.  On the memorable evening I was engaged in my usual duty at that time of observing Nebulae with Lord Posse's great reflecting telescope.  I was, of course, aware that a shower of meteors had been predicted, but nothing that I had heard prepared me for the splendid spectacle so soon to be unfolded.
It was about 10 o'clock at night when an exclamation from an attendant at my side made me look up from the telescope, just in time to see a fine meteor dash across the sky.  It was presently followed by another and then again by others in twos and threes, which showed that the prediction of a great shower was likely to be verified.  At this time the Earl of Rosse (then Lord Oxmantown) joined me at the telescope and after a brief interval, we decided to cease our observations of the Nebulae and ascend to the top of the wall of the great telescope, from whence a clear view of the hemisphere of the heavens could be obtained.
There, for the next two or three hours, we witnessed a spectacle which can never fade from my memory.  The shooting stars gradually increased in number until, sometimes several were seen at once.  Some times they swept over our heads, sometimes to the right, sometimes to the left, but they all diverged from the East.
As the night wore on the constellation Leo ascended above the horizon, and then the remarkable character of the shower was disclosed.  All the tracks of the meteors radiated from Leo.  Sometimes a meteor appeared to come almost directly towards us, and then its path was so foreshortened that it had hardly any appreciable length, and looked like an ordinary fixed star swelling into brilliancy, and then as rapidly vanishing.  Occasionally a luminous train would linger on for minutes after the meteor had flashed across.
It would be impossible to say how many thousands of meteors were seen, each one of which was bright enough to have elicited a note of admiration on any ordinary night."





MIRA 5
December 1983




COLLEGE OBSERVATORY NOW OPERATIONAL
By R Moseley

It's a great pleasure to be able to mark MIRA's first birthday with the news that the Society's 6½" Cooke refractor, housed in our observatory on the College roof, is how operational again.
The final work of replacing the OG and remounting the telescope itself was carried out on Tuesday November 22nd.  Since then several clear nights have been utilised in commencing adjustments and testing.  This process of 'de-bugging' is rather time consuming, but should be completed by early January.  From then on the instrument will be available for members to use on any clear Thursday evening during College term time.  Sessions will commence at 7pm, but please bear in mind that we are limited to College hours, and so the observatory must close at around 9pm in normal circumstances.  If the College theatre is open we can stay longer.  A committee member will be present for these sessions.  Keen observers can arrange telescope time other than on Thursdays, after satisfying the Committee that they are competent to use the instrument alone.
Early star tests have indicated that the OG (the main lens) is of very high quality.  It is centred very nicely (ie squared-on) and may need only very fine adjustment.  No zonal or spherical aberration was noted.  No evidence of false centring.  The only astigmatism seen was a product of the observer's eye!  The telescope passed its achromatism test with flying colours - and its out of focus star rings are a joy to behold, when seeing permits!  Some lunar observations were possible on Nov 23rd, with highly encouraging results.  Moon and planets will be the strong point of the telescope, although local seeing conditions are never likely to be very good.
If you are contemplating a visit to the observatory do remember to dress warmly - the chartroom is heated but it will get very cold in the dome itself.  The night porter will give you directions up to the roof.  If the weather seems doubtful please ring to check whether the session is on or off.
Thanks are due to all who have helped in renovating and reinstalling the refractor.  Bert Bywater has constructed a wide-field monocular finder as an addition to the telescope - as well as repairing the guide 'scope.  Mr John Gilbert, of the College engineering dept. has kindly offered to cast some lead weights for the clock drive.
But most thanks are due to Chairman Ted, who in the face of enormous workloads over the past year, has contributed large amounts of time, energy and expertise to the project.





The Maria Mitchell Observatory
By Paul Porter

Maria Mitchell was born in Nantucket in 1818 at No. 1 Vestal St.  In her late twenties she became famous for her discovery of a telescopic comet.  Later she taught at Vassar College as America's first woman astronomer.  The present Director, Dr. Emilia Belserene explains, "England, Mary Somerville and Caroline Herschel were her idols.  As a result, we are something of a feminist memorial."
The Astronomical Observatory at No. 3 Vestal St. was built in 1908 and houses the telescope given to Maria Mitchell by the "Women of America" in 1869.  Here the Association's astronomer carries on research into variable stars, as well as training students and arranging lectures.  At the nearby Milk St. extension the Loines Observatory allows the public to view celestial objects on open nights.
The telescope is a 7½" Cooke Triplet photographic refractor, with a 5" Clark guide-scope.  The Cooke lens was purchased in 1915 and has now taken over 7,100 photographic plates - mostly in Coma, Cygnus, Scutum and Sagittarius.  The original lens cell was replaced by the Flecher Co. of Philadelphia in the 1940s to accommodate a new spacing. The lens was again removed in 1982 and given a different spacing calculated by Dr.James Baker.  Optician Paul Valleli made the measurements.
The stars photographed with the Cooke are usually between 13 - 15 mag, and the exposures range from 10 - 60 mins.  Most of the work is done by female university undergraduates during the Summer months.





How Low Can You Go?
By Tim Gouldstone

The theoretical horizon from this part of England should enable objects to be seen down to Dec -37.5 degrees.  As there is a good southern horizon from this location at Ansley in North Warwickshire I decided to see how close one could approach this figure.  There is some degree of light pollution due S from here which is caused by the western outskirts of Coventry.
Stars were selected from Norton's and the magnitudes checked from Atlas Coeli.
Using 7x50 binoculars Alpha For, Upsilon 1 Eri, and Upsilon 2 Eri were seen - but Upsilon 4 (41) Eri was not seen.  All these stars were at or near the meridian on the evening of the observation (25 December 1982) which suggests that the lowest limit of possible visibility on this night was about Dec -30 degrees.  Certainly the limit of visibility in the binoculars at this altitude was about mag 4.5.
On 1983 Feb 3 the following stars were observed with 7x50 binoculars:
                         Dec.         Mag.
Kappa CMa.       -32 27'       3.78
Lambda CMa.    -32 32'        4.48
Delta Col.         -33 25'        3.98
Alpha Col.        -34 06'        2.75
Kappa Col.       -35 07'        4.51 (Not seen
Beta Col.          -35 47'       3.22 (Not seen)

These results would seem to indicate a limiting Dec on this evening of -34 30' (plus or minus several degrees with light pollution) cumulating at an altitude of about 3 degrees.
If it shows nothing else, searching around at low altitudes with a pair of wide field binoculars does show up how significant light pollution and atmospheric extinction can be.  It is surprising how frequently even binoculars are limited to objects brighter than mag 4 or 5 over substantial areas of the sky at low altitudes.
Has anyone else any comments on this matter.





Observations from a Dark Site
By Geoff Johnstone

On the 11th/12th August, while on holiday in Wales, we were blessed with clear skies and so I was determined to observe the Perseid meteor shower.
My son and I drove the short distance from our coastal site into the mountains above Llanbedr to escape the lights.  We settled down on lilos at 21.15 UT for our meteor watch, and completed it at 23.05 UT - having seen 29 shower meteors and 4 sporadics.  During the watch I was intrigued by how much further South I could see than I could from my home.  However, I was not equipped with a suitable torch and was unable to read my Norton's Star Atlas easily.
The following night (Aug 12/15) was the shower maximum - and it was again clear.  We commenced our watch at 21.19 UT.  Up to 22.50 UT we observed between us 61 meteors.  Between 22.30 and 25.50 UT I personally observed a further 40 meteors - making a total of 101 meteors seen in 2h 11m.
During the watch I studied the area that had so intrigued me the previous night, and with my torch in a red crisp bag I was able to compare the area with Norton's.  It was possible to see as far South as Dec -35 degrees - almost to the limit of the constellation Sagittarius.
The "Lagoon Nebula" (M 8) was a superb sight with 8x30 binoculars, more than 10 degrees above a clear horizon.
The following night (Aug 15/14) I again observed the area around the Lagoon Nebula.  With the binoculars it was fairly easy to pick out the Messier objects 16, 17, 18, 25 and 28.  It was also easy to observe M 11, the "Wild Duck" cluster in Scutum - and, of course, M 13 in Hercules.
In the dark skies of Wales I observed, for the first time, M 33 in Triangulum.  This galaxy, which has a combined magnitude of 6 to 7, covers a large area of sky - and as a result is very faint and difficult to see.





Deep Sky Notes
...concluding, a survey of Planetary Nebulae.
By Richard Barrett

The "Eskimo" nebula is an exceptional object, in the constellation of Gemini.  It is a bright object (mag 8) which, can be found by identifying Delta Geminorum (mag 5.5), and from there, finding 63 and 61 Geminorum (which form a kite shape with 56 Gem. NGC 2392 (the Eskimo) forms a flat triangle, with 63 and 61.  With a diameter of 40", NGC 2392 is slightly larger than some previous examples, and hence can clearly be seen as a nebula, rather than a star, even at quite low powers.
Another planetary, this time a fairly modest one, that I have seen is a 10th mag object in Auriga.  This nebula (IC 2149) is only 10" in diameter, and hence only appears as a faint star even with my highest power (x133).  The magnitude of this object means that it really needs a 4" telescope or larger, with reasonably clear skies to see it.  It is fairly easy to find, as it lies only about 1½° degrees NW of Beta Aurigae.  It shows a stellar appearance of through my own telescope.

The following list contains most of the bright planetaries visible to north hemisphere observers with, small telescopes (as well as one or two fainter ones of interest).

Object                              Con         Int. Mag.         Size             Cent. Star Mag.
NGC 7662                    AND.        8.5              30"               14
NGC 7009 "Saturn"         AQU.        8.0              25"               12
NGC 7293 "Helix"           AQU.        6.5            12'x16'             13
IC 2149                        AUR.       10.0              10"               14
NGC 6826 "Blinking"       CYG.         8.8              25"               11
NGC 6543 "Cats-Eye"      DRACO     8.6           22"x16"            10
NGC 6392 "Eskimo"        GEM.        8.0              40"               10
NGC 6210                     HER.        9.7           20"x16"            12.5
NGC 3242                     HYDRA      8.9             40"                11
M 57     "Ring"               LYRA        9.0          80"x60"             15.4
NGC 6572                     OPH.        9.0          15"x12"             12
M 76     "Barbell"            PEH.       11.0        140"x70"             16.5
NGC 2438 (within M 46)   PUPPS    11.0              65"               17
M 97     "Owl"                UMa       11.0             150"               14
M 27     "Dumb-bell"       VUL.        8.0             8'x5'               13.5



Recent Deep Sky Observations
By Tim Gouldstone

Here are some observations I have made with the 216 mm reflector on various NGC objects.  I feel that sometimes comments on what we actually see can be more revealing about these objects than what the books say - which often only give details that can be seen under the very finest conditions, etc,!

NGC 6913 (M 29) Cygnus
Described in Becvar as "loose and poor".  About 8 fairly bright stars with suggestion of others.  This cluster can be found by sweeping in declination South of gamma Cygni.

I 6910 Cygnus
Marked in Norton's as Herschel 56/8, loosely scattered aggregate of stars.

NGC 6838 (M 71) Sagittarius
Faint oval cloud, partly resolved into stars.  Easy to find, between delta and gamma Sag.  Globular cluster.

NGC 7089 (M 2) Aquarius
Fine, bright unmistakeable globular - can easily be found by moving in dec. north from beta Aqu, with equatorial.

NGC 598 (M 33) Triangulum
Deceitful object!  I have observed this (with difficulty) with 7x50 binoculars, but efforts to locate it with 216mm spec. at x33 and x85 proved impossible.  Norton's dictum, "use very low power on dark, clear night" is certainly true of this nearby spiral galaxy.

NGC 1068 (M 77) Cetus
Muirden, in 'Astronomy with Binoculars' says this is about the furthest reach of such instruments.  He must have good skies, mighty binoculars or superb eyesight!  Visible in 2l6mm spec. as faint oblong streak, better seen with x85 than x33.  Perhaps it can be seen in binoculars of higher power than x7?  Has anyone tried?  It is a spiral galaxy, about 40 million light years distant.  Just SE of delta Ceti.

NGC 752 Andromeda
Very coarse but spectacular cluster near the wide binocular double 56 Andromedae, can be included in the same field as this object. Visible in 2l6mm spec. even with near-full moon in Taurus. 32/7 in Norton's.

NGC 7662 Andromeda
Noting Richard Barrett's observation in MIRA 4 Sept 83 I searched for this object on Nov. 21, but was not able to find it as full moon in Taurus was making deep sky observation difficult.  Try again!



By Rob Moseley

NGC 1952 (M 1) Taurus
The "Crab Nebula"   1983 Nov 15  01.20 UT  This was the first success with this object after over a year of trying from Coventry.  In my 6" at x60 it was difficult - even in an exceptionally clear sky.  Size estimated at 4x3', slightly elongated N-S, very ill-defined, "ragged".  The star SAO 77313 (mag 7.2) follows by around 20'.

19 Piscium - a Red Star
While observing some doubles in Pisces on Oct 22 I picked up this star purely by chance.  I was immediately struck by its intense redness.  I compared it to the famous Mu Cephei (Herschel's "Garnet Star").  Mu is a full orange/red and more striking - although 19 Piscium seemed redder.  On checking I found that it is a variable of Spectral class C - a cool red carbon star.  Stars of this class are uncommon.  Its B-V value indicates that it is intrinsically far redder than the Garnet star.

NGC 1068 (M 77) Cetus
As a footnote to Tim Gouldstone's earlier remarks, I was recently observing the double 84 Ceti and as it lies so close to M 77 I took a looksee.  Nothing.  6" spec. x60.  Indifferent conditions.  Couldn't split the double either!





Astronomical News Round-Up
Compiled by Geoff Johnstone

M 8 - The Lagoon Nebula
The Lagoon Nebula and its associated cluster NGC 6530 lie near the inner edge of the Milky Way's Sagittarius spiral arm.  Like the Sword of Orion (M 42) M 8 is an emission nebula powered by three massive O class stars no more than 2 million years old.  The three stars are HD 165052, 9 Sagittarii and Herschel 36.  New studies at Kitt Peak reveal the structure of M 8 — and suggest that it is an area of active star formation.

More details on quasars
It is now accepted that Quasars are the active centres of galaxies, and that the red shift is cosmological.
Recently several workers, including RRO Director Alec Boksenberg, have published details of a study of the source known as MR 2251-178.  This galaxy and quasar together have a mass of roughly a million million suns... some ten times larger than our Milky Way.  MR 2251-178 is a relatively close system at 1.2 thousand million light years.  In X-rays alone it emits 10 times more than the entire radiation of the Milky Way.  Wavelength measurements show an envelope of gas (ie the galaxy itself) rotating about the quasar.  From this the mass within 550,000 light years of the quasar has been estimated at 1.3 million million suns.
It cannot be stated what type of galaxy the quasar is imbedded in - it could be an elliptical or a spiral - but velocity measurements suggest that it is part of a cluster of galaxies.

Giant Supercluster
The largest known structure in the Universe is long filamentary supercluster of galaxies stretching 700 million light years, lying some 200 million light years from the Sun.
Studies at Arecibo reveal a supercluster of galaxies in the Lynx-Ursa Major region.  This lines up with a previously known supercluster in Pisces and Perseus.  The adjoining ends are in a region of obscuration, but Doppler shift measurements in the 21 cm band reveal that the two swarms do in fact join - forming a giant supercluster.

The Moon's Ancient Magnetism
S Runcorn, of the University of Newcastle-upon-Tyne, has put forward some controversial theories from his study of the strength of magnetic fields in moon rock.
He suggests that the Moon had a fluid core in its distant history, from which a magnetic field was generated - similar to the Earth's.  His measurements indicate that the axis of rotation of the Moon has changed at three different times.  This could have been caused by huge impacts changing the Moon's moments of inertia.  Runcorn has identified ancient magnetic equators at 4.2, 4.0 and 3.85 thousand million years ago.  Impact basins that are thought to be of similar ages lie along the paleoequators.  As bodies from the asteroid belt would not have struck the Moon's equatorial region, Runcorn proposes that the bodies were in the Moons orbit.  He suggests as evidence that the Orientale impact basin shows signs of formation by a low-angle impact of the sort that would be expected from an object following the Moon around the Earth - or perhaps in its own lunar orbit.

Pioneer 10
On June 13th 1983 Pioneer 10 passed the orbit of Neptune at a distance of 2,814 million miles. At present Neptune is the outermost planet of the Solar System.  At this distance the transmission time to and from the spacecraft is over 4 hours.  The spacecraft is travelling at 30,000 mph, and the transmission time will increase by one minute every four days.  Even at this distance the craft has not crossed into interstellar space.  The Sun's sphere of influence is far larger than anticipated.
The twin probe Pioneer 11 is also leaving the Solar System - but in the opposite direction.  As they move deeper into space they may be able to detect the presence of a massive unseen object beyond the orbits of the known planets.
Subtle, persistent perturbations of the planets Uranus and Neptune have suggested that such an object could exist.  If the object is a planet relatively close to Neptune (a few thousand million miles), only one spacecraft will be affected.  However, if both are affected equally it suggests a dark companion star to the Sun.

Infra-red Telescope
Following the success of the joint UK - USA - Netherlands satellite IRAS, the European Space Agency (ESA) have decided to fund an Infra-red Space Observatory (ISO).  This will consist of a cooled primary mirror 60cm aperture and a number of focal plane instruments, to observe between about 1 and 180 microns.  ISO will have a sensitivity several hundred times greater than IRAS and will have the ability to study a single object for a considerable period of time.  The satellite will have a life of 1½ years and will be launched in the early 1990s.

New Solar System Names
At the recent IAU General Assembly meeting names were given to newly discovered solar system objects.  Decisions were taken only after considerable debate as new objects have been discovered by spacecraft that have not met existing criteria.
The Jupiter satellite 1979 J2 has been christened Thebe.  Two small bodies sharing the orbit of Tethys around Saturn have been named Telesto and Calypso.  1980 S1 and 1980 S3 have been named Janus and Epimethus respectively.
Five dark breaks in Saturn's ring system now bear official names also.  They are Cassini, Encke, Maxwell, Huygens and Keeler.

Well - what do you know?
Did you know that for any astronomical object, if you divide the angular momentum by the total mass and also by its density raised to the 1/6 power, the number obtained will be equal to the mass itself raised to the 0.7 power. Wow!






MIRA 6
March 1984




First Point of Aries... and all that!
By Geoff Johnstone

The intersection of the ecliptic with the celestial equator is known as the Vernal Equinox - or First Point of Aries.

It is called the Vernal Equinox as when the Sun is at that location Spring begins - in the Northern hemisphere.  Of course, if you are an astronomer in the Southern hemisphere it is the Autumnal Equinox.  Therefore it is perhaps more correct to refer to it as the March Equinox.  The First Point of Aries crosses the Meridian at 7.00 pm in early December, although it is no longer in the constellation, of Aries due to precession (Earths wobble).  The Point is now actually among the stars of Pieces.  The name is largely astrological and indicates the beginning of the Zodiac sign, not the constellation.  The Zodiac signs are 50 segments along the ecliptic which at one time extended up and down to the poles of the ecliptic.
The First Point of Aries is the origin of three co-ordinate systems.  The first is that of Right Ascension, in which positions on the celestial sphere are given in hours, minutes and seconds of sidereal time measured eastwards from the First Point, which is designated 0h.
The second system is the celestial longitude and latitude system measured along the ecliptic. It is rarely used these days, except for computing apparent positions of Solar System objects.  Up to two centuries ago it was the main system used and some of the leading atlases of the 17th and 18th centuries used both equatorial and ecliptic co-ordinates.
The third is a modified equatorial system similar to Right Ascension - except that it is measured in degrees Westward from the First Point.  This is called the Sidereal Hour Angle, or SHA.  Therefore an object with an RA of 23 hours will have an SHA of 15°.  This system tends to be favoured by navigators.





Fore-Runners of the Space Shuttle
(Part 2)

The "Martin - Marietta" X-24
By Paul Porter

To acquire the skills and knowledge necessary to produce an aircraft able to orbit in space and then return to land on an aerodrome runway, the Martin-Marietta company began experiments with lifting body designs in 1959.  Following extensive theoretical research the company built an unmanned lifting body vehicle designated X-25A, which it flight tested to confirm that the concept of a wingless aircraft with a bulbous wedge-shaped body was practical.
With the initial success behind it Martin-Marietta was ready to go a stage further by building a manned vehicle under contract to the United States Air Force.  This vehicle was delivered to the USAF in July 1967 as the X-24A and eventually completed a run of nine manned but unpowered flights during 1969.
On March 19 1970 Major Jerauld Gentry of the USAF sat in the cockpit of the X-24A while it was carried to an altitude of 45,000 feet under the wing of a giant Boeing B-52 "Mother Plane". The X-24A was released from the B-52 and Major Gentry ignited the turbo rocket engine to boost his speed and attain greater altitude.  The flight lasted just 7¼ minutes, after which the craft landed safely on Rogers dry lake bed.
During the remainder of 1970 and part of 1971, 28 further flights were made before it was decided to take the X-24A apart and rebuild it as the higher speed X-24B.  When the aircraft re-appeared it was considerably longer with a more pointed nose.  The main difference, however, was that the X-24B was far less bulbous in shape, with a flatter undersurface and neatly curved top-decking.  The programme restarted with an unpowered flight in August 1973, and fourteen powered flights, followed - the last being made in September 1975.
The culmination of this and other research aircraft can be seen in the incredible NASA Space Shuttle, which began its flight tests in 1977.





A Survey of Bright Galaxies
(Part I)
By Richard Barrett

Galaxies are the most numerous objects in the sky, stars included.  The examination of plates taken with large telescopes reveals that many of the "stars" are, in fact, distant galaxies.  For observers with small telescopes there are few galaxies within easy reach, numbering perhaps thirty.
Galaxies vary in size from the immense cD galaxies (eg M 87 in Virgo) at the heart of superclusters - down to dwarf galaxies (eg the Fornax System) which were only discovered when photographic techniques were improved, as they were previously mistaken for plate defects.
Of the galaxies within reach of most amateurs spirals are by far the most common - a prime example being the Andromeda Galaxy (M 31).  It would be unnecessary to give a detailed description of this object as almost any astronomy book will have a photograph at least (the observatory library will, of course, contain much information).  The only difficulty in locating M 31, ie the common one of confusing your guide star in the line from Alpha Andromedae to Alpha Persei.  It is easy to take Alpha Persei as the end star of Andromeda, meaning that instead of searching around Beta you will be looking at Gamma Andromedae.  A star map will clarify this, and care must be taken to look 8 degrees NW of Beta Andromedae.
The Andromieda Galaxy, just visible with the naked eye, and a marvellous sight in binoculars, loses something when viewed with a small telescope.  However, a telescope is necessary to search for the galaxy's two companions.
M 32 is a small elliptical galaxy (classified as E2, ie very slightly elongated), located very close to M 31 (about ½° South).  At low magnifications it appears fairly star-like. Once located though, higher powers may be used to bring out its fuzzy appearance.  It lies at the southerly end of a 90-60-30 triangle of stars of similar magnitude (about 9).  This object is quite bright, but not particularly spectaculars.
The other companion, NGC 205 (M 110) is an E6 (very elongated) elliptical galaxy which can easily be found about ½ degree NW of the Andromeda Galaxy.  The ease of location is due to an isosceles triangle containing at its centre two close stars.  NGC 205, although not in its self spectacular, holds a special fascination for me, because at mag 10.8 it is the faintest object I have seen with my 4" reflector.  It is just visible, using averted vision, on a reasonably clear night.  Two of my own favourite objects are M 81 and M 82.  These galaxies lie in Ursa Major (the Great Bear).  To find: 7 degrees N of 23 UMa (mag 3) is 24 UMa (mag 5).  Very close to this in a SW direction is a 7th mag star, and continuing about ½ degree along the same line is a 6th mag star.  Once this star is found pan carefully one degree E and look for a smudge of light.  This will probably be M 81 (at mag 8 the brighter of the two galaxies).  Slightly more than ½ degree N of this is M 82.
M 82 is the famous "Exploding" irregular galaxy.  It is not as bright as M 81, but its elongation is very noticeable.  With most faint elongated objects the brightness is insufficient to reveal the elongation.  The barely visible light is pretty much shapeless.  But with M 82 the elongation is clearly visible, creating a sense that the object is real - not an elusive, shapeless smudge.
Both of these galaxies are large enough and bright enough to be clearly seen as diffuse objects, and can easily fit into the same low power field of view.  They are a marvellous sight on a clear, still, dark night.  Even with binoculars M 81 can be seen, if they are held very still.
M 81 and M 82 are the brightest members of a widely spread association of galaxies reaching across into the little-known area of Camelopardus.  That's where we go in the next issue.


Galaxies in Andromeda
By Richard Barrett


M 110  (NGC 205)                                                  M 32  (NGC 221)
4" Spec  x64   ½° Field                                           4" Spec  x32   1° Field





MEMBERS OBSERVATIONS


Solar Notes
Throughout last Autumn sunspot activity was very low - with a blank disc for weeks on end.  During the December 4th partial eclipse (which was very unspectacular) many observers remarked on the total absence of spots.
However, on Jan 29 1984 there were dramatic developments with the sudden appearance, of a very large N. hemisphere group.  This was recorded by Harry Brierley in Northampton and Paul Porter here in Coventry.  Paul has supplied a detailed drawing of the group made on the 29th, and another showing its development 48 hours later.

Solar Activity


1984 Jan 29th   10.30 UT                                    1984 Jan 31st   12.35 UT
2.4" OG  x50  Conditions - Fair                             2.4" OG  x50  Conditions - Good
Two small spots to N just forming on 29th   Box shows arrowed group x100



Lunar Notes
By Rob Moseley

The night of Feb 9th 1984 was extremely clear and steady - a fact especially remarked upon by John Richards at our meeting held on the following evening.  Being a Thursday the College Observatory was open to members - but there were no takers on this occasion.  However, this gave an opportunity for some lunar drawing under ideal conditions.
Mt. Piton was well placed, framed by the terminator and the great knife-edged shadow thrown by Gape Agassiz (the S extremity of the Lunar Alps). Note the slender ridge running S from Piton to the craterlet Piton A.  This ridge was also noted under reverse lighting (ie sunset) on 1983 Oct 29, when I was able to use the 8¼" Clark refractor at the Temple Observatory, Rugby.  A more prominent ridge runs NW towards the crater Piazzi-Smyth, which can be seen emerging from the darkness.
After the drawing some pure sightseeing was enjoyed.  The Triesnecker and Hadley rille systems were prominent, and the famous "branch-line", connecting the Hyginus and Aridaeus systems was an easy feature.  The floor of Ptolemaeus, in high relief, was an astonishing sight.  I could count over a dozen low craters and "saucer" depressions.  Seeing remained a good Antoniadi II throughout - conditions I never expected to experience in such an unpromising location.

Mt. Piton


1984  Feb 9th 19.15 UT
6½" OG  x246
Seeing II   Colong  3.2°
Note the great 'knife-edged' shadow to N, thrown by Cape Agassiz




A Visual Sighting of Space Shuttle Columbia
By Vaughan Cooper

During the second orbit of Columbia and approximately 100 minutes after launch on 1985 Nov 28 the shuttle was visible from Coventry.
At 17.54 UT a star-like object rose from the west, becoming brighter as it gained altitude.  As it passed through the southern borders of Lyra Columbia was at its brightest (mag -1) shining with a silvery white light, and heading for the central regions of Cygnus where it very abruptly faded and then disappeared as the craft entered the Earth's shadow.
The duration from first sighting to eclipse was approximately two minutes.



Double Star Notes
By Rob Moseley

'Castor' (Alpha Geminorum) is perhaps the most famous binary system of all.  I have had two interesting views this Winter under good conditions.
On Jan 30 1984 at 00.30 UT, using my 6" reflector at x120 I saw two yellow/white stars, so close that it was difficult to judge the brighter.  x120 only just divided the pair.  I estimated PA to be around 100.  Webb gives a third optical member of the system as a 9th mag star south following.  This comes is included in the field sketch.

On Feb 13 1984, between 20.00 - 15 UT Castor was used as a test object for the drive mechanism on the 6½" refractor.  Powers up to x526 were used under reasonable seeing conditions.
x204  - difficult, although obviously elongated.
x246  - nicely split.
x390  - a wider split, but poor images
x526  - the drive kept the pair almost stationary in the field even at this power.  In 5 minutes there was a drift of about 2 arcmins N. (Polar alignment has still to be fine tuned).  Although the air was "jumpy" two good images were seen, with minute Airey discs and circular diffraction rings.  The split was very wide, 9th mag Castor C was well seen to S.

All three visible stars are, of course, spectroscopic doubles, so the complete system involves 6 stars.  The current ephemeris (taken from the BAA Handbook) gives the main pair as - mags. 1.9 & 2.9, Sep. 2.51", PA 85.2.

The Cooke refractor was also used on Dec 6 1983 to look at some doubles in Aries.  Of these the Otto Struve reject triple, 41 Arietis, was the most interesting.  The 4th mag. primary was seen to have two 11th mag companions, which were quite easy with averted vision.  Both lay around 20" distant.  A very rich field.




A Simple Focusing Aid for Prime-Focus Photography
By Geoff Johnstone

Focusing a single-lens reflex camera at the prime-focus of a telescope is not always easy, particularly when trying to focus on a faint, extended object, such as a comet, nebula or galaxy. Focusing is often made harder as many makes of SLR have dark focusing screens which are not interchangeable. It is very frustrating once having found the object, only to have great difficulty in focusing and perhaps, even, to knock the instrument in the process and then have to start all over again.  I have found it possible to eliminate all these difficulties with my telescope in the following Way.
My telescope has a draw tube to which the camera is attached.  When the camera is removed an eyepiece screws into the centre of the same draw tube.  Over the outside of this is slipped a Jubilee clip, then the rack-mount is fully screwed in.  Next, while pointing the telescope at a bright star, the image is focused through the viewfinder - or better still, by opening the back of the camera and focusing, with a magnifying glass, on a screen placed at the focal plane.  Focusing is achieved by pushing in or pulling out the draw-tube.  This is a bit of a fiddley job, but it only has to be done once.  When satisfied that the camera is focused, the Jubilee clip is pushed up against the telescope and tightened.  In use, all that has to be done on finding an object to photograph, is carefully to remove the eyepiece, attach the camera and push the draw-tube in until it can go no farther.  The camera is now correctly focused.
Using the system saves a great deal of time and frustration.  It also enables the use of inexpensive SLRs such as the Zenith, with its notoriously dark focusing screen.  It further means that incorrect focusing is impossible.  I have two cameras that can be focused with the same position of the Jubilee clip, enabling two types of film to be used concurrently.
A future modification might be to drill and tap the draw-tube at various positions corresponding to tae in-focus distance of different eyepieces or cameras, and then place a screw in the hole appropriate to the optical arrangement in use.




For the Beginner

Getting basic observing skills is just a matter of practice.  This exercise requires no equipment.
Look at the Plough (Ursa Major).  Using the chart, letter the stars from A to G in order of brightness.  This is not as easy as it sounds!
If you do have a pair of binoculars look at each star in turn and note its colour, and any other peculiarity.
After recording them, try and forget these results!  On the next clear night repeat the process.  Then compare.
It is important not to look at any books or charts until after your observations.  The correct, order (and colours) will be printed in the next issue of 'MIRA' as a final check



The plough (Ursa Major) is almost overhead on Spring evenings.