MIRA 14
September 1986



COMET HALLEY



COMET HALLEY

Date           January 11th 1986
Time          18 hours OO mins
Conditions   clear, windy
Instrument  102mm Refractor x46.5
Location      Southam, Warwickshire
Observer     Angela Turner

Nucleus very bright almost stellar coma very bright too.
One star can be clearly seen through the tail of which appeared long and fan shaped-and greatly emphasised in my drawing.






DEEP SKY OBJECTS 

By B. MERRIKIN



M65 & M66


Date   3rd - 4th May 1986

Time   21.00 - 0.55 UT

Instrument: 8 1/2" Spec.


Mag: x80 (kel) = Field, of view 29'

Mag: xl80 (Or) = Field, of view 14'


Seeing: II Clear and steady throughout period, of observation with no deterioration at all.


Remarks.  M65 & M66 an excellent view with both galaxies in the same field, at x80.  M65 has a more starlike centre with just a hint of a dark lane.  M66 has a more mottled, appearance and seems to have brighter portions at the nucleus.  Both galaxies magnify well and are easily found in star-field.





M59, M60, NGC 4647 & 4638 (Virgo)


Remarks.  Drawing shows M59 to left of centre, M60 with NGC 4647 to right of centre and NGC 4638 

to upper centre.  M60 has an even overall appearance with very bright starlike core.  M59 smaller than M60 but also has a bright starlike core.  NGC objects seen as small oval patches, 

but no detail visible.  A pleasing overall view at x80.


M85 a superb sight with a very bright core and an overall mottled appearance and hints of dark areas.  Even better at x180.  At x80 has NGG 4394 in same field, as an oval smudge but with no discernible detail.







FIREBALL



Date           1986 May 3rd

Time           22 hours 20 minutes

Conditions   steady hazy

Instrument  Naked eye

Observer     Angela Turner

Location      Southam Warwickshire.


Notes.

Appeared to come from the constellation of Coma Berernices, making a very distinct sound upon entering the atmosphere.  It lasted for no more than 3 seconds and finally broke up into about five separate components.  Each component was red with yellow surround.  The fireball was extremely bright perhaps -8 or more.

The above was also seen by Mr Barry Merrikin from his home in Rugby who just happened to look up from the eyepiece of his telescope whilst conducting a series of deep sky observations.

Interestingly enough Barry estimated the track of the fireball through a slightly different area of the heavens to Angela's drawing as the track was parallel to δ and β Virgo ie. the right hand arm of the Y of Virgo heading towards Regulus in Leo Major and no sound was heard.

However Barry relates "I was dumbstruck by the shear brilliance of it which made a magnitude estimate very difficult."  After destruction a faint remaining steak was noted just below Leo, heading towards Regulus.







OBSERVING DOUBLE STARS


By Rob Moseley


Multiple star systems are by far the most common class of celestial object available to the Deep Sky observer - and also the most neglected.  Many amateurs have relegated them to mere test objects.  This is a great pity, because they are intrinsically beautiful and far more readily found in urban skies than faint nebulae.

A casual glance at Norton's Star Atlas reveals hundreds of doubles within the range of amateur telescopes.  I must admit that for years those, strange ε's, σ's and β's captured my total neglect.  Of course I had looked at Albireo, Castor and a few other showpieces - but I was never motivated to look further.  Few other amateurs interested in Deep Sky observing seemed to pay them any heed, so I followed suit.  Whenever there was no Moon or favourable planet in the sky I frittered away my time in the largely futile hunt for elusive smudges of light.

And then a couple of years ago I had the good fortune to attend a lecture given by Frank Holden, a member of an almost extinct species - a professional double star observer.  As I listened to his reminiscences of solitary nights making measures with the Lick 36-inch, I became deeply impressed by his lifelong passion for double stars.  I left the meeting resolved to investigate further for myself.

My own telescope is an altazimuth 6-inch (f 1O) reflector - mainly used for Lunar studies.  I quickly realised that it was far better suited to double stars than to galaxies and nebulae.  I dug out my copy of Webb's "Celestial Objects for Common Telescopes" (virtually unused, I am ashamed to say) and set to work.

When I say "work" I really mean "play", as there is little scope for serious study unless measures can be made, and this is a different proposition entirely.  From the outset I regarded doubles as light relief from my preoccupation with the Moon.  My approach was, and still is when using my reflector, to select easy pairs from Webb's excellent lists that lay comfortably within its range.  These are mostly Struve (Σ) objects with separations above 5" and companions no fainter than mag 9.  I saw little point in being over-ambitious - having tasted the bitter cup of failure so many times with Messier and NGC objects.

I also decided to concentrate on handily placed constellations on or near the Celestial Equator.  For each constellation a list of achievable pairs is drawn up well in advance of any observing session.  There are two reasons-for this preparation.  Firstly, it gives enough time to forget the measures given in the catalogue (only the name of the pair is listed), and thus avoids estimates being compromised by fore-knowledge.  Secondly, it enables a constellation on or near the meridian to be utilised whenever an opportunity for an observing session occurs.  I normally limit myself to not more than ten objects in a session of around two hours.

Once the double has been located estimates of position angle and separation are made.  This is where the fun really starts!  At first I naturally found this operation difficult.  With an altazimuth mount it requires close attention to star drift in order to orientate for a PA estimate (with an equatorial its easier).  Judging separation by eye is simply a matter of practise and appreciation of your field diameters under different powers.  After my first 50 doubles I found that my estimates were getting towards average errors of 5" (for pairs separated by less than about 40") and 10 in PA.  I'm sure others could do better!

Its a good general rule in any area of observation not to over-press magnification, and this also applies to double stars.  I normally use a sweeping power of x60, as this will split most of my selections quite comfortably.  For closer pairs (under 5">  I use x120 - this will split down to 2.5" in good seeing.  For the occasional tough-nut I reserve my top power of x240, but T find that constant switching of eyepieces wastes a lot of time, particularly as mine have RAS threads.  For a   close pair my list will simply indicate "H.P." but will give no further clues.  A higher power can improve the accuracy of P.A. estimates because the drift of the pair across the field is more obvious.  If a companion is not seen, the fact is noted and the object re-checked at a later date. Its important not to get "bogged down" and frustrated.  For all pairs observed I make a field sketch at the telescope.

Estimates of colour are of no value in the scientific sense - and yet this is the part of double star observing I tend to enjoy most.  The subtleties of star coloration are only truly appreciated by the double star specialist.  Many are an aesthetic delight.  Once ray eye became used to perceiving colour at low light levels I found that Webb, Smyth and the other 19th century observers were not being that fanciful with their "garnets", "indigos" and "olivacea subrubicundas"!  Stars really do have the most gorgeous coloration's - if real attention is paid to them.  Colours are always more striking with complimentary pairs.  The yellow and lilac of Albireo is the most famous example of quite a common combination.  My favourite is the pair 32 Eridani (470).  The 4th mag primary is a rich yellow, with a 6th mag, comes I have noted as "emerald".  Webb describes the pair as "Topaz and Bright Green".  This companion is one of the few stars I've come across which is unmistakably green - it's a ravishing sight!  The red/green combination is best typified by Antares and its companion, but to British observers the 7th mag. attendant is a stiff test due to its low altitude and consequent poor seeing.

The expression "to my eyes" denotes the significant pitfall in colour estimates.  In its early years the BAA had a Star Colours Section, but it folded quite quickly (as did the Double Star Section!).   Colour appreciation is highly subjective and the physiological processes involved are still imperfectly understood. Colour blindness of various types is a relatively common handicap, especially in men.  Although the normal eye can distinguish thousands of colour gradations, putting a name to record each one is patently impossible.  For example, a random dip into my observing log produces the following terms to cover a close range of hues: Lilac, Pale Lilac, Purple, Purplish, Violet, Violet/Blue, Pinkish White, Pink, Rose, Reddish White etc.  Yet, allowing for etymological imprecision, I usually find reasonable and interesting comparison with the judgements of Webb and others.

But to complicate matters further there are other physiological gremlins at work.  With unequal pairs a fainter white star can "borrow" the complimentary colour of the primary.  There is also aspects of the infamous 'Purkinje Effect' (well known to VS observers) to contend with.  With my 6-inch aperture any star below 9th mag. appears a nondescript blue/grey.  This is because at low light levels the "rods" in the retina are operating alone, the colour sensitive "cones" having shut down.

Magnitude values are not really part of the double star observers province, but they are interesting to estimate and record.  When you go out to observe a Struve, Herschel or Burnham object you should bear in mind that you are very likely to he the only person to have locked at it closely for years.  You certainly won't see any dramatic changes in its configuration (most binaries have periods of hundreds of years, or it may be fixed) - but there is a very slight chance that one of the components may be variable and so far unrecorded.

When I have made my estimates of separation, PA, colour and magnitudes I have the added fun of comparing with Webb (Burnham's Celestial Handbook is another good source).  Its nice when I get it right - but there is always the occasional bizarre failure!

The doubles that teem on the pages of Norton's have come to life for me.  They are so little observed nowadays that many "one-to-one" relationships spring up.  As I sit at my telescope during the quiet watches of the night, watching those twin sparks of light floating through the field of view, my mind often conjures the vision of the Revd. Webb doing exactly the same on his vicarage lawn so long ago.  There is an indefinable tranquillity in observing double stars.  Grab yourself some.





Compilation of Close Doubles

by Bob Marriott


Bumham G.C.  Common Name      RA                Dec            Mags           Sep        Date


3172               Σ 849                   6h  4.4m       17°25'      8.5   8.9      0.81         1910

3239               β 1008  η Gem      6h 10.4m      22°32'       3.0   8.8      0.88         1900

3341               Hu 702                 6h 19.7m      34°26'       8.5   9.0      0.86        1908

3518               OΣ 152                 6h 34.8m      28°20'       6.0   7.8      0.85        1912

13106             A 1053                 6h 35.8m      25°09'       8.8  10.2      0.79        1912

4120               β 579                   7h 29.6m      33°17'       7.2  11.5      0.96        1899

4477               Σ 1196                 8h  7.9m       17°53'       5.0   5.7      0.98        1914

4494               β 204                   8h  9.5m       10°37'       7.1  10.1     0.80        1910

4531               Σ 1211                 8h 13.4m       39°14'      8.7   9.2      0.85        1911

4526               Σ 1205                 8h 13.4m       56°41'      8.5   8.8      0.98        1899

4641              Hu 627                 8h 26.4m       34°46'      9.0  10.0      0.88        1906

13168            Hu 858                 8h 35.1m       16°14'      9.1   9.8       0.85        1909

4731              Ho 354                 8h 38.2m       26°19'      8.2   8.8       0.86        1905

4828              β 587  15 Hyd       8h 47.9m      -06°54'      6.0   9.0       0.76        1907

4901              β 211                   8h 58.1m     +02°58'      7.5  10.0      0.78        1912

5078              A 4                      9h 21.8m       31°28'      8.7  10.2       0.98       1904

5103              Σ 1356  ω Leon     9h 24.4m       09°25'      6.2   7.0       0.95        1915

5295              Hu 631                 9h 59.6m       33°01'      7.0   8.6       0.75        1907

5304              Σ 1406                 10h 1.3m       31°27'      8.0   8.7       0.95        1907

5349              OΣ 213                10h  8.9m       27°47'      7.8   9.5       0.90       1914

13196            Hu 875                10h 15.9m      37°54'      7.0   9.8       0.89        1909

5397              Σ 1426                10h 16.6m        6°48'      7.8   8.3       0.79        1904

5560             OΣ 229                 10h 43.7m      41°31'      6.7   7.1       0.99        1913

5585             Hu 567                 10h 48.9m      22°32'      9.3  10.0      0.81        1910

5651             Ho 47                   10h 58.8m      36°04'      9.0   9.0       0.84        1907

5794             Lewis 2                 11h 25.3m      30°50'      7.0  11.0      0.93        1906

5840             Σ 1554                 11h 32.5m      13°15'      8.8   8.8       0.85        1901




A Selection of Notable Coloured Doubles

by Vaughan Cooper


Eta Cassiopeiae            Yellow & Purple

Alpha Hereulis             Yellow & Emerald

Gamma Andromedae    Yellow & Blue

Gamma Leonis             Yellow & Greenish

Phi Tauri                     Red & Bluish

Beta Cygni                  Gold & Blue

Rho Ononis                 Yellow & Blue

Zeta Sagittae              Light Green & Blue

Alpha Scorpii              Red & Emerald Green

Epsilon Draconis          Yellow & Blue

Epsilon Bootes            Yellow & Blue Green

Beta Cephei               Light Green & Blue









MORETUS



MORETUS

6°W 71°S


DATE. . . . . . . . 28th May 1985

TIME. . . . . . . . 21h 40m - 22h 35m

MOON. . . . . . . 9 Days

CONDITIONS. . Steady, clear, atmos clarity good

INSTRUMENT. . 102mm OG 186x, 260x

LOCATION . . . Southam. Warwickshire

OBSERVER. . . Angela Turner.


A walled plain 75 miles in diameter, and has a high broad terraced wall. The floor is dark, and there is a particular lofty central mountain, crowned by a small pit.Seeing conditions were almost perfect so the crater was very well defined indeed. The west wall was the most impressive feature of this crater, absolutely laden with superb terraces, several dark terraces can be seen, these appear to have landslided in several places.
The south wall appears extremely broad and landslided; one small black crater-pit can be seen, the whole of the south floor area is exceedingly hilly. A dark crater let is adjacent to the south wall.
The east wall was in shadow, but even here it gave the appearance of being very broad and landslided as with the west wall. Three bright white patches were showing in the shadow, and directly east the black shadow intrudes on the bright ramparts, this may be a depression in the rampart.
The north wall by comparison is narrow and quite devoid of any major detail. On the floor much detail could be discerned; the central massive was most distinctive, casting long shadows over to the west wall, hills can be seen right along along this shadow, to the north of it; there is also a hill to the S/W of the shadow at its end. A lower hill can be seen to the N/E of the massive, and a long darkish somewhat pointed shadow extending away from the massive in the S/E, hills are strewn all over the floor but I could see no crater-pits anywhere on the floor.





POSIDONIUS

under a Sunset lamination




A 62 mile diameter crater situated on the north eastern shore of Mare Serenitais.


Date            4th October 1985

Time            4h to 5h 15m

Moon           19 days old

Conditions    Fair with light passing cloud, image fairly steady

Instrument   6" inch. Reflector x60 and x120

Observer      Vaughan Cooper


Notes

Not very satisfied with my drawing had a great deal of trouble in getting the general outline and detail correct of Posidonius.

My drawing interestingly enough shows two well defined craters in the middle of Posidonius where in point of fact only one large crater exists called Posidonius A.  This once again proves how misleading the lunar surface can appear from just one observation from a inexperienced eye through a modest telescope, as apparently to the east of Posidonius A the area consists of a ring of little peaks craters and hills.