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Introduction.

Photographic surveys of Megalithic Observatories.           Digital surveys derived from photographs and video footage taken from stone circles and standing stones in Mid Wales, the Outer Hebrides, Yorkshire and Oxfordshire, demonstrate strong support for the existence of the Megalithic Calendar and high resolution Lunar Standstill observation procedures pursued by prehistoric Britons which appears to have reached a peak between 2000 to 1600 BCE.

Sunset from Lechwedd Penrhiwen to hill notch. A Megalithic Equinox alignment.

0.1.1   Earliest astronomy.          From as early as 4000 B.C. the first British farmers were demonstrating astronomical awareness in the orientations of their ritual monuments. Often these were constructed with the entrances and/or axes of symmetry aligned on points on the horizon where the rising or setting sun stood at the extremes of it's travel; Midsummer's Day and Midwinter's Day, (the solstices).          Also at this early time, prior to 2000 B.C., close attention was being paid to the movement of the rising and setting points of the Moon at the extreme positions of it's orbit. It has been found that the most favoured orientation of early Neolithic ceremonial sites, (long barrows), is in the direction of the rising Moon when at the Northern Major Lunar Standstill, several degrees further north than the midsummer sunrise.

0.1.2   Evolved observatories. These early alignments are too short for high accuracy however, (less than hundreds of feet), and could only give a loose estimation of the solar and lunar extremes with no more accuracy than plus or minus several days or weeks. See page Megalithic Calendar 5. To maintain an accurate to-the-day long-running calendar, the length of the year must be known to better than plus or minus 12 hours. The only way the ancient astronomers could establish a time reference of this reliability was to find the moments of both the summer and winter solstices with an accuracy of better than 12 hours. In practical terms this requires the deployment of alignments many miles in length to render sufficient resolutions. See page Ballochroy, North Kintyre.

Ballochroy Stone Row to Jura, a 19 mile, (30.5 km), alignment. This synthesised image is based on data from Alexander Thom's 1971 publication 'Megalithic Lunar Observatories' p37, Fig.4.1

0.1.3   Sky map of the Megalithic Calendar. Once the days of the two solstices had been established and a careful count of days maintained, the time between could be subdivided into smaller intervals by divisions of the day count. This sky map divides the horizons east and west into eight nearly equal epochs through which the sun progresses twice in a year. The partition points which locate the Calendar Intervals   would be marked on the horizons with natural features or artificial structures.

0.1.4   Early high resolution alignments. Sometime prior to 2500 BCE the necessary skills were developed to support the construction of high resolution observatories.See page Thornborough/Carleton Bank. summer solstice alignment.

Summer solstice sunrises from Thornborough tumulus to Carleton Bank at 20 miles, (32km). Digital extrapolation from high resolution photography.

0.1.5   Proliferation of astronomical sites in the Middle Bronze Age. However the fully developed16 interval calendar with four further sub-divisions may not have been fully established before circa 2000 BCE when high resolution astronomical sites began to proliferate throughout Britain concommitant with a great expansion and stratification in British society and the appearance of bronze implement technology. The majority of these high precision sites have so far been found in the uplands of Western and Northern Britain. This demography may be the result of greater agricultural development on lower, deeper soils but may also reflect the greater opportunity for establishing foresights where seeing conditions are optimal and astronomical elevation is enhanced. These observatories are, necessarily, long-distance alignments marked by a foresight consisting of a large artificial markeror natural horizon feature, or combination of both, set on a far height or distant seascape.

S2, Llananno to Glog Hill. Digital extrapolation of Northern Major Standstill moonrise from photography

0.1.6   Resolutions. The optical resolution of a reliable observatory must be better than 2 minutes of arc. A list of photographed alignments of this calibre are closely examined in this study. All but two of these study sites are original discoveries. The two exceptions are photographically verified observatories originaly identified and surveyed by Alexander Thom. The digitally examined images give strong correlations with Thom's calculated declinations. See pages North Uist 1 & 2. and Rollright 1 & 2.

0.1.7   Dating. The dating of the construction of these sites from high resolution photography may be very confident. Many of the alignments are so accurate that the shift in the Earth's angle of tilt,(Obliquity), may have been detectable during their use over the course of less than two centuries. Employing digital time-rewind procedures on good quality photography can render close estimates of the position of the sun or moon at times many thousands of years in the past. See also Ballochroy and S1, Llananno/Drygarn Fawr

Winter solstice sunset on Carleton Bank in the Cleveland Hills.

0.1.8    Backsights. The immediately obvious parts of these observatories are the backsights. These are the places where an observer must stand when taking a positional fix of the Sun or Moon on the horizon. They are generally marked by either collective stone settings, featuring stone rings, e.g. Sornach Coir Fhinn, and/or linear stone rows, e.g. Ballochroy or solitary standing stones (menhirs), e.g. Lechwedd Penrhiwen or stone chairs e.g. S1 and S2, Llananno.

0.1.9   Foresights. The less obvious parts of a megalithic observatory, the foresights, are often natural features which provide opportunity for clean observations. These natural conditions may be enhanced by adjacent artificial structures on the horizon which 'invite' attention to the alignment. Tumulii and cairns are the most common foresight architecture. e.g.See Two Tumps, Dolfor.     Warren Hill, Llanbister,     Drygarn Fawr, Rhayader.

For examples see: See S2, Llananno. Four stones, Radnor. Two Tumps, Dolfor. Lechweddpenrhiwen, Rhayader.Gorslydan, Llanbister. Ballochroy, Kintyre.

0.1.10   Extra long distance alignments. The foresights may be arranged on the surrounding horizons at distances of up to 50 miles or more from the backsight, so that vast highland amphitheatres and seascapes may be incorporated into unique astronomical designs. Only in weather with the clearest visibility may a visitor be assured that all the astronomical potentials of a site have been realised. See examples of long-distance seeing under special conditions: Horizon Astronomy 6.

Blakeley Raise stone circle, Ennerdale Bridge, Cumbria to The Rinnes, Galloway.

0.1.11   Megalithic observatories today. With an understanding of Alexander Thom's work, (Megalithic Sites in Britain & Megalithic Lunar Observatories),many of these astro-landscapes may still be readily appreciated in places such as the islands of Lewis and North Uist in the Outer Hebrides, Kilmartin Glen in Argyllshire, and the currently researched Llananno in Powys. These sites may still be observed in working order if visited on the relevant day when the Sun is at the declination of an interval in the Megalithic Calendar. To find the times of Megalithic Calendar Intervals in today's calendar see below and page Megalithic Calendar 1, or email us. 0.1.12   Megalithic science. These advanced observatories were not erected solely to determine the sequence of the seasons through an agricultural calendar; they were the basis of a fine engineering program deployed to determine exact dates using the Sun's seasonal progression on the horizon. e.g. S1, Llananno. It is also clear that many of these communities had an equal, if not greater, interest in the movements of the Moon. e.g. S2, Llananno and had developed advanced mathematical procedures for establishing the times of lunar orbital extremes termed Major and Minor Lunar Standstills. As yet the reason for this has not been adequately established. The high precision positional data which may be derived from these lunar sites might have supported eclipse or tidal prediction tables, or a system of navigation similar to the Lunar Distance Method of establishing longitude which was employed by some mariners in the mid-18th century AD. 0.1.13   The Megalithic Calendar today. The ancient Briton's calendar year was based on the solar year, (the time it takes the Earth to orbit the Sun), but refined adjustments had to be incorporated to rationalise the changes in the Earth's orbital speed in different seasons. They divided their calendar into 16 nearly equal parts of 22 or 23 days possibly beginning at the Spring Equinox which fell on the 7th April in 2000 BC. The Megalithic Calendar in the Gregorian. Gregorian Calendar Date. Megalithic Calendar Interval, (CI). Required declination of the sun. 21 June. CI no 5. Summer solstice. +23 deg. 54.3 min. 1800 BC. 2 June & 12 July. CIs 4 & 6. +22 deg. 3.6 min. 7 May.& 6 Aug. CIs 3 & 7. Quarter days. +16 deg.40.2 min. 25 April & 18 Aug. CIs 2.5 & 7.5. +13 deg.13.2 min. 13 April & 30 Aug. CIs 2 & 8. +9 deg.9.6 min. 2 April & 10 Sept. CIs 1.5 & 8.5. +4 deg. 58.8 min. 21 March & 21 Sept. CIs 1 & 9. Equinoxes. +0 deg.26.4 min. 1800 BC. 11 March & 3 Oct. CIs 9.5 & 16.5. -3 deg.59.4 min. 27 Feb.& 15 Oct. CIs 10 & 16. -8 deg.27.6 min. 15 Feb.& 27 Oct. CIs 10.5 & 15.5 -12 deg.39.6 min. 5th Feb.& 6th.Nov. CIs 11 & 15 Quarter days. -16 deg.15.6 min. 11 Jan.& 2 Dec. CIs 12 & 14. -21 deg.51.6 min. 21 Dec. CI 13 Winter solstice. -23 deg.54.3 min. 1800 BC. 0.1.14   Annual discrepancies of the positioning of the Megalithic Calendar within the Gregorian. All of these Gregorian dates are approximates. The Megalithic Calendar Intervals, (CIs), wander slightly in today's Gregorian calendar due to the differing approaches to maintaining accurate time measurement. These discrepancies may amount to + or - 24 hours. Any investigator who wishes to find the modern date of a Megalithic CI must locate the day, from astronomical data tables, when a Required Calendar Declination of the sun occurs. For astronomical data furnished by the US Navy Nautical Office: USNO.. To find sun declinations: GEOCENTRIC POSITIONS. To find sun rise/set times for any location and day. DAILY DATA. For further on the structuring of the Megalithic Calendar and it's movements in today's Gregorian calendar see: para. 2.1.22. page Megalithic Calendar 1. 0.1.15   Horizon astronomy opportunities in Mid Wales. Observations in Mid Wales (extending over 19 years) includes photographs and videos taken from stone circles and standing stones at Sun/Moon rises or sets at significant intervals in the Megalithic Calendar and Lunar Standstill periods. During the development of these studies it is becoming apparent that the Mid Wales landscape was considered by megalithic astronomers an important region for the development of high-resolution observatories in a similar class to the great Highlands and Islands astronomical amphitheatres in Scotland. See S1, Llananno. 0.1.16   Refraction and repeated photographic observations. Zenithonial astronomers doubt such a system is practical, due mainly to the erratic nature of astronomical refraction at low elevations; this may vary by as much as half a degree in declination over 24 hours. However it can be demonstrated, using high resolution data from multiple photographic observations on the same alignments taken in different seasons and years, that many accurate solar and lunar alignments had been established in the British Middle Bronze Age. See S1, Llananno to Two Tumps, Dolfor. and S1, Llananno to Gorslydan, Llanbister. 0.1.17   First quality photographic observations. Many photographs taken from standing stones when the Sun and Moon cross the horizon at times corresponding to dates in the Megalithic Calendar and Lunar Standstills cycles show other megalithic monuments and/or distinct horizon features silhouetted on, or near, the Sun/Moon's discs. Photographs of this calibre are often unambiguous and need no further surveys.e.g. S2, Llananno to Warren Hill. and Penrhiwen 1 & 2.and S1, Llananno to Two Tumps./Gorslydan. and North Uist 1 & 2. S2, Llananno to Warren Hill. Penrhiwen 2. S1 to Gorslydan. North Uist 1. S1 to Two Tumps. 0.1.18    Digital reconstruction of alignments. With less definitive photographs computer surveys employing time- rewind can simulate the situations at the solstices, calendar intervals and lunar standstills around 4000-5000 years ago to a very fine resolution- equal to the best modern theodolite surveys. See page Thornborough/Carleton Bank. summer solstice alignment. These simulations offer close correspondence with Alexander Thom's predicted declinations and support his claim that a sophisticated system of positional horizon astronomy had been developed in the British Bronze age in Scotland and Wales. 0.1.19   Engineering standards of the Bronze Age British astro-mathematical traditions. From about 2000 B.C. to 1600 B.C. throughout Scotland, Cumbria and Wales, according to Thom, the people of the Bronze Age constructed many hundreds of working solar and lunar observatories. The Middle Bronze Age, in Britain, experienced an unprecedented proliferation of ritual architecture. More than 40,000 cairns/tumulii and 1000 stone rings are recognised. There may also have been 10,000 solitary standing stones, (menhirs), and stone rows whose erection can be attributed to this 400 year period of expansion. In most regions of the Mid Wales hill country, similar to the concentrations to be found in the Outer Hebrides, every community, no matter how remote, may have boasted one or more astronomical sites. From examination of the nationwide demography of sites supporting identical declinations for calendar and lunar observations it is certain that a highly organised, self-engendering society of astronomer engineers must have moved throughout Britain in prehistoric times. The level of expertise needed to establish or operate a reliable lunar standstill or multiple solar observatory is comparable to the experience of a modern professional engineer. Pop Up Glossary. 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