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The lunar impact claimed by Zuluaga et al. (2019) during the total eclipse of 21 January has been discussed widely by his research group, introducing some results from the technique of gravitational ray-tracing. A similar event of magnitude 6 was observed visually by the author during the eclipse of 19 years before, that was published under the name of Padua event (Sigismondi and Imponente, 2000a,b) and a video was obtained independently by Gary Emerson (Cudnik, 2002) in the US at the same time. The remarkable repetition of such a phenomenon after 19 years deserves some investigation about known active meteor shower on Jan 21 with radiant comprised between the solar longitude 300.7 degrees of January 21 and +/- 60 degrees and declination also departing no more than 60 degrees from the solar one. The amount of 60 degrees is the FWHM of a simple modulated probability model on the visibility of a lunar meteor impact with the cosine of the angle comprised between the line of sight and the normal to the lunar surface. The candidate of this search is the daytime shower Sgr/Cap DSC115 with meteoroid velocities around 26 km/s., 4 pages including an Italian abstract

Visual observations of 2016 Mercury transit ingress made in visible light (Rome) and in H-alpha line (Tehran) are compared to evaluate the quote 1.84" of active H-alpha regions at the solar latitude of the transit, without a confirmation of the theory of an oblate Sun at minimum activity. A variation of -0.12" in the photospheric radius, within 0.17" is found., Comment: 8 pages, 3 figures, 2 tables. Accepted in GERBERTVS academic journal (www.icra.it/gerbertus)

The declination of the Sun along the year varies according to a sinusoid. Around the solstices this curve is approximated by a parabola. In kinematics a parabola is obtained with a constant acceleration. This acceleration has been estimated in the days 21-29 December 2017, from the measurements taken at the meridian line in the Basilica of Santa Maria degli Angeli in Rome made by Francesco Bianchini in 1702 with purpose of measuring the variation of the obliquity of the ecliptic. The parabola equation is fitted to the data to obtain the solstice's instant with an accuracy of one hour. The departure of the measures is within 4 arcsec (the daytime seeing during these solar transits) from the ephemerides of IMCCE. The pipeline of the algorithm used to obtain the angular data of the center of the Sun, starting from the ground measurements affected by the atmospheric refraction, and corrected by the Cassini equation, is described. Bianchini in 1703 reduced the error on the solstices timings by using the difference in right ascension between the Sun and a star observed at the same meridian line even in daytime (as he did with Sirius in June-July 1703). The present one is an absolute measurement, without stellar references. The meridian diameter is averagely measured 24 arcsec less than the true value, with 20 arcsec of standard deviation, because of different luminosity contrasts in the sky and in the Basilica. Conversely the center of the image is much better defined (the contrast acts symmetrically without moving the center of the image), allowing an accuracy to the nearest arcsecond in the determination of the true obliquity., Comment: 9 pages, 2 figure, 4 links to video of the phenomenon. In Italian with extended English abstract

The darkness of the umbra of the lunar eclipse of August 7 2017 corresponded to the predictions of A. Danjon for the Sun at its minimum. It appeared partial at moonrise in Rome similarly to the one of April 3, 33 AD in Jerusalem, supposed following the Crucifixion of Christ. The hypothesis of Sun at maximum activity for that historical eclipse is discussed., 2 pages, 2 figures in color. Text in English with Italian Abstract. Submitted to Gerbertus

La partecipazione della Casanatense alla mostra "Meridiani e longitudini a Roma", allestita nel Salone monumentale dal 4 al 19 marzo 2005 in occasione della XV Settimana della cultura scientifica e tecnologica, ha consentito ancora una volta di far convergere l’attenzione di studiosi e scienziati sul prezioso e ricco corpus di opere riguardanti l’astronomia che si conserva in questa prestigiosa biblioteca romana. Già nel 1985 con Bibliotheca magica e nel 1991 con gli Arcani delle stelle, riscuotendo peraltro molti consensi dai cultori della materia, era stata data una interessante prospettiva di questo particolare settore del patrimonio casanatense. In quelle occasioni era stata anche presentata una serie di strumenti scientifici, alcuni dei quali acquistati dal prefetto Domenicano p. Giovan Battista Audiffredi (1714-1794), sotto la cui guida la Casanatense raggiunse nel ‘700 l’acme del suo splendore. La collaborazione tra istituzioni così diverse come da un lato la Casanatense – istituto bibliotecario di alta cultura che affonda le proprie radici nel secolo dei lumi e che attualmente è un organismo dipendente dal Ministero per i beni e le attività culturali – e dall’altro lo Studium Urbis – centro culturale nato nel 2000 per iniziativa del prof. Allan Ceen e vocato alla storia dell’architettura ed al disegno urbano in Italia - ha portato al risultato esaltante della mostra Meridiani e longitudini a Roma di cui ora si pubblica il catalogo. Infatti il percorso espositivo casanatense del 2005 è stato la naturale prosecuzione di una ricerca iniziata dallo Studium Urbis nel 2002 con la mostra Meridiano. Italy’s prime meridian, in cui veniva ricostruita la storia del Meridiano di Monte Mario e presentata la collezione di carte geografiche di proprietà dello Studium stesso. Questa interessante collezione cartografica si è perfettamente amalgamata ai preziosi testi a stampa e documenti iconografici conservati nella Casanatense, consentendo di illustrare in modo suggestivo e al tempo stesso puntuale il complesso tema proposto dalla mostra., Semestrale di studi e ricerche di geografia, N. 2 (2006): Meridiani e longitudini a Roma a cura di Costantino Sigismondi

The Clementine Gnomon realized in 1702 by the astronomer Francesco Bianchini (1661-1729) upon the will of Pope Clement XI (1700-1721) in the Basilica of Santa Maria degli Angeli in Rome is fully reviewed about its scientific functions., 78 pages, with color images and photo. Text in Italian

The transit of Mercury occurred two times in this century: 2003, May 7 and 2006, November 8. In 2016 there is another opportunity to observe this phenomenon and measure the solar diameter with the method of comparing the ephemerides with the observations. This method has been presented by I. I. Shapiro in 1980, the data of the observed transits (since 1631) have been re-analyzed by Sveshnikov (2002) and an improvement on the observed data, to avoid the confusion given by the black-drop effect, proposed by C. Sigismondi and collaborators since 2005 exploits the measurement of the chord drawn by the solar limb with the disk of the transiting planet and its extrapolation to zero through the analytic chord fitting the observations before the black drop, in the ingress/egress phases. A network of European observers (IOTA/ES) and observatories (coronograph of Bialkow, PL 56 cm; IRSOL, Locarno CH - 45 cm Gregorian telescope) is active for the 2016 transit. Recommendations to improve the observation of the ingress/egress phases and examples of the data analysis on the 1999 Mercury transit observed by TRACE are also done: the planet should be centered in the field of view of the telescope to avoid optical distortions, and the observations should be prolonged well after the black drop phase, estimated in about 40 seconds and more after the internal contact t2 in the ingress and before the internal contact t3 in egress., Comment: 6 pages, 4 figures, presented at the congress Solar Metrology, Needs and Methods II 21-23 September 2015 Royal Observatory of Belgium

Several group in the World followed the solar diameter with dedicated instruments, namely solar astrolabes, since 1974. Their data have been gathered in several observing stations connected in the R2S3 (Reseau de Suivi au Sol du Rayon Solaire) network and through reciprocal visits and exchanges: Nice/Calern Observatory, Rio de Janeiro Observatorio Nacional/Brazil, IAG/Universidade de Sao Paulo/Brazil, Antalya Observatory/Turkey, San Fernando/Spain. The tradition of these observational efforts is here briefly sketched with the aim to evidence the possibility to analyze against the solar activity all these 42 years data at once by overcoming the problem of the shift between the different series. Each instrument has its own density filter with a prismatic effect responsible of that shift. The overall change of the solar radius during the last century is evident by comparing the Auwers' radius of 959.63" (1891, present IAU standard) with 959.94" (2015, from eclipses and Venus transit data, the latter either observed from space) and the role of ground-based daily measurements has been and it is crucial nowadays with Picard-sol and the Reflecting Heliometer of Rio de Janeiro, to ensure an homogeneus and continuous monitor of the solar diameter without the lifetime limitation of the satellites., 4 pages, one double figure, IAU General Assembly 2015 focus meeting 29 no. 2236038

The success of the first measurement of the light bending by the solar gravitational field is due to the particular stellar field during the Eddington's 1919 total eclipse of the Sun, near the Hyades, giving the opportunity to measure the gravitational bending of the light to the astronomers in two expeditions in Brazil, Sobral, and on the Principe Island in the Atlantic Ocean. The geometrical properties of this field and another field in Leo are discussed in view of repeating this experiment of General Relativity with SOHO satellite data in the context of the International Year of Light 2015., 4 pages, 7 color figures, presented at the XIV Marcel Grossmann meeting on General Relativity, in Rome, Sapienza University on July 13, 2015 in HR1 parallel session

The variation of the solar diameter in time and in position angle has implications in astrophysics and in general relativity, as the long series of studies attest. The Transits of Venus in 2004 and 2012 have been carefully studied because of the rarity of the phenomenon and its historical importance due the AU measure and to the discovery of Venus atmosphere. The characterization of Venus atmosphere and the measure of the solar diameter to the milliarcsecond level of precision have been studied also from satellite images. The results of the solar diameter measurements made with the observations in Athens (2004) and at the Huairou Solar Observing Station in China (2012) are presented. The topic of the oblateness of the Sun at sunset and its intrinsic value is drafted to introduce the general public to the relativistic relevance of measuring the solar figure, in the occasion of the International Year of Light 2015., Comment: 4 pages, 2 composite figures in colors, presented to the PT5 parallel session of the XIV Marcel Grossmann Meeting on General Relativity, Rome Sapienza University, on 17 july 2015

Measuring the solar diameter at all position angles gives the complete figure of the Sun. Their asphericities have implications in classical physics and general relativity, and the behavior of the optical systems used in the direct measurements is to be known accurately. A solar filter is a plane-parallel glass with given absorption, and here we study the departures from the parallelism of the faces of a crystal slab 5 mm thick, because of static deformations. These deformations are rescaled to the filter's dimensions. Related to the Solar Disk Sextant experiment and to the Reflecting Heliometer of Rio de Janeiro a simplified model of the influences of the inclination between the external and the internal surfaces of a glass solar filter, is discussed., Comment: 4 pages, 2 figures, presented at the PT5 parallel session of the XIV Marcel Grossmann Meeting of General Relativity, Sapienza University of Rome, on 17 July 2015

The theory of General Relativity deals with very accurate measurements that show significant divergences from Newtonian predictions only with speeds near to the velocity of light. An introduction for educational purposes, based on naked eye photometry, deals with the radiation near collapsing star's shells like novae and supernovae. The theme of accuracy is drafted from entry level observations to the precision of professional data, often of public domain on the web. Thousand observations of variable stars, included the type 1a SN2014J, the Nova Del 2013 and the Nova Cen 2013, sent to the AAVSO by the author, with SGQ code, during the period 1998-2015 are analyzed to increase the photometric accuracy, in the occasion of the International Year of Light 2015., Comment: 4 pages A4, 2 composite figures in color, on table; submitted to MG14 meeting BN4 parallel session, and to be published in GERBERTVS vol. 9 2015

The page written by the astronomer Francesco Bianchini (1662-1729) and containing the data of the 1701 winter solstice observed at Santa Maria degli Angeli is presented for the first time in figure 2 and widely discussed along this paper. The great meridian line in the Basilica of Santa Maria degli Angeli in Rome was built in 1701/1702 with the scope to measure the Obliquity of the Earth's orbit in the following eight centuries, upon the will of pope Clement XI. During the winter solstice of 1701 the first measurements of the obliquity have been realized by Francesco Bianchini, the astronomer who designed the meridian line, upgrading the similar instrument realized by Giandomenico Cassini in San Petronio, Bononia. In this paper the accuracy of the data observed by Francesco Bianchini is discussed and compared with up-to-date ephemerides. The modern situation of this historical instrument is also presented., 9 pages, 4 figures in color, in Italian with English abstract. ISSN 2385-1961

The Astrarium made by Jacopo Dondi dell'Orologio in Padua in 1344 is one of the first public horologia in the World, their public utility is also shown through the history of the tower bell of Our Lady of Suffragio in Turin, made by the mathematician Francesco Fa\`a di Bruno in 1866. The tower bell of St. Anthony in Lanciano made by Antonio Cibotti was inaugurated by the Pope Paul VI in 1973 through a radio impulse, and now many tower bells are radio synchronized to the Central European Time within a single second of accuracy., Comment: 9 pages, 3 figures in color, in Italian with English abstract

On March 20, 2014 at 6:06 UT (2:06 New York time) Regulus, the 1.3 magnitude brighter star of Leo constellation, is going to be occulted by the asteroid 163 Erigone. The unusual event, visible to the naked eye over NYC, can allow to measure the shape of the asteroid, with reaching a space resolution below the diffraction limit of the eye, and of all instruments not based on interferometry. Ultimately the aperture of the instrument is related to the amount of scintillation affecting the light curve of the occultation, limitating the accuracy of video recorded data. The asteroid profile scans the surface of the star at a velocity of 6 mas/s; the diameter of the star is about 1.3 mas and the detection of the stellar limb darkening signature is discussed, taking into consideration also the Fresnel fringes. New data reduction with R-OTE software of the 2005 Regulus occultation and simulations of the 2014 occultation with Fren_difl software are presented., 7 pages, 9 figures, submitted to J. of Occultation Astronomy ISSN 0737-6766

The Dutch Jesuit astronomer Johan Stein published in 1909 a text about the legend on a papal bull of Pope Callixtus III against the comet of 1456. This comet happened to be the Halley's one. The original documents, either chronicles and observations, and coeval testimonies are deeply investigated by Stein and the falsity of that legend is clearly demonstrated. In the occasion of the 200 years of the restoration of the Societas Jesu made in 1814 by Pope Pius VII an Italian edition of the full text of Johan Stein is here presented., 5 pages, 2 figures, Book-Review in Italian, to appear in Gerbertus V (2014)

The interest on the solar diameter variations has been primary since the scientific revolution for different reasons: first the elliptical orbits found by Kepler in 1609 was confirmed in the case of the Earth, and after the intrinsic solar variability was inspected to explain the climate changes. The CCD Solar Astrolabe of the Observat\'orio Nacional in Rio de Janeiro made daily measurements of the solar semi-diameter from 1998 to 2009, covering most of the cycle 23, and they are here presented with the aim to evidence the observed variations. Some instrumental effects parametrizations have been used to eliminate the biases appeared in morning/afternoon data reduction. The coherence of the measurements and the influence of atmospheric effects are presented, to discuss the reliability of the observed variations of the solar diameter. Their amplitude is compatible with other ground-based and satellite data recently published., Comment: 13 pages, 7 figures, submitted to Solar Physics

The figure of the Sun reflects its inner structure and dynamics, influencing also the perihelion precession of close orbiting bodies, like Mercury. To study the solar figure from ground, the deformation on the solar image induced by the atmosphere has to be known up to one part over a million, and this is done through differential refraction models: a historical review of them is drafted. The solar oblateness has been investigated in order to validate alternative theories to General Relativity and to understand the internal dynamics of our star. The solar figure should possess only micro departures from sphericity according to the standard stellar structure theory and helioseismology data, though variations along the cycle has been observed. Ground-based and satellite data show contrasting observational results. The oblateness measured onboard RHESSI satellite, the one of SDS onboard a stratospheric ballon and that one of the Astrolabe of Rio de Janeiro are presented with their implications in classical and relativistic gravitation. The perspectives offered by the reflecting heliometer in the future measurement of the oblateness are depicted., 14 pages, 8 color figures, proceedings of VI IWARA Meeting, Rio de Janeiro 30 sept - 3 oct 2013, CBPF. To appear in SLAC eConf/C1309292

The third column of the left row in the Basilica of Santa Maria in Aracoeli in Rome, has a hole carved in it, of probable astronomical use. The tube aims at a point a 116 degrees of azimut, East-South-East and 17.3 degrees of altitude, the Sun could be aimed in that direction at 07:00 UTC of 12 october and 7:25 UT of march 2, but the view is obstructed by the church's building. Same situation for the 3.9 magnitude alpha Monocerotis, visible 2000 years ago, taking into account the precession. Other hypotheses on the meridian astronomical use of this hole are here reviewed. In the case of solar observations it cannot be for meridian transits in Rome, since the lower transits occurs now at 24.5 degrees at winter solstice; we investigate the case of stellar transits, of declination 30.8 degrees South. Many alignments are possible leaving the azimut as free parameter, being the columun not in its original collocation, but here we investigate only the meridian transits, and no bright stars could have been seen through that hole, taking also into account the precession 2000 years ago. We conclude that this hole was probably not used for meridian observations., Comment: 8 pages, 5 color figures, in Italian. To appear in Gerbertus vol. 5 (2014)

The variabile star Delta Scorpii is in conjunction with the Sun at the end of November each year. We studied its magnitude by averaging the observations of 28 Nov - 1 Dec from 1996 to 2013 using the coronograph LASCO C3 on-board the SOHO Satellite and we extended of four years, i.e. 25 % of the total light curve, back to 1996, with respect to the present AAVSO dataset on this star. The 0.2 magnitude scatters of the single measurements have been studied and the sources of such disturbances are vignetting and diffraction patterns from the coronograph. The new data collected on Delta Scorpii show its minimum at mv=2.5 magnitudes for 1996 and 1997, confirming the values observed during the minimum of 2009, and the main periodicity of 11 years in the stellar variability., Comment: 9 pages, 10 figures, submitted to JAAVSO

The meridian line traced by Egnazio Danti in the Torre dei Venti in Vatican demostrated the need of the Gregorian Reformation of the Calendar. A review on this instrument is presented, along with the astrometric recognition. This meridian line, dated 1580, is deviated of 72 arcminutes Westward from the true North., Comment: 11 pages, 5 figures and 1 table. Text in Italian

The interest on the solar diameter variations has been primary since the scientific revolution for different reasons: first the elliptical orbits found by Kepler in 1609 was confirmed in the case of the Earth, and after the intrinsic solar variability was inspected to explain the climate changes. The CCD Solar Astrolabe of the Observat��rio Nacional in Rio de Janeiro made daily measurements of the solar semi-diameter from 1998 to 2009, covering most of the cycle 23, and they are here presented with the aim to evidence the observed variations. Some instrumental effects parametrizations have been used to eliminate the biases appeared in morning/afternoon data reduction. The coherence of the measurements and the influence of atmospheric effects are presented, to discuss the reliability of the observed variations of the solar diameter. Their amplitude is compatible with other ground-based and satellite data recently published., 13 pages, 7 figures, submitted to Solar Physics

A bright Nova in Centaurus was discovered on Dec 2, 2013 at magnitude V=5.5. Its luminosity reached mv=3.8 from Dec 5 to 7, becoming the brightest Nova of 2013 and of the last decades. On Dec 14 it brightened at mv=3.2. The observations of the author contributed to the compilation of the IAU Circular 9265 which announced the Nova as V1369 Cen and are here described. The first observations have been made with naked eye, and the use of same altitude calibration stars of similar color allowed an accuracy within 0.1 magnitudes. The method of selecting stars on the same almucantarat (altitude circle) even farther than 20 degrees, reduces the effects of differential atmospheric extinction. Its application is useful not only for bright Novae but also for luminous variable stars like the supergiant Betelgeuse and Antares and some bright Miras., 8 pages, 2 figure in color. To appear in Astronomia Nova Ottobre-Dicembre 2013, http://www.eanweb.com/rivista-astronomia/

The dome of Saint Peter's Basilica plays the role of the Moon during a stellar occultation and Arcturus is the target star. This occultation-like phenomenon is useful for introducing to occultation astronomy a class of student up to university level. It can be organized very easily at the convenience of the audience. Techical and didactical aspects are discussed; the video is available at http://www.youtube.com/watch?v=hIfsj7t-u-c and has been realized with an ordinary camcorder., 3 pages, 1 color figure, presented at CAP2013 conference held in Warszawa from 13 to 18 october 2013. To appear on Journal of Occultation Astronomy 2013-4 ISSN 0737-6766

The sudden and untimely death of Pawel Max Maksym will not diminish his contributions to the field of occultation astronomy, and to Polish society in general. Founder of the Pope Silvester II Observatory in Bukowiec, he was also writing a book to introduce children to astronomy. Graduating in Geography with an experimental thesis in Lunar Occultations at Lodz University, Pawel earned a diploma from the prestigious National Film School in Lodz. An expert observer, he mastered the technique of stellar occultations, fostering the scientific activity of the Observatory. A review of his publications in Minor Planet Circulars and on YouTube is presented here., Comment: 18 pages, 6 figures, 1 table. Submitted to the Journal of Occultation Astronomy

Out of the three quantities that characterize the state of an isolated gaseous body: pressure, temperature and volume the radius is the only one directly measurable for the Sun, what is specially true in the optical window and for ground base measurements. The Heliometer of Observatorio Nacional, in Rio de Janeiro, measures the distance between two opposite limbs of the Sun in the same field of view, through the reflection on a 10 cm parabolic mirror split on its half and forming an appropriate angle. This configuration is free from optical aberrations and focal variations along the measurement direction. The mirrors are made on CCZ vitro-ceramic and the telescope structure is of carbon steel, resulting that there is no flexion or temperature deformation. The instrument is compact, and can perform hundreds of measurements per duty day, around all heliolatitudes. It attains an accuracy on the solar radius of 0.01 arcsec, becoming the ideal instrument to monitor from the ground the solar diameter, and to bridge satellites and astrolabes historical series of data. We discuss the first years of regular observation, with emphasis on the instrumental calibrations and on the statistic study of the derived time series, attitude series, and solar geometry series. On basis of these series we obtain how well the Heliometer and Solar Astrolabe results are matched., Comment: 2 pages, 2 figures, accepted for ICRC 2013 conference, Rio de Janeiro 2-9 July 2013

It is possible to evaluate the absolute magnitude of the Nova Delphini 2013 with visual observations submitted to AAVSO, following the works of Leonida Rosino at Asiago Observatory on the novae of M31. A naif interpretative model of the light curve is presented, based on the decreasing exponential law, in order to open to amateur astronomers a glimpse on the complex theoretical framework of these phenomena., Comment: 3 pages, 2 figures, XXI GAD meeting, La Spezia, 11-13 october 2013; in Italian language

Here the preliminary results of the calibration of the heliometric angle of the Heliometer in Rio de Janeiro are presented. They have been made in 2013 with a reference surveying rod, equipped with two metal spheres acting as artificial star, when illuminated by the Sun, and with the method of drift-scan timing., Comment: 3 pages, 1 figure, Proceedings of the conference ICRC 2013, July 2-9, 2013, CBPF, Rio de Janeiro, Brazil. To be published in the Brazilian Journal of Physics, after the paper of Andrei et al., The Heliometer of Rio de Janeiro in Operation 2010 to 2013

On the spur of Calvary the Shroud appears. On this rock the Scriptures are fulfilled, and this rock, located exactly to the West of the Temple of Jerusalem, becomes mystically the new orient, place of the Resurrection of the Lord. The alignements between the three holy places for the three monotheistic religions, the Anastasis, the Temple, now Dome of the Rock, and the Chapel of the Ascension with the East-West axis are here measured and commented both from an astronomical and topographic point of view, enlighted by the urbanistic roman concepts of Vitruvius and the catechesis of saint Cyril bishop of Jerusalem 13 years after the inauguration of the Constantinian buildings at the Holy Sepulcre., 15 pages, 5 figures, in Italian. Proc. Conference "Terzo incontro sui due Teli" Jerusalem 25-28 November 2012, Notre Dame of Jerusalem Center

D\'ungal's letter to Charlemagne on the double solar eclipse in the year 810 is extremely interesting both for its form and for its subject matter. Part I of the present study deals with the epistula as a literary work (genre, language, sources), dealing in turn with vocabulary, morphology and syntax, rythmical prose and rhetorical figures, literary and Biblical references. If we compare it with D\'ungal's other works, the letter is cast in the canonical oratio structure similar to his later Responsa contra Claudium (ed. Zanna, Firenze 2002) and it is likewise based on lengthy quotations drawns from Macrobius' commentary In Somnium Scipionis. A possible echo of Vitruvius' astronomical presentation in book IX of his De architectura is suggested. Finally, we attempt to define how the author's persona as famulus et orator and reclusus at St-Denis relates to Charlemagne and to abbot Waldo in his pursuit of Chirstian wisdom based on the Bible rahter than of scholarship per se based on academic research. Part II is a thorough technical discussion of the astronomical issue presented to the Irish scholar by the Emperor, i.e. The frequency of solar eclipses and their visibility in the two emispheres in the year 810 (see maps provided). It assesses D\'ungal's case in terms of eclipse theory and reviews previous comments on his letter to Charlemagne by astronomer Ismael Bullialdus (1605-1694). It also introduces us to first-hand knowledge of eclipses in history and nowadays, providing a glimpse into the complex problems tackled by the Irishman and his sources in Late Antique and in the Early Middle Ages. Ample footnotes to the Italian translation of D\'ungal's work are an essential guiding tool for Latinists unfamiliar with astronomy., Comment: 74 pages, 20 figures, in Italian and Latin

The observation of a central eclipse from the umbral band and, even better, from its edge allows to measure the solar diameter with an accuracy up to a part over 100000. The data of the annular eclipse of 22 september 2006 observed from Kourou, French Guyane and their calibration are presented., 10 pages, 5 figures, in Italian. ISSN 1125-5218

The equation of time is fundamental for calculating the rising and setting times of the Sun. The concepts of sidereal and solar day and locak noon, we show how the length of the day depends on solar declination and Earth's orbit position, and also their influence on the local noon shift. In particular we show why in the month of July the setting time is rather constant, while the daylight reduces constantly., Comment: 8 pages, 7 figures, in Italian; Geografia, trimestrale di ricerca scientifica e programmazione regionale, vol. 105-106 (2004)

The horologia are ancient ephemerides, tables of durations of the days and nights during all months of the year. The algorithms used to compute the horologia are here presented and the results are compared with the tables computed by Gerbert in the letter to Adam. The Ptolemaic geography is the framework in which Gerbert made his calculations., 8 pages, 3 figure, 3 tables, in Italian. ISSN 1123-5586

Gerbert of Aurillac was Pope Sylvester II form 999 to 1003. His history is presented in order to understand his outstanding contribution in the establishment of quadrivium sciences (arithmetics, music, geometry and astronomy) in the curricula studiorum of cathedral schools and therefore of forthcoming universitates studiorum. Gerbert allowed the first sharing of arabic scientific scientific culture (e.g. Introducing in his didactic method the astrolabium, the abacus and the monochord) with Christian world participating in person to the mini-renaissance of the tenth century., 7 pages, in Italian. ISSN 1123-5586

Gerbert of Aurillac in the Mensura Fistularum explained how to compute the length of organ pipes. The method is shown on two octaves, starting from a fistula of length L=16 units and radius 1 which is equivalent at a monochord of length {\lambda}=18. The adopted acoustic correction for the first octave to the Pythagorean lengths is L={\lambda}-{\alpha}r with {\alpha}=2. The lower octave starts from L=36-2=34 units. The proportion 16:34=34:x is used for obtaining the next diapason. All lengths of the notes of this second octave follow this proportion and no more the additional acoustic correction. Gerbert finds the same multiplicative law for computing pipes and monochord's lengths, opportune constants allow to switch from monochord (12) to lower organ octave (14+1/3+1/144+1/288) to the higher one (13 + 1/2). The purpose of this treatise is to show the same mathematical order, given by God, below different acoustical phenomena. This is a modern perspective in history of science, because experimental data (practical acoustical corrections) are also taken into account. The treatment is limited to pipes of same diameter, and it is no conceived for organ builders. An Italian translation of the core text of the Mensura Fistularum is offered. The experimental measurement of end and mouth corrections for two pipes of different forms and for the flute is presented to support with modern acoustics approach that discussion., Comment: 32 pages, 18 figures, in Italian, ISSN 0392-0305

The Clementine Gnomon in the Basilica of Santa Maria degli Angeli in Rome has been realized in 1702 with the aim to measure the variation of the obliquity of the Earth axis along the forthcoming centuries. Since then the church and the instrument undergone several restorations and the original conditions of the pinhole changed. The measurements of the position of the image in the days before and of the 2011 winter solstice with respect to the original markers compared with the ephemerides gives us the North-South correction for the position of the pinhole to be restored., 9 pages, 4 figures, to appear in the Journal of Occultation Astronomy (ISSN 0737-6766) January-March 2012

The muons of cosmic rays air showers in the Extreme Energy Events (EEE) project are detected with three Multi-gap Resistive Plate Chambers (MRPC) with good tracking capability. These muon telescopes are located in high schools spread all over Italy. The detection of extensive air showers is made by means of time coincidences between two distant telescopes. The vectorial components of the incoming directions of the muons are known, as well as the UTC time of their arrival on the detectors. The method to calculate the celestial (equatorial and galactic) coordinates of the incoming direction of the muons is presented. This procedure allows recovering galactic or extragalactic sources of the extreme energetic cosmic rays which produce such extensive air showers. A worksheet file (muoni.xls or EEEtest.xls) contains a simulator, to produce data in the same format. This introductory method to positional astronomy for muons, useful also for neutrinos, is presented through explained formulae and an interactive worksheet, tailored for the data format of EEE (http://www.centrofermi.it/eee/)., Comment: 16 pages, 5 figures, the text is in Italian. The accompanying xls file is available at http://www.icra.it/solar/muoni.xls and at http://www.santamariadegliangeliroma.it/documenti/EEEtest.xls; Ateneo Pontificio Regina Apostolorum, Roma (2008) ISBN 978-88-89174-85-2

The equation of time is fundamental for calculating the rising and setting times of the Sun. The concepts of sidereal and solar day and locak noon, we show how the length of the day depends on solar declination and Earth's orbit position, and also their influence on the local noon shift. In particular we show why in the month of July the setting time is rather constant, while the daylight reduces constantly., 8 pages, 7 figures, in Italian; Geografia, trimestrale di ricerca scientifica e programmazione regionale, vol. 105-106 (2004)

The solar eclipse of Good Friday has always been recognized as a problem from the astronomical point of view. The date of Crucifixion has been investigated by many scholars and the most accredited one is friday 3 april 33, when, at sunset an eclipsed Moon rised. Few minutes later the apparition of a third star of medium magnitude stated the beginning of the sabbatical rest: before that time Jesus has been buried, wrapped into the shroud. All these topics are reviewed from an astronomical point of view with some theological considerations., Comment: 29 pages, 11 figures, in Italian. Proc. Conference "Terzo incontro sui due Teli" Jerusalem 25-28 November 2012, Notre Dame of Jerusalem Center

The Jesuit scientist Christopher Clavius (1538-1612) has been the most influential teacher of the renaissance. His contributions to algebra, geometry, astronomy and cartography are enormous. He paved the way, with his texts and his teaching for 40 years in the the Collegio Romano, to the development of these sciences and their fruitful spread all around the World, along the commercial paths of Portugal, which become also the missionary paths for the Jesuits. The books of Clavius were translated into Chinese, by one of his students Matteo Ricci "Li Madou" (1562-1610), and his influence for the development of science in China was crucial. The Jesuits become skilled astronomers, cartographers and mathematicians thanks to the example and the impulse given by Clavius. This success was possible also thanks to the contribution of Clavius in the definition of the Ratio Studiorum, the program of studies, in the Jesuit colleges, so influential for the whole history of modern Europe and all western World., Comment: 6 pages, 5 figures, 12th Italian-Korean Symposium on Relativistic Astrophysics, July 4-8, 2011, Pescara - Italy

The role of Venus and Mercury transits is crucial to know the past history of the solar diameter. Through the W parameter, the logarithmic derivative of the radius with respect to the luminosity, the past values of the solar luminosity can be recovered. The black drop phenomenon affects the evaluation of the instants of internal and external contacts between the planetary disk and the solar limb. With these observed instants compared with the ephemerides the value of the solar diameter is recovered. The black drop and seeing effects are overcome with two fitting circles, to Venus and to the Sun, drawn in the undistorted part of the image. The corrections of ephemerides due to the atmospheric refraction will also be taken into account. The forthcoming transit of Venus will allow an accuracy on the diameter of the Sun better than 0.01 arcsec, with good images of the ingress and of the egress taken each second. Chinese solar observatories are in the optimal conditions to obtain valuable data for the measurement of the solar diameter with the Venus transit of 5/6 June 2012 with an unprecedented accuracy, and with absolute calibration given by the ephemerides. Fruitful observations can be obtained also by amateur astronomers, by following the instructions in this paper. All ground-based observations designed to achieve this goal are warmly welcome to be analyzed by the author, presently visitinig the Huairou Solar Station of National Observatories of China for observing that transit.Finally a miminal observational schedule is suggested., Comment: 6 pages, 3 figures, presented on 7 June 2012 h 15 to the NAOC,National Astronomical Observatories of China,Chinese Academy of Science, Room 601, A20 Datun Road, Chaoyang District, 100012 Beijing

The lifetime of a satellite is limited, and its calibration may be not stable, it is necessary to continue ground-based measures of the solar diameter with methods less affected by atmospheric turbulence, and optical aberrations: planetary transits and total eclipses. The state of art, advantages and limits of these methods are considered., Comment: 4 pages, 1 double figure. Proceedings of EWASS 2012 Conference, Rome 1-6.7.2012, Pontificia Universitas Lateranensis. Symposium 8. "The Sun: new tools and ideas in observational solar astrophysics", Francesco Berrilli, Francesca Zuccarello and Ilaria Ermolli editors. To appear in Memorie della Societa' Italiana di Astronomia Supplements, electronic edition, April 2013

Gerbert of Aurillac wrote to Constantine of Fleury in 978 a letter to describe in detail the procedure to point the star nearest to the North celestial pole. This was made to align a sphere equipped with tubes to observe the celestial pole, the polar circles, the solstices and equinoxes. The use of tubes in astronomical observation is later reported by Alhazen in his treatise on optics (1011-1021). The description of pointing to the celestial pole indicates that the instrument must be accurately aligned with the true pole, materialized at that epoch by a star of fifth magnitude, at the limit of naked eye visibility, and then the instrument must remain fixed. Solstices and Equinoxes are points of the orbit of the Sun, so the sphere could be used as a tool for observing the Sun and probably determine the duration of the tropical year. This sphere was much more than a didactic tool, given the long procedure for the accurate alignement. Moreover "Rogatus a pluribus" (asked by his many students), Gerbert wrote a treatise on acoustic tubes (fistulae) in 980: Mensura Fistularum. He knew the difference in behavior of the fistulae compared with the acoustic strings, already studied by the Pythagoreans, and the treaty is intended to present the law that governs the length of the organ pipes in two octaves, compared to the corresponding acoustic strings. In terms of modern physics we know that acoustic tubes require an "end correction" to be tuned, which is proportional to the diameter of the tube. This proportionality is the same for every note. The mathematical law is simple, but Gerbert preferred to create a law in which the proportions of pipes and strings should be calculated through a series of fractions linked to the number 12 and its multiples., Comment: 8 pages, 5 figures, Atti dell'XI Convegno SIA (Societ\`a Italiana di Archeoastronomia) di Bologna-Marzabotto 2011. In Italian

The asteroid (147857) 2005 UW381 will pass over the supergiant star Betelgeuse on January 2nd 2012. The event is visible on a limited geographical region, and the magnitude drop is only 0.01 magnitudes for a maximum duration of 3.6 seconds. The opportunity to measure this phenomenon can be interesting for dealing with extrasolar planetary transits., 5 pages, 8 figures, to appear in the Journal of Occultation Astronomy (ISSN 0737-6766) January-March 2012

The measurement of the solar diameter is introduced in the wider framework of solar variability and of the influences of the Sun upon the Earth's climate. Ancient eclipses and planetary transits would permit to extend the knowledge of the solar irradiance back to three centuries, through the parameter W=dLogR/dLogL. The method of Baily's beads timing during eclipses is discussed, and a significant improvement with respect to the last 40 years has been obtained by reconstructing the Limb Darkening Function's inflexion point from their light curve and the corresponding lunar valleys' profiles. The case of the Jan 15, 2010 annular eclipse has been studied in detail, as well as the last two transits of Venus. The atlas of Baily's beads, realized with worldwide contributions by IOTA members is presented along with the solar diameter during the eclipse of 2006. The transition between the photographic atlas of the lunar limb (Watts, 1963) and the laser-altimeter map made by the Kaguya lunar probe in 2009 has been followed. The other method for the accurate measurement of the solar diameter alternative to the PICARD / PICARD-sol mission is the drift-scan method used either by the solar astrolabes either by larger telescopes. The observatories of Locarno and Paris have started an observational program of the Sun with this method with encouraging results. For the first time an image motion of the whole Sun has been detected at frequencies of 1/100 Hz. This may start explain the puzzling results of the observational campaigns made in Greenwich and Rome from 1850 to 1955. The meridian line of Santa Maria degli Angeli in Rome is a giant pinhole telescope and it permits to introduce didactically almost all the arguments of classical astrometry here presented. The support to the PICARD mission continues with the analyses of the transit of Venus and the total eclipse of 2012., PhD thesis of University of Nice-Sophia Antipolis, Sapienza University of Rome and French-Italian University; 119 pages with 96 color and b/w figures, tables and schemes. Discussed at the Sapienza University of Rome on 12 December 2011. Revision 23 November 2012

The heliometer of Fraunhofer in Koenigsberg (1824) is a refractor in which the lens is split into two halves to which is applied a linear displacement along the cut. Later in 1890s a variation of the heliometer has been realized in Goettingen using a beam splitting wedge: these methods were both subjected to chromatic and refractive aberrations; the second configuration being much less affected by thermal fluctuations. The mirrored version of the heliometer conceived at the Observatorio Nacional of Rio de Janeiro overcome these problems: the two halves of the vitrified ceramic mirror split at a fixed heliometric angle produce the two images of the Sun exempt of chromatisms and distortions. The heliometer of Rio is a telescope which can rotate around its axis, to measure the solar diameter at all heliolatitudes. A further development of that heliometer, now under construction, is the annular heliometer, in which the mirrors are concentric, with symmetrical Point Spread Functions. Moreover the location of the Observatory of Rio de Janeiro allows zenithal observations, with no atmospheric refraction at all heliolatitudes, in December and January., 6 pages, 3 figures, 1 table; proc. of the XII Italo Korean Meeting on Relativistic Astrophysics, 4-8 July 2011, Pescara, Italy. To appear in Nuovo Cimento B

The outburst of 8 October 2011 of Draconids meteors has been observed visually onboard of Alitalia AZ790 flight. The enhanced zenithal hourly rate around ZHR=300 from 19 UT to 21:50 UT has been observed over central Asia. The data and the method of analysis are described and compared with other observations made worldwide., 5 pages, 2 figures, proc. of the 12th Italian-Korean Symposium on Relativistic Astrophysics, 4-8 July 2011, Pescara, Italy

Hundred observations of Delta Scorpii over 200 days, from April 2 to October 16, 2011, have been made for AAVSO visually and digitally from Rio de Janeiro, Rome and Paris. The three most luminous pixels either of the target star and the two reference stars are used to evaluate the magnitude through differential photometry. The main sources of errors are outlined. The system of Delta Scorpii, a spectroscopic double star, has experienced a close periastron in July 2011 within the outer atmospheres of the two giant components. The whole luminosity of Delta Scorpii system increased from about Mv=1.8 to 1.65 peaking around 5 to 15 July 2011, but there are significant rapid fluctuations of 0.2 - 0.3 magnitudes occurring in 20 days that seem to be real, rather than a consequence of systematic errors due to the changes of reference stars and observing conditions. This method is promising for being applied to other bright variable stars like Betelgeuse and Antares. After August the magnitude remained constant at Mv=1.8 until the last observation on October 16 made in twilight from Rome., 5 pages, 3 figures, Proc. of XII Italian Korean Symposium on Relativistic Astrophysics, July 4-8, 2011, Pescara, Italy. To appear on Nuovo Cimento B

Delta Scorpii is a double giant Be star in the forefront of the Scorpio, well visible to the naked eye, being normally of magnitude 2.3. In the year 2000 its luminosity rose up suddenly to the magnitude 1.6, changing the usual aspect of the constellation of Scorpio. This phenomenon has been associated to the close periastron of the companion, orbiting on a elongate ellipse with a period of about 11 years. The periastron, on basis of high precision astrometry, is expected to occur in the first decade of July 2011, and the second star of the system is approaching the atmosphere of the primary, whose circumstellar disk has a H-alpha diameter of 5 milliarcsec, comparable with the periastron distance. The preliminary results of a photometric campaign, here presented in the very days of the periastron, show an irregular behavior of the star's luminosity, which can reflect some shocks between material around the two stars. The small luminosity increasement detected in the observation of 5 of July 2011 at 20 UT may suggest that the periastron phenomena are now going to start., 9 pages, 3 figures. Proc. of the XII Italo-Korean meeting of Relativistic Astrophysics, 4-8 July, 2011, Pescara -Italy