On January 25 the asteroid (144) removable, has divulged a few seconds for a 10th magnitude star in the constellation of Aries. We talked about Blog a few days earlier, pointing to the high possibility of actually observed a disappearance of the star in the north-west of Italy and surrounding regions. Well, not only the occultation occurred, but was followed and timed by a good number of observers. Although many observations have yet to be reduced, here is a summary of key findings on Euraster .
A Santhià my wife and I we Chiara equipped with two different instruments : I would have been monitoring the star visually to 133x telescope Schmidt-Cassegrain telescope 20cm, dictating to a digital recorder and the time of disappearance resurgence (along with a precise time signal, the DCF-77), she attempted a recovery with a new digital triplet apocromatico Tecnosky 80/480. Era calcolato che Santhià fosse prossima al centro della fascia di occultazione (il nostro sito era appena a 1,7 km a nord-ovest dal centro della fascia prevista), con una probabilità di occultazione effettiva di ben il 97,7%. I tempi da noi rilevati si attestano su 12,5 / 12,6 secondi, quadrando benissimo con la previsione di 12,6 secondi per un'occultazione centrale, nel caso l'asteroide misurasse 160 km di diametro. In alto ho riportato la posa di Chiara, della durata di 41,5 secondi, con in evidenza il tratto dell'occultazione e con l'asteroide debolmente visibile, per lo meno sull'originale (era di 12^ magnitudine).
Il dubbio è che la fascia occultation has shifted slightly to the north, caused suspicion of the Frenchman Philippe Bernascolle observation, an observation which has negative (ie no occultation) near the southern edge of the band provided. Unfortunately there were no observers around the northern edge to confirm or refute this hypothesis, while the southern edge, in more than Bernascolle, there was the Spaniard Jorge Juan, which we are awaiting the final report, which measured a 'occultation of just 3 seconds. The observers further north but there was Sposetti Stefano (Switzerland), which received this interesting graphic and a movie occultation. His group has obtained total less than 8 positive comments!
Usually the study of strings obtained by various observers are summarized in this way: it tries to approximate the shape of the planet an ellipse. Neglecting errors of synchronization between the timings of the various observers, it appears that the outline of removable, is not entirely smooth. For example, both our observations and those of Charles Gualdoni Lorenzo Comolli and are almost in line with each other, but the minimum and maximum durations differ by more than one second. The long timing (12.1 seconds) Gaehrken Bernd and Doris Zwischenbrugger (Alto Adige) in the southern part of the band would seem to provide the clue that the hemisphere pianetino sia di poco più esteso di quello nord. Naturalmente parliamo della sagoma dell'asteroide come appariva quel giorno, non abbiamo modo di verificare se altrove vi fossero caratteristiche superficiali differenti. Le dimensioni effettive della sagoma ellittica di Vibilia risulterebbero di 153 x 128 km circa.
Forse la "scoperta" più interessante scaturita da questa occultazione riguarda l'esatto posizionamento di Vibilia nello spazio, non tanto nel senso nord-sud, ma lungo la sua orbita. Tutti gli osservatori hanno rilevato un anticipo di oltre 8 secondi sul previsto (8,2 a Santhià), denotando che l'oggetto era "avanti" di oltre 100 km. Il margine di errore stimato doveva essere di 3 secondi, dunque This advance has been the real surprise of the evening. Now the position is removable, known better precision.
Of course I reserve the right to edit this post later, according to that arising from subsequent studies. Thanks to all those who have tried this occultation observation of the asteroid!
February 7
addition to recent reports from the canton of Ticino, has come to Jorge Juan, who has timed the occultation period of just two seconds and a half. The size of observed (144) removable, they are slightly modified: 152.5 x 130.7 km, while this is the best result of the combination between the strings obtained.
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