Cassiopeia and Perseus rises behind one of the Three Peaks, to 00,54, 23 August 2009. The mountain in the foreground is lit by debolemte car that was coming, would otherwise have been as black as the background.
for the third time I came here to better understand the quality of this observing site. Even this time the conditions were ideal: in the afternoon a storm front had passed e, sebbene le Tre Cime fossero ormai sotto il cielo sereno, verso Sud si potevano vedere ancora le nuvole e il temporale allontanarsi. Le nuvole sono state visibili per tutta la notte anche quando erano sopra la pianura e le condizioni non sono state mai perfette. Tuttavia questa volta ho potuto capire molte cose.
La prima è che Misurina e Auronzo hanno un effetto limitatissimo sul sito osservativo, se le condizioni climatiche locali sono buone. Le due volte precedenti le luci diffuse di Misurina erano dovute a nebbiolina e umidità che si estendevano fino alla altezza del luogo di osservazione. Questa volta la situazione meteo locale era buona: non c'era umidità, vento a tratti sostenuto e temperatura di 5°C. Misurina e Auronzo erano finalmente ridimensionate a few lights in the darkness of their valleys and did not produce halos that extends above the skyline.
Instead, further, the situation was quite different. From up here the view stretches far away, and in some directions, the horizon is negative (especially to Friuli where the line of sight passes over the sky of roughly Casera Razzo and over mountains about 2200 meters, which are less high share of observation). The clouds above the plain fiulana (100 km away!), Which were in sight, appears to be illuminated from below. If the horizon was hidden would not have seen, but the light coming from there would still potutto illuminate the sky of the observation point above us (it's what happens Casera Razzo and partly to Peralba, where the horizon is not visible, but there comes the light that illuminates the sky).
From here you could see the least guilty. I made panoramic pictures made at different times of the night. As the clouds moved away situazine the best but it was always a degree of brightness of the atmosphere above the plain. I easily detected Udine, Veneto plain, Cortina, Trentino and Alto Adige.
The amount of light coming from the plains (100 km from Udine to 150-200 km in the rest of the plain) is not much. The zenith, and this is good news, it was 21.60 on the Swan! And this in a situation where the skies of the plain shone probably more than normal. I'm pretty sure that above Casera Razzo fly at the same time much more light than usual and that the sky was so below average. Here, even in below average sky is saved. But unfortunately it is not perfect: the greatest flaw is that the whole southern horizon is not perfectly dark. Do not you badly, but you can not see the airglow in the South and the contrast is lowered. I'm talking about a band of about ten degrees above the horizon. More on the situation quickly becomes good.
Constellation Capricorn seemed like the "high". I saw the Southern Fish, the teapot that sank in the mountains. There was a bit 'towards the horizon of extinction. I think it was the other side of the coin delle cattive condizioni meteo a Sud. Alle 2.37 la stella Iota Piscis Austrinis (Mv 4.34) era visibile ad una altezza di 8°, e non era certo il limite. Theta, mv 5.01, era altrettanto evidente, alla altezza di 10°. Se assumo grossolanamente che l'intensità di queste stelle fosse simile alle stelle di mv 6 allo zenith, posso stimare l'estinzione in circa 1-1.5 magnitudini a 8-10°. Poichè a questa altezza la linea di vista attraversa circa 5-7 volte lo spessore di atmosfera allo zenit, ne consegue una stima indicativa di estinzione zenitale pari a 0.17-0.25 magnitudini, che potrebbe essere vero per un sito a 2400 metri. Ma non è detto che la trasparenza in direzione Sud fosse la stessa che allo zenit.
Allo zenit ho stimato la mv limite in 6.8 (stars in Pegasus 6.80 and 6.73 in Hercules, which I mentioned in previous reports were visible in averted with a degree of continuity). The only thing a bit 'out of tune was the visibility of M33 with the naked eye, which did not seem sublime.
This time we chose the square for the comments higher. Thomas and I were with my 40 cm: Mirko has not achieved because the telescope ready to load into the car broke a screw in the support of the secondary.
The choice of the site can also see the high rise of costllazioni east (we could see the zodiacal light). Unfortunately it seems that this square is also preferred by lovers of mountain climbing, that did not allla get nothing but dribs and drabs during the first part of the night. The typical behavior was to arrive in the square, stay a while 'time to decide on which parking space (there were so many who obviously was difficiel choose). Someone did several manual conveyor changing place, of course, with its headlights on. Then followed the preparation stage dellla equipment and finally the lights went out ... just in time for the next arrival. I think for them both imprtante in the front row (someone had even put the boots in a row under the machine ready for use) to be ready to "shoot" the rising of the sun (the guess is that there is a kind of " unreported race who comes first "). Some had even placed at the base of the rock, above the scree and slept in the wall. "Slept" I think esgerato often as every turn on the lights and I have not slept well.
We tried to make little noise. But I guess they thought we were crazy to watch the sky. One thing is certain: there are more passionate amateur climbers. Or rather, amateurs who come to observe the sky in places like that. Amateurs who "can not move" and looking to the skies as dark and as preposterous is seeing any. I do not know however that we are Apassionata the mountain "can not move" and that are climbing the stairwell. Let
List of the observed objects. I mention those on my list. Thomas has even more pointed, especially while doing the views.
NGC6946 was one of the best views ever of this item. The spirals were visible: marcatissime not like those of M51 but still visible and not merely theoretical. To me it seemed even to see some lumps of light in spirals. The outer halo of the galaxy was, and you could see the sky, beyond a certain distance became darker (as if there was a dark cloud around). The nucleus was clear and detached from the rest of the galaxy. Another pop 'of darkness and transparency and diameter Equest object should be spectacular.
We then moved on IC1369 and the nearby nebulosa oscura LDN 970 (Barnard 361); NGC7048 era un dischetto ben visibile; NGC7008; NGC6818; La Helix (secondo Tommaso una delle visioni migliori di sempre, io non ne sono sicuro). Ho osservato Barnard 143 e 142 nel binocolo 15x70.
Siamo poi andati sulla Bubble Nebula, osservandola a diversi ingrandimenti. Era possibile vedere bene, intorno a 170x, la parte più intensa del'arco e la parte più intensa della nebulosità come in questa foto .
Del quintetto di Stephan abbiamo visto forse anche la sesta. La mv limite al telescopio era 16.1 (forse 16.6) a 360x. La IC1296, vicino a M57 era intuibile a ingrandimenti intorno a 260x.
Abbiamo osservato una manciata di Arp e la Jones 1, che a dire il vero a me seemed less than engraved Sivell. We observed M27-magnification supported and I'm to see details inside the stem and ears. M76, however, beyond the usual stem, showed a very faint outer halo 360X.
All in all, most of the objects was more visible than usual, with several exceptions. I definitely missed several things.
The seeing was good, although not paragonabiole than last Thursday. The definition, thanks to the extraction system of the boundary layer was also good on deep sky objects, and perhaps this helped to grasp the details of such irregularities in the spiral NGC6946 or M27 in detail.
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