lunedì, aprile 24, 2006

Che p....

La strada provinciale per Martellago vista dal terrazzo di casa. C'è una piccola zona artigianale e commerciale.
Sembra che illuminare a giorno l'attività sia ormai uno sport molto praticato qua in Veneto (eppure a fine anno devono essere migliaia e migliaia di euro di energia elettrica... per aver tenuto illuminati i piazzali deserti). Non capisco come si possa buttare letteralmente all'aria quello che potrebbe essere un piccolo stipendio... mah! Non si sentono sicuri? E perchè non collegano l'illuminazione all'impianto di anti intrusione? Le luci che si accendono solo in caso di intrusione, quello sì che sarebbe un deterrente.

I due edifici sulla sinistra fino a poco tempo fa non erano illuminati affatto. Era illuminato solo il minimarket a destra. Già sembrava orribilmente fastidioso, senonché i vicini non hanno trovato di meglio che emularlo... anzi fare di più!!

lunedì, aprile 10, 2006

Grazie dell'invito

Salve a tutti e grazie dell'invito.

Spero di contribuire costruttivamente a questo blog nel futuro. Per oggi copio qui un'osservazione recente con binocolo 25x100.

Data: 12/4/2004
Località: Danta di Cadore (BL)
Ora osservazione: 10PM (11/4); 1.00-1.40AM (12/4)
Strumenti: Binocolo 25x100 con montatura azimutale; appoggiato al parapetto per parte della seduta, montato su cavalletto inizialmente.
Condizioni visibilità: Mv limite 5.5-6.0.
Note: osservazione dal terrazzo di casa. Temperatura di poco sotto lo zero.

Oggetti osservati:

Facilmente percepibile la struttura a doppio nucleo e una connessione fra le due. A tratti visibile qualche chiaroscuro in M51. Contate molte stelline entro il triangolo di stelle di settima magnitudine subito a N di M51; stimata una magnitudine limite intorno a 11.5.

Chiaramente visibile, di forma tondeggiante ma senza dettagli evidenti.

M65-M66 – NGC3628:
Facili e molto evidenti, NGC3628 appare la più estesa del trio.

Trovata subito, a ovest della piccola concentrazione di stelle brillanti. Fuso luminoso con rigonfiamento centrale evidente. All’inizio scambiata con la NGC4559, pure di Mv=10.2, e anch’essa allungata ma meno fusolare.

NGC 4594 (Sombrero galaxy):
Facile da trovare a partire dal quadrilatero del Corvus, immersa in campo ricco di stelline di nona magnitudine. Piccola e densa, evidente l’orientazione, ma non il taglio centrale, anche se effettivamente ad ispezione dettagliata si nota una qualche particolarità nell’ellissoide luminoso: una dissimmetria nel modo in cui la luce degrada ai lati corti.

Ammasso in VIR/COM:
Spaziato con il binocolo nella zona a ovest di Denebola. Osservate decine di galassie, impossibile una catalogazione dettagliata in poco tempo.

NGC 3384-3379-3368-3351:
Il gruppetto di galassie appare subito nel campo binoculare, ma sono evidenti pochi dettagli; la forma oblunga della più luminosa del quartetto (M96, NGC3368). Manca una stella di ottava grandezza indicata da TheSky al centro di NGC 3351!

sabato, aprile 08, 2006

Astronomy in Farm Holidays

Questo articolo era apparso su Cloudy Nights, ma è scomparso (!?) quando hanno cambiato formato. Così lo metto qua, sperando che abbia miglior vita.


Foreword. I have no undisclosed interest and nothing to do with the farms and tourist resorts described below. I only spent vacations there, enjoying astronomy and pretty good skies, but I live in another part of Italy (north) and work in a field that has nothing to do with tourism.

Farm Holiday is a way of making vacations - from long summer stays to simple weekends - which is gaining a lot of popularity in recent years, in Italy. To my knowledge, all started some decades ago, when farms in Tuscany began to offer accommodations, B&B, etc. to tourists willing to stay and visit the beautiful Tuscan countryside marked by cities rich of history and art.
Nowadays farms offer many types of accommodations, from simple rooms to services that resemble those of a first class hotel, and different activities, from the participation to the life of the farm, to horse riding, biking, swimming (most farms have swimming pools), sunbaths, gastronomy etc. All this, while being only a few kilometers from cities like Florence, Siena, Assisi etc., to mention only the most famous. The following may be starting points to explore this kind of tourism: .

If a visit to Italy is planned, a farm stay, rather than a hotel in the centre of a city, allows adding astronomy to the vacation. Farms, with careful selection, can be found in places that offer pretty good dark skies. In selecting the place a trade off between passion for astronomy and the vicinity to the cities to be visited during daytime should be carefully evaluated. In fact, the darkest skies are farther from historic centers.

Fig.1 Artificial night sky brightness in central Italy, from Credit: P. Cinzano, F. Falchi (University of Padova), C. D. Elvidge (NOAA National Geophysical Data Center, Boulder). Copyright Royal Astronomical Society. Reproduced from the Monthly Notices of the RAS by permission of Blackwell Science.

Figure 1 shows the artificial night sky brightness in central Italy. It is a portion of a larger map which can be found in the website by Cinzano Colors represent the artificial sky brightness for "standard" atmospheric conditions and at sea level. Elevation and air cleanliness, or conversely haze, may modify the real sky appearance with respect to the chart (see Cinzano for further explanations). Other maps, that account for the above factors can be found in Cinzano's website (and for Italy also the report at ). In Fig.1 blue and green are places where the artificial sky brightness is less than the natural sky glow, and therefore rather good. Yellow means that artificial sky brightness may be from 1 to 3 times the natural sky glow. In practice, in my experience, even yellow areas can be good if their elevation put them above the hazy thermal inversion layer (e.g. above typically 700-1000 meters) and/or if the atmosphere is dry and clean. Orange, and above all red, not only must be avoided, but one must try to stay as far as possible because the horizon, in those directions, will be noticeably polluted.
The map has annotations of places where I have been in the last five years and which are reviewed below. The major cities are also annotated, but for a better result one can superimpose a MapQuest map (it has the same type of projection).
The darkest places, in central Italy, are south of Siena (the blue patch) and especially in Mount Labbro. The latter, thanks to its elevation too, as far as I know is a truly dark site. It is however a bit too far from historic cities and I have never been there. But if one likes wildlife, and has astronomy at his first place (wife and sons permitting :-), he can find a faunistic wildlife park there ( ).

The places where I have been are all within the neighborhoods of important historic centers, but still far enough to offer good skies. Typically, in the Bortle dark sky scale ( they are between class 3 (rural sky) to 4 (rural to suburban transition). This means that the milky way is still impressive and, for my eyes, the naked eye limiting magnitude is between 6 and 6.5 at the zenith. All places are below 500 meters elevation and, in summers when I had been there, sometimes there was a certain amount of haze and humidity that worsened the things in some directions at the horizon. I suppose that in other seasons, or in years with dryer summer climate (like it was 1998) a better Bortle class could even be achieved.

The "dark corner". Once a candidate farm has been found the next requirement is that it has a suitable "dark corner". I mean a place within the property where one is shielded from stray lights and can get dark adaptation. Some holiday farms are not suitable because, even if placed in dark areas, have horrible lighting plants, often lit all night long, and no place where one can be shielded from them. It is important that the dark corner is within the property, for safe and calm observing, and that it is easily accessible with your scope (it depends on the size of the scope: especially stairs may be incompatible with big dobs). To solve this last "problem" I use to explain my needs and ask explanations before booking, and I carefully examine the photographs of the farms' websites to see what type of external lighting plant is used. In some cases I decided to search for a different farm.

Following are short reviews of 6 places where I have been. The descriptions are based on what I found when I was there (which is said for each place). It might be that something is changed in the meanwhile (type of services and activities offered by farms, location of lighting plants etc.) so a check before booking might be useful. Also, the descriptions of sky and weather conditions hold for the summer when I was there. Some summers are hotter and wetter than others, however. For example 2003 was a lot hotter and with more haze and humidity than average. Conversely 1998 was dryer, with the sky almost always dark-blue daytime and crystal clear nighttime. Therefore, small variations in night sky conditions may occur accordingly. Also seasonal variations may be expected.
As for what concerns the visual limiting magnitude estimation I used the meteor observers' method and charts: .
The sky, in general, is pretty good in all the places described below, but one has to understand they were chosen as trade off between astronomy nighttime and the vicinity to interesting historical centers. If one is not interested in the latter, he may find better dark sites a little farther. Nevertheless the sky in the reviewed places is still good enough to show at least magnitude 6 stars, and a lot of rewarding views are possible in a magnitude 6 sky.

As a final advice, before travel, there is custom. I strongly suggest to verify customs regulations and prepare paperworks that may be needed if one enters the EC from a non EC country. In fact a telescope, especially a large dobson, is likely to be noticed, and there is the risk of wasting a lot of time at customs and that they ask some money deposit.

1) PODERE I SETTE (now "Agriturismo la Stella"), Magione, PG ( I have been here twice: on July 1998 and on August 2000. The farm is located near Perugia at 500 meters elevation. A 4 km country (white) road connects it to a freeway down in the valley from which a large number of art cities are rapidly reached: Assisi, Spoleto, Siena, Orvieto, Arezzo, Cortona, Perugia, Todi etc. are all within a half day trip. It is a real farm. The owner, Olindo, is a sympathy brilliant man. I recall with pleasure the evenings and nights on the terrace spent with him and all the other farm guests for the dinners. Food is from farm's products and is prepared by Olindo's wife. He has two daughters who, if you are interested in horse riding, will give you riding lessons and/or accompany you on rides (a specialty of this farm, but I have to mention that is extra cost). There is also a swimming pool and other activities are possible (see details on web site).
The dark corner. There are some places that can be used for observation, shielded by stray light. The best is behind the building on the other side of the country road of the property (the farm has several buildings). Maybe Olindo can even switch some lights off for you if you ask him. I did not ask because in 1998 and 2000 I only had binoculars with me. If you book here ask for the apartment above. It has no stairs and you can easily roll out even a big Dobson. To reach the dark corner just behind the building there are less the 20 meters.
The sky. The farm is in a yellow area in the map of Figure 1 (point marked with "1"). But at 500 meters elevation, the sky is still pretty good, especially the northern horizon. Southern horizon, and above all ESE, suffers from the light pollution from Perugia and its valley. Since I had been there with only binoculars I did not do a lot of evaluations. But I remember that the milky way overhead was well seen, as was the Perseus (for the august meteor shower). Limiting magnitude for me was 6+ (less towards south).

2) IL FORNO ANTICO, Palinuro, SA ( I have been here on July 2001. The farm is located in the Cilento natural park, in southern Italy, about 150 km south of Naples. It is close to the sea and to cape Palinuro, a rocky peninsula where scuba diving is done (I did not). Besides the sea and the natural park, most of the interesting cities are north and need a full day to be reached (300+ km round trip). These include Naples and its neighborhoods, the Vesuvio volcanic mount, the isle of Capri and the Sorrento peninsula, the roman cities of Ercolano and Pompei destroyed by the Vesuvio in 79 A.D., the settling of Paestum etc. A specialty of this farm is its very rich gastronomic offering (recommended).
The sky. The distance from large cities gives this place a darker sky. It is not shown on Fig.1, but on the complete Cinzano's map it would be in a blue area (Bortle 3, more or less). The elevation is not high so that darkness is not fully exploited, as even small haze sometimes cause diffusion of dim lights from behind hills in several directions. To the south the town of Palinuro, the greatest polluting source, causes a small pollution dome. The milky way is well seen even at rather low elevation. I estimated a limiting magnitude of 6.5 or slightly less at the zenith. In my stay here I had a Konus Vista 80 with me (a variation of the ubiquitous ST80) with which I had beautiful large field views, especially of the Sagittarius and Cygnus: M22, the big globular in Sagittarius, showed some resolution; nebulae like the Veil and North America were easily seen. I estimated a limiting magnitude at the telescope of 12.5 at 40x.
The dark corner. There is no real satisfactory "dark corner" inside the property. I found and used the tennis field, where a wall provided me with some shielding from the lights above from the farm and swimming pool. However, the wall was not tall enough to give protection when standing up, but only when sit down (BTW chairs and tables borrowed from the swimming pool are excellent for observing sessions ;-). A much better place is just on the other side of the road near the farm, where a field surrounded by trees forms a good dark place. But the road is for public transit and I did not feel comfortable to stay there alone (maybe in two). If one has a big Dobson this place is not suitable, because most rooms have access with stairs and, anyway, the paths for reaching dark corners is not flat.

3) CONVENTO DI MONTEPOZZALI, Massa Marittima, GR ( I have been here on August 2001. This place was an ancient monastery, now completely and finely restored. Apartments resemble a first class hotel and have lot of room. Those at the ground floor are well suited for hosting even large dobs. The swimming pool is its jewel, the best of all places I have been: large, especially crystal clear water (much better than most tourist villages), the type of pool where water is at the exact same level than the surrounding pavement. The neighboring cities are Massa Marittima, Grosseto, and, but farther, Siena and Volterra. Also the Isle of Elba must be mentioned. It does not offer meals (use neighboring restaurants or the kitchen in you apartment) except once in a week when all guests are invited to a dinner, which is held in suggestive dungeons at the ground floor of the main building.
The Sky. The place is in a green-blue area of the map. Elevation is not high but vicinity to the sea provides dryer climate that inner in the land, eastwards. Often the sky was dark blue in direction of the sea (west) and overhead, whereas clouds were easily seen forming on the higher hills and mountains to the east. The breeze from the sea keeps the air cleaner. Also, the hills are very mild here and westward, from which winds often come, they are preceded only by the Tirrenian sea. This means a greater probability of having good seeing. At night the milky way was well seen down to the Sagittarius. Some light pollution domes were evident along the horizon: one in NW direction from the city of Massa Marittima, another in WSW direction from Follonica (the biggest) and others minor in several directions. Only that from Follonica is somewhat disturbing but, fortunately, it does not affect south, where the Sagittarius stands. I estimated the naked eye limiting magnitude to be 6.2-6.4 at the zenith, and not decreasing very much in many directions toward the horizon (thanks to clear atmosphere). Here I had the Konus Vista 80 above (same 12.5 limiting magnitude at the telescope and same kind of views that the above farm). My apartment was at the first floor but stairs were not a problem for such a small instrument. However if one has a Dobson he should ask for a ground floor apartment.
The dark corner. There is a suitable place for observations past the swimming pool, and near the kids games park. It is a 4-5 meters deep shallow natural depression, which provides good shielding against lights from the farm. The southern horizon is free whereas the remaining ones are 10-20° higher that the theoretical horizon (thus providing protection). From there only the gazebo of the swimming pool glows of indirect light (suggestive... you my find yourself waiting for the ET starship... :-). The place may be accessed from the swimming pool by descending a mild slope. This is the shortest way, but if you have a Dobson, there is a trail, about 100 meters from apartments (wheel barrows needed for large dobs), which accesses the place from south.
The farm owner has some curiosity for astronomy and joined me a couple of nights (the Double Cluster and Andromeda Galaxy impressed him). Thus I think that at booking time he may understand astronomy related needs.

4) FATTORIA LA MURAGLIA, Monteriggioni, SI ( I have been here on August 2002. The place is literally next to Siena: only a few minutes by car, and you can walk at night in Piazza del Campo, a very rewarding experience. Besides Siena you are at the centre of maybe the most famous part of Tuscany: with places like San Gimignano, Monteriggioni, and only a little farther Florence, Pisa, Volterra, Lucca, Arezzo, Pienza. The resort offers either rooms or apartments (with kitchen), all except one at the ground floor.
The sky. Despite vicinity to Siena the sky was better than I expected (the place is in a yellow area in map of Fig.1. Siena, only a few kilometers in straight line, does not pollute much the sky. Probably because the it sits on a territory with marked hills which intercept most of the lights, allowing the leakage only of that part of light pollution which is directed high in the sky, and which has the least impact on sky brightness. From the farm, Siena produces a light dome in the SSE direction, not much large, and which, fortunately, does not affect the south direction. Sagittarius and Scorpius were in fact well seen. From here I observed some of the south most Deep Sky Objects I ever viewed, like M7 and M6 (only ~10° above the horizon) and the views were satisfactory. The scope however, this time was a Borg 76 ED Apo, which replaced the Vista 80 and could be used at much higher magnification (not rarely 100x+ on DSOs). Thanks to this "improved" scope, I remember having satisfactorily wandered in the Scutum Star Cloud, having seen globulars like M56 and M71 immersed in a rich milky way, having seen nebulae like the Veil, M8, M16, M20, M17. Even, near the zenith, the Cocoon. The limiting magnitude at the eyepiece was 13+ (the 13.1 star near M57 was seen easily with adverted vision, and the doughnut shape was evident). At the naked eye the milky way was well seen with still a fair amount of details, and I estimated the limiting magnitude to be 6 or, some nights, slightly better: 6.1-6.2. To the north, the lights from Florence an the Arno valley, heavily populated, formed a cluster of pollution domes from NE to NW, extending high up to ~30°. This despite the distance was 30-40 kilometers in straight line (to better understand see also point marked "4" on map, Fig.1).
The dark corner. The farm has an horrible lighting plant (as seen in photos: many awful spherical bulbs which irradiate half of the light towards the sky and the remaining glares straight into people eyes: an example of how a lighting plant should not be done in my opinion!). Fortunately behind the wine-cellar, a separate building from the main farm, there is a working square not lighted (the owner apparently did not intended that square for guests' use). That place is shielded enough from stray light to permit dark adaptation. The distance from apartments and rooms is 100 meters more or less (wheelbarrows needed for large dobs) with only mild slopes.

5) BORGO POGGIOLO, San Venanzo, TR ( I have been here on August 2003. A Dutch-Italian couple owns the Farm: Sylvia and Giampaolo. The farm stands at the centre of a little populated area between Umbria and Tuscany. A 2.5 km unpaved country road connects this farm and a few others to a minor (paved) road in the area. One needs 30 kilometers and 45 minutes to reach the major freeways on both sides (Umbria and Tuscany). From there interesting centers may be reached like Siena, Arezzo, Orvieto, Perugia, Assisi, Todi, Spoleto etc.
In 17th century it was a country estate. Now, for guests there are both rooms and apartments to choose. Meals are based on genuine traditional kitchen.
I was hosted in the apartment named "Terrazza", which is at the first floor, but fortunately has a large terrace ("Terrazza") with a ramp access. The terrace however is separated from the main apartment by a short stair with a few steps (meaning that a help is needed for big dobs).
The Sky. The place is in the middle of a valley, which is dark because not populated. At night I could count no more that a few tenth of visible distant lights. The greatest visible town is Montegiove to the north (I think 80 people more or less). Unfortunately, this happy valley is surrounded by others that are much more populated. In fact from behind the hills in all directions traces of light pollution were leaking. The worst was from Perugia, at NNE. But also from south (Orvieto) west (Fabro and Città della Pieve), east (who knows what?) light was seen rising from behind the hills. In the map of Fig.1 The place is a tiny green patch surrounded by yellow. Summer 2003 was unfortunately wetter and with more haze than average. Daytime sky was often pale cyan, rather than dark blue. This, at night, showed up with lights from behind the hills diffusing a lot high, sometimes up to 40° (but I believe that in dryer summers, things should be much better). Overhead the sky was very dark however, and clouds were invisible black. The milky way at the zenith was rich and impressive, less at lower elevation. I estimated a limiting magnitude of 6.3-6.5 at the zenith, decreasing to ~6-5 at 40° depending on the haze of the night. Here I went with a 16" Dobson. Most of the times I used the terrace for observations, but sometimes I set up in the grassy fields (see Fig.2). With this "big gun" I saw the 16.1 star near M57 (with adverted vision) and a *lot* of things. Exploring the Scutum Star Cloud took me two whole nights. Dark nebulae were easily seen as rarefaction in the rich starry background. I saw the Trifid like in photos (except colours) and the Crescent nebula better than in many photos. Often not only the brightest parts of the nebulae were visible, but also fainter parts. One night, looking at NGC 7331 I immediately saw two other neighboring galaxies, and, only a little later, even fainter ones. The Stephan's quintet jumped to view when I moved the scope downwards. M51 showed a beautiful spiral structure with dimmest halo also visible, even if it was low close to the polluted northern horizon. The North America was visible at the naked eye. The veil needed a couple of observing hours. M31 was beautiful with binoculars too, and at the eyepiece of the Dobson showed two dark lanes and NGC206 star cloud inside it. M33 besides showing its spiral structure also showed many knotting and HII regions. The globulars, all had their own personality, each different from the others.
Of course much of this rewarding experience depends on the fact that I carried the big gun there, but the sky too had its role. A truly dark sky for a dedicated star party may offer even better views, but having 3 weeks and 21 nights in a row (of which 15 were useful for DSO, counting the moon) allowed me to return on the same areas and discover further things night after night (after having better examined the Uranometria maps during the day).
The dark corner. The entire farm is a dark corner. There are few lights, which are not unnecessary lit. The owners turn them off after the guests leave the dining area. You may even turn the light off yourself in case somebody forgot them lit. I noticed that many guests (besides being interested in looking at the telescope) often switched off the lights themselves to look at the sky (hunting for meteors) and for many it was the first time seeing the milky way (somebody was asking what was that thing!). Sylvia and Giampaolo joined me several nights for a while. So, we spoke about the sky, light pollution etc. Since they love wild life and nature they are well willing to understand and help amateur astronomers staying there. They told me that other amateurs already were there before, but none with a telescope so big :-).
Fig.1 Sunset at Borgo Poggiolo. A grassy field ready for observations (my photograph).

6) CLUB MED METAPONTO, Marina di Pisticci, MT ( ). I have been here on July 2000. I am including this place, even if it is not a farm holiday, because the sky is pretty dark. Especially to the south, over the sea, the milky way was impressive, with the best ever views I had of the Sagittarius at the naked eye (I was here with only little binoculars). Touristic villages like this have a very rich offering of possible activities, but doing something that is not explicitly foreseen may result difficult, and astronomy is clearly not foreseen: the village is lit everywhere and there exist no practical dark corner. I found one place on the sandy trail, which connects the village to its beach. From there the milky way was impressive as said. I do not believe however (because of distance from rooms, sand, number of guests etc.) that one could carry there a big dob and profitably use it. A small Apo is feasible.


7) AGRITURISMO RODELLOSSO, Pienza, SI ( This is the place I have been in Agust 2004. It is at the south border of an arid area known as "Crete Senesi" which are lands of clay hills south of Siena. Major centers, like Arezzo, Perugia etc., as well as minor but very pleasant towns, are near. Among the latter are Montalcino, famous for its wines, Montepulciano and the beautiful Pienza, a town completely rebuilt in the form of an "ideal city" in three years (1558-1561) by Enea Silvio Piccolomini when he became Pope Pio II.
The sky. As shown in Fig.2 large cities are far. At night this was noted because the horizon did not show light domes: in place of them there was a uniform unresolved glow, especially to the north and east. South was better (the Amiata mountain is near and, if one really wishes, it offers a much darker sky). Unfortunately the two nearby (3-4 km) small towns of Pienza and S. Quirico D'Orcia, although not producing a great amount of light pollution in absolute, are rather disturbing because of their vicinity. On haziest nights light domes could be seen in the direction of the small towns. Fortunately, most days had crystal clear atmosphere: in fact, to the west the sea is not far, and winds often clear the atmosphere leaving dark blue sky days and transparent nights (that help fighting light pollution). At night I have recorded limiting magnitude of 6 to 6.5 at the naked eye and zenith (only one hazy night in 15 days happened to record limiting magnitude 5.7). At the telescope (16" Dobson) I have recorded 16.1 (on the M57 sequence). The milky way is fairly well seen: the north America is a naked eye object, as is M31 (but not M33). Again horizon glow progressively compromises the views, starting from 45° from the zenith (but not dramatically).
The Dark Corner is a little critical in this farm: the horizon is free and I have been often disturbed by the headlights of distant cars when it happened that they pointed in my direction. Also two horrible lights 4 km apart (actually in the nearby town of S. Quirico) are bright enough to somewhat disturb dark adaptation (full dark adaptation is very delicate!). Anyway I found the parking lot to be the best place to set up the scope: it was sufficient to unscrew its two lamps to darken it. After midnight most lights of the farm are automatically turned off, letting only two very small courtesy lights that are not seen from the parking lot.
Among the Deep Sky Objects that I have been able to see (besides the most obvious like the Veil, the Lagoon Nebula etc.) is the Cocoon Nebula, seen without any filter (best views without filters). I found it by following the dark nebula at the tip of which it stands. The Spiral Galaxy NGC 6946 in Draco showed faint but understandable spiral arms (unfortunately galaxies are the objects which suffer more of light pollution: I whished I had a darker sky background in that case). I made a little mistake when searching for NGC 6503 and pointed where NCG 6508 stands: it is a much fainter galaxy, but it was there (too faint to be 6503, so I discovered the mistake). Last but not least the Cats Eye Nebula, at 360x (seeing is rather good because there are no high mountains, only smooth hills to the west), showed the "eye pupil", that is a donut shape with a less brighter center and the central star (of course a 16" Dobson is "recommended"). In Scutum IC 1295, the faint large Planetary Nebula close to Globular Cluster NGC 6712 was also recorded.

Fig.3 The landscape at Rodellosso (my photograph).

lunedì, aprile 03, 2006

Notte particolarmente trasparente

Questa sera è una di quelle particolarmente trasparenti. C'è stato un temporale nel tardo pomeriggio e dopo la trasparenza è diventata da record. Al tramonto si vedevano benissimo le Prealpi. A proposito... il Sole rosso tramonta sui Lessini... (No, non posso vivere a Trento! Sarebbe già stato da un pezzo dietro al Bondone! Non lo sopporto!! Soffro di Claustrofobia!!!).
Ma ritorniamo alla trasparenza. Ho misurato la luminosità del fondo cielo con il solito sistema. Risultato: R 19.0, G 19.3, B 19.5. Non male per essere in pianura ai margini di una zona molto inquinata. Questo è certo il meglio del meglio per questo luogo. Chissà se 1 km più in là continua ad esserci mezza magnitudine di vantaggio (non sarebbe male sfiorare 20, anche se solo occasionalmente).
PS la falce di Luna non aveva poi molta importanza: meno di alcuni potenti lampioni del concessionario sulla provinciale.