Places · Observatory
Virgo
Europe's 3 km interferometer. Adding it to the two LIGO sites cut the sky localisation of a neutron-star merger from hundreds of square degrees to tens.
- Where
- Cascina, Italy
- Coordinates
- 43.63°N 10.51°E
- Since
- 2017
- On the map
- Show me
- More
- virgo-gw.eu
The sky from here
This is a zone 7 sky — urban on the nine-grade scale, Bortle 7–8, reaching roughly magnitude 4.2–5.0 unaided. The whole sky is greyish. Stars beyond the fourth magnitude are gone, and the Pleiades are a smudge if they show at all.
That grade puts 28 of the catalogue within easy reach of 10×50 binoculars and 30 within a 130mm — 9 of them need no instrument at all. Genuinely dark sky — zone 2 or darker — starts about 104 km south-west.
There is no season here in which the sky fails to get properly dark — the Sun clears eighteen degrees below the horizon on all 365 nights.
The galactic centre tops out at 17° from this latitude — low enough that the busiest part of the Milky Way is always behind the most atmosphere, which is what separates this sky from a southern one. Of the 110 Messier objects, 14 never set from here and every one of them rises at some point in the year.
Of everything in the catalogue, Sunflower Galaxy, Andromeda Galaxy and Cat's Eye Galaxy are the best served here, climbing to within a few degrees of straight up — an object at the zenith is being seen through the least air it will ever be seen through, and the difference against the same object low in the south is not subtle.
Whirlpool Galaxy, Little Dumbbell and Pinwheel Galaxy never set from this latitude, so they are available on any clear night of the year rather than for one season of it.
Read at 43.63°N 10.51°E. Darkness is estimated rather than measured; everything else follows from the latitude and holds along the whole parallel. How accurate this is.
Nearby
Questions
What part of the sky never rises at Virgo?
Everything south of declination −46°. From 43.6°N that is a cap 44° in radius centred on the south celestial pole, which is 14% of the whole celestial sphere. Nothing about the calendar or the aperture changes that — the cap is below the horizon at every hour of every night. Its mirror image, the same 14% around the north celestial pole, is circumpolar here and never goes down.
How many hours of true darkness does Virgo get?
Between 3 hours 48 minutes on the shortest night of the year, around 21 June, and 11 hours 36 minutes on the longest, around 21 December. That counts only proper astronomical night, with the Sun eighteen degrees down; the merely-dark hours either side of it are longer. The sky here reaches it on every night of the year, which is not true much further from the equator.
When is the Milky Way best from Virgo?
Around 17 June, when the galactic centre transits at local midnight, and usefully from about May to September — earlier each evening as the season goes on. 43.6°N is close enough to the equator that the sky reaches full astronomical darkness on every night of the year, so unlike sites further north there is no part of the season where the core is high and the sky refuses to cooperate.
How far is Virgo from the other sites on this map?
The nearest is Nördlinger Ries, about 584 km to the north. The nearest other observatory is Effelsberg 100-m Radio Telescope, 814 km to the north. Distances are great-circle, so they are what a signal covers rather than what a road does.