Places · Observatory
LIGO Hanford
One of the two 4 km interferometers that recorded the first gravitational wave from a black hole merger. Two sites, because a real signal has to appear in both.
- Where
- Washington, United States
- Coordinates
- 46.45°N 119.41°W
- Since
- 2015
- On the map
- Show me
- More
- ligo.caltech.edu
The sky from here
This is a zone 4 sky — suburban edge on the nine-grade scale, Bortle 4–5, reaching roughly magnitude 5.7–6.5 unaided. The Milky Way is a faint band overhead and gone lower down. The sky is noticeably grey rather than black.
That grade puts 99 of the catalogue within easy reach of 10×50 binoculars and 100 within a 130mm — 21 of them need no instrument at all. Genuinely dark sky — zone 2 or darker — starts about 59 km east.
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 centre of the galaxy only ever reaches 15° above the horizon from here, so the richest part of the Milky Way is always seen through the thickest air. It is the single biggest difference between this sky and one further south. 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 46.45°N 119.41°W. 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 LIGO Hanford?
Everything south of declination −44°. From 46.5°N that is a cap 46° in radius centred on the south celestial pole, which is 16% of the whole celestial sphere. It is out of reach permanently rather than seasonally: no time of year and no instrument brings it above the horizon. The matching 16% around the north celestial pole is the same geometry inverted, and never sets.
How many hours of true darkness does LIGO Hanford get?
From about 2 hours 33 minutes at the thin end of the year, near 21 June, up to 11 hours 45 minutes around 21 December. Astronomical darkness is the Sun more than eighteen degrees below the horizon, which is a stricter thing than the Sun being down. Unlike sites further from the equator, no part of the year here is written off entirely.
When is the Milky Way best from LIGO Hanford?
Mid-June at its highest, with a workable season either side of it running from about May into September. Because 46.5°N keeps full astronomical darkness all year, the whole of that season is usable, which is not the case for observers much further from the equator, who lose the peak of it to summer twilight.
How far is LIGO Hanford from the other sites on this map?
Utah Test and Training Range is the nearest thing to it here — 818 km to the south-east. The nearest other observatory is Mount Wilson Observatory, 1,360 km to the south. These are straight-line distances over the surface, not driving distances, and in this part of the world the two can differ considerably.