Where does the IFO geographical information come from?

e.g https://git.ligo.org/lscsoft/bilby/blob/master/bilby/gw/detectors/H1.interferometer#L9-15

I had a quick look in the document linked but couldn't find these numbers.

We reference two technical documents, the first has the geographical information.

https://dcc.ligo.org/LIGO-T980044/public, see page 10 for Hanford.

@colm.talbot ah thanks! I only saw one DCC reference so must have just missed the other one.

I took at look at page 10 and I can see where the numbers for latitude, longitude, elevation, xarm_tilt and yarm_tilt come from now thanks!

I can't see the following numbers, can you help me track those down too? I think it would be useful to document more clearly where these numbers come from if they don't appear exactly as this in the DCC document.

xarm_azimuth = 125.9994
yarm_azimuth = 215.9994

These are the x_G in that table, the defintiion of the compass direction is different though, we measure clockwise from East=0.

N35.9994 W becomes 125.9994 S54.0006 W becomes 215.9994

There's probably a better way to document these conventions.

@sebastian-khan Can this issue be closed? We might want to have a new issue for creating a reference list for stuff like this.

@moritz.huebner I think it would be good to update file or a documentation page somewhere.

If the numbers are not exactly as written in the document then I think one should document what one needs to do to convert from the document to the numbers in the file.

Feel free to close this but I think this might get forgotten.

mentioned in issue #237 (closed)

@sebastian-khan I opened another issue #237 (closed) with a concrete action item attached.

closed

marked this issue as related to #237 (closed)