This answer to Is Starlink 1130 (Darksat) really dimmer? links to the March 16, 2020 paper in arXiv First observations and magnitude measurement of SpaceX's Darksat which finds only a modest decrease in brightness:

Results. The calibration, image processing and analysis of the Darksat Sloan g’ image gives an estimated Sloan g’ magnitude of 7.57±0.04 at a range of 976.50 km. For STARLINK-1113 an estimated Sloan g’ magnitude of 6.69±0.05 at a range of 941.62 km was found. When scaled to a range of 550 km, a reduction of (55 % ± 4.8 %) is seen in the reflected solar flux between Darksat and STARLINK-1113.

The v1 preprint says

...using the longitude(24.1° west) and latitude (69.9°south) of the Ckoirama observatory...

which puts the Ckoirama observatory under about 4500 meters of freezing antarctic water (first image).

If I invert the latitude and longitude assignments it returns to the Atacama desert where it belongs. If I instead type "Ckoirama observatory" in maps.google.com I get a pin on a map near 24.0894 S, 69.9305 W but the satellite image only shows a hole in the ground. (second image)

looking for Ckoirama observatory (not here!) looking for Ckoirama observatory (it's here somewhere)

click images for full size

The sidebar says:

Antofagasta, Chile W369+6Q Yungay, Antofagasta, Chile
+56 55 263 xxxx
Open now:  Open 24 hours

That link leads to http://www.astro.uantof.cl/research/observatorios/ckoirama-observatory/ which is very informative but has no latitude, longitude or altitude information. 5 Awesome Observatories Around The World mentions that Ckoirama is;

the first observatory built by Chilean engineers

and links to Astrotourism in Chile but no specific information.

Question: What are the latitude, longitude and altitude of Ckoirama observatory? Is there a central location where coordinates like these can be looked up?

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – called2voyage Mar 19 at 13:04

Near the pinned location, at 24.0893°S 69.9306°W, Bing Maps shows a building like the one in the University of Antofagasta photos, with signs of recent construction.

excerpt of Bing Maps aerial view

It's probably a matter of time until Google updates their satellite imagery in that region.

The Minor Planet Center maintains a list of observatory codes with positional information. A related page there says:

The KML file of observatory-code locations has been removed, following a request from some Spanish observers concerned about security at remote, unattended sites.

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A list of "everything in the world" is difficult to create and also maintain: it needs both a dedicated maintainer as well as people who supply the maintainer with the information. Thus on the latter any list will fail for some cases.

The most comprehensible list I know is the ESO-maintained list of observatories: https://www.eso.org/~ndelmott/obs_sites.html

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  • $\begingroup$ Okay I see; Ckoirama observatory doesn't seem to be in there but this is certainly a place where "...things like this be looked-up". Thanks! $\endgroup$ – uhoh Mar 19 at 11:07
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    $\begingroup$ If you look at the page source for the linked website, you'll see that the lists of observatories are directly encoded in the html/javascript. Those lists are over a decade out of date; quoting from the linked website: "Last modified October 10, 2007". $\endgroup$ – David Hammen Mar 19 at 13:11

Question: What are the latitude, longitude and altitude of Ckoirama observatory? Is there a central location where coordinates like these can be looked up?

I can confirm that there was a typo in our publication regarding the longitude and latitude of the Ckoirama observatory. They are in fact longitude = -69.93058889; latitude = -24.08913333; altitude = 966m (mean sea level). These values are recorded direct from the GPS locator system at the telescope.

As for the shed comment....The enclosure is not a standard dome as normally used. Due to the strong westerly thermal winds in this part of the Atacama, it was decided that a flat manoeuvrable roof was the best option for a small 0.6m telescope. A domed enclosure would induce wind pointing restrictions, which would restrict the number of observing nights per year.

Google maps is out of date, so I include some photos of the Ckoirama observatory, one of which shows one of the Starlink satellites.Ckoirama observatory, with a Starlink trail in the sky background. Image credit: Rodrigo Maluenda. Ckoirama at night. Image credit: Rodrigo Maluenda.

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    $\begingroup$ Thank you for stopping by and sharing your information and photos with us, it's always exciting to see an astronomical instrument with the Atacama night sky above it! Also congratulations on getting photometry of StarLink objects and coaxing a system to make a type of measurement very different from what it's been optimized to do! $\endgroup$ – uhoh Mar 19 at 23:28
  • $\begingroup$ Answers to Why is the opening in the Anglo-Australian Telescope's dome so small? show to what lengths some have gone to try to make a dome work in a windy setting. fyi other authors that stopped by and/or errata 1, 2, 3, 4, 5 $\endgroup$ – uhoh Mar 20 at 0:42

What are the latitude, longitude and altitude of Ckoirama observatory?

You already found the latitude and longitude at Google maps: 24.0894 S, 69.9305 W. As far as the International Astronomical Union (IAU) is concerned, Google Earth / Google maps and GPS receiver coordinates are the only preferred sources for the location of an astronomical observatory.

The Minor Planet Center maintains for the IAU a list of astronomical observatories "that report astrometric observations of minor planets, comets or irregular natural satellites" The Minor Planet Center's listing of observatory codes is therefore not a complete listing of observatories worldwide."

From the MPC's page on Updating Locations for Observatory Codes, emphasis mine:

What to Report

When reporting updated coordinates for your site, be sure to include the following information:
- Longitude (in sexagesimal form, to 0.1" or better, preferably 0.01")
- Latitude (in sexagesimal form, to 0.1" or better, preferably 0.01")
- Altitude (in meters)
- Source for coordinates
-- If source is Google Earth, please simply state this.
-- If source is GPS, please state this and indicate whether the altitude is referred to the WGS84 ellipsoid or to mean sea level.
-- Use of other sources is strongly discouraged.

At the bottom of the same page, the MPC issues a disclaimer:

The MPC has no connection with Google Earth, but is simply a satisfied user of the service.

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