Dear user, thanks for your inquiry.

In astronomy many coordinates systems exists to map the location of celestial objects, that serves different purposes, i.e. to easily manage the data in a more natural framework.
The argument is very vast and cannot be shortly explained in a web ticket, we will provide a brief introduction and some supporting links that could help to understand the big picture.

Like in Earth cartography the definition of a common and uniform coordinate system it has also a long history and there is a strong connection between Earth coordinates and celestial coordinates, and this fact was used by sailors for many centuries for determine their point on open sea, determining the altitude and azimuth of some known stars and Sun and hence determine their position.

But how the coordinates of these stars were and are defined? in ancient times the reference system was based on the ecliptic  (the theoretical big circle in the sky) that "contains" the movement of the Sun and the planets, counting the celestial longitude on this circle, and the latitudes as distances from it.
However more recently it was introduced a system, the equatorial system that connect Earth and time to the position of stars in the sky. This system is what is actually used in astronomy. The system is defined in this way:
The big circle corresponding to the projection of the Earth equator on the sky (called the celestial equator), is the reference for the "longitude" that is called in astronomy Rigth Ascension (RA), the perpendicular angular distances to this circle measures the "latitude" that is called Declination (DEC). The zero point of the Rigth Ascension, is measured from the point of the Sun at the equinox of March (i.e. at the intersection of the ecliptic with the celestial equator).

As you can understand, non uniformity on Earth figure, precessional motion, polar motions, all alter this definition.
For creating a fixed reference in space that was not subject to all these problematics, it was created a new reference system called International Celestial Reference System (ICRS) centered on the Solar System barycenter whose orientation align within 0.02 arcsecond of the Earth mean equator and equinox. The ICRS is connected to the International Terrestrial Reference System (ITRS) via the measurments performed by the International Earth Rotation and Reference Systems Service (IERS).

As said before other coordinates systems exists, but what is mostly used is the equatorial system, for other purposes for example deep space missions is more used the ecliptic system. For all these systems precise transformations exists and are precisely defined by the International Astronomical Union in various publications and supported via well maintained software in Fortran and Python.

For analysis of stellar distribution in the Galaxy another system is used and is called galactic coordinates system, which uses as reference the galactic equator (the big circle corresponding to the maximum emission of the 21 cm emission line of Hydrogen), whose zero point is very close to the radio source Sagittarius A*. These coordinates are called galactic longitude (l: lowercase L) and latitude (b, lowercase B). Is interesting to note that the inclination between the galactic equator and celestial equator, galactic equator and ecliptic, are close to 60 degrees, meaning that  the Solar System is higly inclined respect to the fundamental plain of the Galaxy and this creates a helical path as the Sun orbits the Galaxy at 230 km/s, much like Uranus rolls along its orbit around the Sun.

Another system related to the galactic system exist and is called galactocentric rectangular system, in which XYZ linear coordinates (not angles) are calculated from the Galactic Center. Both Galactic coordinate systems are very useful for understand the mass distribution in our Galaxy and to perform cartography of our neighbourhood, however only with the advent of Gaia mission we started to have more precise measurements of the distances of the objects around us.

basic information about the coordinate systems in astronomy
https://en.wikipedia.org/wiki/Astronomical_coordinate_systems
https://en.wikipedia.org/wiki/Equatorial_coordinate_system

a precise definition of the actual reference frames used in astronomy could be found here
https://aa.usno.navy.mil/publications/Circular_179

software libraries
http://www.iausofa.org/
https://docs.astropy.org/en/stable/coordinates/index.html


best regards
Mauro Barbieri

Dear User,

Thanks for contacting us,

indeed this is planned and a new version of the Archive Science Portal, containing also the Planck maps will be soon deployed.

Best regards,

the ESO Archive

Dear User,

The MUSE GEOMETRY and ASTROMETRY calibration frames are taken regularly. They are processed automatically and checked for quality. The quality parameters are monitored in the specially designed Health Check plots:

https://www.eso.org/observing/dfo/quality/MUSE/reports/HEALTH/trend_report_GEOMETRY_HC.html

https://www.eso.org/observing/dfo/quality/MUSE/reports/HEALTH/trend_report_ASTROMETRY_WFM_HC.html

https://www.eso.org/observing/dfo/quality/MUSE/reports/HEALTH/trend_report_ASTROMETRY_NFM_HC.html

The MUSE geometry calibrations are quite high volume (~6 GB, 70 input raw frames) and their processing is hardware demanding. Thus, early in operations the decision was taken to provide the users only with the static (frozen in time) version of the master GEOMETRY_TABLE. The regular monitoring shows if there is a need to produce modified, newer version. Since April 2021 there has not been such a need identified yet. That is why the April 2021 version is still distributed with the 2024 science data. The MUSE astrometry is closely tide with geometry, so it is also provided in the static form. The ASTROMETRY version corresponds to the distributed GEOMETRY version.

There is always a possibility to download the latest calibrations (raw data) from the ESO Archive at: http://archive.eso.org/wdb/wdb/eso/muse/form and process them if the users prefer to repeat the data processing themselves.

Hope this answers your question.

Best regards,

The ESO Archive Team

Please click on 'Continue' on the lower right corner of the popup window.

Could you please be more specific? To which web page are you referring to?

Dear User,

Thank you for reaching out to us.

The heliocentric or barycentric correction provided in the header is suitable for general purposes. However, I cannot confirm its precision. For a more detailed response tailored to your scientific requirements, I recommend opening a ticket at the following URL:  https://support.eso.org/ and click on "Contact us"

Dear Mateus,

Unfortunately these data are not available. Back then data from 3.6m (or 1.54m) was not ingested yet in the ESO Archive.

Sorry we cannot help you.