Wikipedia
Gyldén is the remnant of a lunar crater that is located to the northeast of the walled plain Ptolemaeus on the Moon. It lies along the prime meridian of the selenographic coordinate system, and less than 150 km south of the lunar equator. Nearby craters of note include Herschel to the west, the flooded Réaumur to the north, and Hipparchus to the east.
The heart-shaped rim of this crater is in poor condition, having been eroded by impacts until the disintegrating remnants form an uneven ring of peaks and valleys around the interior floor. The satellite crater Réaumur A is attached to the northern rim. A wide cleft cuts through the western rim, continuing to the north-northwest past Spörer. The interior floor is relatively featureless, although the small crater Gyldén K is located just to the southeast of the midpoint.
Usage examples of "gylden".
Torpadie so impressed the Swedish authorities by solving a nomenclator of 1632 for a historical study that they commissioned him to set up a cryptologic bureau called Room 100, Swedish cryptology got its real start with Yves Gylden.
In 1939, during a 12-hour war game, Gylden headed the cryptanalytical office that solved 38 of the 56 rather simple cryptograms transmitted by the "invaders.