OSGeo
NTv2-BB.gsb: Pulkovo 1942(83) -> ETRS89 in Brandenburg could be included
The above link no longer works. Wayback machine has an interesting old version https://web.archive.org/web/20190512124712/https://www.geobasis-bb.de/geodaten/dienst_progr.htm where it appears the grid has an associated fee
I think I posted the wrong link. It should be:
https://geobasis-bb.de/lgb/de/geodaten/raumbezug-sapos/koordinatentransformation/
which states : "Costs: the delivery of the program is free of charge"
Which links to https://geobroker.geobasis-bb.de/gbss.php?MODE=GetProductInformation&PRODUCTID=3b55a940-95c7-42d6-901b-1215ebffc1f6, which states
Conditions for access and use Terms of use: Data license Germany - attribution - version 2.0, https://www.govdata.de/dl-de/by-2-0 ; dl-de-by-2.0, attribution: "GeoBasis-DE / LGB", example: "© GeoBasis-DE / LGB, dl-de / by-2-0, (data changed)", (brackets = optional)
Restrictions on public access: other restrictions: dl-de-by-2.0 , source: © GeoBasis-DE / LGB, dl-de / by-2-0
ZIP with grid downloaded from https://geobroker.geobasis-bb.de/eco.php?mode=inWarenkorb&aProductId=3b55a940-95c7-42d6-901b-1215ebffc1f6 attached here:
with Terms of use: Data license Germany - attribution - version 2.0, https://www.govdata.de/dl-de/by-2-0 ; dl-de-by-2.0, attribution: "GeoBasis-DE / LGB",
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