Brendan, The four old datums are New Bulgarian 1928, Observatorio Astronomico Militari Bucharasti, New Romanian 1930, and Kustendil. I would guess the most recent is the "System 42" based on the Krassovski ellipsoid. I have an Astro position, "Chernyy Verkh" at Lat = 43* 33' 54.55"N Lon = 23* 16' 51.96"E which is the origin point of the New Bulgarian Datum of 1928, and is referenced to the International ellipsoid. If they followed the lead of the Romanians and the Poles, this is the origin of the new 1970 system in Bulgaria. The Romanian Planuri Directuri (sp?) Lambert Conformal Conic is on the Observatorio Datum and is referenced to the Clarke 1880 Romanian modified ellipsoid. The "Kronstadt Oblique Stereographic of 1934" is on the New Romanian Datum of 1930, and the math model of the projection is the Rousilhe Stereographic favored by the French Navy. (Internaitonal ellipsoid again.) In 1970, the Romanians picked up the Hristow math model in "Stereo 70." The rest is like I said, G-K TM. No polyconics. In 1970, the Poles and the Romanians BOTH picked up the Hristow Oblique Stereographic. If the Bulgarians did something strange, my guess would be the Hristow, not the Polyconic. It looks like a conic projection on a large-scale topo map and is frequently mistaken for Lambert or Polyconic. Stereographic is the standard projection and Grid for circularly shaped countries all over the world. I would think that the Warsaw Pact dudes read the same books as me ... Oh, and by the way, Prof. Hristow was Bulgarian. He wrote in German, he published in Austrian geodetic stuff, but he taught in Sofia. I don't think they EVER used Hassler's Polyconic. Maybe Lallemond's Polyconic for IMW stuff before WWII. Clifford J. Mugnier ([EMAIL PROTECTED]) The Topographic Engineering Laboratory Department of Civil and Environmental Engineering UNIVERSITY OF NEW ORLEANS New Orleans, Louisiana 70148 Voice and Facsimilie: (504) 280-7095 -------------------------------------------------------- ------------- On Wednesday, 23 February, 2000 2:26 AM, Brendan wrote: > Cliff, > > Many thanks for the response, > > I will endeavour to get more data from my contacts. All I > know about the > 1970 system came in an email, this is the relevant bit > > "The official projection used in Bulgaria is called SYSTEM > 1970 and is some > >kind of polyconic projection with secret parameters. > >Although we have been > >trying to get a clue on what these might be for something > >like 3 years we > >couldn't get any information on that from the Military > >Topographic Service > >and other institutions. However, there is a large number > >of (in theory) > >secret black box programmes that would convert your data > >in either LL or > >some other global projection." > > I do not have any of these "black boxes" but will try to > get some. > > Probably very naively, I read your your Uzbekistan paper > and assuming USSR/ > Warsaw pact monolith worked out the two UTM type > projections with the > Krassovsky and the central scale factor of 1 which might > be applicable to > Bulgaria. > > I will look again in PE&RS for the Four datums in Bulgaria > to which you > allude (or should I look elsewhere ?). > > I would certainly like to contact you again if and when I > can get any more > concrete information > > Thanks again Brendan ---------------------------------------------------------------------- To unsubscribe from this list, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MAPINFO-L" in the message body, or contact [EMAIL PROTECTED]
