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Surveyors Information - Geodetic Control Data

Geodetic Survey Control For Maryland

Information on permanently monumented control points including horizontal control, vertical control, High Accuracy Reference Network (HARN) stations, Calibration Baselines and retrieval software can be obtained from the NGS web site or from the National Geodetic survey (NGS) Data Center on CD ROM. The Data Center may be reached at 301-713-3242. The cost of the CD is $50.00.

Maryland HARN

Maryland Harn

The map above shows the location of HARN points in Maryland. The position of these points was determined by GPS observations and have a stated accuracy of 1.0 to 0.1 parts per million.

Calibration Baselines in Maryland

Calibration Baselines in Maryland

The map above shows the approximate location of the six calibration baselines located in Maryland. A calibration baseline consists of a set of very stable survey monuments which are accurately measured using specialized equipment. By comparing their results with the values published for the monuments, surveyors are able to verify the accuracy of their equipment.

Name Location Latitude Longitude
Aberdeen CBL Harford County 39 29 76 10
Cambridge CBL Dorchester County 38 35 76 08
Hagerstown CBL Washington County 39 43 77 44
Howard County CBL Howard County 39 15 76 56
Leonardtown CBL St. Mary's County 38 19 76 33
Pittsville CBL St. Wicomico County 38 23 75 23