EPSG:3839

PROJCS["Pulkovo 1942(58) / 3-degree Gauss-Kruger zone 9",
    GEOGCS["Pulkovo 1942(58)",
        DATUM["Pulkovo_1942_58",
            SPHEROID["Krassowsky 1940",6378245,298.3,
                AUTHORITY["EPSG","7024"]],
            AUTHORITY["EPSG","6179"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.0174532925199433,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4179"]],
    PROJECTION["Transverse_Mercator"],
    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",27],
    PARAMETER["scale_factor",1],
    PARAMETER["false_easting",9500000],
    PARAMETER["false_northing",0],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","3839"]]

PROJCRS["Pulkovo 1942(58) / 3-degree Gauss-Kruger zone 9",
    BASEGEOGCRS["Pulkovo 1942(58)",
        DATUM["Pulkovo 1942(58)",
            ELLIPSOID["Krassowsky 1940",6378245,298.3,
                LENGTHUNIT["metre",1]]],
        PRIMEM["Greenwich",0,
            ANGLEUNIT["degree",0.0174532925199433]],
        ID["EPSG",4179]],
    CONVERSION["3-degree Gauss-Kruger zone 9",
        METHOD["Transverse Mercator",
            ID["EPSG",9807]],
        PARAMETER["Latitude of natural origin",0,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8801]],
        PARAMETER["Longitude of natural origin",27,
            ANGLEUNIT["degree",0.0174532925199433],
            ID["EPSG",8802]],
        PARAMETER["Scale factor at natural origin",1,
            SCALEUNIT["unity",1],
            ID["EPSG",8805]],
        PARAMETER["False easting",9500000,
            LENGTHUNIT["metre",1],
            ID["EPSG",8806]],
        PARAMETER["False northing",0,
            LENGTHUNIT["metre",1],
            ID["EPSG",8807]]],
    CS[Cartesian,2],
        AXIS["northing (X)",north,
            ORDER[1],
            LENGTHUNIT["metre",1]],
        AXIS["easting (Y)",east,
            ORDER[2],
            LENGTHUNIT["metre",1]],
    USAGE[
        SCOPE["Military survey."],
        AREA["Bulgaria and Romania - onshore between 25°30'E and 28°30'E."],
        BBOX[41.28,25.5,48.27,28.5]],
    ID["EPSG",3839]]

PROJCS["Pulkovo_1942_Adj_1958_3_Degree_GK_Zone_9",
    GEOGCS["GCS_Pulkovo_1942_Adj_1958",
        DATUM["D_Pulkovo_1942_Adj_1958",
            SPHEROID["Krasovsky_1940",6378245.0,298.3]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Gauss_Kruger"],
    PARAMETER["False_Easting",9500000.0],
    PARAMETER["False_Northing",0.0],
    PARAMETER["Central_Meridian",27.0],
    PARAMETER["Scale_Factor",1.0],
    PARAMETER["Latitude_Of_Origin",0.0],
    UNIT["Meter",1.0]]

proj4.defs("EPSG:3839","+proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=9500000 +y_0=0 +ellps=krass +units=m +no_defs +type=crs");

{
    "$schema": "https://proj.org/schemas/v0.7/projjson.schema.json",
    "type": "ProjectedCRS",
    "name": "Pulkovo 1942(58) / 3-degree Gauss-Kruger zone 9",
    "base_crs": {
        "type": "GeographicCRS",
        "name": "Pulkovo 1942(58)",
        "datum": {
            "type": "GeodeticReferenceFrame",
            "name": "Pulkovo 1942(58)",
            "ellipsoid": {
                "name": "Krassowsky 1940",
                "semi_major_axis": 6378245,
                "inverse_flattening": 298.3
            }
        },
        "coordinate_system": {
            "subtype": "ellipsoidal",
            "axis": [
                {
                    "name": "Geodetic latitude",
                    "abbreviation": "Lat",
                    "direction": "north",
                    "unit": "degree"
                },
                {
                    "name": "Geodetic longitude",
                    "abbreviation": "Lon",
                    "direction": "east",
                    "unit": "degree"
                }
            ]
        },
        "id": {
            "authority": "EPSG",
            "code": 4179
        },
        "remarks": "Shares same origin definition as Pulkovo 1942 (CRS code 4284) and for low accuracy purposes these systems can be considered consistent with each other. Locally densified during 1957 and 1958. Replaced by 1983 adjustment (CRS code 4178)."
    },
    "conversion": {
        "name": "3-degree Gauss-Kruger zone 9",
        "method": {
            "name": "Transverse Mercator",
            "id": {
                "authority": "EPSG",
                "code": 9807
            }
        },
        "parameters": [
            {
                "name": "Latitude of natural origin",
                "value": 0,
                "unit": "degree",
                "id": {
                    "authority": "EPSG",
                    "code": 8801
                }
            },
            {
                "name": "Longitude of natural origin",
                "value": 27,
                "unit": "degree",
                "id": {
                    "authority": "EPSG",
                    "code": 8802
                }
            },
            {
                "name": "Scale factor at natural origin",
                "value": 1,
                "unit": "unity",
                "id": {
                    "authority": "EPSG",
                    "code": 8805
                }
            },
            {
                "name": "False easting",
                "value": 9500000,
                "unit": "metre",
                "id": {
                    "authority": "EPSG",
                    "code": 8806
                }
            },
            {
                "name": "False northing",
                "value": 0,
                "unit": "metre",
                "id": {
                    "authority": "EPSG",
                    "code": 8807
                }
            }
        ]
    },
    "coordinate_system": {
        "subtype": "Cartesian",
        "axis": [
            {
                "name": "Northing",
                "abbreviation": "X",
                "direction": "north",
                "unit": "metre"
            },
            {
                "name": "Easting",
                "abbreviation": "Y",
                "direction": "east",
                "unit": "metre"
            }
        ]
    },
    "scope": "Military survey.",
    "area": "Bulgaria and Romania - onshore between 25°30'E and 28°30'E.",
    "bbox": {
        "south_latitude": 41.28,
        "west_longitude": 25.5,
        "north_latitude": 48.27,
        "east_longitude": 28.5
    },
    "id": {
        "authority": "EPSG",
        "code": 3839
    }
}

<?xml version="1.0" encoding="utf-8"?>
<Map srs="+proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=9500000 +y_0=0 +ellps=krass +units=m +no_defs +type=crs">
	<Layer srs="+proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=9500000 +y_0=0 +ellps=krass +units=m +no_defs +type=crs">
	</Layer>
</Map>

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 3839, 'EPSG', 3839, '+proj=tmerc +lat_0=0 +lon_0=27 +k=1 +x_0=9500000 +y_0=0 +ellps=krass +units=m +no_defs +type=crs', 'PROJCS["Pulkovo 1942(58) / 3-degree Gauss-Kruger zone 9",GEOGCS["Pulkovo 1942(58)",DATUM["Pulkovo_1942_58",SPHEROID["Krassowsky 1940",6378245,298.3,AUTHORITY["EPSG","7024"]],AUTHORITY["EPSG","6179"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4179"]],PROJECTION["Transverse_Mercator"],PARAMETER["latitude_of_origin",0],PARAMETER["central_meridian",27],PARAMETER["scale_factor",1],PARAMETER["false_easting",9500000],PARAMETER["false_northing",0],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AUTHORITY["EPSG","3839"]]');