pyproj return meridian_convergence of -0.0 degrees for given point in 4326

Question

I am trying to get the correct meridian_convergence for my given point in EPSG:4326

When I try to run the following code I am getting -0.0 were expecting I 0.6 degrees.

import pyproj


lat, long = 30.2675, -97.74278  # expected Grid North 0.6°
# lat, long = 48.1, -92.61      # expected Grid North 0.3°
# lat, long = 42.0352,-168.2065 # expected Grid North 1.9°

crs_nztm= pyproj.CRS("epsg:4326")
p = pyproj.Proj(crs_nztm)
declination = p.get_factors(long, lat, False, True).meridian_convergence

print(declination)
    

For all 3 examples, I am getting -0.0. I have little experience with pyproj and I wonder if my EPSG set is correct or if maybe it is something to do with pyproj rounding. Did anyone encounter this problem?

Answer 1

Ok, is actually really simple. I think I can't project from WGS to WGS. I need to pass UTM coordinate system to allow pyproj to do a correct projection for lat long.

eg.

import pyproj


lat, long = 30.2675, -97.74278  # expected Grid North 0.6°
# lat, long = 48.1, -92.61      # expected Grid North 0.3°
# lat, long = 42.0352,-168.2065 # expected Grid North 1.9°

# ESPG: 32614 - the first point intersects with UTM 14R
crs_nztm= pyproj.CRS("epsg:32614")
p = pyproj.Proj(crs_nztm)
declination = p.get_factors(long, lat, False, True).meridian_convergence

print(declination)

This will return the correct degrees of 0.633763421024677