diff --git a/pyvisgen/simulation/observation.py b/pyvisgen/simulation/observation.py
index e6ee4fb..814aad4 100644
--- a/pyvisgen/simulation/observation.py
+++ b/pyvisgen/simulation/observation.py
@@ -359,13 +359,12 @@ def create_rd_grid(self):
         # define resolution
         res = fov / self.img_size
 
-        ra = torch.deg2rad(self.ra)
         dec = torch.deg2rad(self.dec)
 
         r = (
             torch.arange(self.img_size, device=self.device, dtype=torch.float64)
             - self.img_size / 2
-        ) * res + ra
+        ) * res
         d = (
             torch.arange(self.img_size, device=self.device, dtype=torch.float64)
             - self.img_size / 2
@@ -391,18 +390,13 @@ def create_lm_grid(self):
         3d array
             Returns a 3d array with every pixel containing a l and m value
         """
-        ra = torch.deg2rad(self.ra)
         dec = torch.deg2rad(self.dec)
 
         lm_grid = torch.zeros(self.rd.shape, device=self.device, dtype=torch.float64)
-        lm_grid[:, :, 0] = (
-            torch.cos(self.rd[..., 1]) * torch.sin(self.rd[..., 0] - ra)
-        ).T
+        lm_grid[:, :, 0] = (torch.cos(self.rd[..., 1]) * torch.sin(self.rd[..., 0])).T
         lm_grid[:, :, 1] = (
             torch.sin(self.rd[..., 1]) * torch.cos(dec)
-            - torch.cos(self.rd[..., 1])
-            * torch.sin(dec)
-            * torch.cos(self.rd[..., 0] - ra)
+            - torch.cos(self.rd[..., 1]) * torch.sin(dec) * torch.cos(self.rd[..., 0])
         ).T
         return lm_grid
 
diff --git a/pyvisgen/simulation/scan.py b/pyvisgen/simulation/scan.py
index cf6dc8e..2b92e9e 100644
--- a/pyvisgen/simulation/scan.py
+++ b/pyvisgen/simulation/scan.py
@@ -115,7 +115,7 @@ def angularDistance(rd, ra, dec):
         Returns angular Distance for every pixel in rd grid with respect
         to source position
     """
-    r = rd[..., 0] - torch.deg2rad(ra.to(rd.device))
+    r = rd[..., 0]
     d = rd[..., 1] - torch.deg2rad(dec.to(rd.device))
     theta = torch.arcsin(torch.sqrt(r**2 + d**2))
     return theta