From 45634f01eea1dec911adcb5ce199cf3279f2227b Mon Sep 17 00:00:00 2001
From: Steve Goldman <32876747+s-goldman@users.noreply.github.com>
Date: Wed, 8 Jul 2026 14:27:22 -0400
Subject: [PATCH 1/2] initial commit.

---
 stwcs/distortion/utils.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/stwcs/distortion/utils.py b/stwcs/distortion/utils.py
index 9fe555d..4608d33 100644
--- a/stwcs/distortion/utils.py
+++ b/stwcs/distortion/utils.py
@@ -111,12 +111,16 @@ def make_orthogonal_cd(wcs):
             pv += wcs.idctheta
         cs = np.cos(np.deg2rad(pv))
         sn = np.sin(np.deg2rad(pv))
+        
         pvmat = np.dot(np.array([[cs, sn], [-sn, cs]]), wcs.parity)
         rot = np.arctan2(pvmat[0, 1], pvmat[1, 1])
 
         det = linalg.det(wcs.parity)
         if hasattr(wcs, 'idcscale') and wcs.idcscale is not None:
             scale = (wcs.idcscale) / 3600.  # HST pixel scale provided
+        else:
+            warnings.warn("IDCSCALE is missing, computing it from CD matrix.")
+            scale = np.sqrt(np.abs(det))  # find as sqrt(pixel area)
     else:
 
         det = linalg.det(cd)

From 47bd352d0bf32871f1a1f8cba123985860ed172c Mon Sep 17 00:00:00 2001
From: Steve Goldman <32876747+s-goldman@users.noreply.github.com>
Date: Wed, 8 Jul 2026 14:37:45 -0400
Subject: [PATCH 2/2] added changelog.

---
 CHANGES.rst | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/CHANGES.rst b/CHANGES.rst
index 1b4bad0..45a9218 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,3 +1,14 @@
+===================
+STWCS Release Notes
+===================
+
+
+1.7.8 (TBD)
+-----------
+
+- Bug fix for empty scale value returned from idctab [#249]
+
+
 1.7.7 (2026-03-05)
 ------------------