From 19ecfa7cd3f1d78c2446b86ad5fab29d0179c060 Mon Sep 17 00:00:00 2001
From: Pey Lian Lim <lim@stsci.edu>
Date: Sat, 20 Aug 2016 09:20:28 -0400
Subject: [PATCH] Redshift is always done in photlam to avoid flux unit
 conversion inconsistency.

---
 pysynphot/spectrum.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/pysynphot/spectrum.py b/pysynphot/spectrum.py
index 7f31e49c..0de2dc87 100644
--- a/pysynphot/spectrum.py
+++ b/pysynphot/spectrum.py
@@ -655,7 +655,8 @@ def redshift(self, z):
         """Apply :ref:`redshift <pysynphot-redshift>` to the spectrum.
 
         Redshifted spectrum is never analytic even if the input
-        spectrum is.
+        spectrum is. Output units are always Angstrom and PHOTLAM
+        regardless of user units.
 
         Parameters
         ----------
@@ -671,7 +672,9 @@ def redshift(self, z):
         # By default, apply only the doppler shift.
 
         waveunits = self.waveunits
+        fluxunits = self.fluxunits
         self.convert('angstrom')
+        self.convert('photlam')
         newwave = self.wave*(1.0+z)
         copy = ArraySourceSpectrum(wave=newwave,
                                    flux=self.flux,
@@ -680,6 +683,7 @@ def redshift(self, z):
                                    name="%s at z=%g" % (self.name, z))
 
         self.convert(waveunits)
+        self.convert(fluxunits)
         return copy
 
     def setMagnitude(self, band, value):