diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2f59e99..c5befb4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 # [Unreleased] - yyyy-mm-dd
 
 ### Fixed
+- dial.py to accomodate python change for nan
 - update hsrl.py to use py3 integer divide. fixes date parsing.
 - units for backscatter coeffiecient to km-1 sr-1 in output files generated with aop.py
 - conversion from km to m in icartt.py 
@@ -16,6 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - add configuration file for GEOS-5430 (current FP)
 - add a buddy check code for station observation QC
 - add reader for GloSSAC data
+- support for HALO in hsrl.py
 
 ### Changed
 - use xesmf regridder to station sampling. this is more efficient that using xarray native interp
@@ -106,7 +108,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 - Added list parsing for variables in trajectory sampler
 - fixed byte string bug in aeronet.py
-- - use a local copy of RH in aop calculator.  otherwise it overwrites when fixRH is used
+- use a local copy of RH in aop calculator.  otherwise it overwrites when fixRH is used
 ### Added
 - MPL reader and plot curtain 
 - calculation of total backscatter coefficient in aop.py
diff --git a/src/pyobs/dial.py b/src/pyobs/dial.py
index 45e9201..699bc8f 100644
--- a/src/pyobs/dial.py
+++ b/src/pyobs/dial.py
@@ -6,7 +6,7 @@
 import os
 
 import h5py
-from   numpy    import ones, zeros, interp, NaN, isnan, array, ma
+from   numpy    import ones, zeros, interp, nan as NaN, isnan, array, ma
 from   datetime import datetime, timedelta
 
 from matplotlib.pyplot import imshow, xlabel, ylabel, title, colorbar, \
diff --git a/src/pyobs/hsrl.py b/src/pyobs/hsrl.py
index db459fb..7797256 100644
--- a/src/pyobs/hsrl.py
+++ b/src/pyobs/hsrl.py
@@ -2,7 +2,7 @@
 """
    Implements Python interface to the HSRL L2 data.
 """
-
+import os
 import h5py
 import numpy as np
 from   datetime import datetime, timedelta
@@ -79,8 +79,15 @@
                            'Relative_Humidity',
                          )
                }
+SDS_HALO = {
+    '/': ('lat', 'lon', 'time', 'z',
+          '1064_bsc_cloud_screened', '1064_ext', '1064_aer_dep',
+          '532_bsc_cloud_screened', '532_ext', '532_aer_dep'),
+    'Nav_Data': ('gps_date', 'date', 'gps_alt', 'gps_lat', 'gps_lon', 'gps_time'),
+    'State': ('Pressure', 'Temperature', 'Relative_Humidity')
+} 
 
-NAV = ( 'Altitude','date', 'gps_date','gps_lat','gps_lon','gps_time')
+NAV = ( 'Altitude','date', 'gps_date','gps_lat','gps_lon','gps_time','lat','lon','time','z')
 
 # Short names
 # -----------
@@ -169,7 +176,17 @@ def __init__ (self,hsrl_filename,Nav_only=False,verbose=True,freq=3.0,
         
         # Handle incosistency of date across HSRL datasets
         # -----------------------------------------------
-        if self.nt != self.date.shape[0]:
+        if getattr(self, 'date', None) is None:
+            import re
+            match = re.search(r'_(\d{8})_', os.path.basename(hsrl_filename))
+            if match:
+                dt_str = match.group(1)
+                # Format as MM/DD/YYYY to match HSRL convention
+                dates = '%s/%s/%s' % (dt_str[4:6], dt_str[6:8], dt_str[0:4])
+                self.date = np.array([dates for i in range(self.nt)])
+            else:
+                raise ValueError(f"Missing date variable and could not parse YYYYMMDD from filename: {hsrl_filename}")
+        elif self.nt != self.date.shape[0]:
           date_ = self.date[0,0]
           yy = int(date_)//10000
           mm = (int(date_) - yy * 10000)//100