Fixed issues where both inst combined and TM1, TM2, etc. spectra were being retrieved for spectral fitting.

Signed-off-by: David Turner <djturner@umbc.edu>

Author: David Turner

xga/sources/base.py

@@ -1,5 +1,5 @@
 #  This code is part of X-ray: Generate and Analyse (XGA), a module designed for the XMM Cluster Survey (XCS).
-#  Last modified by David J Turner (djturner@umbc.edu) 5/5/26, 1:46 PM. Copyright (c) The Contributors.
+#  Last modified by David J Turner (djturner@umbc.edu) 5/5/26, 10:40 PM. Copyright (c) The Contributors.
 
 import gc
 import os
@@ -2309,6 +2309,12 @@ def _get_phot_prod(self, prod_type: str, obs_id: str = None, inst: str = None, l
                                               telescope=telescope)
             matched_prods = [p[-1] for p in broad_matches if extra_key in p[-2]]
 
+        # This part of the code ensures that if inst is None (the default), only products for 'real'
+        #  instruments are returned. To retrieve a multi-instrument combined product, the user must
+        #  explicitly specify inst='combined'.
+        if inst is None:
+            matched_prods = [m_prod for m_prod in matched_prods if m_prod.instrument != 'combined']
+
         if len(matched_prods) == 1:
             matched_prods = matched_prods[0]
         elif len(matched_prods) == 0:
@@ -2345,6 +2351,12 @@ def _get_prof_prod(self, search_key: str, obs_id: str = None, inst: str = None,
         # Fetch all the matching profiles for the specified telescope
         matched_prods = self.get_products(search_key, obs_id, inst, just_obj=True, telescope=telescope)
 
+        # This part of the code ensures that if inst is None (the default), only products for 'real'
+        #  instruments are returned. To retrieve a multi-instrument combined product, the user must
+        #  explicitly specify inst='combined'.
+        if inst is None:
+            matched_prods = [m_prod for m_prod in matched_prods if m_prod.instrument != 'combined']
+
         matched_prods: List[BaseProfile1D]
 
         # Matching the radii is going to take a maybe slightly (but practically not really) dangerous approach. The
@@ -2443,6 +2455,12 @@ def _get_lc_prod(self, outer_radius: Union[str, Quantity] = None, obs_id: str =
         #  user (None by default) - we'll then sweep through whatever list is returned and narrow them down
         matched_prods = self.get_products(search_key, obs_id, inst, telescope=telescope)
 
+        # This part of the code ensures that if inst is None (the default), only products for 'real'
+        #  instruments are returned. To retrieve a multi-instrument combined product, the user must
+        #  explicitly specify inst='combined'.
+        if inst is None:
+            matched_prods = [m_prod for m_prod in matched_prods if m_prod.instrument != 'combined']
+
         matched_prods: List[LightCurve]
 
         # Checking for matching radii first - this will likely whittle down the LCs best of all. We have
@@ -3354,6 +3372,12 @@ def _get_spec_prod(self, outer_radius: Union[str, Quantity], obs_id: str = None,
         else:
             matched_prods = self.get_products('spectrum', obs_id=obs_id, inst=inst, telescope=telescope)
 
+        # This part of the code ensures that if inst is None (the default), only products for 'real'
+        #  instruments are returned. To retrieve a multi-instrument combined product, the user must
+        #  explicitly specify inst='combined'.
+        if inst is None:
+            matched_prods = [m_prod for m_prod in matched_prods if m_prod.instrument != 'combined']
+
         # Checking for matching radii first - this will likely whittle down the spectra best of all. We have
         #  had matching problems sometimes because of float precision (the last digit flips and is no longer
         #  an exact match to the other radius)

xga/xspec/fit/_common.py

@@ -1,5 +1,5 @@
 #  This code is part of X-ray: Generate and Analyse (XGA), a module designed for the XMM Cluster Survey (XCS).
-#  Last modified by David J Turner (djturner@umbc.edu) 5/5/26, 1:41 PM. Copyright (c) The Contributors.
+#  Last modified by David J Turner (djturner@umbc.edu) 5/5/26, 10:41 PM. Copyright (c) The Contributors.
 
 import os
 from typing import List, Union, Tuple, Dict
@@ -293,26 +293,19 @@ def _spec_obj_setup(stacked_spectra: bool, tel: str, source: BaseSource, out_rad
     try:
         if tel in ['erosita', 'erass'] and (len(source.obs_ids[tel]) > 1):
             # For erosita with multiple observations, we need combined-obs spectra to avoid duplicated events
-            # The inst parameter controls whether we want multi-instrument (stacked) or per-instrument
-            if stacked_spectra:
-                # Scenario 3: Multi-obs + multi-inst combined (obs_id='combined', inst='combined')
-                search_inst = 'combined'
-            else:
-                # Scenario 2: Multi-obs + individual insts (obs_id='combined', inst=<specific>)
-                # Leaving inst=None returns all per-instrument combined-obs spectra
-                search_inst = None
+            # The inst parameter controls whether we want multi-instrument (stacked) or per-instrument.
+            # Due to strict instrument filtering in get_spectra, inst=None will only return 'real' TMs.
+            search_inst = 'combined' if stacked_spectra else None
 
             spec_objs = source.get_spectra(out_rad_vals[src_ind], obs_id='combined', inst=search_inst,
                                            inner_radius=inn_rad_vals[src_ind],
                                            group_spec=group_spec, min_counts=min_counts,
                                            min_sn=min_sn, telescope=tel)
         else:
-            # Single observation (or non-eROSITA): use regular spectra
-            # For multi-instrument stacking, inst='combined' retrieves Scenario 1 products
-            # search_inst = 'combined' if stacked_spectra else None
-            # This part of the if-else will be for missions with no implemented spectrum
-            #  stacking method I think, so search_inst must be None.
-            search_inst = None
+            # Single observation (or non-eROSITA): use regular spectra.
+            # For multi-instrument stacking, inst='combined' retrieves multi-instrument products.
+            # inst=None retrieves all individual instrument products.
+            search_inst = 'combined' if stacked_spectra else None
 
             spec_objs = source.get_spectra(out_rad_vals[src_ind], inner_radius=inn_rad_vals[src_ind],
                                             group_spec=group_spec, min_counts=min_counts, min_sn=min_sn,