Tag "IMC" if IMC looses lock at the same time as the main IFO when refined on ASC-AS_A detector

Ran ./test script at LHO and LLO. Passed at both sites.

If the channel used to refine time is H1:ASC-AS_A_DC_NSUM_OUT_DQ, then refine.py will also refine time of lockloss using IMC channel.

If a refined time is found for both ASC-AS_A and IMC_TRANS, then the refined times will be compared. If IMC refined time is within 50ms of the ASC-AS_A refined time, then tag IMC is added. Example below.

Note that at LLO, the IMC channel is the only refinement channel used currently, this can be implemented at LLO if a different, more accurate of the IFO refinement channel is used.

No plots are made but a future addition would be to add the IMC channel onto the normal refine.py plot.

Good to implement ASAP as Iain Morton found that no O4 losses prior to the emergency vent had this type of IMC/PSL caused lockloss but since September 27th the majority of our locklosses have this characteristic. Details in LHO alog 80366.

locklost/plugins/refine.py

@@ -234,3 +234,24 @@ def refine_time(event):
         refined_gps=refined_gps,
         threshold=threshold,
     )
+
+    # if refined time uses channel 'H1:ASC-AS_A_DC_NSUM_OUT_DQ',
+    # check 'H1:IMC-TRANS_OUT_DQ' looses lock at the same time.
+    if params['CHANNEL'] != 'H1:ASC-AS_A_DC_NSUM_OUT_DQ':
+        return
+
+    IMC_params = config.INDICATORS[0]
+    logger.info("refining time using channel: {}".format(IMC_params['CHANNEL']))
+    # find threshold and refined time using indicator channel
+    IMC_threshold, IMC_refined_gps = find_transition(
+        [IMC_params['CHANNEL'], ],
+        segment,
+        IMC_params['THRESHOLD'],
+        event.gps + 1,
+        IMC_params['MINIMUM'],
+    )
+
+    if IMC_refined_gps and refined_gps:
+        if IMC_refined_gps <= refined_gps + (50 * 10**-3):
+            logger.info("IMC refined time within 50ms of AS_A refined time.")
+            event.add_tag('IMC')