slicecamd: fine-acquire tuning validated on-sky 2026-06-17

Config/slicecamd.cfg.in

@@ -90,11 +90,19 @@ FINE_ACQUIRE_MIN_SAMPLES=3
 #
 FINE_ACQUIRE_SETTLE_FRAMES=2
 
+# FINE_ACQUIRE_SETTLE_SEC=<sec>
+# Time-based settle <sec> applied after each move, in addition to SETTLE_FRAMES,
+# to let the TCS physically finish the move before sampling resumes. This matters
+# when autoexpose shortens the exposure (e.g. bright targets): the frame-count
+# settle then elapses too quickly in wall-clock. Set to 0 to disable.
+#
+FINE_ACQUIRE_SETTLE_SEC=3.0
+
 # FINE_ACQUIRE_GAIN=<g>
 # Proportional gain <g> = {0..1} applied to the commanded offset when the residual
 # is at or below FINE_ACQUIRE_GAIN_THRESHOLD arcsec.
 #
-FINE_ACQUIRE_GAIN=0.7
+FINE_ACQUIRE_GAIN=1.0
 
 # FINE_ACQUIRE_GAIN_LARGE=<g>
 # Proportional gain <g> applied when the residual exceeds FINE_ACQUIRE_GAIN_THRESHOLD.

slicecamd/slicecam_interface.cpp

@@ -542,6 +542,14 @@ namespace Slicecam {
       return;
     }
 
+    // time-based settle: wait for the TCS to physically finish the move before
+    // sampling resumes. The frame-count settle (settle_frames) is too short in
+    // wall-clock when autoexpose shortens the exposure (e.g. bright targets), so
+    // apply a configurable time-based settle on top of it; settle_sec=0 disables.
+    if ( this->fineacquire_state.settle_sec > 0.0 ) {
+      std::this_thread::sleep_for( std::chrono::duration<double>( this->fineacquire_state.settle_sec ) );
+    }
+
     // reset samples and discard settle_count frames for telescope settling
     this->fineacquire_state.reset();
     this->fineacquire_state.settle_frames = this->fineacquire_state.settle_count;
@@ -1332,6 +1340,19 @@ namespace Slicecam {
         applied++;
       }
       else
+      if ( config.param[entry] == "FINE_ACQUIRE_SETTLE_SEC" ) {
+        try { this->fineacquire_state.settle_sec = std::stod( config.arg[entry] ); }
+        catch ( const std::exception &e ) {
+          message.str(""); message << "ERROR invalid FINE_ACQUIRE_SETTLE_SEC "
+                                   << config.arg[entry] << ": " << e.what();
+          logwrite( function, message.str() );
+          return ERROR;
+        }
+        message.str(""); message << "SLICECAMD:config:" << config.param[entry] << "=" << config.arg[entry];
+        logwrite( function, message.str() );
+        applied++;
+      }
+      else
       if ( config.param[entry] == "FINE_ACQUIRE_GAIN" ) {
         try { this->fineacquire_state.gain = std::stod( config.arg[entry] ); }
         catch ( const std::exception &e ) {

slicecamd/slicecam_interface.h

@@ -87,13 +87,14 @@ namespace Slicecam {
     std::vector<double> ddec_samp;  ///< dDEC samples, degrees
     int    max_samples  = 10;       ///< samples before evaluating a move
     int    min_samples  = 3;        ///< minimum samples before scatter-gated early exit
-    double prec_arcsec  = 0.1;      ///< MAD scatter threshold per axis for early exit (arcsec)
-    double goal_arcsec  = 0.3;      ///< convergence threshold, arcsec
-    double gain         = 0.7;      ///< gain applied when offset <= gain_threshold_arcsec
+    double prec_arcsec  = 0.35;     ///< MAD scatter threshold per axis for early exit (arcsec)
+    double goal_arcsec  = 0.4;      ///< convergence threshold, arcsec
+    double gain         = 1.0;      ///< gain applied when offset <= gain_threshold_arcsec
     double gain_large   = 1.0;      ///< gain applied when offset > gain_threshold_arcsec
     double gain_threshold_arcsec = 2.0; ///< offset above which gain_large is used
     int    settle_frames = 0;       ///< countdown of frames to discard while telescope settles
     int    settle_count  = 2;       ///< configured: frames to discard after each move
+    double settle_sec    = 3.0;     ///< time-based settle (sec) after each move; 0 disables (needed when autoexpose shortens frames so the frame-count settle is too brief in wall-clock)
     int    consecutive_centroid_failures = 0; ///< counts consecutive centroid failures
     // exposure compensation (shared by the reactive trim and, later, autoexpose)
     double exptime_min     = 0.1;   ///< clamp: minimum auto-adjusted exposure (sec)