Select on angular velocity (minimum and maximum). Fixes #50

configuration.ini-dist

@@ -52,7 +52,8 @@ low_app = 18            # Arcsec per pixel low scale - Resolution of camera
 high_app = 20           # Arcsec per pixel high scale - Resolution of camera
 
 [Processing]
-drdtmin = 5.0           # Minimum predicted satellite velocity (pixels/s)
+drdtmin = 0.1           # Minimum predicted satellite velocity (deg/s)
+drdtmin = 5.0           # Maximum predicted satellite velocity (deg/s)
 trkrmin = 10.0          # Track selection region around prediction (pixels)
 ntrkmin = 10            # Minimum number of points making up a track
 trksig = 5.0            # Track selection sigma

process.py

@@ -63,6 +63,7 @@ if __name__ == "__main__":
 
     # Extract settings
     drdtmin = cfg.getfloat('Processing', 'drdtmin')
+    drdtmax = cfg.getfloat('Processing', 'drdtmax')
     trksig = cfg.getfloat('Processing', 'trksig')
     trkrmin = cfg.getfloat('Processing', 'trkrmin')
     ntrkmin = cfg.getint('Processing', 'ntrkmin')
@@ -141,7 +142,7 @@ if __name__ == "__main__":
 
             # Extract tracks
             if is_calibrated(ff):
-                extract_tracks(fname, trkrmin, drdtmin, trksig, ntrkmin, root_dir, results_dir)
+                extract_tracks(fname, trkrmin, drdtmin, drdtmax, trksig, ntrkmin, root_dir, results_dir)
 
             # Stars available and used
             nused = np.sum(pix_catalog.flag == 1)

stvid/extract.py

@@ -9,6 +9,8 @@ import ppgplot as ppg
 from scipy import optimize, ndimage
 from termcolor import colored
 import datetime
+import astropy.units as u
+from astropy.coordinates import SkyCoord
 
 # Gaussian model
 def model(a, nx, ny):
@@ -246,8 +248,14 @@ def plot_header(fname, ff, iod_line):
     ppg.pgctab(heat_l, heat_r, heat_g, heat_b, 5, 1.0, 0.5)
 
 
+# Calculate angular velocity
+def angular_velocity(ident, w, texp):
+    p = SkyCoord.from_pixel([ident.x0, ident.x1], [ident.y0, ident.y1], w, 1, mode="all")
+    return p[0].separation(p[1]).to(u.deg).value/texp
+
+
 # Extract tracks
-def extract_tracks(fname, trkrmin, drdtmin, trksig, ntrkmin, path, results_path):
+def extract_tracks(fname, trkrmin, drdtmin, drdtmax, trksig, ntrkmin, path, results_path):
     # Read four frame
     ff = fourframe(fname)
 
@@ -295,9 +303,9 @@ def extract_tracks(fname, trkrmin, drdtmin, trksig, ntrkmin, path, results_path)
         if ident.state == "remove":
             continue
 
-        # Skip slow moving objects
-        drdt = np.sqrt(ident.dxdt**2 + ident.dydt**2)
-        if drdt < drdtmin:
+        # Select on angular velocity 
+        drdt = angular_velocity(ident, ff.w, ff.texp)
+        if (drdt < drdtmin) | (drdt > drdtmax):
             continue
 
         # Extract significant pixels along a track