17:32:33 Averaging darks. 17:32:33 Adding dark image 1 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0009(1).fits 17:32:35 Adding dark image 2 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0010(1).fits 17:32:37 Adding dark image 3 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0011(1).fits 17:32:39 Adding dark image 4 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0012(1).fits 17:32:41 Adding dark image 5 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0013(1).fits 17:32:43 Adding dark image 6 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0014(1).fits 17:32:45 Adding dark image 7 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0015(1).fits 17:32:47 Adding dark image 8 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0016(1).fits 17:32:48 Adding dark image 9 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0017(1).fits 17:32:52 Averaging darks. 17:32:52 Adding dark image 1 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0009(2).fits 17:32:54 Adding dark image 2 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0010(2).fits 17:32:56 Adding dark image 3 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0011(2).fits 17:32:58 Adding dark image 4 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0012(2).fits 17:33:00 Adding dark image 5 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0013(2).fits 17:33:02 Adding dark image 6 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0014(2).fits 17:33:03 Adding dark image 7 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0015(2).fits 17:33:05 Adding dark image 8 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0016(2).fits 17:33:07 Adding dark image 9 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0017(2).fits 17:33:11 Averaging darks. 17:33:11 Adding dark image 1 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0009.fits 17:33:14 Adding dark image 2 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0010.fits 17:33:16 Adding dark image 3 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0011.fits 17:33:18 Adding dark image 4 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0012.fits 17:33:19 Adding dark image 5 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0013.fits 17:33:21 Adding dark image 6 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0014.fits 17:33:23 Adding dark image 7 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0015.fits 17:33:25 Adding dark image 8 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0016.fits 17:33:27 Adding dark image 9 to dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\_Ha_0017.fits 17:33:30 Master darks(s) ready. 17:34:02 Averaging flat dark frames. 17:34:02 Adding flat-dark image 1 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0009(1).fits 17:34:04 Adding flat-dark image 2 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0009.fits 17:34:06 Adding flat-dark image 3 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0010(1).fits 17:34:08 Adding flat-dark image 4 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0010.fits 17:34:10 Adding flat-dark image 5 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0011(1).fits 17:34:11 Adding flat-dark image 6 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0011.fits 17:34:13 Adding flat-dark image 7 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0012(1).fits 17:34:15 Adding flat-dark image 8 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0012.fits 17:34:17 Adding flat-dark image 9 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0013(1).fits 17:34:19 Adding flat-dark image 10 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0013.fits 17:34:21 Adding flat-dark image 11 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0014(1).fits 17:34:23 Adding flat-dark image 12 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0014.fits 17:34:24 Adding flat-dark image 13 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0015(1).fits 17:34:26 Adding flat-dark image 14 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0015.fits 17:34:28 Adding flat-dark image 15 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0016(1).fits 17:34:30 Adding flat-dark image 16 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0016.fits 17:34:32 Adding flat-dark image 17 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0017(1).fits 17:34:34 Adding flat-dark image 18 to flat-dark average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARKFLAT\_Ha_0017.fits 17:34:36 Combining flats and flat-darks. 17:34:36 Adding flat image 1 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0007.fits 17:34:38 Adding flat image 2 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0008.fits 17:34:40 Adding flat image 3 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0009.fits 17:34:42 Adding flat image 4 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0010.fits 17:34:43 Adding flat image 5 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0011.fits 17:34:45 Adding flat image 6 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0012.fits 17:34:47 Adding flat image 7 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_B_0013.fits 17:34:52 Combining flats and flat-darks. 17:34:52 Adding flat image 1 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0007.fits 17:34:54 Adding flat image 2 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0008.fits 17:34:56 Adding flat image 3 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0009.fits 17:34:58 Adding flat image 4 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0010.fits 17:35:00 Adding flat image 5 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0011.fits 17:35:02 Adding flat image 6 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0012.fits 17:35:03 Adding flat image 7 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_C_0013.fits 17:35:08 Combining flats and flat-darks. 17:35:08 Adding flat image 1 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0007.fits 17:35:10 Adding flat image 2 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0008.fits 17:35:12 Adding flat image 3 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0009.fits 17:35:14 Adding flat image 4 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0010.fits 17:35:16 Adding flat image 5 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0011.fits 17:35:18 Adding flat image 6 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0012.fits 17:35:20 Adding flat image 7 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_G_0013.fits 17:35:24 Combining flats and flat-darks. 17:35:24 Adding flat image 1 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0007.fits 17:35:26 Adding flat image 2 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0008.fits 17:35:28 Adding flat image 3 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0009.fits 17:35:30 Adding flat image 4 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0010.fits 17:35:32 Adding flat image 5 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0011.fits 17:35:34 Adding flat image 6 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0012.fits 17:35:35 Adding flat image 7 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_Ha_0013.fits 17:35:40 Combining flats and flat-darks. 17:35:40 Adding flat image 1 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0007.fits 17:35:42 Adding flat image 2 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0008.fits 17:35:44 Adding flat image 3 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0009.fits 17:35:46 Adding flat image 4 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0010.fits 17:35:48 Adding flat image 5 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0011.fits 17:35:49 Adding flat image 6 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0012.fits 17:35:51 Adding flat image 7 to flat average. C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\_R_0013.fits 17:35:56 Master flat(s) ready. 17:36:49 Analysing group NGC2252_Ha_600 for outliers. Average image quality (nr stars/hfd)=105, σ=8,7 17:37:43 Grayscale stack (classify by image filter unchecked) 17:37:43 Stack method Sigma clip average 17:37:43 Oversize 0 pixels 17:37:43 Analysing images. 17:37:43 Analysing group NGC2252_Ha_600 for outliers. Average image quality (nr stars/hfd)=105, σ=8,7 17:37:43 Stacking (Sigma clip average), HOLD ESC key to abort. 17:37:43 Analysing darks. 17:37:43 Master darks(s) ready. 17:37:43 Analysing flats. 17:37:43 Master flat(s) ready. 17:37:43 Reference image selected based on quality (star_detections/hfd) is: C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0016.fits 17:37:43 Loading master dark file C:\Users\vega\Documents\N.I.N.A\2022-02-09\DARK\master_dark_9x600s_at_-28C_2022-02-10.fit 17:37:45 Loading master flat file C:\Users\vega\Documents\N.I.N.A\2022-02-09\FLAT\master_flat_corrected_with_flat_darks_Ha_7xF_18xFD_2022-02-10.fit 17:37:47 Adding light file: 1-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0016.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:37:47 Creating grayscale x 2 binning image for solving/star alignment. 17:37:54 Adding light file: 2-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0017.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:37:54 Creating grayscale x 2 binning image for solving/star alignment. 17:37:55 176 of 176 quads selected matching within 0.007 tolerance. Solution x:=1.000041*x+ -0.000102*y+ 0.136301, y:=0.000110*x+ 1.000005*y+ 2.827812 17:38:01 Adding light file: 3-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0018.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:01 Creating grayscale x 2 binning image for solving/star alignment. 17:38:02 229 of 229 quads selected matching within 0.007 tolerance. Solution x:=1.000137*x+ -0.000184*y+ -2.003594, y:=0.000349*x+ 1.000097*y+ 13.669347 17:38:08 Adding light file: 4-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0019.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:08 Creating grayscale x 2 binning image for solving/star alignment. 17:38:09 128 of 128 quads selected matching within 0.007 tolerance. Solution x:=1.000417*x+ -0.000301*y+ 1.723095, y:=0.000507*x+ 1.000083*y+ 22.832707 17:38:15 Adding light file: 5-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0020.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:15 Creating grayscale x 2 binning image for solving/star alignment. 17:38:16 30 of 30 quads selected matching within 0.007 tolerance. Solution x:=0.999455*x+ -0.000959*y+ -0.444521, y:=0.000630*x+ 0.999694*y+ 32.708113 17:38:22 Adding light file: 6-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0021.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:22 Creating grayscale x 2 binning image for solving/star alignment. 17:38:24 150 of 150 quads selected matching within 0.007 tolerance. Solution x:=1.000174*x+ -0.000340*y+ 2.661037, y:=0.000610*x+ 1.000220*y+ 35.557449 17:38:30 Adding light file: 7-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0022.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:30 Creating grayscale x 2 binning image for solving/star alignment. 17:38:31 145 of 146 quads selected matching within 0.007 tolerance. Solution x:=1.000269*x+ -0.000272*y+ -4.493501, y:=0.000725*x+ 1.000336*y+ 16.724564 17:38:37 Adding light file: 8-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0023.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:37 Creating grayscale x 2 binning image for solving/star alignment. 17:38:38 201 of 201 quads selected matching within 0.007 tolerance. Solution x:=1.000298*x+ -0.000218*y+ -3.043022, y:=0.000794*x+ 1.000329*y+ 19.366389 17:38:44 Adding light file: 9-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0024.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:44 Creating grayscale x 2 binning image for solving/star alignment. 17:38:45 137 of 138 quads selected matching within 0.007 tolerance. Solution x:=1.000417*x+ -0.000041*y+ 5.113557, y:=0.000848*x+ 1.000523*y+ 16.838446 17:38:51 Adding light file: 10-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0025.fits dark compensated to light average. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:38:51 Creating grayscale x 2 binning image for solving/star alignment. 17:38:52 143 of 144 quads selected matching within 0.007 tolerance. Solution x:=1.000521*x+ 0.000089*y+ 0.736966, y:=0.000878*x+ 1.000610*y+ 15.366997 17:38:59 Calculating pixels σ of light file 1-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0016.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:05 Calculating pixels σ of light file 2-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0017.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:11 Calculating pixels σ of light file 3-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0018.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:17 Calculating pixels σ of light file 4-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0019.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:23 Calculating pixels σ of light file 5-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0020.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:29 Calculating pixels σ of light file 6-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0021.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:35 Calculating pixels σ of light file 7-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0022.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:40 Calculating pixels σ of light file 8-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0023.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:46 Calculating pixels σ of light file 9-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0024.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:39:52 Calculating pixels σ of light file 10-10 C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0025.fits Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:00 Combining 1-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0016.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:08 Combining 2-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0017.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:16 Combining 3-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0018.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:24 Combining 4-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0019.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:32 Combining 5-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0020.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:39 Combining 6-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0021.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:47 Combining 7-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0022.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:40:55 Combining 8-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0023.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:41:03 Combining 9-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0024.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:41:11 Combining 10-10 "C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252_Ha_0025.fits", ignoring outliers. Using 9 dark(s), 7 flat(s), 18 flat-dark(s) 17:41:19 █ █ █ Saving result 10 as C:\Users\vega\Documents\N.I.N.A\2022-02-09\LIGHT\NGC2252, 2022-02-10, 10x600L, SkyWatcher, (Ha), SBIG ST-8300 CCD Cam_stacked.fits Finished in 218 sec. The FITS header contains a detailed history.