Gerhard Dangl - grazing star occultation 2007/10/06

Grazing star occultation by the Earthmoon
October 06, 2007
SAO 98425

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On October 06, 2007 the Earthmoon apparently grazed the star SAO 98425. At about 01h04 UTC the Earthmoon grazed and occulted with the dark side of the northpol area the star SAO 98425 in a height of 12 degrees above the east horizon. About 23 seconds later the star was visible again.

The Earthmoon grazes and ocults the star SAO 98425

Diagram created with Guide 8 from Bill J Gray

This grazing star occultation on the dark side of the moon was captured with my equipment on video with an accuracy of some milliseconds. Evaluation of the video was done later.

Diagram of equipment setup

View to the east from observation place southern from Sparbach

Observation report

Date Observer Position - Sparbach Observer 2007/10/06 48° 44´ 43.7" North (WGS84) Gerhard Dangl Star 15° 13´ 20.8" East (WGS84) 3830, Nonndorf 12 ZC 1370 = SAO 98425 554m (MSL), 599m (WGS84) AUSTRIA

TELESCOPE: Type: Newton Focal length: 1200mm Aperture: 254 mm Magnification: video/primary focus/recorded field 1112" x 830" Mount: Equatorial EQ6 with EQMOD Motor drive: Yes TIMING & RECORDING: Timekeeping: GPS 1PPS Garmin18 LVC + KIWI-OSD Sensor/Camera: WAT-902H2 Ultimate, CCIR, 1/2" Sony CCD-Sensor ICX419ALL Mode of recording: It=20ms (50 Img/s), Video CCIR, AVI, YUY2, Huffyuv, Device of recording: Xpert V-Stream Videograbber USB2.0, Notebook Harddisk Time insertion: KIWI-OSD OBSERVING CONDITIONS: Atmospheric transparency: good Wind: 0 - 0.5m/s Star image stability: good Temperature: 278 Kelvin (+05 deg Celsius) ADDITIONAL COMMENTS: Predictions with Occult3.6 Video evaluation accomblished with VirtualDub1.6.16 and Limovie 0.9.27 Only clear glass filter (Astronomik) for CCD protection was used 3-D position and timing with Garmin GPS18 LVC receiving 10 satellites Horizontal dilution of precision 0.8, geoidal separation 44.4m

Table with precalculations prepared with Occult3.6 from Dave Herald

Occultation Predictions for Nonndorf_10Zoll in Oktober 2007
E.Long.   15 14  8.2   Lat.  48 47 13.5   Alt. 600m.   T.dia 254mm.   dMag 0.0

      day  Time   P   Star  Sp  Mag    % Elon Sun  Moon   CA   PA  VA  WA Libration   A   B   RV   Cct   R.A. (J2000)  Dec
 y  m  d  h  m  s      No  D       V  ill     Alt Alt Az   o    o   o   o   L    B   m/o m/o "/sec   o  h  m   s    o  m  s
Graze of 1370WA0 nearby at Lat = +48.75 +0.25(E.Long -15.24), CA = 1.5N
      06  1  4  2 Gr   1370WA0  6.9  23-  57     12  76
Closest distance to graze path is 3km at azimuth 159
07 10 06  1  4  4 g    1370WA0  6.9   23-  57     12  76   2N  17  59   1 +7.7 -2.0 +1.0-2.7 .202 +113  9 11 56.9  18  2 39
      1370 is double :   6.8  9.5  130"  253.0

  Table with results of video measurement
  Disappearance   start   01:04:13.902 (+/-10ms) UTC
  Disappearance   50%     01:04:13.922 (+/-10ms) UTC
  Disappearance   full    01:04:13.942 (+/-10ms) UTC

  Reappearance     start   01:04:36.942 (+/-10ms) UTC
  Reappearance     50%     01:04:37.082 (+/-10ms) UTC
  Reappearance     full    01:04:37.122 (+/-10ms) UTC

  Occultation duration           23.160 (+/-20ms)

Measurement data - Excelformat 1.3MB
Measurement data table - Excelformat