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ASTERIODAL OCCULTATION - REPORT FORM

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EAON & IOTA-ES

EUROPEAN ASTEROIDAL OCCULTATION NETWORK

INTERNATIONAL OCCULTATION TIMING ASSOCIATION EUROPEAN SECTION

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1. DATE: 26 Dec 2019
   STAR: UCAC4-508-025991
   ASTEROID: (798) Ruth

2. OBSERVER
   
   Name: Stefano SPOSETTI
   Address: 6525 GNOSCA - Switzerland
   Email: stefanosposetti@ticino.com

3. OBSERVING STATION
   
   Nearest city: CH-6525 Gnosca
   Station: 143 (MPC-code)
   Longitude (DD MM SS.s): 09 01 26.5 (E)
   Latitude (DD MM SS.s): 46 13 53.2 (N)
   Altitude: 260 m
   (WGS84)

4. TIMING OF EVENTS
   
   Occultation recorded: POSITIVE
   Type of event:
   "S"tart observation;
   "I"nterrupt-start;
   "D"isappearance;
   "B"link;
   "F"lash;
   "E"nd observation;
   "I"nterrupt-end;
   "R"eappearance;
   "O"ther (specify)

   Personal Equation Substracted: -
   Event Time (UTC) Accuracy + Comments
   code: HH:MM:SS.ss S.sss

-S : 00:40:40
-D : 00:44:15.44 ± 0.040 s
-R : 00:44:18.88 ± 0.040 s
-E : 00:46:05

   Duration: 3.44 s ± 0.080 s

5. TELESCOPE
   
   -Type: Schmidt-Cassegrain, Celestron 11-inch
   -Aperture: 280 mm
   -Focal length: 930 mm (with focal reducer)
   -Magnification: FOV 23x18 arcmin
   -Mount: Equatorial
   -Motor drive: Yes

6. TIMING & RECORDING
   
   -Camera/Sensor: Videocamera WAT-910HX-RC, CCIR, 1/2"
   -Videocamera settings: Shutter = x4, Gain = 41/41, Gamma = 1.00
   -Device of recording: Personal computer
   -Grabber: Imaging Source DFG/SV1 PCI, composite input
   -Software: Virtualdub v. 1.10.4, saved on Harddisk as Lagarith compressed file
   
   -Time insertion device: IOTA-VTI, v.1.1.42
   -Timekeeping: GPS 1PPS (US Global Sat EM-406A)
   -Integration time: 0.080 s
  
7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: good
   -Wind: none 
   -Star image stability: good
   -Minor Planet visible during the occultation: barely

8. ADDITIONAL COMMENTS
   Prediction:
   -Occultwatcher, IOTA feed
   -Rank: 94
   -Probability: 69.0 %
   -Combined magnitude: 12.2 mag
   -Star magnitude: 12.4 mag V
   -Asteroid magnitude: 14.1 mag
   -Lightdrop: 1.9 mag
   -Max duration: 3.3 s
   -Event time: 00:44:16 UT
   -Error in time: 3 s
   -Moon distance: -
   -Moon illumination: none

   Other comments:
   -Target sky position: elevation = 52 deg, azimut = 209 deg
   -Tangra v. 3.6.19 was used to generate the lightcurve (aperture photometry, average background)
   -S/N ratio ~ 5 during pre- and after- event
   -Signal dropped from 900 to about 150, i.e about 1.9 mag
   -Measured mid-event UT time: 00:44:17.16
   -A correction of - 0.060 s was applied because of the use of an integration camera (so called "Dangl-correction")
   -A lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2020/01/2019_12_26_Ruth_Gnosca.png