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ASTEROIDAL 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: 15 Jan 2022
   STAR: UCAC4 590-015078
   ASTEROID: (22721) 1998 ST50

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 : 20:15:10
-D : 20:18:17.70 ± 0.15 s
-R : 20:18:18.90 ± 0.15 s
-E : 20:21:10

   Duration: 1.20 ± 0.30 s

5. TELESCOPE
   
   -Type: Newton
   -Aperture: 420 mm
   -Focal length: 1640 mm
   -Mount: Equatorial
   -Motor drive: yes

6. TIMING & RECORDING

   -Camera/Sensor: Videocamera  QHY174M-GPS, SONY IMX174 CMOS sensor
   -Device of recording: personal computer, USB3 input, SharpCap PRO v. 4.0.8395 software, saved on SSD as SER file
   -binning = 1x1, sensor uncooled, camera bit depth = MONO16, area size in pixel = 960x600, USB traffic = 5, setted exposure = 300 ms, gain = 480, offset = 0, contrast = 0, brightness = 0, gamma = 1, banding suppression = 0, banding threshold = 12, apply flat = none, subtract dark = none
   -Timekeeping: GPS UTC clock
   -Integration time: 0.300 s

7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: good, moonlight
   -Wind: no 
   -Star image stability: good
   -Minor Planet visible during the occultation: no

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, IBEROC feed
   -Rank: 13
   -Probability: 7.4 %
   -Combined magnitude: 14.6 mag
   -Star magnitude: 14.6 mag V; 14.1 mag R
   -Asteroid magnitude: 18.4 mag
   -Lightdrop: 3.83 mag; 3.9 mag R
   -Max duration: 0.9 s
   -Event time: 20:18:17 UT
   -Error in time: 6 s
   -Moon distance: 16 deg
   -Moon illumination: 96 %

   Other comments:
   -Target sky position: elevation = 71 deg, azimut = 161 deg
   -Tangra v. 3.7.3 was used to generate the lightcurve (aperture photometry, average background). Time reference: Start Frame 
   -AOTA v4.12.16.0 was used to calculate D and R times and uncertainties. Eric Frappa checked the results.
   -Measured lightdrop:-
   -Measured mid-event time: 20:18:18.3 UT   
   -The lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2022/01/2022_01_15_1998ST50_Gnosca.png