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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: 25 Aug 2022
   STAR: UCAC4 348-153318
   ASTEROID: (20607) Vernazza

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: UNCERTAIN
   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 - 19:18:00
D - 19:20:50.5 ± 0.2 sec
R - 19:20:51.5 ± 0.2 sec
E - 19:24:00

   Duration: 1.0 ± 0.4 sec

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 = 2x2, sensor cooled, sensor temperature = 0 °C, camera bit depth = MONO16, area size in pixel = 960x600, USB traffic = 5, setted exposure = 400 ms, gain = 480, offset = 0, contrast = 0, brightness = 0, gamma = 1, banding suppression = 47, banding threshold = 85, apply flat = none, subtract dark = none
   -Timekeeping: GPS UTC clock
   -Integration time: 0.400 s

7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: fair/good
   -Wind: no 
   -Star image stability: fair/good
   -Minor Planet visible during the occultation: read additional comments

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, ITALOccult feed
   -Rank: 32
   -Probability: 13.3 %
   -Combined magnitude: 13.2 mag
   -Star magnitude: 13.2 mag V; 12.2 mag R
   -Asteroid magnitude: 18.6 mag
   -Lightdrop: 5.41 mag; 6.0 mag R
   -Max duration: 3.7 s
   -Event time: 19:20:46 UT
   -Error in time: 9 s
   -Moon distance: -
   -Moon illumination: -
   -https://cloud.occultwatcher.net/event/601-20607-263819-646711-U153318

   Other comments:
   -Target sky position: elevation = 23 deg, azimut = 172 deg
   -Tangra v. 3.7.3 was used to generate the lightcurve (aperture photometry, average background). Time reference: Start Frame 
   -Star UCAC4 348-153318 lies about 5 arcsec north from a bit fainter star. Therefore the potential lightdrop caused by the occultation is less than the predicted 5.4 mag
   -Lightdrop only on two frames
   -Measured lightdrop: ~ 1.5 mag
   -Eric Frappa checked and refined the analysis with AOTA v. 4.2022.18
   -Measured mid-event time: 19:20:51.0 UT   
   -The lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2022/08/2022_08_25_Vernazza_Gnosca.png