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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: 11 Apr 2020
   STAR: UCAC4 541-054062
   ASTEROID: (667) Denise

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 : 03:02:30
-D : 03:05:39.594 ± 0.050 s
-R : 03:05:44.643 ± 0.050 s
-E : 03:08:30

   Duration: 5.05 s ± 0.10 s

5. TELESCOPE
   
   -Type: Schmidt-Cassegrain, Celestron 11-inch
   -Aperture: 280 mm
   -Focal length: 930 mm (with focal reducer)
   -Magnification: FOV 39x23 arcmin
   -Mount: Equatorial
   -Motor drive: Yes

6. TIMING & RECORDING
   
   -Camera/Sensor: Prototype digital camera with integrated GPS-VTI, SONY IMX174 CMOS sensor
   (Website of the project: https://groups.io/g/d-vti-cam/)
   -Device of recording: Personal computer, USB3 input, DvtiCamControl v 4.8.6. software, saved on Harddisk as SER file
   -binning = 2x2, pixels = 960 x 600, camera bit depth = 16, gain = +20dB, correction algorithm "Fixed pattern noise reduction" applied
   -Timekeeping: within the camera, GPS UTC clock
   -Integration time: 0.100 s
 
7. OBSERVING CONDITIONS
   
   -Atmospheric transparency: good, moonlight
   -Wind: none 
   -Star image stability: good
   -Minor Planet visible during the occultation: barely

8. ADDITIONAL COMMENTS
   
   Prediction:
   -Occultwatcher, UKOCL feed
   -Rank: 97
   -Probability: 39.3 %
   -Combined magnitude: 12.8 mag
   -Star magnitude: 13.1 mag V, 12.7 mag R
   -Asteroid magnitude: 14.3 mag
   -Lightdrop: 1.5 mag
   -Max duration: 6.1 s
   -Event time: 03:05:37 UT
   -Error in time: 2 s
   -Moon distance: 52 deg
   -Moon illumination: 87 %

   Other comments:
   -Target sky position: elevation = 41 deg, azimut = 251 deg
   -Tangra v. 3.6.23 was used to generate the lightcurve (aperture photometry, average background)
   -S/N ratio (computed by Tangra) ~ 4.5 during pre- and after-event
   -Signal star+asteroid (mean of pre- and after-event) = 6145 ± 1186; signal asteroid (mean during the event) = 1785 ± 1187; Signal drop = 1.35 mag
   -Measured mid-event UT time: 03:05:42.1
   -Many thanks to Stefan Meister and Andreas Schweizer for the loan of the camera and their help
   -A lightcurve can be seen here:
http://sposetti.ch/wp-content/uploads/2020/04/2020_04_11_Denise_Gnosca.png