ASTEROIDAL OCCULTATION - REPORT FORM

    +------------------------------+  +------------------------------+
    |            EAON              |  |            IOTA/ES           |
    |                              |  |   INTERNATIONAL OCCULTATION  |
    |     EUROPEAN  ASTEROIDAL     |  |      TIMING  ASSOCIATION     |
    |     OCCULTATION NETWORK      |  |       EUROPEAN SECTION       |
    +------------------------------+  +------------------------------+

1 DATE: 26 June 2022             STAR: UCAC4 335-214009  (15.0 mag)
  ASTEROID: Sulamitis                No: 752 

2 OBSERVER: Name: Marek Zawilski            Abbr:
            E-mail: marek.zawilski@p.lodz.pl
            Address: ul.Julianowska 5/7 m.322, 91-473 Lodz, Poland
            Assistance: Mieczyslaw Borkowski

3 OBSERVING STATION: Nearest cities: Lodz and Poddebice
  Station: Tobolice
  Latitude:  51d 54' 45.8" N
  Longitude: 19d 03' 21.9" E
  Altitude:  136 m MSL
  Datum (WGS84 preferred): WGS84

  Single, OR Double or Multiple station (Specify observer's name):
  SINGLE

                         +----------------------------------+
4 TIMING OF EVENTS:      |                                  |
                         |OCCULTATION RECORDED: INCONCLUSIVE|
                         |                                  |
                         +----------------------------------+
  Type of event
  Start observation   Interrupt-start   Disappearance   Blink   Flash
  End observation     Jnterrupt-end     Reappearance    Other (specify)

                                                  Comments
  Event   Time (UT)    P.E.   Acc.   
  Code   HH:MM:SS.ss   S.ss   S.ss
  
    S  - 23:36:10      - N/A  1.0   
    E  - 23:38:00      - N/A  1.0    
 
               Predicted mid-event : 26 Jun;23:36:53 UT  +/- 2 sec

  Was your reaction time applied to the above timings? N/A

5 TELESCOPE: Type: Cassegrain       Aperture: 203mm    Magnification: ---
             Mount: Equatorial     Motor drive: YES   Foc.length: 2032mm reduced to 1016mm

6 TIMING & RECORDING:
  Time source: Laptop time controlled by the GPS Shelyak TimeBox device (time error +0.000 s with 9 satellites).
  Sensor: ZWO ASI 120MM, shutter set for 700 ms, video time resolution 7000 ms, image resolution 1280x960 px, gain 91, brightness 9.
  Recording: SHARPCAP v.4.0.8667.0 software.

7 OBSERVING CONDITIONS:
  Atmospheric transparency: very good        Wind: none            Temperature: +19 deg C
  Star image stability: poor (low altitude)                 Minor planet visible: no 

8 ADDITIONAL COMMENTS:
 
  The light curve analyze using Tangra software showed a small drop of the star brightness caused by the asteroid. 
  The star image was not very stable for the occulted and comparison star. 
  The D and R times according to the AOTA analysis.
  The observation was made inside the predicted path. 
  The asteroid was brigther than the star, the summed image of both bodies was at the magnitude limit of the telescope and camera used.
  The observation not sure, large differences in relation to the prediction.

  Predicted max. 7.4 sec. duration with 0.5 mag. drop.
  Event probability at site : 99.5%
  Distance from center line : 22 km in 276° direction, inside the predicted path.
  Local * conditions (Alt,Az): 13°, @158° in Capricornus.
  Moon (Alt, Az): below the horizon.

------------------------------------------
magDrop: 0.688  +/- 0.245  (0.95 ci)

snr: 1.86

D time: [23:36:38.3620]
D: 0.6800 containment intervals:  {+/- 0.5818} seconds

R time: [23:36:51.6590]
R: 0.6800 containment intervals:  {+/- 0.5818} seconds

Duration (R - D): 13.2970 seconds
Duration: 0.6800 containment intervals:  {+/- 1.0484} seconds

------------------------------------------
Eric Frappa's comments:
I'm sorry but I'm afraid that this observation is totally unusable and I would not recommend any report of it.
The SNR is very low, the candidate is well within the noise and the number of points at occultation level not numerous enough to secure any result. 

The number of points of the entire observation is also  insufficient to perform a meaningful noise analysis.

Finally with a 200mm telescope, I have some doubts that you were able to  detect the signal of a 15 mag star, especially at low altitude. 

Without being able to detect the star signal alone, any detection of the occultation is impossible.

In summary, this observation is inconclusive (too difficult for your setup and conditions) and deserves no report.

The occulted star was not alone, since his signal was combined with the one of the asteroid leading the an object of magnitude ~13.9. 
This does not mean that you were able to detect the star alone which was 1 magnitude fainter.

If I look at the frame provided in the Tangra .lc file, I see no clear evidence for a limiting magnitude of 15 or more. 

Your limiting magnitude was possibly between 14 and 14.5 (but there is a lot of hot pixels making the evaluation difficult on a single frame, so I can be wrong).
Anyway, notice that this point does not invalidate my other comments  that make this observation unusable.