VEJLEDNING TIL ASTEROIDEOBSERVATIONER         - side 14 -

               





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          RAPPORTEN --NOVEMBER 2007-- TIL   EAON / IOTA-ES    VAR FORMELT RIGTIGT UDFORMET
          IFØLGE OFFICIELLE FORMULAR,   og den ses her nedenfor (affattet på engelsk).
          I rapporten refereres til et (gratis) program "LIMOVIE", som er velegnet til
          studium af okkultations-video-AVI-filer.
          (Link til "LIMOVIE" findes ovenfor)

        *-------------------------------------------*-----------------------------------------*

                      ASTEROIDAL OCCULTATION REPORT FORM

        *-------------------------------------------*-----------------------------------------*

                                                EAON & IOTA-ES

               EUROPEAN ASTEROIDAL OCCULTATION NETWORK

                          INTERNATIONAL OCCULTATION TIMING
                                ASSOCIATION EUROPEAN SECTION

        *-------------------------------------------*-----------------------------------------*

     1. DATE: 2007-11-8    STAR: UCAC2 3198516   ASTEROID: 329SVEA (13.7m V)

     2. OBSERVER:
           Name:      Mogens Blichfeldt
           Phone:     ++45 86 99 77 07
           Address:  Randersvej 90, Bendstrup
                            DK-8544 Moerke
                          Denmark


     3. OBSERVING STATION:
           Nearest city:         Aarhus
           Latitude:                56° 21’ 56”.7 Nord   (GPS)
           Longitude:             10° 19’ 42”.5 East     (GPS)
           Altitude:                 21 m  over sealevel;   diff. MSL - WGS84 43.1
           Fixed/mobile:         Fixed (Observation: At the above mentioned address)

        *-------------------------------------------*-----------------------------------------*

     4. TIMING OF EVENT:
           Occultation recorded:       POSITIVE
           Type of event:                 “S”tart observation;
                                                     “I”nterrupt-“s”tart;
                                                     "D”isappearance;
                                                     "B”link;
                                                     "F”lash;
                                                     "E”nd observation;
                                                     "I”nterrupt “e”nd;
                                                     "R”eappearance;
                                                     "O”ther (specified)

     Event time   (UTC)
     Code:   HH:MM:SS.ss       S.ss  +/- S.
     -
     -    S        00:32:17.363s        +/- 0.031 s
                     corrected (see below):
                     00:32:17.368s        +/- 0.026s
     -    E        00:32:25.923s        +/- 0.0313 s
                     corrected (see below):
                     00:32:25.928s        +/- 0.026s

                     Duration of occultation:
                     8.56s                       +/- 0.031s
                     corrected (see below):
                     8.56s                       +/- 0.026s
                     Central flash:
                     00:32:21.583s +/- 0.081s

     5. TELESCOPE:
           Type:                     Schmidt-Cassagrain (Celestron 11)
           Aperture:               0.280 m f/10 (+Reducer to abt. f/5)   
           Mount:                  Equatorial with motor drive units    (GPS)
           Detector:               MINTRON 12V1C-Ex videocamera operating   
                                                        in integrating mode: "SENSE 8", (i.e. integrating
                                                        over 4/25 second)

      6. TIMING & RECORDING:
           Timekeeping:         Time source: GPS18LVC,5m(GARMIN) plus
                                                                 KIWI-OSD (#42-0203)
           Recording mode:                  Recording PC / to MPEG converted to
                                                         AVI-file (video with 25 full-frames per second)
                                                         studied with LIMOVIE and at light-transition-
                                                         events deeper study by means of "AstroArt" (3-D-
                                                         representation of target-star inclusive asteroid) after
                                                         conversion to BMP-file-sequences (at start/end of
                                                         occultation and at (observed) central flash).

           Device of recording:            PC

     7. OBSERVING CONDITIONS:
            Atmospheric transparency:         good
            Wind:                                            no
            Image star stability:                    good
            Temperature:                               abt. 5 °C
            Humidity:                                      ? %
            Minor planet visibility:                 yes (clearly more than 7 minutes before and
                                                                   after occultation)

     8. ADDITIONAL COMMENTS:

     .      reference maps:      Jean Schwaenen & Steve Preston

     .     .
     .In this case at occultation (with modeSENSE8 of the camera) the first
     shown integration?result (of 4 video-full-frames) which indicated occultation
     did show the target-star-light as completely disappeared in the noise-back-
     ground. Thus, it is easily deducted that the occultation did start during the
     exposure of the VERY FIRST frame of this 4-video-full-frame-sequence. As
     the end of the occultation was indicated as a full return of the starlight follow-
     ing only full-occultation indicating sequences of 4-video-full-frames, it is easily
     accordingly deducted that the occultation has to have ended during the last
     frame of the last 4-video-full-frame-sequence indicating occultation. Tests
     with having the camera viewing the short light-flashes occurring at the
     comencing of each UTC-second from the LED-diode comprised by the
     KIWI-OSD device and studying the PC-recorded video-file have shown that
     the time-laps from end of frame-exposure with the camera to timestamping
     by KIWI-OSD is nearly negligible (<0.001 second) the correction between
     the stamped time of the first mentioned frame of the first 4-video-full-frame-
     sequence with occultation, as each full-frame has a duration of 0.04 second,
     is (i.e. as a complete video-full-frame-sequence lasts 0.16s):

      0.04 * 4 * (7/8) second = 0.14 second +/- 0.031 second,

     and accordingly at occultation-end:

      0.04 * 4 * (1/8) second = 0.02 second +/- 0.031 second.

     According to prediction the maximum of occultation-duration is expected to
      be: 8.7 seconds.

     The observed duration is 8.56s +/- 0.031s, i.e. the observation could have
     taken place close to the middle of the "passing" starlight-shadowpath, and
     thus it might be possible to view a "central flash" at mid-occultation. The 3-D-
     representation of LIMOVIE is good, and it did (vaguely) indicate an appea-
     rance of a faint light boble at the targetstar-position exactly at mid-occulta-
     tion. A study as mentioned above of the better 3-D-representation of the
     targetstar (-position) by means of the astro-program "AstroArt" of the mid-
     occultation BMP-files did not leave any doubt: A central flash is clearly
     present.

     As the central flash in time has to take place EXACTLY at mid-occultation,
     a correction of the start- and end-times of the occultation is providable:

     Thus it is easily seen, that counting the number of 4-video-full-frame-
     sequences having taken place during occultation results in 53½ of them,
     and thus mid-occultation has to take place just around the middle of the
     mid-sequence ("mid-sequence" = the sequence with the flash), as above sta-
     ted: It is seen that 0.08 +/- 0.031s has to be subtracted from the stamped time
     of the FIRST frame of the 4-video-full-frame-sequence (in which all 4 are pre-
     sent as equal looking (recorded) full-frames belonging to this sequence), and
     which gives a mid-occultation time, which is:

     UTC: 00:32:21.583s +/- 0.081s

     Hereof the limits for the star- and end-times of the occultation necessarily
     have to and must be limited to be the above mentioned corrected start- and
     end-times for the occultation event (i.e. as thus the "central flash" can not
     take place earlier than UTC: 00h:32m:21.612s and on the other hand not
     later than UTC: 00h:32m:21.664s, and the corrections are easily deducted).

     The thus observed mid-occultation time also fits well with the forecasted time
     of the occultation for the asteroid as observed at the present geographical
     position:

     UTC: 00h:32m: ca. 23s

     Accordingly, the observed occultation took place ca. 1.4 seconds earlier than
     predicted. The path of the shadow as thus observed has to be shifted
      70 through 80 km.s (corresponding to ½ sigma for the predicted path) more to
     the East, i.e. in comparison with the predicted path.

     Reported by the observer: Mogens Blichfeldt
     .


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