VEJLEDNING TIL ASTEROIDEOBSERVATIONER - side 14 -
BEREGNINGSRESULTATER tilgår: Ret uregelmæssigt og gældende for en passende tidsperiode pr. gang. Efter disse findes øvrige links anført her dels af generel art, dels inter- RAPPORTEN --NOVEMBER 2007-- TIL EAON / IOTA-ES VAR FORMELT RIGTIGT UDFORMET *-------------------------------------------*-----------------------------------------* ASTEROIDAL OCCULTATION REPORT FORM *-------------------------------------------*-----------------------------------------* EAON & IOTA-ES EUROPEAN ASTEROIDAL OCCULTATION NETWORK INTERNATIONAL OCCULTATION TIMING *-------------------------------------------*-----------------------------------------* 1. DATE: 2007-11-8 STAR: UCAC2 3198516 ASTEROID: 329SVEA (13.7m V) 2. OBSERVER: 3. OBSERVING STATION: *-------------------------------------------*-----------------------------------------* 4. TIMING OF EVENT: Event time (UTC) 5. TELESCOPE: 6. TIMING & RECORDING:
9 Oplysningsmateriale om behandlede observationsresultater
essante LINKS med forudsigelser og andre oplysninger.
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)
ASSOCIATION EUROPEAN SECTION
Name: Mogens Blichfeldt
Phone: ++45 86 99 77 07
Address: Randersvej 90, Bendstrup
DK-8544 Moerke
Denmark
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)
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)
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
8.56s +/- 0.031s
corrected (see below):
8.56s +/- 0.026s
Central flash:
00:32:21.583s +/- 0.081s
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)
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).
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)
. 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
.