#1
>Here is a very preliminary report:
>After receiving the updated track on Jun 6, I contacted the SAAO,
>Cape Town, Bloemfontein and observers generally. Sutherland was
to
>attempt a PEP observation and so was I from my home. Last minute
>weather prediction made me fly to Cape Town instead and I drove
to
>Malmesbury between Cape Town and Sutherland. So far, I have the
>following reports, from North to South:
>Pretoria Rain
>Johannesburg and environs Rain
>Vanderbijlpark No report but probably cloud. Frans de Jager and
I
> recently videorecorded a graze and we would have liked to do the
>same for Ceres. No report but he probably had cloud.
>Bloemfontein As above
>Sutherland No report yet.
>Malmesbury Thick fog up to middle of predicted period, when it
>started to clear. No attempt.
>SAAO Misty. Very dubious dis and reappearance visually, about a
>minute after Goffins times.
>Pinbelands Misty
>Simon's Town Clear. Very dubious disappearance about 90 seconds
>after Goffin's time.
>
>The light drop must have been much less than mag .6 but it would
have
>been well within reach of my PEP if circumstances had been more
>favourable.
>
>I hope you had better results in the Western Hemisphere.
>
>Sincerely
>
>Danie.
#2
Dear Mr. Dunham:
It was a pity but the night of the occultation was cloudy here in Cordoba. We can't observe nothing. On friday, we calculated with your data about the central path, and our results was that we were out of the shadow. Anyway the night was cloudy. If you can, we want the data of the other observers and we put to your disposition to the next occultations. Our equipments is a reflector of 1.54 m with a CCD camera frozen with liquid nitrogen 1024 x 1024. We can obtain 1 frame per 0.7 sec
Best regards
Rene Duffard Santiago
#3
>From: Javier Licandro <licandro@asterix.fisica.edu.uy> >
Subject: Re: Ceres Occulta >
To: dunham@erols.com (David and Joan Dunham) >
I received a report from Observatorio Astronomico Cristo Rey (Rosario, ARGENTINA). They observed the SAO 159866 ocultation by CERES, using an SSP5 photometer attached to the 250mm f/15 telescope of the Observatorio Astronomico Gemini Austral (long= 60:38:56 W, lat= -32:57:53, >alt= 36m). They sent me via fax a light curve (counts vs. time), that >shows an strange shape, not simetrical, it goes from 1800 count to 1000 count (about 0.6 magnitudes). The minimun is about 2h35m15s (as I can see the time resolution is 1s). I expect to receive more reports. The observers were J.L.Sanchez, V.A.Buso, L.A.Mansilla,G.Ballan, M.V.Jasinkas, G.A.Ubrig. >
Sincerelly,
Javier Licandro
#4
This weekend I went to Rosario and I saw the persons who
observed the occultation by Ceres last June 10.
They used a photometer SSP-5 Optec and record in video tape the counts
and
a chronometer in the same image.
The photometer has a 4 digit display and they put a chronometer beside
it.
In the video tape they recorded 20 minutes of the event. The photometer
was
connected to a time presicion of 1 second, so the time resolution is
that.
They used the Jhonson B filter.
Here I copy a table with time vs counts after 2:45 TU.
0 1824
1 1818
2 1819
3 1784
4 1779
5 1751
6 1745
7 1760
8 1718
9 1706
10 1560
11 1483
12 1376
13 1135
14 999
15 1026
16 1655
17 1720
18 1771
19 1807
20 1827
21 1817
22 1766
23 1798
24 1793
25 1786
26 1795
27 1821
28 1749
29 1768
In the other side They took CCD images with another telescope. That
images
show the transit of Ceres. If you want that images please tell me.
I must
transforms it into fit images. They used a ST4 camera and the images
are in
this format.
The correct ubication of the telescopes with the photometer is:
lat S 32 59.064
long W 60 39.488
elev idem
this coordenates were taken with sattelite.
Rene Duffard
Observatorio Astronomico Cordoba
Cordoba. Argentina.
Final Update
Sorry, it's now less than 3 hours before the occultation, but there is little change from Federspiel's prediction including the CAMC star position update. The path should still cross Namibia, Argentina, and southern Chile, but some data indicate a half-path-width shift to the south, which would bring most of South Africa into the path. In the table below, first is given E. Goffin's original prediction, followed by Federspiel's updated path, whose details were distributed over a week ago. The last 3 entries are based on astrometric observations of both objects during the last few nights, but all of them have some problems, described below.
Sorry also that I was preoccupied with another asteroidal occultation, expected in North America, on Friday night, and I forgot to bring home the e-mail addresses of several observers to whom I sent data from my jhuapl e-mail, especially in South America. So LIADA, I hope you receive this before the event and can send it to all of your southern observers, especially to the exploder account that was set up in Buenos Aires. Good luck with your observations!
MIN. GEOCENTRIC Correction from Federspiel U. T. SEP. Time, Path Path Based on h m " min. " widths 2 43.7 1.82S -1.0 0.03N 0.04N E. Goffin nominal prediction 2 44.7 1.85S 0.0 0.00 0.00 Federspiel with CAMC star update 2 41.7 2.15S -3.0 0.30S 0.42S Manek 2 44.4 1.80S -0.3 0.05N 0.07N Bolster 2 44.0 2.24S -0.7 0.39S 0.54S Rogers
On June 6, Jan Manek obtained 5 photographic exposures with the 35cm telescope at Stefanik Observatory, Prague, Czech Republic. Unfortunately, the objects were rather far separated in the field and Ceres was actually outside the reference star net. The altitude was 21 deg. above the horizon. The other observations were made last night. Bob Bolster obtained one CCD image of both objects with the C14 at his observatory in Alexandria, Virginia. The altitude was 28 deg. and the error for each object was 0.6" in declination, but the relative positions are probably better. John Rogers used his 25cm SCT at Camarillo, California, to obtain 12 exposures, 6 10-second exposures and 6 20-second exposures. The altitude was 36 to 37 degrees. Both Ceres and the target star were saturated in all of the CCD frames, necessary in order to get enough usable faint GSC reference stars. The R.A. residuals for Ceres, and both R.A. and Dec. of SAO 159866, agreed well from the 10 sec. to the 20 sec. exposures. However, the Dec. residuals for Ceres for the 10 sec. exposures averaged +0.4", while those for the 20 sec. exposures averaged -0.5" (compared to Ceres' diameter of 933 km that subtends 0.72"). All of his observations were used with equal weight in my calculations. The central line data for each prediction is given below.
*** Manek central line
h m s
AT U.T. 2 34 0, W. LONG.= -25.423, LAT.= -23.820
AT U.T. 2 35 0, W. LONG.= -11.363, LAT.= -28.935
AT U.T. 2 36 0, W. LONG.= -0.758, LAT.= -32.582
AT U.T. 2 37 0, W. LONG.= 8.625, LAT.= -35.544
AT U.T. 2 38 0, W. LONG.= 17.458, LAT.= -38.045
AT U.T. 2 39 0, W. LONG.= 26.063, LAT.= -40.179
AT U.T. 2 40 0, W. LONG.= 34.630, LAT.= -41.987
AT U.T. 2 41 0, W. LONG.= 43.290, LAT.= -43.484
AT U.T. 2 42 0, W. LONG.= 52.142, LAT.= -44.668
AT U.T. 2 43 0, W. LONG.= 61.266, LAT.= -45.523
AT U.T. 2 44 0, W. LONG.= 70.739, LAT.= -46.020
*** Bolster central line
AT U.T. 2 37 0, W. LONG.= -14.606, LAT.= -22.762
AT U.T. 2 38 0, W. LONG.= -3.236, LAT.= -26.769
AT U.T. 2 39 0, W. LONG.= 6.300, LAT.= -29.898
AT U.T. 2 40 0, W. LONG.= 15.017, LAT.= -32.503
AT U.T. 2 41 0, W. LONG.= 23.335, LAT.= -34.718
AT U.T. 2 42 0, W. LONG.= 31.480, LAT.= -36.608
AT U.T. 2 43 0, W. LONG.= 39.597, LAT.= -38.202
AT U.T. 2 44 0, W. LONG.= 47.790, LAT.= -39.509
AT U.T. 2 45 0, W. LONG.= 56.143, LAT.= -40.526
AT U.T. 2 46 0, W. LONG.= 64.730, LAT.= -41.239
AT U.T. 2 47 0, W. LONG.= 73.625, LAT.= -41.622
*** Rogers central line
AT U.T. 2 37 0, W. LONG.= -16.185, LAT.= -28.207
AT U.T. 2 38 0, W. LONG.= -4.594, LAT.= -32.309
AT U.T. 2 39 0, W. LONG.= 5.242, LAT.= -35.535
AT U.T. 2 40 0, W. LONG.= 14.336, LAT.= -38.231
AT U.T. 2 41 0, W. LONG.= 23.110, LAT.= -40.526
AT U.T. 2 42 0, W. LONG.= 31.798, LAT.= -42.479
AT U.T. 2 43 0, W. LONG.= 40.553, LAT.= -44.112
AT U.T. 2 44 0, W. LONG.= 49.486, LAT.= -45.427
AT U.T. 2 45 0, W. LONG.= 58.685, LAT.= -46.411
AT U.T. 2 46 0, W. LONG.= 68.227, LAT.= -47.037
David Dunham, IOTA, 1996 June 10, 0:15 UT
Joan and David Dunham (301) 474-4722
dunham@erols.com
See data at end of page for previous astrometry updates referred
to above.
An occultation of the 7.7-mag. spectral type K2 star Z.C. 2346 (SAO 159866 = PPM 231555) by (1) Ceres is predicted to be visible from Namibia, possibly South Africa, Argentina, and Chile around 2:40 U.T. of 1996 June 10th. This is the brightest star predicted to really be occulted by the largest asteroid in many years. Some members of the European section of IOTA are planning a possible expedition to Namibia to observe the event with high-speed CCD recording systems, if a reasonably good astrometric update can be obtained for this event. A few meridian circle observations would be ideal, since they could be made during the next two weeks around new moon, and would allow a path update about two weeks before the occultation. Ceres is near opposition on June 10th, facilitating meridian circle observations, and the asteroid is already being observed in some meridian circle programs, such as the one with the Carlsberg instrument at La Palma. CCD astrometry will also be useful, but only during the last day or two before the event when the objects will be close enough to observe in the same frames.
The information below is given in the form that I have used previously for other events for which astrometric updates were desired:
1996 Event
Date U.T. Asteroid V Star mag. R.A. (J2000) Dec. M S
h m s o ' "
Jun10 2:44 1 Ceres 7.2 SAO 159866 7.7 162029.408 -184125.00 x
Date UT mot. Notes, nominal region of visibility
h
Jun10 2 12.94 Namibia, S. Africa (2:35-2:37 UT); Argentina (2:44-2:46 UT);
Chile (2:46 UT)
The SAO gives mag. 8.2. So the magnitude drop could be from 0.3 to 0.6; it will be quite difficult to detect visually, even with good atmospheric seeing. Video, CCD, and photoelectric recordings should be made when possible. A central occultation is expected to last 80.2 seconds. With a diameter of 933 km, Ceres will subtend 0.72". The times above will probably be accurate to within +/-2 minutes, but they will be updated if any astrometry is obtained. The star is in Scorpius about 1.5 deg. west of Chi Ophiuchi. E. Goffin's world map and finder charts for this occultation are available here. The finder chart has been annotated.
David Dunham, IOTA, 1996 May 10
June 4 update from Martin Federspiel, adjusting for revised position of star.
Calculation of the zentral line of the occultation of PPM 231555 by Ceres
Source of orbital elements of Ceres: EMP 1996
Position of star (J2000) RA 16 20 29.402
DE -18 41 24.99
Source: CAMC (new measurement by Bob Argyle)
least geocentric distance between star and Ceres:
1996 June 10 Time: 2 44 43 TT
apparent distance d=1.85''
parallax of Ceres pi= 4.92''
apparent motion of Ceres mu=32.36''/h
path of Ceres' shadow (center) on the Earth:
latitude longitude time TT radius direction
-18.66 27.77 2:36:35. ! .967 105.11
-22.50 17.25 2:37:11. ! .906 106.74
-25.25 9.59 2:37:48. ! .846 108.62
-27.52 3.06 2:38:24. ! .787 110.78
-29.48 -2.86 2:39: 1. ! .729 113.28
-31.23 -8.40 2:39:37. ! .673 116.21
-32.80 -13.70 2:40:14. ! .619 119.66
-34.22 -18.84 2:40:50. ! .567 123.76
-35.51 -23.88 2:41:27. ! .519 128.64
-36.68 -28.87 2:42: 3. ! .476 134.46
-37.74 -33.84 2:42:40. ! .438 141.37
-38.70 -38.81 2:43:16. ! .408 149.44
-39.54 -43.81 2:43:53. ! .387 158.57
-40.28 -48.86 2:44:30. ! .377 168.47
-40.91 -53.98 2:45: 6. ! .378 178.59
-41.42 -59.18 2:45:43. ! .391 188.34
-41.83 -64.47 2:46:19. ! .415 197.21
-42.10 -69.88 2:46:56. ! .447 204.98
-42.25 -75.43 2:47:32. ! .486 211.60
-42.25 -81.14 2:48: 9. ! .531 217.16
-42.10 -87.03 2:48:45. ! .580 221.83
-41.78 -93.16 2:49:22. ! .632 225.74
-41.25 -99.56 2:49:58. ! .687 229.05
-40.49 -106.34 2:50:35. ! .744 231.86
-39.42 -113.65 2:51:11. ! .802 234.27
-37.94 -121.78 2:51:48. ! .862 236.35
-35.79 -131.43 2:52:24. ! .922 238.16
-31.86 -145.71 2:53: 1. ! .983 239.74
Martin Federspiel
Astrometry results from Jan Manek on Sun 9th
From: Jan Manek <jmanek@vol.cz>
Subject: (1) Ceres astrometry
Cc: David and Joan Dunham <dunham@erols.com>,
Edwin Goffin <goffin@twi.agfa.be>, Jim Hart <jim@anomalies.com>,
Mike Kretlow <kretlow@hrz.uni-siegen.d400.de>
Hi all,
I have just finished reduction of Ceres astrometry (films from nigth June 6/7).
Below you can find five positions of star and asteroid each. However I would
like to point out the fact, that the star distribution on plates wasn't good
and Ceres itself was outside of the reference stars net (!). As I have to use
second order terms in reduction, this results in a rather large uncertainity
factor as of the Ceres positions quality. I am sorry for this. Please use
the results carefully. Unfortunately I will not be able to get tonight any
other observations.
Jan
--------------------------------------------------------------------------------
Station 541 Stefanik Observatory
Observations by Jan Manek.
35cm RL + photo, GSC reference stars (J2000.0).
00001 1996 06 06.92756 16 23 24.834-18 36 02.29 541
00001 1996 06 06.93088 16 23 24.698-18 36 02.77 541
00001 1996 06 06.93400 16 23 24.501-18 36 03.19 541
00001 1996 06 06.93928 16 23 24.236-18 36 03.20 541
00001 1996 06 06.94218 16 23 24.006-18 36 04.23 541
PPM231555 1996 06 06.92756 16 20 29.338-18 41 24.23 541
PPM231555 1996 06 06.93088 16 20 29.340-18 41 24.46 541
PPM231555 1996 06 06.93400 16 20 29.340-18 41 24.36 541
PPM231555 1996 06 06.93928 16 20 29.345-18 41 24.27 541
PPM231555 1996 06 06.94218 16 20 29.348-18 41 24.58 541
--------------------------------------------------------------------------------
-----------------------------------------------------------------------------
Jan Manek
Stefanik Observatory Private :
Petrin 205 Werichova 950
118 46 Praha 1 152 00 Praha 5 - Barrandov |_|_|
Czech Republic Czech Republic / \
Internet : jmanek@mbox.vol.cz |-O-O-|
--------------------------------------------------------------------U---U----
>Subject: Ceres astrometry > >Date: 1996-6-9 >To: David Dunham >From: Bob Bolster >Subj: Astrometry of (1) Ceres > >Tonight I obtained CCD images of Ceres and target star SAO 159866. > >The following are details of the Ceres data. > >Instrument: C-14 (0.36m) Schmidt-Cass. with telecompressor, f/5.5, (eff. >focal length=1956 mm). ST-6 CCD camera. > >Time of measured image: 1996-6-9 02:44:14 UT. Length of exp.=15 s. > >Measurement: Positions of the target star, asteroid, and 8 field stars >were measured. These are positions relative to the 8 field stars: > > Target star RA 16h 20m 29.300 +/- 0.026 s > Dec -18d 41' 24."77 +/- 0.60 > > 1 Ceres RA 16h 21m 23.897 +/- 0.026 s > Dec -18d 39' 46."21 +/- 0.60 > >The target star coordinates agree very well with other data. The >Ceres position agrees well (-0.01 m) in RA and in dec. (-0.3") with the >position predicted by the "Guide" software. > >P.S. Tried to get astrometry on Tokio, but precision was not very good >and target star pos was off in dec.. Observed the appulse - saw no events. > >Bob