Results of the Occultation by (334) Chicago on 2002 Dec. 24
Updated: 2003 Jan. 17
First is my message of December 25 giving the coordinates of the
observing stations, followed by Andrew Lowe's message of January 2
giving the timings provided by the observers, and the first circular
fit to the observations that he made.
David Dunham
__________________________________________________________
Reports have been received of Dec. 24th's occultation of
SAO 97327 by (334) Chicago from eight observers listed below; V is a
video observation and v is visual. The reported central times were
within 0.1 minute of those predicted from Steve Preston's last
update.
Dist. U.T. dur. W.Long. Lat. h City/ State/ Observer
km C h m s o o m Town Prov.
115N v10 2.2 miss 113.530 53.521 674 EDMONTON AB UNIV.ALTA.OBS.,Hube
9N V 9 58.4 4.82 75.349 39.927 0 Springfield PA Don D'Egidio
5N V 9 58.4 4-5 75.573 39.978 143 W. Chester PA Clifford Bader
~30S V 9 58.4 10.2 75.996 39.788 165 Oxford, PA David Dunham mobile
71S v10 2.2 12.3 114.001 51.836 988 Olds, Alberta Andrew Lowe mobile
84S V 9 58.4 11 76.872 39.607 268 Hampsted MD Marc Damashek
93S v 9 58.7 12.1 79.800 40.700 382 Sarver, PA John Holtz
103S v 9 58.4 12 77.081 39.505 235 Marston MD Curt Roelle
138S v 9 58.8 11.7 81.407 40.883 340 N.Canton OH Richard Emmons
149S -- Southern limit with very possible 1-sigma south shift
152S v10 2.1 10.5 114.114 51.0861101 Calgary AB Gary Billings
Billing's observation from Calgary shows that there was somewhat
more than a 1-sigma south shift of the path, probably about 0.4
path-width south. The total spread of the observations is 161 km
across the path, very good coverage for a path that was about 188 km
wide. So light curve observations of (334) Chicago are needed to
help determine the 3-dimensional shape of the asteroid.
Damashek and Roelle reported that the reappearance occurred in
distinct steps a second apart, with the first reappearanace to 10th
or 11th mag., indicating that the star is probably a close binary,
with separation on the order of only 6 milli-arc-seconds.
David Dunham, IOTA
__________________________________________________________
To: IOTAoccultations@yahoogroups.com
From: "Andrew Lowe "
Date: Thu, 02 Jan 2003 03:01:34 -0000
Subject: Updated (334) Chicago Occultatation Timings
David Dunham has provided me with his original e-mail correspondence
from the observers of the 2002 Dec 24 occultation of HIP 38465 by
(334) Chicago. I summarized the occultation Universal Times below.
As far as I know, the list is complete, but the timings by at least
Dunham will be refined later.
D'Egidio 09:58:22.47 to 09:58:27.24
Bader 09:58:23.187 to 09:58:28.706
Dunham 09:58:20.0 to 09:58:30.2 (UTC is +/-1.5 sec. only)
Lowe 10:02:05.7 to 10:02:18.0
Damashek 09:58:21.90 to 09:58:34.06; 2nd star R 09:58:33.13
Holtz 09:58:39.7 to 09:58:51.8
Roelle 09:58:22. to 09:58:35.
Emmons 09:58:48.0 to 09:58:59.5
Billings 10:02:05.0 to 10:02:15.5
I've revised the occultation summary plot in the "Photos" section
of the IOTAoccultations egroup Yahoo Web site.
The best-fit circular solution is 170.6 km.
The latest (Jan. 26) chord plot by Andrew Lowe is here.
Andrew Lowe
Calgary, Alberta, Canada
_____________________________________________________
Late January 2003 additional and refined reports are here:
From: David Dunham [dunham@erols.com]
Sent: Sunday, January 26, 2003 3:39 AM
To: IOTAoccultations@egroups.com
Subject: Two more timings of the Dec. 24th (334) Chicago occultation
I thought I had missed it, but I finally had a chance to
carefully examine my video tape of the occultation of SAO 97327
by (334) Chicago on 2002 Dec. 24, and found that I did record
the occultation.
Location: west of Oxford, Pennsylvania, just north of Park
and Ride lot on n.e. corner of intersection of US 1 and
PA route 472, at
Long. 75.9955 deg. W., Lat. 39.7882 deg. N., h 540 ft.
determined from topozone.com (but somewhere I have
more accurate GPS coordinates, to be reported later;
these here should be accurate to about 70m).
Telescope: C-5 with f/3.3 focal reducer and Watec 902H
camera, undriven (this was set up as a remote
station, but I returned to it and used it as my
only station; more about that later).
The absolute timings below are accurate to only about
1.5 second; it will take some doing since I didn't
record good time signals until after the event, but
the U.T.'s should be determinable to about 0.1 sec.
UTC
h m s
9:56:39 Star first appeared in field of view
9:58:20.0 Disappearance
9:58:30.2 Reappearance (duration accurate to about 0.2s,
but can be refined to 0.03s later)
The system was not sensitive enough to
record the secondary star reappearance
9:59:12 Star drifted out of field of view
Fortunately, my location fills a gap on the northern side
of the asteroid, between Bader's and Lowe's chords.
It was my 7th and last asteroidal occultation video
recorded in 2002.
_____________________________________________________________
Marc Damashek sent me his tape of the event made at his
home in Hampstead, MD, with a C-11 and PC-164C.
Wayne Warren and I made a time-inserted copy which gives
the following times, accurate to about 0.02s, for his events:
UTC
h m s
9:58:21.90 Disappearance of primary star
9:58:33.13 Reappearance of secondary star, about mag. 10.5
9:58:34.06 Reappearance of primary star
______________________________________________________________
David
______________________________________________________________
IOTA ASTEROIDAL OCCULTATION REPORT FORM
Asteroid (or other object): 334 Chicago Star: SAO97327
Date (U.T.): 24 December 2002 Predicted Time (U.T.): 0958.4
Observer Name: Donald J. D'Egidio Telephone: 610-544-4064
Postal Address: 385 Lester Road, Springfield PA 19064-2103 USA
E-mail Address: djd521@comcast.net Fax: 610-328-1294
TELESCOPE: Aperture: 27.9 cm Focal length: 279 cm Type: Schmidt-Cassegrain
Eyepiece Power: Supercircuits PC23C video camera with 0.6 focal reducer
Observing site name: Springfield PA USA
Longitude: -075 deg 20m 56.1s E Latitude: 39 deg 55m 38.6s N
Height above sealevel: 81m How determined?: See note 1
Sky Transparency (Circle one, or delete two): Good
Star Image Stability ("seeing"; as above): Fair
Other Conditions: (Wind, Clouds, Lights, etc.): Not significant
EVENT TIMINGS: (All times in Universal Time)
Time Source: GPS 1PPS signal
Recording method: Videotape with GPS time insertion
Was the Asteroid Visible in your Scope? No
Approx. Limiting Mag.: 9 (camera)
Universal Time Accuracy, Remarks
h m s
Started Observing: 09: 50: 00 See note 2 for accuracy estimates.
Start of Disappearance: 09: 58: 22.456 First definite dimming (notes 3,5)
Full Disappearance: 09: 58: 22.489 Star fainter than camera limit
Start of Reappearance: 09: 58: 27.227 Star first visible (notes 4,5)
Full Reappearance: 09: 58: 27.277 Star normal brightness
Stopped Observing: 09: 58: 51
Was your reaction time applied to the above timings? -- Not applicable,
timings obtained by videotape review of individual 16.7 millisecond NTSC
video fields.
If you could tell, did the object pass NORTH, SOUTH, EAST, or WEST of the
star (circle one, or delete three)? If possible,
estimate the distance of closest approach in arc seconds:
List all Interruptions in Observing: None
Additional comments:
Note 1: Longitude and Latitude determined by GPS WGS84 datum, Height
determined by USGS 1:24000 topographical map NAD27 datum.
Note 2: Listed times are at midpoint of video field where event occurred
(one field earlier than when displayed). Possible UTC errors for
individual events assuming uncorrelated variables +/- .01 second, worst
case +/- .02 second. Intervals between events should be correct to within
+/- .02 second worst case.
Note 3: Star brightness was less than observed scintillation limit.
Note 4: Star brightness within observed scintillation limits.
Note 5: It was not possible to distinguish between stepped and gradual
events due to allowances for scintillation and partial-field integration,
but it is evident this was not an instantaneous event.
Donald J. D'Egidio
26 Jan 2003