Cora»Occultation

2026-02-18 / UCAC4 530-048860 / (54) Alexandra

#	OBS	Observer	Occ	Meth.	Instr.	CC	TSRC	UT1	UT2	UT3	UT4	UT2E	UT3E	Dur.	Chrd
1	show	Piotr Walczak, Romuald Michalak	O+	VID	M130	PL	GPS	21:35:37	21:36:35.53	21:36:44.69	21:37:46	0.120	0.120	9.16	133.7
2	show	Sven Andersson	O+	VID	M360	DE	GPS	21:36:37	21:37:01.909	21:37:12.459	21:37:37	0.008	0.008	10.55	154.0
3	show	Anna Marciniak	O+	CCD	M350	PL	NTP	21:34:57	21:36:51.34	21:37:01.42	21:38:50	0.040	0.040	10.08	147.2
4	show	Nikolai Wuensche	O+	VID	M300	DE	GPS	21:35:08	21:37:01.90	21:37:12.01	21:39:08	0.100	0.100	10.11	147.6

UT1/UT4: Begin/End of observation | UT2/UT3: Begin/End of occultation | Dur: Reported duration in seconds | Chrd: Corresponding chord length in km | More

4 observations found in db: sodis

Available (probably) matching predictions (click on the link to switch):

JPL#210 : 4c7a0f20-de6b-11f0-4858-afbeceb507df [db: asteroids]

Using prediction 4c7a0f20-de6b-11f0-4858-afbeceb507df for map and profile fit

Get observations as KML file (reduced site location resolution)

Ellipse and circular profile fits to the timings (chords)

Auto-Fit Result:
Size = 166 x 131 km
a',b' = 83.1, 65.7 km
X0,Y0 = -332.6, 11.1 km
Mean diameter = 148 km

From 4 chords (CCD,VID)

You can enter space separated chord numbers (example: 11 4 8) or a method like VIS to ignore all visual timings, or a time source like RAD and NTP (but not GPS).
If the plot disappears, then there are less than 2 chords left (too much ignored, go back with browser).

Check SiMDA for size and mass data.

Check Johnston Archive for satellites.

Sky projection (artificial light) for occ. time: 2026-02-18, 21:36 UT (JD = 2461090.400)

DAMIT	Q	P (h)	λ, β	JD0	JD-JD0	φ0	Version	Modified	Vol-equiv D	Cmnt
# 136	None	7.023	156°, 13°	2.438949e6	22141.4	0.0°	size from AO is 128+/-11 km	2013-07-23	135.0 +/- 20.0 km	2011-03-28
# 1817	4.0	7.023	154°, 17°	2.438949e6	22141.4	0.0°	None	2017-06-19	143.0 +/- 5.0 km	2017-06-07

Q: model quality flag (0-5, 5=highest) | P: rotation period | λ,β: ecl. lon. and lat. of spin axis (J2000) | JD: initial time (epoch) | φ0: initial rotation angle for JD0

Image size: 300px. Transparent image background for copy & paste

Map with groundtrack and observer stations

Event Details
Occultation UUID [and DB] : 4c7a0f20-de6b-11f0-4858-afbeceb507df [asteroids] Occultation Date + Time : 2026-02-18 at 21:36:10 UT +/- 0.01 min [1] Object Designation : (54) Alexandra Orbit Class : MBA Star Designation : GDR3 0610642782104949248 Star Coordinates (ICRF) : RA = 08 56 27.6193, DE = +15 54 46.497 [2] Star Magnitudes : G = 11.15 mag, RP = 10.44 mag, BP = 11.52 mag Object Magnitude : V = 12.69 mag Estimated Magnitude Drop : 1.8 mag Estimated Max. Duration : 11.4 sec Object Mean Diameter : 165.8 km (src: astorb) Speed of the shadow : 14.6 km/s Elongation to Moon & Sun : 145° (sunlit = 2%), Sun = 162° Cross-track uncertainty : 1.4 mas = 2 km = 0.01 path-width (1-sig) RUWE and duplicate source : 2.72 mas, dup.src = 1 (0:false, 1:true) Ephemeris Reference : JPL#210 Note : FP:true Object is a Gaia mass determination target ! [1] time t0 of closest geocentric approach c/a, [2] including proper motion until t0

Event Details

 Occultation UUID [and DB] : 4c7a0f20-de6b-11f0-4858-afbeceb507df [asteroids]

 Occultation Date + Time   : 2026-02-18 at 21:36:10 UT +/- 0.01 min  [1]
 Object Designation        : (54) Alexandra
 Orbit Class               : MBA
 Star Designation          : GDR3 0610642782104949248
 Star Coordinates (ICRF)   : RA = 08 56 27.6193, DE = +15 54 46.497  [2]
 Star Magnitudes           : G = 11.15 mag, RP = 10.44 mag, BP = 11.52 mag
 Object Magnitude          : V = 12.69 mag
 Estimated Magnitude Drop  : 1.8 mag
 Estimated Max. Duration   : 11.4 sec
 Object Mean Diameter      : 165.8 km  (src: astorb)
 Speed of the shadow       : 14.6 km/s
 Elongation to Moon & Sun  : 145° (sunlit = 2%), Sun = 162°
 Cross-track uncertainty   : 1.4 mas = 2 km = 0.01 path-width (1-sig)
 RUWE and duplicate source : 2.72 mas, dup.src = 1  (0:false, 1:true)

 Ephemeris Reference       : JPL#210
 Note                      : FP:true

 Object is a Gaia mass determination target !

 [1] time t0 of closest geocentric approach c/a, [2] including proper motion until t0

More Data and Informations

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