Varuna.20140211 Occultation February 11, 2014

(last updated 2014 01 14)

Finder Charts

 

Across the globe pictured above, the three solid lines correspond to the northern limit, centerline, and southern limit of Varuna's shadow. The northern and southern limits correspond to a radius of 500 km. The upper and lower dashed lines indicate 3-sigma errors. The shaded area represents where the sun is more than 0 degrees below the horizon.
Table 1: Prediction Details
Varuna Geocentric Mid-time (yyyy month dd hh:mm:ss)

2014 February 11 05:21:39± 00:01:071 UT

Varuna Minimum Geocentric Separation 0.1205± 0.03371 arcsec
Position Angle (Varuna relative to the star; measured north through east) –169.27 degrees
Geocentric Velocity 22.68 km/sec
Occultation Star USNO-B R magnitude 16.072

1One standard deviation of random error.
2The UCAC bandpass (579-642nm) is between V and R.


Table 2: Reference Star Position
Reference star position:
(UCAC2, at epoch of event)
RA (h:m:s; J2000) Dec (d:m:s; J2000) Notes
Varuna.20140211 Catalog 07 52 26.6920± 0.0920 +26 41 34.1200 ± 0.0880
Varuna.20140211 Measured3 07 52 26.6938± 0.0153 +26 41 34.0129 ± 0.0202
From 45 Lowell 42-inch frames
Table 3: Projected KBO Offsets from Reference Ephemeris at the Time of the Event
Body RA (arcsec) Dec (arcsec)  
Varuna

+0.0148± 0.0480

–0.0724± 0.0260 See Notes 5 and 6

3Measured position corresponds to RA offset of +0.0263 and Dec. offset of –0.1070.

4All "offsets" are defined in the ("corrected" – "reference") or ("observed" – "calculated") sense. The offsets should be added to reference positions to get the measured positions, which we use to calculate the prediction.

4Data analyzed using UCAC2 reference network. A weighted average of the data from the two telescopes was used to calculate the RA and DEC. The errors given are 1 standard deviation.

5The reference positions for Varuna are those given by JPL Horizon's ephemeris (Varuna source file: JPL19; Earth center source file: DE405).

6Data from the USNO 61-inch, SMARTS 0.9m, and Lowell 42-inch telescopes over the span of 3 years were reduced with respect to stars in the UCAC2 catalog. A model was developed to fit the residuals obtained from our measured positions compared to that of the object's JPL ephemeris. All residuals obtained from the different telescopes were consistent with the model. The model includes the first-order effects of errors in the orbital elements of Varuna: (i) constant offsets in RA and Dec, (ii) linear (in time) offsets in RA and Dec, and (iii) sinusoidal terms with the Earth's orbital period. The model was propagated to obtain the predicted position and error of the KBO at the time of the occultation. The errors listed for the KBO are 1 standard deviation.

 

Table 4: Site Information

Site
East Longitude
Latitude

Site Altitude6

(km)

Distance7

(km)

Velocity

(km/s)

CTIO
–70 48 54
–30 09 54
2.215
582 S.
23.01
Florida Institute of Technology
–80 37 25
+28 03 44
0.
4463 N.
25.51
Haleakala
–156 15 24
+20 42 24
3.054
3219 N.
22.95
McDonald Obs
–104 01 21
+30 40 17
2.076
4150 N.
23.07
Geocenter
----------
---------
center of Earth
3742 N.
22.68

6Altitude of each observatory is measured in kilometers above sea level.

7"Distance" refers to the closest approach distance of the "Site" to the center of Varuna's shadow in the shadow plane. The errors on all closest approach distances are ±1046 km (one standard deviation). "S." means the site is south of the center of Varuna's shadow. "N." means the site is north of the center of Varuna's shadow.

Table 5: Varuna.20140211 Occultation Predictions for Individual Sites

Site
KBO Immersion (UT)9
UT Mid-Time
KBO Altitude
Solar Altitude9

KBO Emersion (UT)9

CTIO
-----------
05:18:52
26
-----------
-----------
Florida Institute of Technology
-----------
05:20:08
70
-----------
-----------
Haleakala
-----------
05:25:06
42
–15
-----------
McDonald Obs
-----------
05:21:44
86
-----------
-----------
Geocenter
-----------
05:21:39
-----------
-----------
-----------

9The errors on all times are ±1:07 (1 minute and 07 seconds; one standard deviation). The solar altitude is given for locations where it is relevant (solar altitude greater than -18°). No entry in the immersion and emersion columns indicates that the occultation is not predicted to be visible at that site.

 


Last updated by Carlos Zuluaga (czuluaga@mit.edu) 2014-01-14 09:45

Please direct all inquiries to PAL (planetary-astronomy@mit.edu)

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