Varuna.20140211; February 11, 2014

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 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

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.

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

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	-----------	-----------	-----------

Varuna.20140211 Occultation February 11, 2014