Titan.20180617 Occultation June 17, 2018

(last updated 2018 05 15)

 

Across the globe pictured above, the three solid lines correspond to the northern limit, centerline, and southern limit of Titan's shadow. The northern and southern limits correspond to a radius of 2576 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
Titan Geocentric Mid-time (yyyy month dd hh:mm:ss)

2018 June 17 05:39:11 UT

Titan Minimum Geocentric Separation 0.701 arcsec
Position Angle (Titan relative to the star; measured north through east) –4.87 degrees
Geocentric Velocity 24.52 km/sec
Occultation Star Gaia DR2 magnitude 13.23148

1One standard deviation of random error.


Table 2: Reference Star Position
Reference star position:
(Gaia DR2, at epoch of event)
RA (h:m:s; J2000) Dec (d:m:s; J2000) Notes
Titan.20180617 Catalog 18 27 35.1957 ± 0.2 mas –22 26 32.541 ± 0.2 mas
Gaia DR2 position with proper motion
     
Table 3: Projected Titan Offsets from Reference Ephemeris at the Time of the Event
Body RA (arcsec) Dec (arcsec)  
Titan

+0.0 ± 0.

+0.0 ± 0.0 JPL SAT389

3Measured position corresponds to RA offset of +0.0 and Dec. offset of +0.0.

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 Titan are those given by JPL Horizon's ephemeris (Titan source file: SAT389).

 

Table 4: Site Information

Site
East Longitude
Latitude

Site Altitude6

(km)

Distance7

(km)

Velocity

(km/s)

Anderson Mesa
–111 32 12
+35 05 48
2.2
592 N.
24.84
Appalachian State University
–81 24 43
+35 15 03
0.
849 N.
24.89
DCT
–11 25 20
+34 44 39
2.361
572 N.
24.84
Florida Institute of Technology
–80 37 26
+28 03 43
0.
326 N.
24.93
Inst. de Astonomia (UNAM)
–115 28 00
+31 02 43
2.79
265 N.
24.84
Magdalena Ridge Obs.
–107 11 05
+33 58 36
2.219
583 N.
24.86
McDonald Observatory (Mt. Locke)
–104 01 21
+30 40 17
2.076
408 N.
24.88
Merida
–70 52 00
+08 47 24
3.61
1337 S.
24.97
Palomar
–116 51 54
+33 21 24
1.706
393 N.
24.82
Ralph Buice Observatory
–84 19 04
+33 46 44
0.
708 N.
24.90
San Pedro Martir, Mexico
–115 27 49
+31 02 39
2.83
265 N.
24.84
SRO
–119 24 48
+37 04 14
1.41
576 N.
24.80
SVH
–74 56 46
+40 57 37
0.
1071 N.
24.87
Wallace
–71 29 06
+42 36 36
0.107
1127 N.
24.86
Williams College
–73 12 07
+41 05 54
0.
1144 N.
24.86
WIRO
–105 58 36
+41 05 54
2.943
999 N.
24.83
Geocenter
----------
---------
center of Earth
4606 S.
24.52

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 Titan's shadow in the shadow plane. The errors on all closest approach distances are ±0 km (one standard deviation). "S." means the site is south of the center of Titan's shadow. "N." means the site is north of the center of Titan's shadow.

Table 5: Titan.20180617 Occultation Predictions for Individual Sites

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

Titan Emersion (UT)9

Anderson Mesa
05:39:24
05:41:05
22
–26
05:42:46
Appalachian State University
05:37:45
05:39:23
30
–30
05:41:01
DCT
05:39:24
05:41:05
23
–26
05:42:46
Florida Institute of Technology
05:37:42
05:39:24
39
–38
05:41:07
Inst. de Astonomia (UNAM)
05:39:41
05:41:24
23
–28
05:43:07
Magdalena Ridge Obs.
05:39:13
05:40:53
25
–28
05:42:34
McDonald Observatory (Mt. Locke)

05:39:06

05:40:48
29
–33
05:42:30
Merida
05:37:22

05:38:50

59
–55
05:40:19
Palomar
05:39:41
05:41:23
21
–26
05:43:06
Ralph Buice Observatory
05:37:55
05:39:35
33
–33
05:41:14
San Pedro Martir, Mexico
05:39:41
05:41:24
23
–28
05:43:07
SRO
05:39:41
05:41:23
17
–21
05:43:04
SVH
05:37:24
05:38:58
26
–25
05:40:33
Wallace
05:37:13
05:38:47
25
–22
05:40:20
Williams College
05:37:19
05:38:52
25
–23
05:40:25
WIRO
05:39:02
05:40:37
20
–23
05:42:13
Geocenter
-----------
05:39:11
-----------
-----------
-----------

9The errors on all times are ±0:0 (0 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) 2018-05-15 19:22 UT

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