(last updated 2018 05 15)
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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.
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Table 1: Prediction Details |
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| 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 G magnitude | 13.23148 |
| Occultation Star Gaia DR2 BP magnitude | 13.8468 |
| Occultation Star Gaia DR2 RP magnitude | 12.4947 |
| J | 11.483 |
| H | 10.970 |
| K | 10.812 |
| B | 13.760 |
| V | 13.240 |
| R | 14.150 |
| UCAC2 | 13.30 |
| UCAC4 | 13.333 |
1One standard deviation of random error.
Table 2: Reference Star Position |
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| 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 |
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Table 3: Projected Titan Offsets from Reference Ephemeris at the Time of the Event |
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| 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). |
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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 |
Gloucester |
–70 41 46 |
+42 39 04 |
0. |
1123 N. |
24.86 |
Inst. de Astonomia (UNAM) |
–115 28 00 |
+31 02 43 |
2.79 |
265 N. |
24.84 |
La Luz Observatory |
–101 19 29 |
+21 03 11 |
2.400 |
271 S. |
24.92 |
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 |
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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 |
Gloucester |
05:37:11 |
05:38:44 |
25 |
–23 |
05:40:17 |
Inst. de Astonomia (UNAM) |
05:39:41 |
05:41:24 |
23 |
–28 |
05:43:07 |
La Luz Observatory |
05:39:07 |
05:40:50 |
38 |
–43 |
05:42:33 |
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 |
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05:39:11 |
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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) 2018-05-26 00:33 UT
Please direct all inquiries to PAL (planetary-astronomy@mit.edu)