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Victor L'vov et al.: Forthcoming Occultations of Astrometric Radio Sources by Planets, IVS 2010 General Meeting Proceedings, p.320324 http://ivscc.gsfc.nasa.gov/publications/gm2010/lvov.pdf

Forthcoming Occultations of Astrometric Radio Sources by Planets
Victor L'vov, Zinovy Malkin, Svetlana Tsekmeister
Central Astronomical Observatory at Pulkovo of Russian Academy of Sciences Contact author: Victor L'vov, e-mail: epos-gao@mail.ru

Abstract
Astrometric observations of radio source occultations by solar system b odies may be of large interest for testing gravity theories, dynamical astronomy, and planetary physics. In this paper, we present an updated list of the occultations of astrometric radio sources by planets expected in the coming years. Such events, like solar eclipses, generally speaking can only be observed in a limited region. A map of the shadow path is provided for the events that will occurr in regions with several VLBI stations and hence will be the most interesting for radio astronomy experiments.

1. Intro duction
Observations of occultations of compact radio sources by Solar System planets may be interesting for several astronomical and physical applications, such as testing GR [1], improvement of planet orbits and their tie to ICRF [2], and planetary research [3, 4]. Our previous computations of occultations of astrometric radio sources by planets and their close approaches were published in [1]. In this paper we present the updated list of the forthcoming occultations that may be of interest for radio astronomy observations. The main differences with respect to the previous work are the use of an extended astrometric source list and the computation of event maps for a better planning of observations.

2. Forthcoming Occultations
Most computations of occultation events of geodetic radio sources by planets were performed using the codes APPROACH and OCCULT, which utilize the Ephemeride Package for Ob jects of the Solar System (EPOS) data and environment1 . Source coordinates were taken from the catalog of astrometric radio source positions of Leonid Petrov, version 2009c2 . The list of occultations is presented in Table 1 with their basic features. One can see that most of the events are visible in regions with radio astronomy observatories, and several of them can be observed by many antennas. The nearest most interesting event is the occultation of the source 1946200 by Mars in February 2011 visible in North America with VLBA, VLA, GBT, and other radio astronomy facilities. Figure 1 and Table 2 present more detailed information about several of the nearest events that can be observed in regions with several geodetic VLBI antennas. The shadow path maps are shown in Figure 1. Table 2 lists the detailed parameters of several of the nearest events, such as
1 2

http://neopage.pochta.ru/ENG/ESUPP/main.htm http://astrogeo.org/vlbi/solutions/2009c astro/

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Occultations of Astrometric Radio Sources by Planets

Table 1. Occultations of radio sources by planets in 20112030 (d is the angular distance from the Sun, and the letter indicates east or west elongation).

Planet Venus Mars Venus Venus Jupiter Venus Venus Mercur Jupiter Mercur Saturn Mercur Venus Mercur Mercur Mercur Y 2011 2011 2012 2015 2016 2020 2020 2022 2025 2027 2028 2029 2029 2029 2029 2030

y y y y y y

Date M 02 05 12 08 04 01 07 11 09 03 10 01 02 04 12 02

Source D 26 03 24 06 10 16 17 14 18 21 24 14 28 16 27 27 1946200 0127+084 1631208 0947+064 1101+077 2220119 0446+178 1529195 0725+219 2220119 0223+113 1958179 2221116 0243+181 1858212 2208137

d, deg 42W 19W 23W 15E 144E 38E 42W 4E 65W 27W 173W 5E 6W 19E 8E 9W

Region of visibility Antarctic, S. America N. America S. America, Antarctic, Africa America Australia, SE Asia S. America, Europe, Africa N. America S. America America N. America by ring; Asia, Europe, N. Africa Australia, Antarctic, S. Africa Africa, SE Asia, Australia Asia, N. America S. America, Australia S. America, Africa

the elevation, azimuth, and position angle on the planetary limb at the beginning and the end of the occultation. Detailed parameters for other events are available on request.

3. Conclusion
Observations of the occultations of radio sources by planets are attractive for several interesting applications in physics and planetary science. They can effectively supplement the observations of radio source occultations by the Moon and spacecraft radio occultations by planets. The list of occultations presented in this paper can be used for scheduling observations in different modes such as VLBI, connected-element interferometer, or single-dish mode, depending on the scientific task. The list of occultations as well as an updated list of close approaches of planets to radio sources is available at http://www.gao.spb.ru/english/as/ac_vlbi/.

References
[1] Malkin, Z.M., L'vov, V.N., Tsekmeister S.D. (2009) Forthcoming Close Angular Approaches of Planets to Radio Sources and Possibilities to Use Them as GR Tests. Solar System Research, v. 43, No. 4, p. 313. [2] Linfield, R.P. (1992) Occultation of a compact radio source by Venus. Astronomical Journal, v. 104, p. 880. [3] Leblanc, Y., Ladreiter, H.P. (1992) Neptune's radio emissions. Advances in Space Research, v. 12, p. 23. [4] Black, G., Campbell, D., Nicholson, P., Sault, R. (2000) New Long-Wavelength Radio Source Occultations by Saturn's Rings. Bulletin of the American Astronomical Society, v. 32, p. 1086.
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0127+084, Mars, May 03, 2011

1631208, Venus, Dec 24, 2012

0947+064, Venus, Aug 06, 2015

1101+077, Jupiter, Apr 10, 2016

2220119, Venus, Jan 16, 2020

0446+178, Venus, Jul 17, 2020

Figure 1. Visibility of selected nearest occultations of radio sources by planets. The visibility regions of the occultations are shown in light (for the 2016 event, the region covers the whole depicted hemisphere).
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Table 2. Detailed features of the nearest occultations of radio sources by planets: B -- at the beginning, E -- at the end.

Planet Venus Mars

Date Feb 26, 2011 May 03, 2011

Station OHIGGINS SYOWA KOKEE MK-VLBA OV-VLBA DSS13 KP-VLBA BR-VLBA PIETOWN LA-VLBA FD-VLBA GILCREEK GGAO7108 HN-VLBA WESTFORD FORTLEZA OHIGGINS HARTRAO SYOWA YEBES40M FORTLEZA SC-VLBA WESTFORD HN-VLBA GGAO7108 FD-VLBA LA-VLBA PIETOWN KP-VLBA DSS13 OV-VLBA BR-VLBA GILCREEK MK-VLBA KOKEE 14: 14: 18: 18: 18: 18: 18: 18: 18: 18: 18: 18: 18: 18: 18: 10: 10: 10: 10: 18: 18: 18: 18: 18: 18: 19: 19: 19: 19: 19: 19: 19 19: 19: 19:

Venus

Dec 24, 2012

Venus

Aug 06, 2015

Time B 18:18 18:20 10:19 10:19 11:31 11:32 11:38 11:43 11:46 11:50 11:52 11:59 12:37 12:42 12:43 06:07 07:13 08:02 08:11 41:27 44:31 49:35 53:34 53:44 54:33 02:27 03:07 03:41 04:48 06:13 06:34 06:39 10:09 17:05 17:31

, TT E 14:22: 14:23: 18:12: 18:12: 18:13: 18:13: 18:13: 18:13: 18:13: 18:13: 18:13: 18:13: 18:14: 18:14: 18:14: 10:09: 10:10: 10:11: 10:11: 19:23: 19:20: 19:29: 19:32: 19:32: 19:34: 19:42: 19:42: 19:43: 19:44: 19:45: 19:46: 19:44: 19:43: 19:58: 19:59:

03 11 26 28 40 41 45 45 53 57 55 20 41 48 49 25 03 28 16 00 16 43 45 53 07 29 45 28 46 56 03 22 42 37 12

El., deg B E 46 45 11 11 41 42 46 46 61 61 63 63 67 67 50 50 64 64 63 63 67 67 28 29 47 46 42 41 41 41 45 46 31 32 68 67 37 37 9 1 39 31 63 54 50 46 50 46 55 51 63 66 58 60 59 62 59 63 54 59 52 56 43 46 21 23 31 41 27 37

Az. B 20 118 278 278 345 348 359 347 7 11 19 318 55 57 58 244 286 83 43 91 79 68 30 29 24 334 334 330 322 318 318 324 302 275 274

, deg E 21 119 278 278 347 349 360 348 8 12 20 319 56 58 58 244 287 83 44 98 81 76 43 42 39 357 353 349 341 334 333 336 311 279 279

Pos. angle B E 35 309 55 290 60 256 66 250 65 251 69 247 77 239 49 266 75 240 74 241 84 232 17 298 84 232 78 237 79 237 80 300 136 244 87 293 129 252 284 68 236 117 260 94 284 70 284 69 281 73 274 80 279 75 278 76 276 78 279 75 281 73 291 63 305 49 269 86 271 83

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Table 2. (continued)

Planet Jupiter

Date Apr 10, 2016

Station TIGOCONC LA-VLBA KP-VLBA DSS13 OV-VLBA BR-VLBA GILCREEK MK-VLBA KOKEE USSURISK HOBART26 VERAMZSW TSUKUB32 KASHIM34 GIFU11 SESHAN25 TIDBIN64 AIRA VERAIRIK PARKES VERAISGK CHICHI10 VERAOGSW

Venus Venus

Jan 16, 2020 Jul 17, 2020

Time B 07:02:05 07:05:34 07:06:09 07:06:55 07:07:09 07:07:37 07:10:03 07:12:22 07:12:53 07:15:37 07:16:01 07:16:13 07:16:27 07:16:28 07:16:31 07:16:34 07:16:41 07:16:48 07:16:48 07:16:56 07:17:13 07:17:14 07:17:14 :: ::

, TT E 10:07: 10:15: 10:14: 10:15: 10:15: 10:17: 10:20: 10:16: 10:16: 10:25: 10:15: 10:24: 10:24: 10:24: 10:24: 10:25: 10:16: 10:24: 10:24: 10:16: 10:25: 10:23: 10:23: :: ::

53 00 31 16 37 21 51 11 52 14 13 24 25 21 39 38 04 57 59 27 02 43 44

El., deg B E 15 -21 49 13 55 17 56 21 55 22 46 21 32 26 71 58 67 60 7 40 9 34 15 48 14 50 14 50 11 48 -2 38 12 41 6 45 6 45 12 43 0 42 16 56 16 56

Az. B 68 54 52 42 38 29 351 308 306 267 288 272 271 271 269 260 288 265 265 287 262 270 270

, deg E 97 90 88 84 83 78 45 72 65 305 328 311 308 308 303 286 327 294 294 325 283 300 300

Pos. angle B E 268 133 274 128 273 128 273 128 273 128 274 128 274 127 271 130 271 130 273 130 265 137 272 130 272 131 272 131 272 131 272 131 266 136 271 131 271 131 266 136 271 132 271 131 271 131

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