This analysis provides details of the circumstances of an encounter during which Spot 4 imaged ERS-1.
Vang is the angular velocity of the target from the vantage point of the observer.
PhA is the phase angle of the target, defined as the angle between the target, observer and the sun. The target is fully illuminated when phase angle is zero deg; and fully in shadow when phase angle is 180 deg.
ILL is the percent illumination of a sphere located at the position of the target.
mv is the target's estimated visual magnitude, the measure of brightness used in astronomy.
AZ and EL are the target's azimuth and elevation. Azimuth is measured clockwise from north. Elevation is relative the observer's local horizontal; negative values indicate that the target is below local horizontal.
The latitude reported for both objects is the geodetic latitude.
The altitude reported for both objects is relative to Earth's oblate shape.
Orbital elements are as issued by NASA/OIG. The meaning and format of the 2-line orbital elements is explained here.
Target object: ERS-1 3.5 2.0 2.0 5.0 v 25.7 1 21574U 91050A 98126.17263383 .00000070 00000-0 42286-4 0 6689 2 21574 98.5426 201.3026 0001235 83.1087 277.0239 14.32247747355922 Observer object: Spot 4 5.0 3.0 0.0 5.5 d 13.6 1 25260U 98017A 98126.17055851 .00000456 00000-0 23474-3 0 1561 2 25260 98.7362 201.2859 0000952 82.4523 277.6761 14.20029398 6122 Encounter date: 1998 May 6 UTC Target Observer -------------------- -------------------- Time Range Vang PhA ILL AZ EL Lat Lon Alt Lat Lon Alt UTC km deg/s deg % mv deg deg deg deg km deg deg km -------- ------ ------ --- --- ---- --- --- ------ ------- ----- ------ ------- ----- 09:55:00 42 0.04 11 99 -3.1 312 -79 20.0 N 11.8 E 787 19.9 N 11.9 E 828 09:55:01 42 0.04 11 99 -3.1 312 -79 19.9 N 11.8 E 787 19.9 N 11.9 E 828 09:55:02 42 0.04 11 99 -3.1 311 -79 19.9 N 11.8 E 787 19.8 N 11.9 E 828 09:55:03 42 0.04 11 99 -3.1 311 -79 19.8 N 11.8 E 787 19.8 N 11.9 E 828 09:55:04 42 0.04 11 99 -3.1 311 -79 19.7 N 11.8 E 787 19.7 N 11.8 E 828 09:55:05 42 0.04 11 99 -3.1 310 -79 19.7 N 11.8 E 787 19.6 N 11.8 E 828 09:55:06 42 0.04 11 99 -3.1 310 -80 19.6 N 11.8 E 787 19.6 N 11.8 E 828 09:55:07 42 0.04 11 99 -3.1 310 -80 19.6 N 11.7 E 787 19.5 N 11.8 E 828 09:55:08 42 0.04 11 99 -3.1 309 -80 19.5 N 11.7 E 787 19.5 N 11.8 E 828 09:55:09 42 0.04 11 99 -3.1 309 -80 19.4 N 11.7 E 787 19.4 N 11.8 E 828 09:55:10 42 0.04 11 99 -3.1 309 -80 19.4 N 11.7 E 787 19.4 N 11.8 E 828 09:55:11 42 0.04 11 99 -3.1 308 -80 19.3 N 11.7 E 787 19.3 N 11.7 E 828 09:55:12 42 0.04 11 99 -3.1 308 -80 19.3 N 11.7 E 787 19.2 N 11.7 E 828 09:55:13 42 0.04 11 99 -3.1 308 -80 19.2 N 11.7 E 787 19.2 N 11.7 E 828 09:55:14 42 0.04 11 99 -3.1 307 -80 19.2 N 11.6 E 787 19.1 N 11.7 E 828 09:55:15 42 0.04 11 99 -3.1 307 -80 19.1 N 11.6 E 786 19.1 N 11.7 E 828 09:55:16 42 0.04 11 99 -3.1 307 -80 19.0 N 11.6 E 786 19.0 N 11.7 E 828 09:55:17 42 0.04 11 99 -3.1 306 -80 19.0 N 11.6 E 786 18.9 N 11.7 E 828 09:55:18 42 0.04 11 99 -3.1 306 -80 18.9 N 11.6 E 786 18.9 N 11.6 E 828 09:55:19 42 0.04 11 99 -3.1 305 -80 18.9 N 11.6 E 786 18.8 N 11.6 E 828 09:55:20 42 0.04 11 99 -3.1 305 -80 18.8 N 11.6 E 786 18.8 N 11.6 E 828 09:55:21 42 0.04 11 99 -3.1 305 -81 18.7 N 11.5 E 786 18.7 N 11.6 E 828 09:55:22 42 0.04 11 99 -3.1 304 -81 18.7 N 11.5 E 786 18.6 N 11.6 E 828 09:55:23 42 0.04 11 99 -3.1 304 -81 18.6 N 11.5 E 786 18.6 N 11.6 E 828 09:55:24 42 0.04 11 99 -3.1 303 -81 18.6 N 11.5 E 786 18.5 N 11.6 E 828 09:55:25 42 0.04 11 99 -3.1 303 -81 18.5 N 11.5 E 786 18.5 N 11.5 E 828 09:55:26 42 0.04 11 99 -3.1 303 -81 18.4 N 11.5 E 786 18.4 N 11.5 E 828 09:55:27 42 0.04 12 99 -3.1 302 -81 18.4 N 11.5 E 786 18.4 N 11.5 E 828 09:55:28 42 0.04 12 99 -3.1 302 -81 18.3 N 11.5 E 786 18.3 N 11.5 E 828 09:55:29 42 0.04 12 99 -3.1 301 -81 18.3 N 11.4 E 786 18.2 N 11.5 E 828 09:55:30 42 0.04 12 99 -3.1 301 -81 18.2 N 11.4 E 786 18.2 N 11.5 E 827 09:55:31 42 0.04 12 99 -3.1 300 -81 18.1 N 11.4 E 786 18.1 N 11.5 E 827 09:55:32 42 0.04 12 99 -3.1 300 -81 18.1 N 11.4 E 786 18.1 N 11.4 E 827 09:55:33 42 0.04 12 99 -3.1 299 -81 18.0 N 11.4 E 786 18.0 N 11.4 E 827 09:55:34 42 0.04 12 99 -3.1 299 -81 18.0 N 11.4 E 786 17.9 N 11.4 E 827 09:55:35 42 0.04 12 99 -3.1 298 -81 17.9 N 11.4 E 786 17.9 N 11.4 E 827 09:55:36 42 0.04 12 99 -3.1 298 -82 17.8 N 11.3 E 786 17.8 N 11.4 E 827 09:55:37 42 0.04 12 99 -3.1 297 -82 17.8 N 11.3 E 786 17.8 N 11.4 E 827 09:55:38 41 0.04 12 99 -3.1 297 -82 17.7 N 11.3 E 786 17.7 N 11.4 E 827 09:55:39 41 0.04 12 99 -3.1 296 -82 17.7 N 11.3 E 786 17.6 N 11.3 E 827 09:55:40 41 0.04 12 99 -3.1 296 -82 17.6 N 11.3 E 786 17.6 N 11.3 E 827 09:55:41 41 0.04 12 99 -3.1 295 -82 17.6 N 11.3 E 786 17.5 N 11.3 E 827 09:55:42 41 0.04 12 99 -3.1 295 -82 17.5 N 11.3 E 786 17.5 N 11.3 E 827 09:55:43 41 0.04 12 99 -3.1 294 -82 17.4 N 11.2 E 786 17.4 N 11.3 E 827 09:55:44 41 0.04 12 99 -3.1 294 -82 17.4 N 11.2 E 786 17.4 N 11.3 E 827 09:55:45 41 0.04 12 99 -3.1 293 -82 17.3 N 11.2 E 786 17.3 N 11.3 E 827 09:55:46 41 0.04 12 99 -3.1 293 -82 17.3 N 11.2 E 786 17.2 N 11.2 E 827 09:55:47 41 0.04 12 99 -3.1 292 -82 17.2 N 11.2 E 786 17.2 N 11.2 E 827 09:55:48 41 0.04 12 99 -3.1 291 -82 17.1 N 11.2 E 786 17.1 N 11.2 E 827 09:55:49 41 0.04 12 99 -3.1 291 -82 17.1 N 11.2 E 786 17.1 N 11.2 E 827 09:55:50 41 0.04 12 99 -3.1 290 -82 17.0 N 11.1 E 786 17.0 N 11.2 E 827 09:55:51 41 0.04 12 99 -3.1 290 -82 17.0 N 11.1 E 786 16.9 N 11.2 E 827 09:55:52 41 0.04 12 99 -3.1 289 -82 16.9 N 11.1 E 786 16.9 N 11.2 E 827 09:55:53 41 0.04 12 99 -3.1 288 -82 16.8 N 11.1 E 786 16.8 N 11.1 E 827 09:55:54 41 0.04 12 99 -3.1 288 -82 16.8 N 11.1 E 786 16.8 N 11.1 E 827 09:55:55 41 0.04 12 99 -3.1 287 -83 16.7 N 11.1 E 786 16.7 N 11.1 E 827 09:55:56 41 0.04 12 99 -3.1 287 -83 16.7 N 11.1 E 786 16.7 N 11.1 E 827 09:55:57 41 0.04 12 99 -3.1 286 -83 16.6 N 11.0 E 786 16.6 N 11.1 E 827 09:55:58 41 0.04 12 99 -3.1 285 -83 16.5 N 11.0 E 786 16.5 N 11.1 E 827 09:55:59 41 0.04 12 99 -3.1 285 -83 16.5 N 11.0 E 786 16.5 N 11.1 E 827 09:56:00 41 0.04 12 99 -3.1 284 -83 16.4 N 11.0 E 786 16.4 N 11.0 E 827 09:56:01 41 0.04 12 99 -3.1 283 -83 16.4 N 11.0 E 786 16.4 N 11.0 E 827 09:56:02 41 0.04 12 99 -3.1 283 -83 16.3 N 11.0 E 786 16.3 N 11.0 E 827 09:56:03 41 0.04 12 99 -3.1 282 -83 16.2 N 11.0 E 786 16.2 N 11.0 E 827 09:56:04 41 0.04 12 99 -3.1 281 -83 16.2 N 11.0 E 786 16.2 N 11.0 E 827 09:56:05 41 0.04 12 99 -3.1 280 -83 16.1 N 10.9 E 786 16.1 N 11.0 E 827 09:56:06 41 0.04 12 99 -3.1 280 -83 16.1 N 10.9 E 786 16.1 N 11.0 E 827 09:56:07 41 0.04 12 99 -3.1 279 -83 16.0 N 10.9 E 786 16.0 N 11.0 E 827 09:56:08 41 0.04 12 99 -3.1 278 -83 16.0 N 10.9 E 786 15.9 N 10.9 E 827 09:56:09 41 0.05 12 99 -3.1 278 -83 15.9 N 10.9 E 786 15.9 N 10.9 E 827 09:56:10 41 0.05 12 99 -3.1 277 -83 15.8 N 10.9 E 786 15.8 N 10.9 E 827 09:56:11 41 0.05 12 99 -3.1 276 -83 15.8 N 10.9 E 786 15.8 N 10.9 E 827 09:56:12 41 0.05 12 99 -3.1 275 -83 15.7 N 10.8 E 786 15.7 N 10.9 E 827 09:56:13 41 0.05 12 99 -3.1 275 -83 15.7 N 10.8 E 786 15.7 N 10.9 E 827 09:56:14 41 0.05 12 99 -3.1 274 -83 15.6 N 10.8 E 786 15.6 N 10.9 E 827 09:56:15 41 0.05 12 99 -3.1 273 -83 15.5 N 10.8 E 786 15.5 N 10.8 E 827 09:56:16 41 0.05 12 99 -3.1 272 -83 15.5 N 10.8 E 786 15.5 N 10.8 E 827 09:56:17 41 0.05 12 99 -3.1 271 -83 15.4 N 10.8 E 786 15.4 N 10.8 E 827 09:56:18 41 0.05 12 99 -3.1 271 -83 15.4 N 10.8 E 786 15.4 N 10.8 E 827 09:56:19 41 0.05 12 99 -3.1 270 -83 15.3 N 10.7 E 786 15.3 N 10.8 E 827 09:56:20 41 0.05 12 99 -3.1 269 -83 15.2 N 10.7 E 786 15.2 N 10.8 E 827 09:56:21 41 0.05 13 99 -3.1 268 -83 15.2 N 10.7 E 786 15.2 N 10.8 E 827 09:56:22 41 0.05 13 99 -3.1 267 -83 15.1 N 10.7 E 786 15.1 N 10.7 E 827 09:56:23 41 0.05 13 99 -3.1 267 -83 15.1 N 10.7 E 786 15.1 N 10.7 E 827 09:56:24 41 0.05 13 99 -3.1 266 -83 15.0 N 10.7 E 786 15.0 N 10.7 E 827 09:56:25 41 0.05 13 99 -3.1 265 -83 14.9 N 10.7 E 786 14.9 N 10.7 E 827 09:56:26 41 0.05 13 99 -3.1 264 -83 14.9 N 10.6 E 786 14.9 N 10.7 E 827 09:56:27 41 0.05 13 99 -3.1 263 -83 14.8 N 10.6 E 786 14.8 N 10.7 E 827 09:56:28 41 0.05 13 99 -3.1 263 -83 14.8 N 10.6 E 786 14.8 N 10.7 E 827 09:56:29 41 0.05 13 99 -3.1 262 -83 14.7 N 10.6 E 786 14.7 N 10.6 E 827 09:56:30 41 0.05 13 99 -3.1 261 -83 14.6 N 10.6 E 786 14.7 N 10.6 E 827 09:56:31 41 0.05 13 99 -3.1 260 -83 14.6 N 10.6 E 786 14.6 N 10.6 E 827 09:56:32 41 0.05 13 99 -3.1 259 -83 14.5 N 10.6 E 786 14.5 N 10.6 E 827 09:56:33 41 0.05 13 99 -3.1 258 -83 14.5 N 10.6 E 786 14.5 N 10.6 E 827 09:56:34 41 0.05 13 99 -3.1 258 -83 14.4 N 10.5 E 786 14.4 N 10.6 E 827 09:56:35 41 0.05 13 99 -3.1 257 -83 14.4 N 10.5 E 786 14.4 N 10.6 E 827 09:56:36 41 0.05 13 99 -3.1 256 -83 14.3 N 10.5 E 786 14.3 N 10.6 E 827 09:56:37 41 0.05 13 99 -3.1 255 -83 14.2 N 10.5 E 786 14.2 N 10.5 E 827 09:56:38 41 0.05 13 99 -3.1 254 -83 14.2 N 10.5 E 786 14.2 N 10.5 E 827 09:56:39 41 0.05 13 99 -3.1 253 -83 14.1 N 10.5 E 786 14.1 N 10.5 E 827 09:56:40 41 0.05 13 99 -3.1 253 -83 14.1 N 10.5 E 786 14.1 N 10.5 E 827 09:56:41 41 0.05 13 99 -3.1 252 -83 14.0 N 10.4 E 786 14.0 N 10.5 E 827 09:56:42 41 0.05 13 99 -3.1 251 -83 13.9 N 10.4 E 786 13.9 N 10.5 E 827 09:56:43 41 0.05 13 99 -3.1 250 -83 13.9 N 10.4 E 786 13.9 N 10.5 E 827 09:56:44 41 0.05 13 99 -3.1 249 -83 13.8 N 10.4 E 786 13.8 N 10.4 E 827 09:56:45 41 0.05 13 99 -3.1 248 -83 13.8 N 10.4 E 786 13.8 N 10.4 E 827 09:56:46 41 0.05 13 99 -3.1 248 -83 13.7 N 10.4 E 786 13.7 N 10.4 E 827 09:56:47 41 0.05 13 99 -3.1 247 -83 13.6 N 10.4 E 786 13.7 N 10.4 E 827 09:56:48 41 0.05 13 99 -3.1 246 -83 13.6 N 10.3 E 786 13.6 N 10.4 E 827 09:56:49 41 0.05 13 99 -3.1 245 -83 13.5 N 10.3 E 786 13.5 N 10.4 E 827 09:56:50 41 0.05 13 99 -3.1 244 -83 13.5 N 10.3 E 786 13.5 N 10.4 E 827 09:56:51 41 0.05 13 99 -3.1 244 -83 13.4 N 10.3 E 786 13.4 N 10.3 E 827 09:56:52 41 0.05 13 99 -3.1 243 -83 13.3 N 10.3 E 786 13.4 N 10.3 E 827 09:56:53 41 0.05 13 99 -3.1 242 -83 13.3 N 10.3 E 786 13.3 N 10.3 E 827 09:56:54 41 0.05 13 99 -3.1 241 -83 13.2 N 10.3 E 786 13.2 N 10.3 E 827 09:56:55 41 0.05 13 99 -3.1 240 -83 13.2 N 10.3 E 786 13.2 N 10.3 E 827 09:56:56 41 0.05 13 99 -3.1 240 -83 13.1 N 10.2 E 786 13.1 N 10.3 E 827 09:56:57 41 0.05 13 99 -3.1 239 -83 13.0 N 10.2 E 786 13.1 N 10.3 E 827 09:56:58 41 0.05 13 99 -3.1 238 -83 13.0 N 10.2 E 786 13.0 N 10.2 E 827 09:56:59 41 0.05 13 99 -3.1 237 -83 12.9 N 10.2 E 786 12.9 N 10.2 E 827 09:57:00 41 0.05 13 99 -3.1 237 -83 12.9 N 10.2 E 786 12.9 N 10.2 E 827