Special Whistler Mode Experiments with the IMAGE Satellite
A special campaign of whistler-mode transmissions from the IMAGE satellite will be from November 21 to December 4, 2001 and will be conducted at the times given in the table at the bottom of this message. The Radio Plasma Imager instrument on IMAGE, called RPI, normally operates at distances up to apogee at about 8 Earth Radii by radio sounding at frequencies ranging from 3 kHz to 3 MHz. When IMAGE is near perigee, either inside the plasmasphere or at low altitudes over the southern hemisphere polar regions, some of the signals launched between 3 kHz and about 500 kHz may propagate in the whistler mode, depending upon the local plasma parameters. An outstanding problem to be investigated under these conditions concerns whistler-mode propagation from an in situ source to the ground. It is not expected that detection of RPI signals on the ground will be a common occurrence, and the conditions under which such detection may occur will be of great scientific interest. Ground observers are therefore strongly encouraged to participate in the upcoming campaign and in future campaigns that will hopefully be scheduled.
There will be two sets of experiments, at 5-15 kHz (VLF) and at 130 and 380 kHz. The 5-15 kHz experiments will be performed on the incoming (towards perigee), southward traveling part of every orbit, starting at about the point where the magnetic field line through the satellite is at about 50 degrees N latitude. They will continue until the the 130 and 380 kHz experiment begins. The 130 and 380 kHz transmissions will begin when the satellite is four minutes before the closest approach to the South Pole, and continue four minutes past closest approach.
The format of the VLF transmissions will be 0.125 seconds on, 0.375 seconds off, at 5, 7, 9, 11, 13, and 15 kHz, repeated over and over.
Details of the satellite orbit, both graphical and tabular, may be found at the Satellite Situation Center web site:
SSCWeb was used to get IMAGE orbital parameters to illustrate the operations before and during the first South Pole crossing. For the VLF operation, if we had an observer in the North Pacific, somewhere between Hawaii and California, they might be in a good place to hear IMAGE. We have 23 other opportunities during the two weeks, though. Note that Longitudes are give in East Longitude, whereas in the US, we are used to using West Longitude in our hemisphere. ArcLen is the distance from the satellite to the Earth's surface along the magnetic field line. DipL-Val is the a measure of magnetic latitude of the field line.
Time GEO NorthBtrace GEO Radius yyyy ddd hh:mm Lat Long Lat Long ArcLen (RE) DipL-Val Notes 2001 325 07:02 49.20 207.88 67.72 218.56 2.56 3.46 8.3 2001 325 07:04 48.13 207.41 67.08 217.97 2.50 3.40 7.8 2001 325 07:06 47.03 206.94 66.46 217.36 2.44 3.33 7.3 2001 325 07:08 45.88 206.46 65.82 216.72 2.38 3.27 6.9 2001 325 07:10 44.68 205.99 65.12 216.11 2.32 3.20 6.4 2001 325 07:12 43.43 205.52 64.40 215.49 2.26 3.13 6.0 2001 325 07:14 42.13 205.05 63.66 214.85 2.20 3.07 5.6 2001 325 07:16 40.76 204.58 62.85 214.24 2.14 3.00 5.3 2001 325 07:18 39.34 204.11 62.03 213.61 2.08 2.93 4.9 2001 325 07:20 37.84 203.64 61.14 212.99 2.02 2.86 4.6 2001 325 07:22 36.27 203.16 60.22 212.35 1.96 2.79 4.3 2001 325 07:24 34.62 202.69 59.23 211.74 1.90 2.72 4.0 2001 325 07:26 32.88 202.22 58.20 211.11 1.84 2.65 3.8 2001 325 07:28 31.04 201.75 57.10 210.50 1.78 2.57 3.5 VLF start 2001 325 07:30 29.09 201.28 55.95 209.89 1.72 2.50 3.3 2001 325 07:32 27.03 200.81 54.73 209.30 1.67 2.43 3.1 2001 325 07:34 24.84 200.34 53.44 208.71 1.61 2.35 2.9 2001 325 07:36 22.51 199.88 52.08 208.15 1.56 2.28 2.7 2001 325 07:38 20.02 199.41 50.66 207.60 1.51 2.21 2.5 2001 325 07:40 17.36 198.95 49.17 207.08 1.47 2.13 2.3 2001 325 07:42 14.51 198.48 47.64 206.61 1.43 2.06 2.2 2001 325 07:44 11.44 198.02 46.07 206.18 1.40 1.98 2.1 2001 325 07:46 8.14 197.56 44.51 205.82 1.38 1.91 1.9 2001 325 07:48 4.57 197.10 43.00 205.55 1.38 1.84 1.8 2001 325 07:50 0.72 196.65 41.62 205.41 1.39 1.77 1.8 2001 325 07:52 -3.46 196.20 40.49 205.44 1.44 1.70 1.7 2001 325 07:54 -7.99 195.75 39.73 205.70 1.52 1.63 1.7 2001 325 07:56 -12.91 195.31 39.54 206.30 1.67 1.56 1.7 2001 325 07:58 -18.23 194.88 40.10 207.35 1.90 1.50 1.7 2001 325 08:00 -24.00 194.46 41.53 209.01 2.26 1.45 1.7 2001 325 08:02 -30.22 194.06 43.90 211.47 2.82 1.39 1.9 2001 325 08:04 -36.90 193.67 47.10 214.96 3.72 1.35 2.1 2001 325 08:06 -44.00 193.32 50.92 219.73 5.23 1.31 2.5 2001 325 08:08 -51.49 193.03 55.08 226.11 8.02 1.28 3.3 2001 325 08:10 -59.27 192.82 59.24 234.54 15.08 1.26 4.6 VLF end 2001 325 08:12 -67.26 192.81 N/A N/A N/A 1.25 7.5 2001 325 08:14 -75.31 193.31 -nan0x -nan0x-nan0xf 1.25 14.2 SP start 2001 325 08:16 -83.28 196.10 -nan0x -nan0x-nan0xf 1.26 27.9 2001 325 08:18 -88.67 337.79 -nan0x -nan0x-nan0xf 1.28 32.5 South Pole 2001 325 08:20 -81.33 4.54 -nan0x -nan0x-nan0xf 1.31 19.2 2001 325 08:22 -74.21 6.16 63.98 312.26 23.35 1.34 10.8 SP end
Note that during the VLF operation, the longitude remains relatively constant. In the case above the longitude of the foot of the earth's magnetic field line through the satellite only changes from 210 to 234 degrees East longitude. (The longitude of the foot of the field line is the important parameter, because the waves travel approximately along the field lines.) Over the latitudes of the US the longitude changes very little.
Below is one line for each orbit at approximately a field line foot point of 50 degrees latitude, so you can identify which orbits are near your location.
Time GEO NorthBtrace GEO yyyy ddd hh:mm Lat Long Lat Long ArcLen One location of longitude 2001 325 07:38 20.02 199.41 50.66 207.60 1.51 N. Pacific 2001 325 21:54 17.31 344.87 49.70 337.73 1.47 Azores Islands 2001 326 12:12 11.32 129.86 50.08 128.59 1.53 China, Japan 2001 327 02:12 29.06 279.04 49.64 277.16 1.61 West Virginia 2001 327 16:38 14.33 62.16 49.78 62.17 1.50 Uzbekistan 2001 328 06:46 22.39 209.47 50.57 217.79 1.52 N. Pacific 2001 328 21:04 17.14 354.46 50.52 348.76 1.48 Mauritania 2001 329 11:22 11.06 139.45 50.31 138.87 1.52 Japan 2001 330 01:22 29.03 288.62 49.91 284.75 1.60 New Jersey 2001 330 15:48 14.10 71.74 49.59 71.67 1.49 Afganistan 2001 331 05:54 24.66 219.52 50.54 227.46 1.54 N. Pacific 2001 331 20:16 13.98 3.57 49.52 359.36 1.45 England 2001 332 10:32 10.74 149.03 50.34 149.75 1.51 E. Australia 2001 333 00:32 28.95 298.20 50.46 292.54 1.60 Maine 2001 333 14:58 13.78 81.32 49.41 81.06 1.48 E. India 2001 334 05:02 26.76 229.56 50.59 236.64 1.56 Washington 2001 334 19:26 13.62 13.15 49.55 10.42 1.45 Italy 2001 335 09:42 10.30 158.61 49.96 161.16 1.49 New Zealand 2001 335 23:44 26.62 307.31 49.72 300.35 1.53 Guyana no operations - superceded by another experiment 2001 337 04:12 26.54 239.15 49.35 244.97 1.52 California 2001 337 18:34 16.23 23.21 50.70 21.73 1.47 Greece 2001 338 08:50 13.10 168.67 50.40 173.06 1.46 New Zealand 2001 338 22:54 26.41 316.91 50.75 309.02 1.53 Brazil
There is a receiver at the South Pole station programmed to receive the 130 and 380 kHz transmissions.
RPI whistler mode team