PDS_VERSION_ID = PDS3 RECORD_TYPE = STREAM OBJECT = TEXT INTERCHANGE_FORMAT = ASCII PUBLICATION_DATE = 1998-01-16 NOTE = "Internal memo discussing DSS 14 antenna performance (including actual versus nominal performance) during the Clementine bistatic radar experiment." END_OBJECT = TEXT END 70-m Antenna Performance Nominal vs Observed DSS 14 1994-09-09 ================= Moon topocentric positions as calculated by MICA (U.S. Naval Observatory observing ephemeris for Macintosh, V1.0) are: Table 1 Moon -- Apparent Topocentric Positions Local Zenith and True North Location: W116 deg 53' 22", N35 deg 25' 33", 1002m (Longitude referred to Greenwich meridian) Date Time Zenith Azimuth Distance (UT1) Distance (E of N) to Object h m s deg ' " deg ' " km ---------------------- ----------- ----------- ---------- 1994 Apr 09 17:30:00.0 35 31 53.0 143 00 20.1 399584.758 1994 Apr 09 17:40:00.0 34 21 08.3 146 45 07.7 399520.604 1994 Apr 09 17:50:00.0 33 17 06.6 150 42 43.7 399465.383 1994 Apr 09 18:00:00.0 32 20 29.0 154 52 56.6 399419.215 1994 Apr 09 18:10:00.0 31 31 56.3 159 15 09.2 399382.200 1994 Apr 09 18:20:00.0 30 52 07.4 163 48 14.2 399354.420 1994 Apr 09 18:30:00.0 30 21 37.2 168 30 32.6 399335.943 1994 Apr 09 18:40:00.0 30 00 54.5 173 19 54.4 399326.818 1994 Apr 09 18:50:00.0 29 50 19.7 178 13 43.6 399327.075 1994 Apr 09 19:00:00.0 29 50 03.6 183 09 06.4 399336.728 1994 Apr 09 19:10:00.0 30 00 06.3 188 03 02.9 399355.773 1994 Apr 09 19:20:00.0 30 20 16.9 192 52 39.2 399384.190 1994 Apr 09 19:30:00.0 30 50 14.9 197 35 18.5 399421.938 1994 Apr 09 19:40:00.0 31 29 31.4 202 08 50.2 399468.961 1994 Apr 09 19:50:00.0 32 17 31.5 206 31 34.4 399525.186 1994 Apr 09 20:00:00.0 33 13 36.1 210 42 23.0 399590.521 1994 Apr 09 20:10:00.0 34 17 04.2 214 40 38.2 399664.858 1994 Apr 09 20:20:00.0 35 27 14.6 218 26 07.9 399748.073 1994 Apr 09 20:30:00.0 36 43 27.2 221 59 00.8 399840.024 1994 Apr 09 20:40:00.0 38 05 03.9 225 19 41.4 399940.553 1994 Apr 09 20:50:00.0 39 31 29.4 228 28 45.0 400049.487 Table 2 Moon -- Apparent Topocentric Positions True Equator and Equinox of Date Location: W116 deg 53' 22", N35 deg 25' 33", 1002m (Longitude referred to Greenwich meridian) Date Time Right Ascension Declination (UT1) h m s h m s deg deg ' " deg ---------------------- ----------- ----- ------------ ----- 1994 Apr 09 17:30:00.0 0 15 36.866 +5 21 51.46 1994 Apr 09 17:40:00.0 0 15 48.442 +5 23 38.35 1994 Apr 09 17:50:00.0 0 15 59.917 +5 25 24.79 1994 Apr 09 18:00:00.0 0 16 11.302 4.047 +5 27 10.78 5.453 1994 Apr 09 18:10:00.0 0 16 22.613 +5 28 56.30 1994 Apr 09 18:20:00.0 0 16 33.863 +5 30 41.33 1994 Apr 09 18:30:00.0 0 16 45.066 +5 32 25.87 1994 Apr 09 18:40:00.0 0 16 56.236 +5 34 09.91 1994 Apr 09 18:50:00.0 0 17 07.388 +5 35 53.44 1994 Apr 09 19:00:00.0 0 17 18.535 4.327 +5 37 36.44 5.627 1994 Apr 09 19:10:00.0 0 17 29.691 +5 39 18.92 1994 Apr 09 19:20:00.0 0 17 40.872 +5 41 00.86 1994 Apr 09 19:30:00.0 0 17 52.092 +5 42 42.27 1994 Apr 09 19:40:00.0 0 18 03.363 +5 44 23.13 1994 Apr 09 19:50:00.0 0 18 14.702 +5 46 03.44 1994 Apr 09 20:00:00.0 0 18 26.120 4.609 +5 47 43.20 5.795 1994 Apr 09 20:10:00.0 0 18 37.632 +5 49 22.41 1994 Apr 09 20:20:00.0 0 18 49.252 +5 51 01.07 1994 Apr 09 20:30:00.0 0 19 00.993 +5 52 39.18 1994 Apr 09 20:40:00.0 0 19 12.868 +5 54 16.75 System Noise Temperature ------------------------ From Table 2 of DSN 810-5, Rev D, Vol I, TCI-10, Rev G: SPD with diplexer 19.5+1.3/-0.7 K without diplexer 15.2+1.3/-0.7 K Therefore, diplexer adds 4.3 K Elevation angles derived from Table 1 above. Non-diplexed LNA-1 S-band system noise temperature inferred from Figure 2 of DSN 810-5, Rev D, Vol I, TCI-10, Rev G. Diplexed system temperature obtained by adding 4.3 K. Assume all uncertainties to be +1.3/-0.7 K. Date Time Zenith Elevation DSN 810-5 Predicted (UT1) Distance Angle System Temperature no diplex w/diplex h m s deg ' " deg K K ---------------------- ----------- ----- ---- ---- 1994 Apr 09 17:30:00.0 35 31 53.0 1994 Apr 09 17:40:00.0 34 21 08.3 1994 Apr 09 17:50:00.0 33 17 06.6 56.71 15.6 19.9 1994 Apr 09 18:00:00.0 32 20 29.0 57.66 1994 Apr 09 18:10:00.0 31 31 56.3 58.47 1994 Apr 09 18:20:00.0 30 52 07.4 59.13 1994 Apr 09 18:30:00.0 30 21 37.2 59.64 1994 Apr 09 18:40:00.0 30 00 54.5 59.98 1994 Apr 09 18:50:00.0 29 50 19.7 60.16 1994 Apr 09 19:00:00.0 29 50 03.6 60.17 15.4 19.7 1994 Apr 09 19:10:00.0 30 00 06.3 60.00 1994 Apr 09 19:20:00.0 30 20 16.9 59.66 1994 Apr 09 19:30:00.0 30 50 14.9 59.16 1994 Apr 09 19:40:00.0 31 29 31.4 58.51 1994 Apr 09 19:50:00.0 32 17 31.5 57.71 1994 Apr 09 20:00:00.0 33 13 36.1 56.77 1994 Apr 09 20:10:00.0 34 17 04.2 55.72 15.7 20.0 1994 Apr 09 20:20:00.0 35 27 14.6 1994 Apr 09 20:30:00.0 36 43 27.2 1994 Apr 09 20:40:00.0 38 05 03.9 1994 Apr 09 20:50:00.0 39 31 29.4 Measured system temperature from ambient load measurements was 21.51 K (S-RCP) 20.12 K (S-LCP) Measured system temperatures are slightly higher than nominal, but go ahead and use them for analysis. For these observations, ignore variations with elevation angle. Gain ---- From Table 2 of DSN 810-5, Rev D, Vol I, TCI-10, Rev G: Gain at 2295 MHz is 63.34+/-0.10 dB at 45 deg elevation angle at LNA-1 input ignoring atmospheric effects For nominal atmosphere (0.00 <= CD <= 0.90) G = 63.30+/-0.10 dB at 60 deg elevation angle Gain scales as 20 log(f/fR), so gain would be down 0.08 dB at 2273 MHz G = 63.22+/-0.10 dB Conclude gain during DSS 14 observations should be G = 63.22+/-0.10 dB Beamwidth --------- From Table 2 of DSN 810-5, Rev D, Vol I, TCI-10, Rev G: Full-width at half-power points: 0.108+/-0.003 degrees Pointing -------- During observations of the Moon, DSS 14 was directed to use "planetary pointing" predicts. There were two sets: one for the South Pole and a second for the Moon's center. Each set included three points; the antenna pointing between was based on interpolation. The center-of-Moon coordinates agree to 0.002 deg (worst case) with Table 2 (above) from the MICA calculations. South Pole ========== Time (UTC) Right Ascension (deg) Declination (deg) ------------------- --------------------- ----------------- 1994-04-09T18:10:00 4.199 5.257 1994-04-09T18:59:00 4.427 5.398 1994-04-09T19:50:00 4.666 5.542 Center of Moon ============== Time (UTC) Right Ascension (deg) Declination (deg) ------------------- --------------------- ----------------- 1994-04-09T18:00:00 4.049 5.454 1994-04-09T18:59:00 4.324 5.625 1994-04-09T20:00:00 4.610 5.796 According to Sal Abbate, Mike Wert acknowledges 0.1 dB difference in RCP and LCP pointing at S-band; he says this translates to about 0.02 degrees difference in angular pointing. Analysis of data when the 70-m antenna was tracking the South Pole shows RCP at 65.98K and LCP at 74.69K, approximately 12% different compared with 0% and 20% if the pointing offset were parallel to or perpendicular to the limb, respectively. Ellipticity ----------- From Table 2 of DSN 810-5, Rev D, Vol I, TCI-10, Rev G: Defined as the ratio of peak to trough received voltages with a rotating linearly polarized signal source and a nominally circularly polarized receiving antenna 0.6 dB (max) which translates to Vmax/Vmin <= 1.07 Dick Simpson 23 Dec 1997 editorial improvements: 15 Jan 1998