COVER INFORMATION Station: ONSALA85 (Code On ) Experiment: Snapshot Ionospheric Testing Observations Exp. Code: N05L3 Schedule Version: 1.02 Processed by SCHED version: 6.01 Release: Late March 2005 PI: James M Anderson Address: Joint Institute for VLBI in Europe Oude Hoogeveensedijk 4 7991 PD Dwingeloo The Netherlands Phone: +31 (0)521 596 542 EMAIL: anderson@jive.nl Fax: +31 (0)521 596 539 Phone during observation: +31 (0)521 596 500 Observing mode: Snapshot observations of sources at 18cm (256 Mb/s) Notes: ALBUS Ionospheric modeling test observations Phase referencing is too fast for JODRELL1 All targets are strong Schedule for ONSALA85 (Code On ) Page 2 Snapshot Ionospheric Testing Observations UP: D => Below limits; H => Below horizon mask. blank => Up. Early: Seconds between end of slew and start. Dwell: On source seconds. Tapes: Drive, Index, Start footage / Direction, Head Group, End footage. TPStart: Tape motion start time. Frequencies are LO sum (band edge). ---------------------------------------------------------------------------------------- Start UT Source Start / Stop Early Tapes TPStart Stop UT LST EL AZ HA UP ParA Dwell (see above) ---------------------------------------------------------------------------------------- --- Mon 6 Jun 2005 Day 157 --- Next scan frequencies: 1637.99 1637.99 1645.99 1645.99 1653.99 1653.99 1661.99 1661.99 Next BBC frequencies: 137.99 137.99 145.99 145.99 153.99 153.99 161.99 161.99 Next scan bandwidths: 8.00 8.00 8.00 8.00 8.00 8.00 8.00 8.00 23 00 00 J1323+7942 16 49 29 62.7 342.2 3.4 0.0 0 1 1 0 23 00 00 23 02 00 =1323+799 16 51 29 62.7 342.1 3.5 0.0 120 F 1 0 23 02 00 J1139+7654 16 51 29 57.8 335.4 5.2 0.0 -88 1 1 0 23 02 00 23 04 00 =1136+771 16 53 29 57.7 335.4 5.2 0.0 32 F 1 0 23 04 00 J1323+7942 16 53 29 62.6 342.1 3.5 0.0 -88 1 1 0 23 04 00 23 06 00 =1323+799 16 55 30 62.5 342.0 3.5 0.0 32 F 1 0 23 06 00 J1139+7654 16 55 30 57.6 335.5 5.3 0.0 -88 1 1 0 23 06 00 23 08 00 =1136+771 16 57 30 57.5 335.5 5.3 0.0 32 F 1 0 23 08 00 J1323+7942 16 57 30 62.4 341.9 3.6 0.0 -88 1 1 0 23 08 00 23 10 00 =1323+799 16 59 30 62.3 341.9 3.6 0.0 32 F 1 0 23 10 00 J1139+7654 16 59 30 57.4 335.5 5.3 0.0 -88 1 1 0 23 10 00 23 12 00 =1136+771 17 01 31 57.2 335.6 5.4 0.0 32 F 1 0 23 13 00 J1323+7942 17 02 31 62.2 341.8 3.6 0.0 -28 1 1 0 23 13 00 23 14 00 =1323+799 17 03 31 62.2 341.7 3.7 0.0 32 F 1 0 23 14 00 J1406+7828 17 03 31 64.5 341.1 2.9 0.0 -38 1 1 0 23 14 00 23 15 40 =1406+787 17 05 11 64.4 341.0 3.0 0.0 62 F 1 0 23 15 40 J1323+7942 17 05 11 62.1 341.7 3.7 0.0 -38 1 1 0 23 15 40 23 17 20 =1323+799 17 06 51 62.0 341.6 3.7 0.0 62 F 1 0 23 17 20 J1406+7828 17 06 51 64.4 340.9 3.0 0.0 -38 1 1 0 23 17 20 23 19 00 =1406+787 17 08 32 64.3 340.8 3.0 0.0 62 F 1 0 23 19 00 J1323+7942 17 08 32 61.9 341.6 3.7 0.0 -38 1 1 0 23 19 00 23 20 40 =1323+799 17 10 12 61.9 341.5 3.8 0.0 62 F 1 0 23 20 40 J1406+7828 17 10 12 64.2 340.7 3.1 0.0 -38 1 1 0 23 20 40 23 22 20 =1406+787 17 11 52 64.1 340.6 3.1 0.0 62 F 1 0 Schedule for ONSALA85 (Code On ) Page 3 Snapshot Ionospheric Testing Observations UP: D => Below limits; H => Below horizon mask. blank => Up. Early: Seconds between end of slew and start. Dwell: On source seconds. Tapes: Drive, Index, Start footage / Direction, Head Group, End footage. TPStart: Tape motion start time. Frequencies are LO sum (band edge). ---------------------------------------------------------------------------------------- Start UT Source Start / Stop Early Tapes TPStart Stop UT LST EL AZ HA UP ParA Dwell (see above) ---------------------------------------------------------------------------------------- --- Mon 6 Jun 2005 Day 157 --- 23 22 20 J1323+7942 17 11 52 61.8 341.5 3.8 0.0 -38 1 1 0 23 22 20 23 24 00 =1323+799 17 13 32 61.7 341.4 3.8 0.0 62 F 1 0 23 24 00 J1357+7643 17 13 32 64.3 336.4 3.3 0.0 -30 1 1 0 23 24 00 23 25 40 =1357+769 17 15 13 64.2 336.3 3.3 0.0 70 F 1 0 23 25 40 J1323+7942 17 15 13 61.7 341.4 3.9 0.0 -30 1 1 0 23 25 40 23 27 20 =1323+799 17 16 53 61.6 341.4 3.9 0.0 70 F 1 0 23 27 20 J1357+7643 17 16 53 64.2 336.3 3.3 0.0 -30 1 1 0 23 27 20 23 29 00 =1357+769 17 18 33 64.1 336.2 3.3 0.0 70 F 1 0 23 29 00 J1323+7942 17 18 33 61.5 341.3 3.9 0.0 -30 1 1 0 23 29 00 23 30 40 =1323+799 17 20 14 61.4 341.3 3.9 0.0 70 F 1 0 23 30 40 J1357+7643 17 20 14 64.0 336.1 3.4 0.0 -30 1 1 0 23 30 40 23 32 20 =1357+769 17 21 54 63.9 336.1 3.4 0.0 70 F 1 0 23 32 20 J1323+7942 17 21 54 61.4 341.2 4.0 0.0 -30 1 1 0 23 32 20 23 34 00 =1323+799 17 23 34 61.3 341.2 4.0 0.0 70 F 1 0 23 40 00 J1745+1720 17 29 35 49.8 174.0 -0.3 0.0 145 1 1 0 23 40 00 23 44 00 =1743+173 17 33 36 49.9 175.5 -0.2 0.0 240 F 1 0 23 44 00 J1752+1734 17 33 36 50.0 172.8 -0.3 0.0 -8 1 1 0 23 44 00 23 45 40 =1750+175 17 35 16 50.0 173.4 -0.3 0.0 92 F 1 0 23 45 40 J1745+1720 17 35 16 49.9 176.1 -0.2 0.0 -8 1 1 0 23 45 40 23 47 20 =1743+173 17 36 56 49.9 176.7 -0.1 0.0 92 F 1 0 23 47 20 J1752+1734 17 36 56 50.1 174.0 -0.3 0.0 -8 1 1 0 23 47 20 23 49 00 =1750+175 17 38 37 50.1 174.6 -0.2 0.0 92 F 1 0 23 49 00 J1745+1720 17 38 37 49.9 177.3 -0.1 0.0 -8 1 1 0 23 49 00 23 50 40 =1743+173 17 40 17 49.9 177.9 -0.1 0.0 92 F 1 0 23 50 40 J1752+1734 17 40 17 50.1 175.3 -0.2 0.0 -8 1 1 0 23 50 40 23 52 20 =1750+175 17 41 57 50.1 175.9 -0.2 0.0 92 F 1 0 23 53 20 J1745+1720 17 42 57 49.9 178.9 0.0 0.0 51 1 1 0 23 53 20 23 54 00 =1743+173 17 43 37 49.9 179.2 0.0 0.0 40 F 1 0 23 54 00 J1756+1535 17 43 37 48.1 175.1 -0.2 0.0 -11 1 1 0 23 54 00 23 55 40 --- 17 45 18 48.1 175.7 -0.2 0.0 89 F 1 0 Schedule for ONSALA85 (Code On ) Page 4 Snapshot Ionospheric Testing Observations UP: D => Below limits; H => Below horizon mask. blank => Up. Early: Seconds between end of slew and start. Dwell: On source seconds. Tapes: Drive, Index, Start footage / Direction, Head Group, End footage. TPStart: Tape motion start time. Frequencies are LO sum (band edge). ---------------------------------------------------------------------------------------- Start UT Source Start / Stop Early Tapes TPStart Stop UT LST EL AZ HA UP ParA Dwell (see above) ---------------------------------------------------------------------------------------- --- Mon 6 Jun 2005 Day 157 --- 23 55 40 J1745+1720 17 45 18 49.9 179.8 0.0 0.0 -11 1 1 0 23 55 40 23 57 20 =1743+173 17 46 58 49.9 180.4 0.0 0.0 89 F 1 0 23 57 20 J1756+1535 17 46 58 48.1 176.3 -0.2 0.0 -11 1 1 0 23 57 20 23 59 00 --- 17 48 38 48.2 176.9 -0.1 0.0 89 F 1 0 --- Start: Mon 6 Jun 2005 Day 157 -- Stop: Tue 7 Jun 2005 Day 158 --- 23 59 00 J1745+1720 17 48 38 49.9 181.0 0.0 0.0 -11 1 1 0 23 59 00 00 00 40 =1743+173 17 50 18 49.9 181.7 0.1 0.0 89 F 1 0 00 00 40 J1756+1535 17 50 18 48.2 177.5 -0.1 0.0 -11 1 1 0 00 00 40 00 02 20 --- 17 51 59 48.2 178.1 -0.1 0.0 89 F 1 0 00 02 20 J1745+1720 17 51 59 49.9 182.3 0.1 0.0 -11 1 1 0 00 02 20 00 04 00 =1743+173 17 53 39 49.9 182.9 0.1 0.0 89 F 1 0 00 04 00 J1719+1745 17 53 39 49.8 192.7 0.6 0.0 -24 1 1 0 00 04 00 00 05 40 =1717+178 17 55 19 49.8 193.3 0.6 0.0 76 F 1 0 00 05 40 J1745+1720 17 55 19 49.9 183.5 0.2 0.0 -24 1 1 0 00 05 40 00 07 20 =1743+173 17 57 00 49.9 184.1 0.2 0.0 76 F 1 0 00 07 20 J1719+1745 17 57 00 49.7 193.9 0.6 0.0 -24 1 1 0 00 07 20 00 09 00 =1717+178 17 58 40 49.7 194.5 0.7 0.0 76 F 1 0 00 09 00 J1745+1720 17 58 40 49.9 184.7 0.2 0.0 -24 1 1 0 00 09 00 00 10 40 =1743+173 18 00 20 49.8 185.4 0.2 0.0 76 F 1 0 00 10 40 J1719+1745 18 00 20 49.6 195.1 0.7 0.0 -24 1 1 0 00 10 40 00 12 20 =1717+178 18 02 00 49.6 195.7 0.7 0.0 76 F 1 0 00 12 20 J1745+1720 18 02 00 49.8 186.0 0.3 0.0 -24 1 1 0 00 12 20 00 14 00 =1743+173 18 03 41 49.8 186.6 0.3 0.0 76 F 1 0 00 17 00 J2148+0657 18 06 41 24.0 116.6 -3.7 0.0 -22 1 1 0 00 17 00 00 26 00 =2145+067 18 15 43 25.0 118.7 -3.5 0.0 518 F 1 0 00 29 00 J2129-1538 18 18 43 7.0 134.1 -3.2 0.0 110 1 1 0 00 29 00 00 30 00 =2126-158 18 19 43 7.1 134.4 -3.2 0.0 60 F 1 0 00 30 00 J2129-1821 18 19 43 4.6 135.4 -3.2 0.0 -10 1 1 0 00 30 00 00 31 40 =2126-185 18 21 24 4.8 135.8 -3.1 0.0 90 F 1 0 Schedule for ONSALA85 (Code On ) Page 5 Snapshot Ionospheric Testing Observations UP: D => Below limits; H => Below horizon mask. blank => Up. Early: Seconds between end of slew and start. Dwell: On source seconds. Tapes: Drive, Index, Start footage / Direction, Head Group, End footage. TPStart: Tape motion start time. Frequencies are LO sum (band edge). ---------------------------------------------------------------------------------------- Start UT Source Start / Stop Early Tapes TPStart Stop UT LST EL AZ HA UP ParA Dwell (see above) ---------------------------------------------------------------------------------------- --- Tue 7 Jun 2005 Day 158 --- 00 31 40 J2129-1538 18 21 24 7.3 134.7 -3.1 0.0 -10 1 1 0 00 31 40 00 33 20 =2126-158 18 23 04 7.5 135.1 -3.1 0.0 90 F 1 0 00 33 20 J2129-1821 18 23 04 4.9 136.1 -3.1 0.0 -10 1 1 0 00 33 20 00 35 00 =2126-185 18 24 44 5.1 136.5 -3.1 0.0 90 F 1 0 00 35 00 J2129-1538 18 24 44 7.6 135.5 -3.1 0.0 -10 1 1 0 00 35 00 00 36 40 =2126-158 18 26 24 7.8 135.9 -3.1 0.0 90 F 1 0 00 36 40 J2129-1821 18 26 24 5.3 136.9 -3.1 0.0 -10 1 1 0 00 36 40 00 38 20 =2126-185 18 28 05 5.4 137.2 -3.0 0.0 90 F 1 0 00 38 20 J2129-1538 18 28 05 7.9 136.2 -3.0 0.0 -10 1 1 0 00 38 20 00 40 00 =2126-158 18 29 45 8.1 136.6 -3.0 0.0 90 F 1 0 00 40 00 J2130-0927 18 29 45 13.7 133.9 -3.0 0.0 -21 1 1 0 00 40 00 00 41 40 =2127-096 18 31 25 13.8 134.3 -3.0 0.0 79 F 1 0 00 41 40 J2129-1538 18 31 25 8.2 137.0 -3.0 0.0 -21 1 1 0 00 41 40 00 43 20 =2126-158 18 33 06 8.4 137.4 -2.9 0.0 79 F 1 0 00 43 20 J2130-0927 18 33 06 14.0 134.7 -3.0 0.0 -21 1 1 0 00 43 20 00 45 00 =2127-096 18 34 46 14.2 135.1 -2.9 0.0 79 F 1 0 00 45 00 J2129-1538 18 34 46 8.5 137.7 -2.9 0.0 -21 1 1 0 00 45 00 00 46 40 =2126-158 18 36 26 8.7 138.1 -2.9 0.0 79 F 1 0 00 46 40 J2130-0927 18 36 26 14.3 135.5 -2.9 0.0 -21 1 1 0 00 46 40 00 48 20 =2127-096 18 38 06 14.5 135.9 -2.9 0.0 79 F 1 0 00 49 20 J2129-1538 18 39 06 8.9 138.7 -2.8 0.0 39 1 1 0 00 49 20 00 50 00 =2126-158 18 39 47 9.0 138.9 -2.8 0.0 40 F 1 0 00 50 00 J2131-1207 18 39 47 12.0 137.0 -2.9 0.0 -13 1 1 0 00 50 00 00 51 40 =2128-123 18 41 27 12.2 137.4 -2.8 0.0 87 F 1 0 00 51 40 J2129-1538 18 41 27 9.1 139.2 -2.8 0.0 -13 1 1 0 00 51 40 00 53 20 =2126-158 18 43 07 9.3 139.6 -2.8 0.0 87 F 1 0 00 53 20 J2131-1207 18 43 07 12.3 137.8 -2.8 0.0 -13 1 1 0 00 53 20 00 55 00 =2128-123 18 44 47 12.5 138.1 -2.8 0.0 87 F 1 0 00 55 00 J2129-1538 18 44 47 9.4 140.0 -2.7 0.0 -13 1 1 0 00 55 00 00 56 40 =2126-158 18 46 28 9.6 140.4 -2.7 0.0 87 F 1 0 Schedule for ONSALA85 (Code On ) Page 6 Snapshot Ionospheric Testing Observations UP: D => Below limits; H => Below horizon mask. blank => Up. Early: Seconds between end of slew and start. Dwell: On source seconds. Tapes: Drive, Index, Start footage / Direction, Head Group, End footage. TPStart: Tape motion start time. Frequencies are LO sum (band edge). ---------------------------------------------------------------------------------------- Start UT Source Start / Stop Early Tapes TPStart Stop UT LST EL AZ HA UP ParA Dwell (see above) ---------------------------------------------------------------------------------------- --- Tue 7 Jun 2005 Day 158 --- 00 56 40 J2131-1207 18 46 28 12.7 138.5 -2.8 0.0 -13 1 1 0 00 56 40 00 58 20 =2128-123 18 48 08 12.8 138.9 -2.7 0.0 87 F 1 0 00 58 20 J2129-1538 18 48 08 9.7 140.8 -2.7 0.0 -13 1 1 0 00 58 20 01 00 00 =2126-158 18 49 48 9.9 141.1 -2.7 0.0 87 F 1 0 SETUP FILE INFORMATION: NOTE: If DOPPLER, FREQ, or BW were used, see the individual scans for the final BBC settings. Setup file: eo999.18cm Matches group on21cm1 in /aps3/sched/catalogs/freq.dat Values from E-mail J.Conway (CR 21Oct02) Setup group: 4 Station: ONSALA85 Total bit rate: 256 Format: MKIV1:2 Bits per sample: 2 Sample rate: 16.000 Number of channels: 8 Passes/head pos: 1 Speedup factor: 1.00 1st LO= 1500.00 1500.00 1500.00 1500.00 1500.00 1500.00 1500.00 1500.00 Net SB= U U U U U U U U Pol. = RCP LCP RCP LCP RCP LCP RCP LCP BBC = 2 1 4 3 6 5 8 7 BBC SB= U U U U U U U U IF = 2N 1N 2N 1N 2N 1N 2N 1N The following frequency sets based on this setup were used. Frequency Set: 4 Setup file default. No pcal detection. LO sum= 1637.99 1637.99 1645.99 1645.99 1653.99 1653.99 1661.99 1661.99 BBC fr= 137.99 137.99 145.99 145.99 153.99 153.99 161.99 161.99 Bandwd= 8.000 8.000 8.000 8.000 8.000 8.000 8.000 8.000 Track assignments are: track1= 2, 10, 18, 26, 3, 11, 19, 27 barrel=roll_off SOURCE LIST -- Snapshot Ionospheric Testing Observations Catalog positions marked with *. Precession of date coordinates is based on stop time of first scan. Names used in schedule marked with *. Short names used in VLA and SNAP files marked with +. Observation date used in B1950/J2000 coordinate conversion (PRECDATE): 1979.900 No adjustments are made for rates (DRA, DDEC). Scan hours are for recording scans only. Baseline hours are only counted for scans above horizon at both ends. Source Source position (RA/Dec) Error (B1950) (J2000) (Date) (mas) * J1139+7654 11 36 50.402483 * 11 39 51.538717 11 40 13.600280 1.47 1136+771 77 11 09.68453 * 76 54 32.34642 76 53 06.06924 0.65 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.100 scan hours, 1.894 baseline hours above horizon. * J1323+7942 13 23 30.967861 * 13 23 51.569831 13 24 00.836917 2.82 1323+799 79 58 27.57995 * 79 42 51.84705 79 41 25.76771 0.44 J1323+79 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.283 scan hours, 8.751 baseline hours above horizon. * J1357+7643 13 57 42.117003 * 13 57 55.371534 13 58 02.806741 0.87 1357+769 76 57 53.35424 * 76 43 21.05104 76 41 58.55255 0.40 J1357+76 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.185 baseline hours above horizon. * J1406+7828 14 06 56.652670 * 14 06 36.566944 14 06 41.585608 3.71 1406+787 78 42 22.78156 * 78 28 10.40623 78 26 49.33489 0.63 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.161 baseline hours above horizon. * J1719+1745 17 17 00.324732 * 17 19 13.048481 17 19 28.559864 0.32 1717+178 17 48 08.51599 * 17 45 06.43721 17 44 37.64380 0.22 J1719+17 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 1.739 baseline hours above horizon. * J1745+1720 17 43 22.235899 * 17 45 35.208167 17 45 50.704699 0.32 1743+173 17 21 09.18647 * 17 20 01.42378 17 19 43.97628 0.22 J1745+17 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.300 scan hours, 8.450 baseline hours above horizon. * J1752+1734 17 50 33.364387 * 17 52 46.002901 17 53 01.452521 0.39 1750+175 17 34 56.75224 * 17 34 20.35018 17 34 06.02002 0.56 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.350 baseline hours above horizon. * J1756+1535 17 54 37.953509 * 17 56 53.102132 17 57 08.795390 0.32 15 35 39.32316 * 15 35 20.82657 15 35 08.41956 0.24 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.232 baseline hours above horizon. * J2129-1538 21 26 26.777538 * 21 29 12.175905 21 29 30.394943 0.21 2126-158 -15 51 50.34727 *-15 38 41.04110 -15 37 18.72623 0.30 J2129-15 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.250 scan hours, 9.451 baseline hours above horizon. * J2129-1821 21 26 33.897232 * 21 29 21.419113 21 29 39.890466 0.27 2126-185 -18 34 32.47350 *-18 21 22.79035 -18 19 59.57129 0.49 J2129-18 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.231 baseline hours above horizon. * J2130-0927 21 27 38.408364 * 21 30 19.088248 21 30 36.744372 0.23 2127-096 -09 40 49.81991 *-09 27 37.43511 -09 26 16.73888 0.37 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.505 baseline hours above horizon. * J2131-1207 21 28 52.676063 * 21 31 35.261755 21 31 53.136782 0.21 2128-123 -12 20 20.53564 *-12 07 04.79603 -12 05 42.84703 0.30 J2131-12 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.083 scan hours, 2.844 baseline hours above horizon. * J2148+0657 21 45 36.078475 * 21 48 05.458673 21 48 21.701858 0.30 2145+067 06 43 40.90460 * 06 57 38.60420 06 58 59.23842 0.20 J2148+06 /aps3/sched/catalogs/sources.vlba VLBA Calib Srcs - GSFC sols. - catalog 2004f_astro 0.150 scan hours, 7.749 baseline hours above horizon. The solar corona can cause unstable phases for sources too close to the Sun. SCHED provides warnings at individual scans for distances less than 10 degrees. The distance from the Sun to each source in this schedule is: Source Sun distance (deg) J1139+7654 70.1 J1323+7942 73.5 J1357+7643 76.8 J1406+7828 75.8 J1719+1745 139.3 J1745+1720 138.4 J1752+1734 137.7 J1756+1535 139.3 J2129-1538 116.6 J2129-1821 117.4 J2130-0927 114.3 J2131-1207 115.0 J2148+0657 103.7 Barry Clark estimates from predictions by Ketan Desai of IPM scattering sizes that the Sun will cause amplitude reductions on the longest VLBA baselines at a solar distance of 60deg F^(-0.6) where F is in GHz. For common VLBI bands, this is: 327 MHz 117. deg 610 MHz 81. deg 1.6 GHz 45. deg 2.3 GHz 36. deg 5.0 GHz 23. deg 8.4 GHz 17. deg 15.0 GHz 12. deg 22.0 GHz 9. deg 43.0 GHz 6. deg