COVER INFORMATION Station: MEDICINA (Code Mc ) 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 MEDICINA (Code Mc ) 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: 342.99 342.99 350.99 350.99 358.99 358.99 366.99 366.99 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 48 24 50.4 347.4 3.4 119.6 0 1 1 0 23 00 00 23 02 00 =1323+799 16 50 24 50.3 347.3 3.4 119.0 120 F 1 0 23 02 00 J1139+7654 16 50 24 45.9 341.4 5.2 89.2 -13 1 1 0 23 02 00 23 04 00 =1136+771 16 52 24 45.8 341.4 5.2 88.7 107 F 1 0 23 04 00 J1323+7942 16 52 24 50.2 347.3 3.5 118.5 -13 1 1 0 23 04 00 23 06 00 =1323+799 16 54 25 50.1 347.2 3.5 118.0 107 F 1 0 23 06 00 J1139+7654 16 54 25 45.6 341.5 5.2 88.3 -14 1 1 0 23 06 00 23 08 00 =1136+771 16 56 25 45.5 341.5 5.3 87.8 106 F 1 0 23 08 00 J1323+7942 16 56 25 50.0 347.1 3.5 117.4 -14 1 1 0 23 08 00 23 10 00 =1323+799 16 58 25 50.0 347.1 3.6 116.9 106 F 1 0 23 10 00 J1139+7654 16 58 25 45.4 341.5 5.3 87.3 -14 1 1 0 23 10 00 23 12 00 =1136+771 17 00 25 45.3 341.5 5.3 86.8 106 F 1 0 23 13 00 J1323+7942 17 01 26 49.8 347.0 3.6 116.1 46 1 1 0 23 13 00 23 14 00 =1323+799 17 02 26 49.8 346.9 3.6 115.8 60 F 1 0 23 14 00 J1406+7828 17 02 26 52.2 346.9 2.9 126.2 -9 1 1 0 23 14 00 23 15 40 =1406+787 17 04 06 52.1 346.8 3.0 125.8 91 F 1 0 23 15 40 J1323+7942 17 04 06 49.7 346.9 3.7 115.3 -9 1 1 0 23 15 40 23 17 20 =1323+799 17 05 46 49.7 346.8 3.7 114.9 91 F 1 0 23 17 20 J1406+7828 17 05 46 52.0 346.7 3.0 125.3 -9 1 1 0 23 17 20 23 19 00 =1406+787 17 07 27 52.0 346.7 3.0 124.8 91 F 1 0 23 19 00 J1323+7942 17 07 27 49.6 346.8 3.7 114.4 -9 1 1 0 23 19 00 23 20 40 =1323+799 17 09 07 49.5 346.7 3.8 114.0 91 F 1 0 23 20 40 J1406+7828 17 09 07 51.9 346.6 3.0 124.4 -9 1 1 0 23 20 40 23 22 20 =1406+787 17 10 47 51.8 346.5 3.1 123.9 91 F 1 0 Schedule for MEDICINA (Code Mc ) 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 10 47 49.5 346.7 3.8 113.6 -9 1 1 0 23 22 20 23 24 00 =1323+799 17 12 27 49.4 346.7 3.8 113.1 91 F 1 0 23 24 00 J1357+7643 17 12 27 52.3 343.6 3.2 119.1 -10 1 1 0 23 24 00 23 25 40 =1357+769 17 14 08 52.2 343.5 3.3 118.6 90 F 1 0 23 25 40 J1323+7942 17 14 08 49.3 346.6 3.8 112.7 -10 1 1 0 23 25 40 23 27 20 =1323+799 17 15 48 49.2 346.6 3.9 112.2 90 F 1 0 23 27 20 J1357+7643 17 15 48 52.1 343.5 3.3 118.2 -10 1 1 0 23 27 20 23 29 00 =1357+769 17 17 28 52.0 343.4 3.3 117.7 90 F 1 0 23 29 00 J1323+7942 17 17 28 49.2 346.5 3.9 111.8 -10 1 1 0 23 29 00 23 30 40 =1323+799 17 19 09 49.1 346.5 3.9 111.3 90 F 1 0 23 30 40 J1357+7643 17 19 09 51.9 343.3 3.4 117.2 -10 1 1 0 23 30 40 23 32 20 =1357+769 17 20 49 51.8 343.3 3.4 116.8 90 F 1 0 23 32 20 J1323+7942 17 20 49 49.0 346.4 3.9 110.9 -10 1 1 0 23 32 20 23 34 00 =1323+799 17 22 29 49.0 346.4 4.0 110.4 90 F 1 0 23 40 00 J1745+1720 17 28 30 62.6 531.0 -0.3 -6.7 110 1 1 0 23 40 00 23 44 00 =1743+173 17 32 31 62.7 533.1 -0.2 -5.2 240 F 1 0 23 44 00 J1752+1734 17 32 31 62.7 529.3 -0.3 -8.0 -9 1 1 0 23 44 00 23 45 40 =1750+175 17 34 11 62.8 530.2 -0.3 -7.3 91 F 1 0 23 45 40 J1745+1720 17 34 11 62.7 533.9 -0.2 -4.5 -9 1 1 0 23 45 40 23 47 20 =1743+173 17 35 51 62.7 534.8 -0.2 -3.9 91 F 1 0 23 47 20 J1752+1734 17 35 51 62.8 531.0 -0.3 -6.7 -9 1 1 0 23 47 20 23 49 00 =1750+175 17 37 32 62.9 531.9 -0.3 -6.1 91 F 1 0 23 49 00 J1745+1720 17 37 32 62.8 535.7 -0.1 -3.2 -9 1 1 0 23 49 00 23 50 40 =1743+173 17 39 12 62.8 536.5 -0.1 -2.6 91 F 1 0 23 50 40 J1752+1734 17 39 12 62.9 532.8 -0.2 -5.4 -9 1 1 0 23 50 40 23 52 20 =1750+175 17 40 52 62.9 533.6 -0.2 -4.8 91 F 1 0 23 53 20 J1745+1720 17 41 52 62.8 537.9 -0.1 -1.5 50 1 1 0 23 53 20 23 54 00 =1743+173 17 42 32 62.8 538.3 -0.1 -1.3 40 F 1 0 23 54 00 J1756+1535 17 42 32 60.9 532.8 -0.2 -5.4 -11 1 1 0 23 54 00 23 55 40 --- 17 44 13 60.9 533.6 -0.2 -4.7 89 F 1 0 Schedule for MEDICINA (Code Mc ) 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 44 13 62.8 539.1 0.0 -0.6 -11 1 1 0 23 55 40 23 57 20 =1743+173 17 45 53 62.8 540.0 0.0 0.0 89 F 1 0 23 57 20 J1756+1535 17 45 53 61.0 534.4 -0.2 -4.1 -11 1 1 0 23 57 20 23 59 00 --- 17 47 33 61.0 535.2 -0.2 -3.5 89 F 1 0 --- Start: Mon 6 Jun 2005 Day 157 -- Stop: Tue 7 Jun 2005 Day 158 --- 23 59 00 J1745+1720 17 47 33 62.8 540.9 0.0 0.7 -11 1 1 0 23 59 00 00 00 40 =1743+173 17 49 13 62.8 541.8 0.1 1.3 89 F 1 0 00 00 40 J1756+1535 17 49 13 61.0 536.1 -0.1 -2.9 -12 1 1 0 00 00 40 00 02 20 --- 17 50 54 61.0 536.9 -0.1 -2.3 88 F 1 0 00 02 20 J1745+1720 17 50 54 62.8 542.6 0.1 2.0 -12 1 1 0 00 02 20 00 04 00 =1743+173 17 52 34 62.8 543.5 0.1 2.6 88 F 1 0 00 04 00 J1719+1745 17 52 34 62.3 557.2 0.6 12.8 -22 1 1 0 00 04 00 00 05 40 =1717+178 17 54 14 62.2 558.0 0.6 13.4 78 F 1 0 00 05 40 J1745+1720 17 54 14 62.8 544.4 0.1 3.3 -22 1 1 0 00 05 40 00 07 20 =1743+173 17 55 55 62.7 545.2 0.2 3.9 78 F 1 0 00 07 20 J1719+1745 17 55 55 62.2 558.8 0.6 14.0 -22 1 1 0 00 07 20 00 09 00 =1717+178 17 57 35 62.1 559.7 0.6 14.6 78 F 1 0 00 09 00 J1745+1720 17 57 35 62.7 546.1 0.2 4.6 -22 1 1 0 00 09 00 00 10 40 =1743+173 17 59 15 62.7 547.0 0.2 5.2 78 F 1 0 00 10 40 J1719+1745 17 59 15 62.0 560.5 0.7 15.2 -22 1 1 0 00 10 40 00 12 20 =1717+178 18 00 55 61.8 561.3 0.7 15.8 78 F 1 0 00 12 20 J1745+1720 18 00 55 62.6 547.8 0.3 5.9 -22 1 1 0 00 12 20 00 14 00 =1743+173 18 02 36 62.6 548.7 0.3 6.5 78 F 1 0 00 17 00 J2148+0657 18 05 36 29.0 470.4 -3.7 -42.3 72 1 1 0 00 17 00 00 26 00 =2145+067 18 14 38 30.5 472.4 -3.6 -41.6 540 F 1 0 00 29 00 J2129-1538 18 17 38 15.7 492.0 -3.2 -33.4 146 1 1 0 00 29 00 00 30 00 =2126-158 18 18 38 15.9 492.2 -3.2 -33.3 60 F 1 0 00 30 00 J2129-1821 18 18 38 13.6 493.7 -3.2 -32.9 -9 1 1 0 00 30 00 00 31 40 =2126-185 18 20 19 13.8 494.1 -3.2 -32.7 91 F 1 0 Schedule for MEDICINA (Code Mc ) 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 20 19 16.1 492.6 -3.2 -33.0 -9 1 1 0 00 31 40 00 33 20 =2126-158 18 21 59 16.3 492.9 -3.1 -32.8 91 F 1 0 00 33 20 J2129-1821 18 21 59 14.0 494.4 -3.1 -32.5 -9 1 1 0 00 33 20 00 35 00 =2126-185 18 23 39 14.2 494.7 -3.1 -32.2 91 F 1 0 00 35 00 J2129-1538 18 23 39 16.5 493.3 -3.1 -32.6 -9 1 1 0 00 35 00 00 36 40 =2126-158 18 25 19 16.7 493.6 -3.1 -32.4 91 F 1 0 00 36 40 J2129-1821 18 25 19 14.4 495.1 -3.1 -32.0 -9 1 1 0 00 36 40 00 38 20 =2126-185 18 27 00 14.6 495.4 -3.0 -31.8 91 F 1 0 00 38 20 J2129-1538 18 27 00 16.9 494.0 -3.0 -32.2 -9 1 1 0 00 38 20 00 40 00 =2126-158 18 28 40 17.2 494.3 -3.0 -32.0 91 F 1 0 00 40 00 J2130-0927 18 28 40 22.2 490.5 -3.0 -33.3 -15 1 1 0 00 40 00 00 41 40 =2127-096 18 30 20 22.4 490.9 -3.0 -33.1 85 F 1 0 00 41 40 J2129-1538 18 30 20 17.4 494.7 -3.0 -31.8 -15 1 1 0 00 41 40 00 43 20 =2126-158 18 32 01 17.6 495.0 -3.0 -31.5 85 F 1 0 00 43 20 J2130-0927 18 32 01 22.7 491.3 -3.0 -32.9 -15 1 1 0 00 43 20 00 45 00 =2127-096 18 33 41 22.9 491.7 -2.9 -32.7 85 F 1 0 00 45 00 J2129-1538 18 33 41 17.8 495.4 -2.9 -31.3 -15 1 1 0 00 45 00 00 46 40 =2126-158 18 35 21 18.0 495.8 -2.9 -31.1 85 F 1 0 00 46 40 J2130-0927 18 35 21 23.1 492.0 -2.9 -32.5 -15 1 1 0 00 46 40 00 48 20 =2127-096 18 37 01 23.3 492.4 -2.9 -32.2 85 F 1 0 00 49 20 J2129-1538 18 38 01 18.3 496.4 -2.9 -30.7 45 1 1 0 00 49 20 00 50 00 =2126-158 18 38 42 18.4 496.5 -2.8 -30.6 40 F 1 0 00 50 00 J2131-1207 18 38 42 21.1 494.0 -2.9 -31.6 -10 1 1 0 00 50 00 00 51 40 =2128-123 18 40 22 21.3 494.4 -2.9 -31.4 90 F 1 0 00 51 40 J2129-1538 18 40 22 18.6 496.9 -2.8 -30.4 -10 1 1 0 00 51 40 00 53 20 =2126-158 18 42 02 18.8 497.2 -2.8 -30.2 90 F 1 0 00 53 20 J2131-1207 18 42 02 21.6 494.8 -2.8 -31.2 -10 1 1 0 00 53 20 00 55 00 =2128-123 18 43 42 21.8 495.2 -2.8 -30.9 90 F 1 0 00 55 00 J2129-1538 18 43 42 19.0 497.6 -2.8 -29.9 -10 1 1 0 00 55 00 00 56 40 =2126-158 18 45 23 19.2 498.0 -2.7 -29.7 90 F 1 0 Schedule for MEDICINA (Code Mc ) 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 45 23 22.0 495.5 -2.8 -30.7 -10 1 1 0 00 56 40 00 58 20 =2128-123 18 47 03 22.2 495.9 -2.7 -30.5 90 F 1 0 00 58 20 J2129-1538 18 47 03 19.4 498.3 -2.7 -29.5 -10 1 1 0 00 58 20 01 00 00 =2126-158 18 48 43 19.6 498.7 -2.7 -29.2 90 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 mc18cm in /aps3/sched/catalogs/freq.dat updated from Maccaferri (CR 2Dec00) Setup group: 5 Station: MEDICINA 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= 1295.00 1295.00 1295.00 1295.00 1295.00 1295.00 1295.00 1295.00 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: 5 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= 342.99 342.99 350.99 350.99 358.99 358.99 366.99 366.99 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