Goldstone Radar Observations Planning: 1566 Icarus
Goldstone delay-Doppler image of Icarus obtained on June 17. Resolution is 75 m x 0.48 Hz. Range increases down and Doppler frequency increases to the right. The image spans an interval of about 1.7 hours and includes considerable rotation by this object, which has a rotation period of 2.3 h. The image uses false color.
Goldstone echo power spectrum from June 13. This is a sum of 7 runs at a frequency resolution of 2 Hz. The data have not been properly normalized. Red and green curves indicate echo power in the OC and SC polarizations.
Goldstone echo power spectrum obtained on June 14. The frequency resolution is 0.5 Hz. This is a sum of 11 runs.
Collage of echo power spectra from June 16. The times spanned by each frame are listed on the figure. The frequency resolution is 0.5 Hz.
1566 Icarus was discovered on Jun 27, 1949 by Walter Baade at Palomar Observatory. Its name was chosen from Greek mythology because Icarus, the son of Daedalus, got very close to the Sun. Asteroid Icarus has a perihelion distance of only 0.187 au (40 solar radii) that is one of the closest known. Icarus has been the subject of many observations at optical wavelengths and there is considerable information about its physical characteristics (Gehrels et al. 1970, Chapman et al. 1975, De Angelis 1995, Hicks et al. 1998). Icarus has a rapid rotation period of 2.27 h, a moderate lightcurve amplitude of 0.2 magnitudes, a Q-class spectral classification, and a diameter of 1.3 km (Harris 1998). About 2/3 of NEAs with such rapid rotation periods have satellites although one has not yet been detected for Icarus. Icarus makes periodic close approaches within 0.1 au of Earth. The last occured in 1968 at 0.042 au when Icarus became the first asteroid to be detected with radar. R. Goldstein observed Icarus at Goldstone and G. Pettengill observed it at Haystack. The observations were CW-only and they provided estimates of the asteroid's radar cross section, size, and rotation period. Goldstein et al (1968) reported a radius of 0.3-0.6 km, a rotation period of 1.5-3 h, and a radar cross section of 0.1 km^2. The 1968 observations also yielded the first radar astrometry for an asteroid. Icarus was observed with radar again in 1996 at a distance of 0.10 au (Mahapatra et al. 1999). The SNRs were weak and suitable only for CW observations. Mahapatra et al. obtained an OC radar cross section of 0.05 km^2 +- 35% that appears smaller than the values reported by Goldstein (1968) and Pettengill et al. (1969). Mahapatra et al. also raised questions about the validity of the previously reported diameter of 1.3 km and the pole direction of lambda = 214 +- 5 deg, beta= 5 +- 5 deg. In 2015 Icarus should yield SNRs strong enough for ranging, delay-Doppler imaging, and 3D shape estimation. Observations are scheduled at both Goldstone and Arecibo. At Goldstone the images could achieve a resolution of 75 m/pixel and at Arecibo the resolution is likely to be 7.5 m/pixel. Because of its very low perihelion distance, the orbital motion of Icarus exhibits perturbations due to solar oblateness and general relativity. Detailed astrometric measurements should eventually permit isolation of the relativistic effects and act as a test of general relativity. Radar ranging measurements in 2015 will help facilitate this. Goldstone observations of Icarus are scheduled on June 13/14, 14/15 and 16/17. Observations at Arceibo are scheduled on June 17-21. Icarus will be an excellent target for optical observations in the second half of June when it will reach 13th magnitude and be visible in relatively small telescopes. After 2015, the next opportunity for radar observations of Icarus will occur at Arecibo in 2024 during a distant approach within 0.23 au. The Minor Planet Center has classified Icarus as a "Potentially Hazardous Asteroid."
Orbital and Physical Characteristics Name Icarus (1949 MA) Asteroid number 1566 Discoverer W. Baade, Palomar Observatory Discovery date 1949 Jun 27 orbit type Apollo Close approach date 2015 June 16 Close approach dist. 0.0538 au Close approach dist. 20.9 lunar distances (8.0 million km) semimajor axis 1.078 au eccentricity 0.827 inclination 22.8 deg perihelion distance 0.187 au (40.2 solar radii) aphelion distance 1.969 au Tisserand parameter 5.299 --> Asteroidal absolute magnitude (H) 15.95, 16.3 +- 0.3 mag Tedesco (1989), Harris (1998) diameter 1.27 km Harris (1998) Pincipal axis ratio a/b/c 1.23/1.0/0.7 De Angelis (1995) optical albedo 0.14 rotation period 2.2735 +- 0.0002 h De Angelis (1995) pole direction lambda = 49 or 229 +- 3 deg, beta=0 +- 3 deg Gehrels et al. (1970) lambda = 214 +- 5 deg, beta= 5 +- 5 deg De Angelis (1995) Max. lightcurve amplitude 0.22 Gherels et al. (1970) spectral class SU, Q Chapman et al. (1975), Tholen (1989), Hicks et al. (1998), DeMeo et al. (2014) Radar Observations: 1968: Goldstein (1968, 1969) and Pettengill et al. (1969) 1996: Mahapatra et al. (1999) Last update: 2015 June 18
Icarus was discovered well before MPECs existed. The discovery was probably announced in an IAU Circular in 1949, but Circulars that far back are not available online.
SNR Calculations
GOLDSTONE SNRs Assumptions: D = 1.0 km, P = 2.27 h, OC radar albedo = 0.13, pole lambda = 214 deg, beta = 5 deg WK DOY start date window RA, dec dist delta runs SNR/day SNR/run 24 160 2015 Jun 9 12:32-02:03 69, +50 0.131 +39 198 13 1 24 161 2015 Jun 10 12:32-02:28 73, +52 0.116 +35 232 22 2 24 162 2015 Jun 11 12:35-03:08 79, +56 0.100 +31 278 38 3 24 163 2015 Jun 12 12:46-04:13 89, +59 0.086 +24 344 72 4 24 164 2015 Jun 13 13:14-06:01 106, +63 0.072 +15 437 140 8 Scheduled 24 165 2015 Jun 14 14:34-07:58 137, +64 0.061 +2 523 270 13 Scheduled 25 166 2015 Jun 15 17:23-08:53 170, +56 0.055 -16 507 400 20 25 167 2015 Jun 16 20:00-09:06 190, +42 0.054 -35 436 410 22 Scheduled 25 168 2015 Jun 17 21:35-09:02 201, +27 0.060 -52 353 310 18 25 169 2015 Jun 18 22:35-08:53 208, +16 0.069 -66 278 200 13 25 170 2015 Jun 19 23:16-08:43 212, +7 0.082 -75 220 130 9 25 171 2015 Jun 20 23:45-08:33 215, +1 0.095 -81 177 85 7 26 173 2015 Jun 22 00:06-08:23 217, -4 0.110 -84 146 58 5 26 174 2015 Jun 23 00:22-08:13 219, -8 0.126 -85 123 33 3 26 175 2015 Jun 24 00:35-08:05 220, -10 0.142 -83 105 18 2 26 176 2015 Jun 25 00:45-07:57 221, -13 0.158 -81 91 10 1 Goldstone SNRs assume Ptx = 440 kW and T = 18 K. In the SNR calculations we adopted a diameter somewhat smaller than that reported by Harris et al. 1998, so the SNRs here should be conservative. Bandwidth changes due to variations in the subradar latitude (delta) should be up to 20%. ARECIBO SNRs w DOY start date window RA, dec delta dist runs SNR/day SNR/run 25 168-169 2015 Jun 17-18 22:52-01:18 200, +29 -66 0.059 72 3600 450 25 169-170 2015 Jun 18-19 23:04-01:50 207, +17 -75 0.068 72 2700 330 25 170-171 2015 Jun 19-20 23:31-01:50 211, +8 -81 0.080 51 1600 240 26 172 2015 Jun 21 00:08-01:30 215, +1 -84 0.093 25 700 150 Assumptions: Ptx = 800 kW, Tsys = 23 K Due to the high subradar latitudes, the bandwidths at Arecibo should be narrow and change by a factor of about four if the pole direction we adopted is correct.
Track Assignments
DOY BOA BOT EOT EOA 164 2255 0025 0130 0200 DSS-14 GSSR AST ICARUS 165 2245 0015 0345 0415 DSS-14 GSSR AST ICARUS 167 2145 2315 0330 0400 DSS-14 GSSR AST ICARUS Transmit Authorization Times: Goldstone tracks: UT UT PDT Duration Round-trip DOY Date TX Window TX Window hh:mm time (sec) SNR/RTT Rotations 164-165 Jun 13-14 2325-0130 1625-1830 Jun 13 2:05 68.9 8 0.916 165-166 Jun 14-15 2315-0345 1615-2045 Jun 14 3:30 60.2 13 1.539 167-168 Jun 16-17 2215-0330 1515-2030 Jun 16 5:15 54.0 22 2.309 The start times assume that transmit authorization occurs only 30 min after precal starts. If it doesn't, we'll update the website accordingly. Elevation limits at Goldstone: Date__(UT)__HR:MN R.A._(a-appar)_DEC. Azi_(a-appr)_Elev 2015-Jun-13 23:25 *m 108.21769 63.58066 337.3557 57.0308 2015-Jun-14 01:30 * 110.23674 63.80657 327.9224 45.5503 2015-Jun-14 23:15 *m 136.49677 64.17489 1.5460 61.2322 2015-Jun-15 03:45 N 142.52989 63.54631 327.2837 44.4886 2015-Jun-16 22:15 *m 187.05306 44.88334 57.9186 40.5409 2015-Jun-17 02:50 *t 189.85587 42.07752 354.8806 83.3192 2015-Jun-17 03:30 C 190.23733 41.66499 310.5392 79.7322 Arecibo tracks: UT UT PDT Duration Round-trip Date TX Window TX Window hh:mm time (sec) Rotations Jun 17-18 2252-0118 1552-1818 Jun 17 2:26 59 1.07 Jun 18-19 2304-0150 1604-1850 Jun 18 2:46 68 1.22 Jun 19-20 2331-0150 1631-1850 Jun 19 2:19 80 1.02 Jun 21-21 0000-0130 1700-1830 Jun 20 1:30 93 0.66
Uncertainties
1566 Icarus JPL/Horizons solution 79, # obs: 863 (1949-2014): Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta POS_3sigma DOP_S_3sig DOP_X_3sig RT_delay_3sig 2015-Jun-01 00:00 * 58.93611 38.52820 0.28466925933857 0.448 0.43 1.55 0.000640 2015-Jun-02 00:00 * 59.36732 39.23349 0.26632980638835 0.471 0.39 1.42 0.000626 2015-Jun-03 00:00 * 59.89112 40.01535 0.24822834866175 0.497 0.36 1.30 0.000613 2015-Jun-04 00:00 * 60.53060 40.89170 0.23035532568331 0.526 0.33 1.18 0.000602 2015-Jun-05 00:00 * 61.31745 41.88545 0.21270647934715 0.558 0.29 1.07 0.000593 2015-Jun-06 00:00 * 62.29639 43.02618 0.19528418817036 0.595 0.27 0.97 0.000584 2015-Jun-07 00:00 * 63.53268 44.35269 0.17809964958526 0.637 0.24 0.88 0.000578 2015-Jun-08 00:00 * 65.12532 45.91624 0.16117645403203 0.685 0.23 0.83 0.000573 2015-Jun-09 00:00 * 67.23149 47.78471 0.14455653222704 0.742 0.23 0.84 0.000570 2015-Jun-10 00:00 * 70.11470 50.04625 0.12831029925841 0.807 0.26 0.93 0.000569 2015-Jun-11 00:00 * 74.24647 52.80684 0.11255445989686 0.885 0.30 1.10 0.000570 2015-Jun-12 00:00 * 80.53431 56.15912 0.09748407054033 0.979 0.37 1.35 0.000572 2015-Jun-13 00:00 * 90.83700 60.03558 0.08343074367309 1.096 0.46 1.69 0.000573 2015-Jun-14 00:00 *m 108.77293 63.64670 0.07096352076258 1.257 0.69 2.49 0.000568 2015-Jun-15 00:00 *m 137.49670 64.09212 0.06102864891809 1.508 1.34 4.88 0.000544 2015-Jun-16 00:00 *m 167.94853 57.15072 0.05498902709513 1.870 2.56 9.31 0.000482 2015-Jun-17 00:00 *m 188.16362 43.81906 0.05414588341088 2.179 3.61 13.10 0.000376 2015-Jun-18 00:00 *m 199.77834 29.34421 0.05871431682856 2.200 3.59 13.04 0.000253 2015-Jun-19 00:00 *m 206.78275 17.24816 0.06760373232586 1.978 2.84 10.32 0.000158 2015-Jun-20 00:00 *m 211.35098 8.18722 0.07937777744567 1.686 2.04 7.41 0.000114 2015-Jun-21 00:00 *m 214.53829 1.57080 0.09295188651571 1.420 1.43 5.20 0.000117 2015-Jun-22 00:00 *m 216.88423 -3.31462 0.10765428076046 1.204 1.01 3.69 0.000137 2015-Jun-23 00:00 *m 218.68560 -7.00659 0.12308934257865 1.032 0.73 2.67 0.000157 2015-Jun-24 00:00 *m 220.11696 -9.86771 0.13902183592993 0.897 0.54 1.98 0.000173 2015-Jun-25 00:00 *m 221.28692 -12.13773 0.15530759178081 0.788 0.42 1.51 0.000186 2015-Jun-26 00:00 *m 222.26626 -13.97681 0.17185511811437 0.700 0.33 1.19 0.000197 2015-Jun-27 00:00 *m 223.10296 -15.49420 0.18860437321284 0.628 0.27 0.97 0.000205 2015-Jun-28 00:00 *m 223.83061 -16.76621 0.20551474555348 0.568 0.23 0.82 0.000211 ********************************************************************************************** Apparent Magnitudes, Solar Elongations, Lunar Elongations, and Lunar Illumination: Date__(UT)__HR:MN R.A._(a-appar)_DEC. delta APmag S-brt S-O-T /r T-O-M/Illu% 2015-Jun-06 00:00 62.30984 43.02959 0.19530759216878 22. 8. 22.5258 /L 125.7/ 87.0 2015-Jun-07 00:00 63.54774 44.35622 0.17812342541319 22. 8. 23.5362 /L 114.4/ 78.6 2015-Jun-08 00:00 65.14238 45.91982 0.16120077211992 21. 8. 24.6879 /L 103.3/ 68.6 2015-Jun-09 00:00 67.25107 47.78820 0.14458160956052 21. 8. 26.0532 /L 92.6/ 57.6 2015-Jun-10 00:00 70.13754 50.04937 0.12833641409569 20. 7. 27.7503 /L 82.7/ 46.1 2015-Jun-11 00:00 74.27355 52.80904 0.11258196850613 20. 7. 29.9749 /L 74.1/ 34.9 2015-Jun-12 00:00 80.56683 56.15929 0.09751341820944 19. 7. 33.0513 /T 67.6/ 24.4 2015-Jun-13 00:00 90.87522 60.03157 0.08346244123697 18. 7. 37.5072 /T 64.1/ 15.4 2015-Jun-14 00:00 108.81023 63.63519 0.07099799908708 17. 6. 44.1417 /T 64.3/ 8.2 * 2015-Jun-15 00:00 137.50766 64.07316 0.06106579602706 16. 6. 53.9246 /T 68.5/ 3.2 * 2015-Jun-16 00:00 167.92459 57.13620 0.05502731214207 14.75 5.28 67.2965 /T 75.6/ 0.6 2015-Jun-17 00:00 188.13068 43.81837 0.05418210207664 13.95 4.88 82.7984 /T 82.5/ 0.4 * 2015-Jun-18 00:00 199.74814 29.35461 0.05874555610887 13.58 4.60 97.2133 /T 85.8/ 2.5 2015-Jun-19 00:00 206.75689 17.26328 0.06762923617553 13.53 4.41 108.3253 /T 84.4/ 6.5 2015-Jun-20 00:00 211.32890 8.20302 0.07939832005065 13.66 4.29 116.0475 /T 79.2/ 12.3 2015-Jun-21 00:00 214.51923 1.58568 0.09296859738366 13.87 4.21 121.2123 /T 71.9/ 19.4 2015-Jun-22 00:00 216.86754 -3.30110 0.10766813915262 14.11 4.16 124.6370 /T 63.2/ 27.6 2015-Jun-23 00:00 218.67081 -6.99440 0.12310109156497 14.35 4.14 126.9023 /T 53.9/ 36.5 2015-Jun-24 00:00 220.10372 -9.85671 0.13903202002566 14.59 4.13 128.3868 /T 44.0/ 45.8 2015-Jun-25 00:00 221.27496 -12.12775 0.15531660971792 14.81 4.12 129.3338 /T 33.7/ 55.2 2015-Jun-26 00:00 222.25536 -13.96770 0.17186326529395 15.03 4.13 129.9014 /T 23.1/ 64.6 2015-Jun-27 00:00 223.09297 -15.48584 0.18861187191895 15.23 4.13 130.1949 /T 12.3/ 73.6 2015-Jun-28 00:00 223.82140 -16.75848 0.20552176576122 15.42 4.14 130.2857 /T 3.383/ 81.8 2015-Jun-29 00:00 224.46487 -17.84017 0.22256470281928 15.61 4.16 130.2238 /T 12.0/ 88.9 2015-Jun-30 00:00 225.04123 -18.77072 0.23972061428306 15.78 4.17 130.0447 /T 24.1/ 94.6 2015-Jul-01 00:00 225.56391 -19.57982 0.25697496392379 15.94 4.19 129.7742 /T 36.7/ 98.3 2015-Jul-02 00:00 226.04319 -20.28996 0.27431705386002 16.10 4.21 129.4315 /T 49.8/ 99.8 2015-Jul-03 00:00 226.48709 -20.91850 0.29173890574056 16.25 4.22 129.0311 /T 63.2/ 98.8 2015-Jul-04 00:00 226.90193 -21.47900 0.30923449788255 16.39 4.24 128.5840 /T 76.9/ 95.1 2015-Jul-05 00:00 227.29280 -21.98222 0.32679922669442 16.53 4.26 128.0988 /T 90.7/ 89.0 2015-Jul-06 00:00 227.66382 -22.43680 0.34442951345637 16.66 4.28 127.5823 /T 104.5/ 80.7 2015-Jul-07 00:00 228.01836 -22.84974 0.36212251004125 16.79 4.29 127.0398 /T 118.3/ 70.8 2015-Jul-08 00:00 228.35923 -23.22678 0.37987587654860 16.91 4.31 126.4759 /T 132.0/ 59.8 2015-Jul-09 00:00 228.68877 -23.57269 0.39768761427610 17.02 4.33 125.8939 /T 145.3/ 48.4 2015-Jul-10 00:00 229.00894 -23.89142 0.41555594240351 17.14 4.35 125.2969 /T 158.0/ 37.2 2015-Jul-11 00:00 229.32140 -24.18632 0.43347920911540 17.25 4.36 124.6872 /T 168.4/ 26.8 2015-Jul-12 00:00 229.62753 -24.46020 0.45145582949359 17.35 4.38 124.0670 /T 168.1/ 17.7 2015-Jul-13 00:00 229.92852 -24.71549 0.46948424405115 17.45 4.40 123.4378 /T 157.8/ 10.2 2015-Jul-14 00:00 230.22537 -24.95423 0.48756289318467 17.55 4.41 122.8012 /T 145.8/ 4.8 2015-Jul-15 00:00 230.51893 -25.17819 0.50569020382858 17.64 4.43 122.1583 /T 133.6/ 1.4
Setups
The main goal during the first track (June 13-14) is to get a range. Due to its diameter of 1.3 km and 2.273-h rotation period, we are expecting a maximum bandwidth of about 55-60 Hz. The setup below will resolve the echo and also allow us to see it quickly. CW setup: --------------------------------------------------------------------------- TX polarization RCP RCV polarization LCP & RCP Frequency hops: no hopping Bandwidth: 5000 Hz TXoffset +500 Hz FFT for PFS files: 1000 for 5.0 Hz resolution Ranging setups: --------------------------------------------------------------------------- 10-usec baud 10 usec code 127 PRP 1270 usec FFT 64 ncoh 1 bandwidth 787 Hz resolution 12.3 Hz TXOFF +100Hz (echo in bin 32 + 8 = 40) --------------------------------------------------------------------------- 11-usec baud 11 usec code 127 PRP 1397 usec FFT 64 ncoh 1 bandwidth 716 Hz resolution 11.2 Hz TXOFF +100 Hz (echo in bin 32 + 9= 41) ---------------------------------------------------------------------
Instructions
NOTE: Data should be moved to the appropriate subdirectories in aardvark:/export/data0/a1566/raw/
POINTING:
OSOD and predicts will be on aardvark: ...not available yet... POINTING TX Offsets Date (UTC) DOY hhmmss RA Dec Macro LHA Dec RTT OSOD ... to be added ... Transmit offsets are given in millidegrees.
PRDX.OUT.14f-14-14.?? TRANSMITTER: STATION #14, RECEIVER: STATION #14 RECEIVER U.T. RANGE DOPPLER LHA DEC RA EL
1566 Icarus GOLDSTONE MASTERLOG
June 13 <--- UTC ---> rcsta rcend Setup Code Bandwidth osod PFS FFT delta f TX Offset Runs HHMMSS-HHMMSS CW, no hops 5000 Hz 82 2500 2 Hz +500 Hz 8 234028-235826 10 us ncoh=1 127 787 Hz 82 32 24.6 Hz +100 Hz 6 000615-001914 11 us ncoh=1 127 716 Hz 82 32 22.4 Hz +100 Hz 9 002354-004359 11 us ncoh=1 127 716 Hz 84 32 22.4 Hz +100 Hz 5 004605-005642 1 us ncoh=1 1023 490 Hz 84 32 30.5 Hz +100 Hz 13 010105-013038 2015 6 13 23:50:00 P 1123284.559 5.0 8560.D6 -14 -14 MB,LB,SN,JDG,MWB Correction of -3 Hz to s82 from CW echoes w/2 Hz res'n. Echo is ~35 Hz wide. 2015 6 14 00:30:00 R 70.58381478 20.0 8560.D6 -14 MB,LB,SN,MWB GSSR, delay correction based on 10 and 11 usec bauds and 127 length code Range correction to s82 is -1600 usec 2015 6 14 01:10:00 R 70.27222912 3.0 8560.D6 -14 MB,LB,SN,JDG,MWB GSSR, delay correction based on 1 usec baud, 1023 length code Range correction to s84 is -12 usec ----------------------------------------------------------------------- June 14 <--- UTC ---> rcsta rcend Setup Code Bandwidth osod PFS FFT delta f TX Offset Runs HHMMSS-HHMMSS CW, no hops 5000 Hz 90 10,000 0.5 Hz +500 Hz 11 232137-234306 10 us ncoh=1 127 787 Hz 90 32 24.6 Hz +100 Hz 3 234643-235146 0.5 us ncoh=16 255 s 490 Hz 90 128 3.8 Hz +100 Hz 7 235736-001047 NOTE: klystron problems cancelled the rest of the track 2015 6 14 23:30:00 P 822302.025 5.0 8560.D6 -14 -14 MB,SN,LB,MWB,JDG Correction of 0 Hz to s90 from CW echoes w/.5 Hz res'n. Echo is ~30 Hz wide. 2015 6 15 00:00:00 R 60.90328894 2.0 8560.D6 -14 MB,LB,SN,MWB,JDG GSSR, delay correction based on 0.5 usec baud, 255 length code Range correction to s90 is -3 usec ----------------------------------------------------------------------- June 16 <--- UTC ---> rcsta rcend Setup Code Bandwidth osod PFS FFT delta f TX Offset Runs HHMMSS-HHMMSS 10 us ncoh=1 127 787 Hz 92 32 24.6 Hz +100 Hz 3 224941-225410 0.5 us ncoh=16 255 490 Hz 92 1024 0.48 Hz +100 Hz 16 230029-232821 CW, no hops 5000 Hz 92 10,000 0.5 Hz +500 Hz 73 233236-014530 0.5 us ncoh=16 255 490 Hz 92 1024 0.48 Hz +100 Hz 55 014958-032952 2015 6 16 23:20:00 R 53.98421338 2.0 8560.D6 -14 MB,LB,SN,MWB,JDG GSSR, delay correction based on 0.5 usec bauds and 255 length code Range correction to s92 is -0.5 usec -----------------------------------------------------------------------
Dr. Lance A. M. Benner | PHONE: (818) 354-7412 Mail Stop 183-601 | FAX: (818) 393-4445 Jet Propulsion Laboratory | email: lance.benner@jpl.nasa.gov California Institute of Technology | Plan: To live long and prosper Pasadena, CA 91109-8099 http://echo.jpl.nasa.gov/asteroids/Icarus/Icarus_planning.html
Asteroid Radar Astronomy
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