Technical description of the global solution opa2024a 1. Origin of input data: databases from IVS data center, version 4 or more. 2. Authentic processing steps after data retrieval: use VGOSDB format. Pre-2018 data were originally stored in MK3 format in Paris Observatory disks. These data were transformed to VGOSDB. Some of them (oldest ones) were preliminary re-calced with Calc 11.0. Post-2018 data were directly retrieved in VGOSDB format and processed with no modification. 3. Origin of meteorological data: use database content. 4. Use numerical weather model: ECMWF for computing VMF1. 5. Setting of mapping functions: VMF1. 6. Origin of cable cal data: use database content. 7. Application of cable cal flags: use database settings. 8. Selection/settings of geophysical models: replace database settings. 8.1. Nutation/precession: IAU 2000A nutation and IAU 2006 precession. 8.2. Short-period tidal variations in x, y, UT1: IERS 2010. 8.3. Troposphere mapping functions: VMF1. 8.4. A priori mean gradients: from VLBI data or DAO weather model. 8.5. Solid Earth tide: IERS 2010. 8.6. Ocean loading displacements: FES 2004. 8.7. Atmospheric loading displacements: APLO. 8.8. Permanent tide correction: applied. 8.9. Thermal expansion: Nothnagel (2008). 8.10. A priori station positions and velocities: ITRF 2020 or database content for new stations. 8.11. A priori source coordinates: ICRF3 or database content for new sources. 8.12. Galactic aberration: applied with amplitude of 5.8 micros/yr and epoch 2015.01.01. 9. Parameterization 9.1. Clock: quadratic + continuous piece-wise linear with 60-mn interval. 9.2. Atmosphere: continuous piece-wise linear 20-mn interval. 9.3. Gradients: estimated at 6-hr interval at all sites. 9.4. Earth orientation: polar motion and rate, UT1 and rate, nutation offsets. 9.5. Station positions: 9.5.1. Most of the station positions and velocities estimated globally at epoch 2000.01.01. 9.5.2. Jumps: applied. 9.5.3. Nonlinear position variations modeled with splines using Solve's option SPLINE_POS for: HRAS_085 PIETOWN GILCREEK 9.5.4. The data relevant to the stations used for polarization tests or backend tests were removed: NOTOX WIDE85_3 VLBA85_3 MOJAVLBA LEFT85_1 HARTDBBC YEBESDBC YEBDBBC \ ONSALAAN YEBEDBBC OHIGGADS WETTDBBC LEFTKOK LEFT85_3 NYALDBBC HOBADBBC \ SVERT13V 9.6. Station velocities: estimated as global parameters. 9.7. Source coordinates 9.7.1. All global. 9.7.2. The data relevant to the following sources were removed: The radio stars: 0236+610 0459-753 1612+339 0334+004 0323+285 1458-083 \ The known gravitational lenses: 0218+35A 0218+35B 0218+357 1422+231 1830-21A 1830-21B 1830-211 0132-097 9.8. Antenna axis offsets: estimated for the following sites which have observed in more than 5 sessions and treated as global parameters. 10. Outlier elimination: use database settings. 11. Constraints (only of interest for direct EOP estimates) 11.1. Sources: loose no-net rotation is uniformly applied to the 303 ICRF3 defining sources: 0002-478 0007+106 0009-148 0010+405 0013-005 0016+731 0017+200 0035-252 \ 0038-326 0044-846 0046+316 0047+023 0048-097 0054+161 0059+581 0104-408 \ 0107-610 0110+495 0133+476 0149+218 0159+723 0202-172 0202+319 0208-512 \ 0215+015 0221+067 0227-369 0227+403 0230-790 0234-301 0235+164 0235-618 \ 0237-027 0239+175 0256-005 0300+470 0302+625 0305+039 0307+380 0308-611 \ 0312+100 0316-444 0322+222 0332-403 0334-131 0346-279 0346+800 0347-211 \ 0355-669 0400-319 0402-362 0403-132 0406-127 0415+398 0420+022 0430+289 \ 0437-454 0454-234 0454-810 0454+844 0458-020 0506+101 0506-612 0507+179 \ 0510+559 0515+208 0522-611 0524+034 0524-485 0529+483 0530-727 0534-340 \ 0536+145 0537-286 0539-057 0544+273 0548+084 0552+398 0556+238 0605-085 \ 0607-157 0613+570 0615+820 0627-199 0641+392 0642-349 0646-306 0648-165 \ 0657+172 0700-197 0700-465 0716+714 0727-115 0736+017 0738+491 0738-674 \ 0742-562 0743-006 0743+259 0743+277 0748+126 0749+540 0759+183 0800+618 \ 0802-010 0804-267 0804+499 0805+410 0808+019 0809-493 0818-128 0826-373 \ 0829+089 0834-201 0834+250 0847-120 0855-716 0912+297 0918-534 0920+390 \ 0926-039 0930-080 0943+105 0951+268 0954+658 0955+476 1004-217 1004-500 \ 1012+232 1015+057 1016-311 1022+194 1022-665 1027-186 1034-374 1036-529 \ 1040+244 1042+071 1053+704 1059+282 1101-536 1111+149 1116-462 1124-186 \ 1130+009 1133-032 1143-245 1143-332 1143-696 1144-379 1144+402 1149-084 \ 1150+497 1219+044 1221+809 1222+131 1226+373 1227+255 1236+077 1243-072 \ 1243-160 1244-255 1245-457 1251-713 1300+580 1306-395 1308+328 1312-533 \ 1313-333 1324+224 1325+126 1325-558 1330+022 1330+476 1334-127 1348+308 \ 1351-018 1357+769 1406-076 1406-267 1412-368 1418+546 1420-679 1423+146 \ 1424-418 1428+370 1435-218 1443-162 1448-648 1448+762 1451-400 1502+106 \ 1504+377 1508+572 1510-089 1511-476 1511-558 1514+197 1519-273 1520+319 \ 1520+437 1538+149 1555+001 1556-245 1557+032 1600-445 1602-115 1606+106 \ 1606-398 1608+243 1619-680 1623+578 1624-617 1636+473 1639-062 1642+690 \ 1647-296 1657-261 1659+399 1705+018 1706-174 1717+178 1718-259 1725+044 \ 1730-130 1737-081 1741-038 1745+624 1746+470 1749+096 1751+288 1753+204 \ 1754+155 1758+388 1759-396 1806-458 1815-553 1823+689 1831-711 1846+322 \ 1849+670 1908-201 1908+484 1909+161 1921-293 1925-610 1929+226 1929-457 \ 1935-692 1936+046 1936-155 1937-101 1949-052 1951+355 1954-388 2000+148 \ 2000+472 2002-375 2008-159 2017+745 2022-077 2029+121 2036-034 2037+216 \ 2037-253 2052-474 2059+034 2109-811 2111+400 2113+293 2121+547 2142+110 \ 2142-758 2143-156 2149+056 2155-304 2155+312 2209+236 2210-257 2214+350 \ 2215+150 2216-038 2220-351 2227-088 2229+695 2232-488 2236-572 2244-372 \ 2245-328 2250+190 2254+074 2318+049 2319+317 2319+444 2325-150 2331-240 \ 2335-027 2336+598 2353-686 2353+816 2355-106 2355-534 2356+385 11.2. Stations: loose no-net rotation/translation on positions and velocities is applied to a sub-network: BADARY BR-VLBA FD-VLBA FORTLEZA GILCREEK HARTRAO HOBART26 \ KASHIMA KATH12M KOKEE NL-VLBA NOTO NYALES20 ONSALA60 \ OV-VLBA RICHMOND SC-VLBA SESHAN25 WARK12M WESTFORD WETTZELL 12. Generation of pre-reduced datum-free normal equations: will be done later in the SINEX (rapid) solution processed in independent mode. 13. Further details 13.1. Data type: group delays. 13.2. Data editing: 5 degree elevation cutoff. 13.3. Data weighting: weights are defined as follows: 1/sqrt(f**2+a**2) where "f" is the formal uncertainty of the ionosphere free linear combination of group delays at X- and S-band obtained by fringe fitting on the base of achieved signal to noise ratio. Station-dependent parameter "a" was computed for each session by an iterative procedure such that the ratio of the sum of squares of the weighted residuals to the estimate of their mathematical expectation is about unity. 13.4. Standard errors reported: all errors are derived from least-squares estimation propagated from the data weights and the constraints applied to the troposphere, clock and EOP parameters. 13.5. Software: Calc 11.0, Solve revision date 2023.xx.xx. 13.6. Other informations about the solution are reported at http://ivsopar.obspm.fr.