2023.12.23 a) added support of computation of path delay for Earth orbiting satellites b) Added option --missing for vtd_apriori_update.py that checks for missing static apriori. It updates the specified file only if it is missing 2023.03.14 a) Added support of a priori proper motions and parallaxes for computation of path delay. Added new keyword SOURCE_PRLX_PRP_MOTION in the VTD control file for specifing a priori proper motions and/or parallaxes used for path delay computation. The format of the a priori file is desceribed in doc/prlx_prp_format.txt b) Made a change: Galactic aberration is not computed for obsercts with non-zero a priori parallaxes. 2022.10.01 JPL planetary ephemeride was upgraded to de440. The older ephemeride files are not supported. VTD control files should be updated to point to ephemeride file de440. The de440.eph file distributed with VTD is valid for 1970-2070 time range. 2022.08.30 a) Added support of IONOSPHERE_SCALE control file keyword. The ionospheric contribution computed from TEC maps is multiplied by that parameter. b) Added support of SOU_DEBIAS_MODE control file keyword. It specifies the name of the source position de-bias model. It is for compensation of the source position bias caused by the the deficiency of an ionospheric model or other models. The contribution of the de-bias model to path delay is computed on the basis of an empirical model that describes the postion bias in declinatin as a function of declination. Supported models: MOD1 and MOD2. 2021.04.30 a) Added computation of W-projection of the baseline vector b) Added accouning for aberration in computation of uvw baseline vector projections c) Added difxvtd utility for computation of the path delay for the DiFX correlator. 2020.11.05 a) now wher source structure path delay is computed, correlated flux density is computed as well and is available as DER_DEL(VTD__COR_FD1) and DER_DEL(VTD__COR_FD2) for high and low frequencies. 2020.03.22 a) Added support of CAPITAINE_2005 precession expression. b) Added support of MEAN_POLE_MODEL keyword. Supported values: NONE, IERS2010, IERS2022. c) keyword MPL_FILE is removed. d) Undated vtd_control_update so it upgrades old VTD. controls of format revision 2019.03.03 to the current format revision. e) Added option -d (--download) in vtd_apriori_update.py This option removes the old local VTD a priori files and downloads them from the remote server instead of upgrade. This option has to be used when the number of sites with a priori loading and slant path delay is changed at the remote server. f) Added support of dowloading harmonic vairaitons of site position displacements caused by loading in vtd_apriori_update.py . Support of two new mnadatory keywords is added in vtd_apriori_update.py HPS_URL: LOAD_HPS_DIR: g) Extended read/write locks in vtd_apriori_update.py for ionosphere TEC maps and slant path delay. 2019.10.13 Fixed a bug in bindisp_merge related to locking. Changed name of lock files. 2019.09.15 Enabled handling read/write locks in vtd_apriori_update.py to prevent crashing software that reds loadings during update time: Added support one new source catalogue format # Source position file format 1.0 of 2019.08.08 Fixed several bugs related to configuration with curl. 2019.05.25 Added vtd_apriori_update.py program for automatic downloading ephemeral a priori: the Earth orientation parameters, expansion coefficients of the ionosphere contribution, time series of 3D crustal deformations caused by mass loading, and the expansion coefficients of slant path delay. Fixed a long-standing bug related to handling locks when loading mass loading displacements. Added ./reconfigure command that re-runs stored configuration. ./reconfigure -d displays the last configuration. Forced shell intermediate files, for instance object files created by the compiler be group readable and group writable. Forced make invoke shell bypassing startup scripts which made running make significantly faster. Added support of environment variables in VTD control file. Format: ${VAR_NAME}, where VAR_NAME is an environment variable. VTD expands the environment variable at any occurrence of the control file. Nested environment variables are supported. Added setting stack size and environment variable GOMP_STACKSIZE on start-up of executables. That eliminated necessity to setup stackszie and GOMP_STACKSIZE to avoid a crash during loading the executable. Added document vtd_apriori_update.txt (and .html) in doc/ directory. 2019.04.04 Fixed examples. Fixed VTD_LOAD to prevent a crash in the attempt to compute solid tides displacement for an orbiting radiotelescope. 2019.03.03 Added support up to 9 ionosphere TEC map files. 2018.10.15 Added support --with-curl configure option. cfitsio-3.42 and newer may be compiled with curl support, and in that case VTD needs be linked against curl. 2018.06.30 Made a change needed to be compatible with ners-20180628 related to computation of accumulated secular term in nutation. 2018.05.31 Added support of value NERS for EOP_TIME_SCALE, UZT_MODEL, UZT_USE keyword in the control file. Thus, when NERS is used, VTD control file should have these definitions: LEAP_SECOND: NERS EOP_SERIES: NERS EOP_TIME_SCALE: NERS UZT_MODEL: NERS UZT_USE: NERS HARMONIC_EOP_FILE: NERS PRECESSION_EXPRESSION: NERS NUTATION_EXPANSION: NERS EROT_COMPAT: NONE GEODESIC_NUTATION: NONE Fixed several bugs related to gfortran 8.1 2018.04.04 Added utility bindisp_merge for merging loading binary files Fixed support of NERS 2017.12.27 Added support of value NERS for the keyword LEAP_SECOND. LEAP_SECOND: NERS will force VTD to download the table of leap seconds using the default NERS configuration file. 2017.10.27 Fixed a regression bug in the previous release that prevented installation. 2017.10.17 Added computation of group delay and delay rate with respect to geocenter for the 1st and the 2nd station of a baseline. These parameters are placed in DEL_DEL and DEL_RAT arrays. 2017.05.15 a) Fixed errors related to computation of source structure delays. b) Fixed bugs in the installation procedure. c) Fixed regression bug in vtd_example_03 2016.11.17 Added support for NERS (Network Earth Rotation Service). NERS retrieves the Earth rotation parameters from the NERS server automatically. Thus, there is no need to refresh the Earth rotation series manually. To set the NERS, the following five parameters are specified: AEM_FILE: NONE ERM_FILE: NONE EOP_SERIES: file PRECESSION_EXPRESSION: NERS NUTATION_EXPANSION: NERS where file is the name of the NERS client configuration file. Keyword HARMONIC_EOP_FILE supports a special value: HARMONIC_EOP_FILE: NERS in that case the harmonic Earth orientation variations are taken from the Network Earth Rotation Service. VTD now depends on ners library. 2016.08.30 a) Added support for BWG (beam waveguide) antennas. For computing axis offset, the BWG antennas are the same as AZEL, however the feedhorn rotation angle for BWG antennas is different than for AZEL. Added support of alias for NASR (the same as NASP) for Nasmyth right-handed mounting and NASL (the same as NASL) for Nasmyth left-handed mounting. b) Added support for NERS EOP time series 2016.02.17 a) Added partial derivative over relativistic parameter Gamma for VLBI observations b) Added generation of the file with definitions of environment variables for bash shell as well. The have names vtg_vars.sh and export_vtd_vars.sh 2015.08.07 changed BINDISP format of file with station displacements: extended the header. 2014.08.20 a) Added support of a new keyword ATMOSPHERE_PATH_DELAY_PARTIAL. In the previous version the role of partial derivative of atmosphere path delay in zenith direction played WET_MAPPING_FUNCTION. In the new version WET_MAPPING_FUNCTION is used only for computing a priori path delay. b) Added new qualifiers of ATMOSPHERE_PATH_DELAY_PARTIAL: partial derivative of path delay with respect to atmosphere path delay in zenith direction played -- TOTAL_SCALE -- partial derivative is equal to the ratio of slant path delay to the path delay in zenith direction -- WATER_SCALE -- partial derivative is equal to the ratio of water vapor component of slant path delay to the water vapor component of path delay in zenith direction -- GAUSSIAN_LAYER -- partial derivative is defined for the model when the dependence of concentration of residual atmosphere with height is described as a Gaussian function with the specified mean (i.e. layer height) and the specified full width half maximum (FWHM). The height of the layer is specified in the 3rd qualifier and the FWHM is specified in the 4th qualifier. c) Added new program vtd_control_update that automatically converts the specified control file in the old format to the current format. 2014.06.29 Added support of multiple slant path delay that define delays for the same station for different ranges of epochs 2014.04.04 Added support of MAC OS (Darwin) operating system. 2014.02.18 Made changes in dealing with external atmosphere path delay to support the new data format. 2013.09.30 a) Added support of new mountings NASM and NASP (Nasmyth minus and Nasmyth plus, f.e. YEBES40M). b) Added support of feed horn angle computation for antennas with EQUA, X-YE, NASM, NASP mounting type. c) Added parameter FEED1 and FEED2 in DER_DEL array. d) VTD now correctly computes path delay for antennas with mounting types EQUA, X-YE, NASM and NASP. e) Changed form of station description file and added column antenna diameter. 2013.02.08 a) Fixed installation bug: vtd checked wrong header b) Fixed a typo in fitslib library header c) Fixed an uninitialized variable bug which may cause a crash segmentation fault 2012.11.29 a) Fixed installation bug that did prevent installation of vtd_example_06. b) Added support of EROT_COMPAT NO_SARG argument. If this option is set, then UT1 and polar motion are set to zero regardless values EOP files. This may be needed for testing. c) Fixed a bug: library so-name was incorrectly set to libfitio.so.1 instead of libfitlib.so.1 2012.11.25 a) Added support of a case when one of the stations is on the orbit b) Added routine for computation of light time between the orbiting and downlink station. 2010.06.20 a) Added support of ionosphere path delay. b) Added support of slanted path delay biases. c) Added C-language bindings d) Improved documentation. Added two new documents: Formats of a priori files for VTD and VTD a priori files management e) Increased VTD__NDER. 2009.05.30 a) Added support of the contribution of slanted path delay in the neutral atmosphere. b) Added support for antenna thermal deformation. 2008.05.02 a) Added support of two new keywords in the control file: ANTENNA_THERMAL_DEFORMATION, GALACTIC_ABERRATION. b) renamed EXTERNAL_PATH_DELAY_FILE to EXTERNAL_DELAY_DIR c) added keywords EXTERNAL_DELAY_DIR_2ND, EXTERNAL_DELAY_DIR_3RD EXTERNAL_DELAY_DIR_4TH d) added keywords SOURCE_COORDINATES_2ND, SOURCE_COORDINATES_3RD, SOURCE_COORDINATES_4TH 2007.06.18 a) Added support of three new keywords in the control file: ANTENNA_DEFORMATIONS_FILE, EXTERNAL_PATH_DELAY_FILE, PARALLACTIC_ANGLE b) Added computed of reduction for the feed-horn rotation c) Added support of reduction for source structure d) Fixed examples e) Updated documentation 2007.01.11 a) Renamed VTD_DO to VTD_DELAY. b) Added new parameter DOPPLER_EXPR in the control file. c) Added new routine VTD_DOPPLER for computation of the Doppler frequency shift. d) Added vtd_example_02 and vtd_example_03. e) Updated documentation. f) Fixed a minor error in the routine for computation of the time delay for near zone objects.