# file holding conversion from utc to ut1. # this uses an offset (in millisecs) for a utc date that you # specify and a rate ms/day. # # The file format is: # col1 # is a comment # year daynumber offset rate. # the year,daynumber,offset, rate are mjd/utc based. # # you can have multiple lines of year daynumber... # The pointing program will search for the largest year and daynumber that # is less than or equal to the current date. # # You must restart pointing for the new value to take affect. # The dayNumber search will use AST 0 hours when comparing which # year/daynumber to use UTC to UT1 (since we update the trak clock tick # at ast 0 hours not utc 0 hours). # # history # 29apr98 - updated routines to use current mjd as offset. Before dut1 was # -155 ms, after it was -15.86. this was a fixed error since # jul97. # remember to move new copy to idl/data #---------------------------------------------------------------------- # Note on how to update the values: # # - you must update this after every leap second, and whenever the # linear approximation no longer matches the correct value. # 1. get the data values from the eos bulletin # web site: http://maia.usno.navy.mil/ # click on Earth orientation Parameters (EOP).... # 2. store file in /home/online/vw/etc/Pnt/ut1Utcmmmyy.dat # 3. edit file removing all text except the prediction lines you # want to fit... eg: # 2006 12 8 54077 -0.0738 0.3429 0.24181 # 4. edit utcToUt1.pro in this directory inserting new filename and # number of points you kept in 3. # 5. from idl .run utcToUt1. look at plot and see where it turns over. # decrease npts till you get a good linear fit. Then # edit ut1Utcmmmyy.dat to hold that many points # 6. enter in utcToUt1.dat at the bottom the info: # year daynoStartOf Fit offsetMs rate/dayMs # these are on the plot. # 7. the actual code in pnting converts dayno back to julday so there # are no problems crossing year boundaries. # # y= m*(dnum-dnum0) + offsetAtDnum0 # y is the offset for daynumber dnum # m is the slope in millisecs/day # dnum0 is the day number listed in the file below # offsetAtDnum0 is the offset for dnum0 listed in file below # # year daynumber offset 0UTC rateUt1 # at dayNum # millisecs millisecs/day # # 30sept 1july # ((.39872)-(.526928))/(273-182)..30sept- 1jul 1997.. 1997 182 526.9 -1.4089 # # 27apr98 31jan98 # (-.013644)- (.164900))/(117 - 31) 1998 117 -13.644 -2.0761 # # linfit prediction 1oct98 to 31dec98..see file ut1Utc01oct98.dat 1998 274 -156.997 -1.443 # # linfit prediction 1jan99 to daynum 150..see file ut1Utc01jan99.dat 1999 1 722.215 -1.495 # linfit prediction 16apr to dec31. linear weight 1->0.file:ut1Utcapr99.dat # max deviation 20 millisecs till day 306 then goes to hell 1999 106 584.49 -.524 # # linfit prediction 8sep99->31dec99 linfit, weight 1 filte ut1Utcsep99.dat 1999 251 488.01 -1.3053 # # linfit prediction 28feb00->18jun99 linfit, file: ut1Utcfeb00.dat 140 pnts 2000 28 334.334 -1.253 # # linfit prediction 05jan01->02jun01 linfit, file: ut1Utcjan01.dat 150 pnts 2001 5 98.0766 -.997906 # linfit prediction 19sep01->30apr02 linfit, file: ut1Utcsep01.dat 224 pnts 2001 262 -34.2684 -.739952 # linfit prediction 20sep02->27may02 linfit, file: ut1Utcsep02.dat 250 pnts # peak error over region: 8ms rms: 3.7 ms 2002 263 -233.771 -.659164 # linfit prediction 01aug03->06apr04 linfit, file: ut1Utcaug03.dat 250 pnts # peak error over region: 15ms rms: 5.9 ms 2003 213 -339.259 -.351523 # linfit prediction 01jan06->08deg06 linfit, file: ut1Utcjan06.dat 342 pnts # peak error over region: 35ms rms: 20 ms 2006 1 311.989 -.193788 # linfit prediction 08dec06->25jun07 linfit, file: ut1Utcdec06.dat 200 pnts # peak error over region: 15ms rms: 60 ms 2006 342 71.140 -1.174340 # linfit prediction 27dec07->21nov08 linfit, file: ut1Utcdec07.dat 361 pnts # peak error over region: -35ms rms: 20 ms 2007 331 -261.167 -.701459 # linfit prediction 01jan09->11dec09 linfit, file: ut1Utcjan09.dat 345 pnts # peak error over region: 38ms rms: 22.7 ms 2009 1 367.131 -.691979 # peak error over region: 30ms rms: 17.4 ms 2010 36 59.162 -.661890 # peak error over region: 50ms (only at end) rms: 23.1 ms 2011 105 -208.715 -.564566 # lin fit prediction 24feb12 ->06jun12 (then leap sec) # peak error over region: 16ms rms: 6.9 ms 2012 55 -469.827 -1.052878 # lin fit prediction 01jul12-01oct12 after leap sec # peak error over region: 5ms rms: 4.1 ms 2012 183 421.452 -.322170 # lin fit prediction 01oct12-jun13 from jun12 dataset # peak error over region: 13ms rms: 6 ms 2012 275 388.359 -1.101452 # lin fit prediction 05jul13-30sep13 from 04jul13 dataset # peak error over region: 8.5ms rms: 4.2 ms 2013 186 66.382 -.538438 # lin fit prediction 21oct13-15jun14 from oct13 dataset # peak error over region: 10ms rms: 5.9 ms 2013 294 -4.587 -1.338775 # lin fit prediction 11jul14-11jul15 from jul14 dataset # peak error over region: 10ms rms: 5.9 ms 2014 192 -277.344 -1.152726 # lin fit prediction 01jul15-30sep15 from jul15 dataset # peak error over region: 5ms rms: 3.2 ms 2015 182 329.538 -.493420 # lin fit prediction 01oct15-15jun16 from jul15 dataset.. never used.. # peak error over region: 8ms rms: 3.9 ms 2015 274 271.987 -1.219109 # lin fit prediction 08dec15-08dec16 from dec15 dataset # peak error over region: 40ms rms: 26.8 ms 2015 338 90.972 -1.178290 # lin fit prediction 01jan17-01dec17 from jan17 dataset # peak error over region: 20ms rms: 16.8 ms 2017 1 573.049 -1.231839 # lin fit prediction 01dec17-30nov18 # peak error over region: 30ms rms: 16.3 ms 2017 335 235.699 -.953616 # lin fit prediction 14sep18-30jun19 # peak error over region: 20ms rms: 5.6 ms 2018 257 58.651 -.916664 # lin fit prediction 01jul19-26jun20 # peak error over region: 40ms rms: 13.5 ms 2019 182 -128.586 -.753258 # lin fit prediction 01nov19-30oct20 # peak error over region: 30ms rms: 15. ms 2019 305 -157.096 -.409666 # lin fit prediction 12feb21-11feb22 # peak error over region: 35ms rms: 21.5 ms # --> rate: .0282668.. should have been .282668 # updated 02sep21 #2021 43 -189.901 .0282668 2021 43 -189.901 .282668 # updated 04jul23, 182=01jul23 2023 182 -5.255 -.018366