Aug. 28, 2009: testarrow.pro synchmap_bvect.pro V14 synchmap_bcomp.pro L6, L7, V11, V12, V13 crncl0_time_ctimes.pro mmgbra_remapmmgf.pro updbccm_crnclog.pro drcsc_updsc20090810b.pro July 2, 2009: Phil create ~wso/src/misc/ctimes.c and ~wso/bin/_linux4/ctimes Replace times with ctimes in date_crncl0_ctimes.pro, date_crncl0.pro with date_crncl0_ctimes.pro in test36_0630.pr test36_0702.pro Copied from test36_0702.pro 1 date_crncrlz1.pro Get approached time date0_crncrl,crn,crl,date0.pro Get initial time fdoy_date.pro Get fdoy crl_yyyymmddtime.pro 2 time_crncl0.pro Call times to get CM time time_crncl0_ctimes.pro Call ctimes to get CM time 4 rseve_xyxvxvyvz0701.pro Get rse366,ve366 crtsnp_crncrl.pro plt0625.pro Get figure LosBrSycF_sdatestime09.pro mkremapmmg.pro mmgbra_remapmmgf.pro updmsc_crnclog09.pro ldrcmsc_updmsc.pro time_crncl0.pro is replaced by drcmsc_updmsc20090318.pro time_crncl0_ctimes.pro xticsm_crnclog09.pro pscimg06.pro zgrid.pro updsc_annot09.pro testctel_suninfo.pro datetime_scrncl0_suninfo.pro testctel_suninfo_2064_165.050_195.500_0.009.ps year_sec_date.pro date_year_sec.pro cl0i_date_suninfo.pro testctel.pro datetime_scrncl0_200905.pro testctel_2064_165.050_195.505_0.0003.ps cl0_yyyymmddtime.pro testctel_2064_165.050_195.505_0.05.ps (cl0_date.pro, fday_date.pro) testctel_200906.pro datetime_scrncl0_200906.pro --July 1, 2009 cl0_yyyymmddtime.pro is sensitive to time of 7.2 sec, Carrington longitude changes 0.001 degrees (0.001*3600=3.6 sec) suninfo.c: Carrington longitude changes 0.01 ~ 36sec ct2083:360 -- 2009:05:03_04h:11m:00s ct2083:000 -- 2009:05:30_09h:26m:00s =========================================================================== times => 2009:05:03_00h:38m:53s 2009:05:30_07h:15m:16s CT2083:358 <= CT2084:359 <= times --------------------------------------------------------------------------- CT2083:360.03<= CT2084:360.03<= suninfo --------------------------------------------------------------------------- CT2083:360.114<= cl0_yyyymmddtime.pro CT2083:360 2009:05:03_04h:12m:53s <= datetime_scrncl0_200905.pro http://umtof.umd.edu/pm/crn/ for start and end time for each CRN From http://umtof.umd.edu/pm/crn/CARRTIME.HTML The rotation of the Sun and the orbital motion of the Earth are in the same direction (both counterclockwise when viewed from north of Earth's orbital plane). As a consequence the apparent (synodic) solar rotation period is a bit longer than the true (sidereal) period. (Hint: it may help to think of the sideREAL period as the 'real' period.) If you think about it you can convince yourself that the sidereal period is equal to the synodic period divided by (1+frac), where frac = 27.2753/365.25 = the fraction of a year the Earth moves in its orbit during one synodic solar rotation. The Earth is farthest from the Sun in July and closest in January. Objects that are farther from the Sun have a smaller angular velocity (a longer 'year') than do closer objects. Hence the synodic period is a bit smaller in July than in January. Previously we determined the start and stop times of Carrington rotations by assuming a constant period of 27.2753 days. The phase was taken from the Astronomical Almanac, which gives a value for Carrington longitude of 349.03 degrees at 0000 UT on 1 January 1995. One can then derive the Carrington longitude in degrees (call it OLD) as a function of time: OLD = 349.03 - (360.* X / 27.2753), where X is the number of days since 1 January 1995. It is understood that OLD is to be taken modulo 360. Note that the Carrington longitude decreases as time increases. If one now compares the values of OLD with the values listed in the Almanac one finds reasonable agreement, with maximum discrepancies of about 4 hours. To get a better estimate of the start and stop times, we find the difference between OLD and the values listed in the Astronomical Almanac, and then fit the difference (ALMANAC - OLD) with a sine-cosine series: Fit#1 = f + X/g + a*SIN(2*π*X/e) + b*SIN(4*π*X/e) + h*SIN(6*π*X/e) + c*COS(2*π*X/e) + d*COS(4*π*X/e) + i*COS(6*π*X/e) In Figure 1 the red data points are the values of (ALMANAC - OLD), and the blue line reperesents Fit#1. The improved estimate is then NEW = OLD + Fit#1 The values of (NEW - ALMANAC) are plotted in Figure 2. The maximum discrepancy is now about 2 minutes. Notice that the data points between Days ~ 350 and 700 appear disjoint from the rest of the data set. This appears to be caused by a small offset in the Almanac tables for 1996. Each volume of the Almanac presents data for the stated year, for the last day of the previous year and the first day of the next year. The last day of the previous year is referred to as "January 0", and the first day of the subsequent year is called "December 32". This repetition of data allows a comparison of data from the 1995, 1996, and 1997 almanacs, shown in Table 1. It appears that the longitudes listed for 1996 is systematically very slightly larger than for either 1995 or 1997. The fitting procedure described above can be generalized to allow for a different offset in 1996. We define: Fit#2 = Fit#1 + j for the year 1996 Fit#2 = Fit#1 for all other years NEW2 = OLD + Fit#2 Values of (ALMANAC - NEW2) are shown in Figure 3. The residuals are less than 1 minute nearly all of the time. The function NEW2 is then used to generate the Carrington rotation start and stop times in our plots and listings.