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diff --git a/math/slalib/doc/read.me b/math/slalib/doc/read.me new file mode 100644 index 00000000..e7f5f358 --- /dev/null +++ b/math/slalib/doc/read.me @@ -0,0 +1,437 @@ +READ.ME + +Revision date 31 May 1999 SLALIB Version 2.3-0 + +----------------------------------------------------------------------- + +FILES IN THE ORIGINAL SOURCE DIRECTORY (VAX) + + READ.ME this file + *.FOR Fortran source (separate modules) + *.OBS ditto, but obsolete routines + *.NEW ditto, but new and not yet ready for release + *.VAX Fortran source for VAX/VMS + *.CNVX Fortran source for Convex + *.MIPS Fortran source for DECstation + *.SUN4 Fortran source for Sun SPARCstation + *.LNX Fortran source for Linux + *.PCM Microsoft Fortran source for PC + *.C C functions needed for Linux version + PC.BAT rebuilds PC version + REP.BAT on PC, compiles one module and updates library + CREATE.COM complete rebuild of VAX and Unix releases + PUT.COM compile one module and update libraries + VAX_TO_UNIX.USH script to complete transfer to Unix platforms + SLA.NEWS NEWS item for latest release + MAKEFILE Unix make file + MK C-shell script to run make + SUN67.TEX document + +FILES IN [.RELEASE] DIRECTORY ON VAX + + SLALIB.OLB object library + SLALIB.TLB source library + SUN67.TEX document + +FILES IN [.UNIX] DIRECTORY ON VAX + + MAKEFILE make file for DECstation and Sun SPARC + MK C-shell script to run make + SLA.A archive file containing everything else + VAX_TO_UNIX script to complete transfer to Unix platforms + SLA.NEWS NEWS item for latest release + SUN67.TEX document + +FILES IN (INFORMAL) FTP DIRECTORIES + + The files distributed informally through anonymous FTP may differ + slightly in both content and name from the ones listed above. For + example the PC Fortran modules may be stored in archive files and + called xxx.f_pcm rather than XXX.PCM etc. + +----------------------------------------------------------------------- + +DISTRIBUTION - THIS DIRECTORY + + Nothing from this directory needs to be distributed. + +DISTRIBUTION - [.RELEASE] DIRECTORY + + SLALIB.* SLALIB_DIR + SLA.NEWS SLALIB_DIR + SUN67.TEX DOCSDIR + +INSTRUCTIONS FOR SAVING SPACE + + Extract from the SLALIB_DIR BACKUP save set only the file SLALIB.OLB. + +----------------------------------------------------------------------- + +PORTING FORTRAN SLALIB TO OTHER SYSTEMS + +FORTRAN SLALIB runs on VAX (VMS), PC (Linux+f2c), PC (Microsoft FORTRAN), +Convex (ConvexOS), DECstation (Ultrix), DEC Alpha (OSF-1) and Sun +SPARCstation (SunOS and Solaris). + +For most platforms, the required changes are confined to these routines: + + sla_GRESID + sla_RANDOM + sla_WAIT + +VAX, CONVEX, DECSTATION/ALPHA, SUN & PC + +Versions suitable for the above platforms are supplied in the +development directory as *.VAX, *,CNVX, *.MIPS, *.SUN4, *.PCM and +*.LNX respectively. + + +----------------------------------------------------------------------- + +LATEST RELEASE INFORMATION + +The latest release of SLALIB includes the following changes (most recent +at the end): + +* In sla_RCC, the topocentric term of coefficient 1.3184D-10 sec + had the wrong sign. Minus is correct. + +* The IAU decided in 1991 to rename the Terrestrial Dynamical + Time, TDT, which is now called "Terrestrial Time" or TT. + Appropriate changes have been made in the SLALIB documentation. + The same IAU resolutions introduced the timescales TCG and TCB; + there are at present no SLALIB routines to handle these new + timescales. + +* The Keck 1 Telescope has been added to sla_OBS. + +* The handling of the random-number seed in the PC versions of + sla_RANDOM and sla_GRESID was flawed and has been improved. + +* The UTC leap second at the end of June 1993 has been added to the + routine sla_DAT. Existing applications which call sla_DAT or + sla_DTT require relinking. + +* Some unnecessary code in sla_AMPQK has been removed. + +* Minor reorganization of the sla_REFRO code has led to an improvement + in speed of about 20%, and precautions have been taken against + potential arithmetic errors. + +* There have been small revisions to sla_FK425 and sla_FK524. The + results are not significantly affected, except in the pathological + case of large proper motion combined with immense distance, where + sla_FK524 could produce erroneous radial velocity values. The + latest versions are close to the algorithms published in the 1992 + Explanatory Supplement to the Astronomical Almanac. + +* The leap second at the end of June 1994 has been added to sla_DAT. + +* THE SLA_RVLSR ROUTINE HAS BEEN RETIRED. Its place has been taken + by two new routines: sla_RVLSRK and sla_RVLSRD. The original + sla_RVLSR had used a "kinematical" LSR. When this was later changed + to a "dynamical" LSR for (what seemed liked good reasons at the time), + the small differences were noticed by spectral-line radio observers, + who had to fall back on old copies of the routine to remain consistent + with existing practice. The new routines provide both sorts of LSR: + sla_RVLSRK uses a kinematical LSR and sla_RVLSRD uses the dynamical LSR. + +* The sla_PA routine (computation of parallactic angle) used an + unnecessarily complicated formulation, which has been simplified. + The results are unaffected. + +* The sla_ZD routine (computation of zenith distance) used a + straightforward cosine-formula-based method, which suffered from + decreased accuracy near the zenith. A better, vector-derived, + formulation has been substituted, without materially affecting + the results. Because sla_ZD is double precision, the old + formulation was always adequate; however, had anyone transcribed + the code in single precision errors approaching 1 arcmin could + have resulted. The new formulation delivers good results all + over the sky even in a single precision version. + +* Routines have been added to transform equatorial coordinates + (HA,Dec) to horizon coordinates (Az,El) and back. Single and + double precision are both supported. The routines are called + sla_E2H, sla_DE2H, sla_H2E, sla_DH2E. + +* A new routine has been added to the tangent-plane projection set. + The single and double precision versions are called sla_TPRD and + sla_DTPRD respectively. Given the RA,Dec of a star and its + xi,eta coordinates, the routine determines the "plate centre". + +* The existing routine sla_PREC for obtaining the precession matrix + uses the official IAU model and should continue to be used for + canonical purposes. A new version, called sla_PRECL, uses a + more up-to-date model which delivers better accuracy, especially + over intervals of millennia. + +* The routine sla_PVOBS was returning velocities in AU per sidereal + second rather than per UT second. This has been corrected. The + maximum error was equivalent to about 0.001 km/s. + +* In sla_MAPQK and sla_MAPQKZ, the area within which the gravitional + light-deflection term is restrained has been extended from its + original 300 arcsec radius to about 920 arcsec, just inside the + Sun's disc. + +* A chapter of explanation, with examples, has been added to SUN/67, + which has also undergone various cosmetic revisions. + +* There were two discrepancies between the documentation of sla_DCMPF + (program comments and SUN/67) and the code. The first was that the + formulae for the nonperpendicularity used PERP instead of PERP/2; + the documentation has been corrected. The other was that the + documentation showed the zero point corrections being applied first, + whereas the code returned zero point corrections corresponding to + being applied last. The code has been corrected to match the + documentation. + +* The C module slaCldj gave incorrect answers for dates during + January and February. The error, which did not affect the Fortran + version, has been corrected. + +* THE CALL FOR TPRD AND DTPRD HAS BEEN CHANGED. An integer status + argument has been added; non-zero means the supplied RA,Dec + and Xi,Eta describe an impossible case. (This can only happen + near the pole and with non-zero Xi.) Also, a slightly neater + formulation has been introduced. + +* Three new routines have been added. ALTAZ takes a star's HA,Dec + and produces position, velocity and acceleration for azimuth, + elevation and parallactic angle. PDA2H predicts the HA at which + a given azimuth will be reached. PDQ2H does the same for + position angle. + +* In the OBS routine, the wrong sign was returned for the Perkins + 72 inch telescope at Lowell - fixed. + +* A revised model for the equation of the equinoxes has been + installed in EQEQX, in line with recent IAU resolutions. The + change amounts to less than 3 mas. + +* A bug in DFLTIN has been corrected. A negative number following + an E- or D-format number without intervening spaces lost its + sign. + +* Four stations have been added to OBS: + + TAUTENBERG Tautenberg 1.34 metre Schmidt + PALOMAR48 Palomar 48-inch Schmidt + UKST UK 1.2 metre Schmidt, Siding Spring + KISO Kiso 1.05 metre Schmidt, Japan + ESOSCHMIDT ESO 1 metre Schmidt, La Silla + +* The EARTH and MOON routines could give an integer divide by zero + for years before 1 BC. This has been corrected. + +* CALYD (provided to support the EARTH and MOON routines) has been + upgraded to work outside the interval 1900 March 1 to + 2100 February 28. The status value indicating dates outside that + range has been dropped; a new error value for year before -4711 + has been introduced. + +* A new routine, CLYD, has been added. It is a version of CALYD + without the century-default feature and is to enable 1st-century + dates to be supplied to EARTH and MOON. + +* Two new routines, PLANETS and RDPLAN, have been added, which + compute approximate planetary ephemerides. + +* A new routine, DMOON, implements the same (Meeus) model as the + MOON routine, but in full and in double precision. The time + argument is a straightforward MJD rather than MOON's year and + day-in-year. + +* The REFRO code has been speeded up by a factor of two (and is + also clearer). + +* REFV and REFZ have, in different ways, been made more accurate for + cases close to the horizon. The improvement to REFV is relatively + modest, but REFZ is now capable of delivering useful results for + rise/set phenomena. + +* AOPQK has been speeded up for low-elevation cases. + +* Versions of the tangent-plane routines working directly in x,y,z + instead of spherical coordinates have been added. They may be + faster in some applications. The routines are DV2TP, V2TP, DTP2V, + TP2V, DTPXYZ, TPXYZ. + +* The coordinates of the Australia Telescope Compact Array have been + added to OBS. The name is 'ATCA'. + +* Despite their recent introduction THE ROUTINES DTPRD, DTPXYZ, TPRD + AND TPXYZ HAVE BEEN WITHDRAWN. They have been replaced by the new + routines DTPS2C, DTPV2C, TPS2C and TPV2C. These are functionally + equivalent to the earlier routines but return two solutions instead + of one: the second solution can arise near a pole. + +* The UTC leap second at the end of 1995 has been added to sla_DAT. + +* The refraction routine REFRO has been extensively revised. The + principal motivation was to improve the radio predictions by + introducing better humidity models. The models previously in + use had been entirely adequate for the optical case, for which + they had been devised, but improved models were required for + the radio case. None of the changes significantly affects the + optical results with respect to the earlier version of the REFRO + routine. For example, at 70 deg zenith distance the new version + agrees with the old version to better than 0.05 arcsec for any + reasonable combination of parameters. However, the improved + water-vapour expressions do make a significant difference in the + radio band, at 70 deg zenith distance reaching almost 4 arcsec + for a hot, humid, low-altitude site during a period of low pressure. + +* There was a bug in the (private) C version of RDPLAN. The + answers were unaffected but there could be floating-point + problems on some platforms. + +* A new routine has been added, GMSTA. This gives greater numerical + precision than the existing GMST function by allowing the date and + time to be specified separately rather than as a single MJD. + +* Measures taken in MAPQK to avoid trouble when processing Solar + positions had not been carried through into MAPQKZ. The two + routines now use the same strategy. + +* In REFRO, at zenith distances well beyond 90 deg and under some + conditions, it was possible to encounter arithmetic errors due to + failure of the tropospheric model-atmosphere to deliver sensible + temperatures. This is inherent in the published algorithm. To + avoid the problem, the temperature delivered by the model has been + constrained to the range 200 to 320 deg K. + +* A new routine has been added, ATMDSP, for rapidly recalculating + the A,B refraction coefficients for different wavelengths. + +* The first UTC leap-second date in the DAT routine was one day early. + This will have had no effect on the results for more recent epochs. + +* The C version of OBS had some problems related to character string + handling. A call using the "number" option retured an invalid + station ID, and station ID and name strings of the stipulated 10 + and 40 character lengths were improperly terminated. + +* A new routine, POLMO has been added. This is a specialist tool + to do with Earth polar motion. + +* DC62S and CC62S could give floating point errors if vectors in + unlikely units were supplied. The handling of difficult cases + has been improved. + +* Support for Linux has been added. + +* The C version of REFRO was not re-entrant. It is now; there has + been a small (4%) speed penalty. + +* RANDOM, GRESID and WAIT have been dropped from the C version. They + could not easily be made re-entrant and posed perennial platform- + dependency problems. + +* The value for the arcsec to radians factor in several routines + had an incorrect (and superfluous) 19th digit, which has been + removed. + +* There was a minor bug in DV2TP and V2TP, to do with protection + against the special case where the tangent point is the pole. + +* In OBS, the position of the Parkes radiotelescope has been revised, + and the ATNF Mopra observatory has been added. + +* Two new routines have been added. PAV (single precision) and DPAV + (double precision) are like BEAR and DBEAR but start with direction + cosines rather than spherical coordinates - they return the position + angle of one point with respect to the other. + +* The C version of REFRO still wasn't re-entrant, but is now. + +* The C version of DTF2D used to accept 60.0 in the seconds field; + this has been corrected. + +* The PLANET and RDPLAN routines now include Pluto. The ephemeris + is accurate (sub-arcsecond) but covers the 20th and 21st centuries + only. + + !!! IMPORTANT NOTE !!! + + RDPLAN used to interpret any planet number outside the range 1-8 + as meaning the Sun. The new version uses planet number 9. Existing + programs using 9 for the Sun should be changed to use 0. The rule + has not been changed, except that the range is now 1-9 instead of + 1-8, as it is unlikely that the equivalent problem will arise in the + future. + +* Two new routines have been added, PLANEL and PLANTE. They are + analogues of PLANET and RDPLAN but for the case where orbital + elements are available. They can be used for predicting the + positions of asteroids and comets, and, if up-to-date osculating + elements are supplied, more accurate positions for the major + planets than can be provided through the PLANET and RDPLAN + routines. + +* The REFRO routine could give inaccurate results for low temperatures + (subzero C). This was caused by over-cautious defensive programming, + which prevented the tropospheric temperature falling below 200 K. + +* A new routine has been added, REFCOQ. This calculates the coefficients + of a two-term refraction model. It complements the existing REFCO + routine, being much faster at the expense of some accuracy. + +* The 1997 July 1 UTC leap second has been added to the DAT routine. + +* A bug in the C version of SVD (slaSvd) caused occasional false + indications of ill-conditioning. The results of least-squares + fits do not seem to have been affected. The Fortran version + (sla_SVD) did not have the bug. + +* The Subaru telescope (Japanese National 8-metre telescope, Mauna Kea) + has been added to the OBS routine. + +* The DAT routine has been extended back to the inception of UTC in + 1960. + +* The "earliest date possible" in DJCL was two days out (disagreeing + with DJCAL, which had the correct value). + +* The GMSTA code has been improved. + +* A new routine, PV2EL, takes a heliocentric J2000 equatorial position + and velocity and produces the equivalent set of osculating elements. + +* The 1999 January 1 UTC leap second has been added to the DAT routine. + +* Four new routines have been introduced which transform between the + FK5 system and the ICRS (Hipparcos) system. FK52H and H2FK5 transform + star positions and proper motions from FK5 coordinates to Hipparcos + coordinates and vice versa. FK5HZ and HFK5Z do the same but for the + case where the Hipparcos proper motions are zero. + +* Six new routines have been introduced for dealing with orbital elements. + Four of them (sla_EL2UE, sla_PV2UE, sla_UE2EL and sla_UE2PV) provide + applications with direct access to the "universal variables" method + that was already being used internally. Compared with using conventional + (angular) elements and solving Kepler's equation, the universal variables + approach has a number of advantages, including better handling of near- + parabolic orbits and greater efficiency. The remaining two routines + (sla_PERTEL and sla_PERTUE) generate updated elements by applying + major-planet perturbations. The new elements can then be used to + predict positions that are much more accurate. For minor planets, + sub-arcsecond accuracy over a decade is achievable. + +* Several observatory sites have been added to the OBS routine: CFHT, + Keck 2, Gemini North, FCRAO, IRTF and CSO. The coordinates for all + the Mauna Kea sites have been updated in accordance with recent aerial + photography results made available by the Institute for Astronomy, + University of Hawaii. + +* A coding error in DAT produced incorrect results for dates in the + first 54 days of 1972. + +----------------------------------------------------------------------- + + + P.T.Wallace + + ptw@star.rl.ac.uk + +44-1235-44-5372 |