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                 *                PPM South Star Catalogue                 *
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-
-                                       compiled by
0                             U. Bastian (1) and S. Roeser (1)
-                                  in collaboration with
0                          L.I. Yagudin (2) and V.V. Nesterov (3)
-                                 with contributions from
0                         D.D. Polozhentsev (2), Kh.I. Potter (2),
                            R. Wielen (1) and Ya.S. Yatskiv (4)
-
-
0                      1) Astronomisches Rechen-Institut, Heidelberg,
                       2) Pulkovo Observatory, St. Petersburg,
                       3) Sternberg Institute, Moscow,
                       4) Kiev Observatory, Kiev.
-
-
0                      Heidelberg, October 1992
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                 *              Introduction to PPM South                  *
                 *                                                         *
                 *                                                         *
                 ***********************************************************
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0          Preface
           =======
0          The idea of this introduction to PPM South is to deliver a short
           explanation together with the catalogue itself.  It briefly
           describes the way in which PPM South was constructed and the
           contents of the catalogue on magnetic tape. It should not be
           understood as a detailed description of the work performed in the
           construction of the catalogue. This will be given in a
           forthcoming paper (Roeser et al., 1993).
-
-
0          Contents
           ========
-           1. Scope of PPM South                                      3
            2. Construction of the catalogue                           4
            3. Properties of PPM South                                 8
            4. Practical usage of PPM South                           12
            5. List of Critical Comments on Individual Stars          13
            6. List of Remarks on Individual Stars                    18
            7. Explanation of the machine-readable version            20
0              References                                             23
               Acknowledgements                                       25
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                                                                      Page 3
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           1. Scope of PPM South
           =====================
0          PPM South gives positions and proper motions of 197179 stars
           south of about -2.5 degrees declination. Its main purpose is to
           provide a convenient, dense and accurate net of astrometric
           reference stars on the southern celestial hemisphere. This net is
           designed to represent as closely as possible the new IAU (1976)
           coordinate system on the sky, as defined by the FK5 star
           catalogue (Fricke et al., 1988).  In other words, it is a
           representation of this system at higher star densities and
           fainter magnitudes.
0          Until recently the SAO Catalogue served the same purpose.  There
           are three major reasons to replace SAOC now:
0          1) SAOC is a representation of the now obsolete FK4 system of
           positions and proper motions.  Astronomers should have a direct
           access to the FK5 system.
0          2) The accuracy of positions and proper motions in SAOC is no
           longer satisfactory. Astronomers should have a more accurate
           tool.  Over more than a century astrometrists have accumulated a
           vast treasure of measured star positions. The fact that much of
           this treasure is now available in machine-readable form and the
           power of present-day computers make it easy to analyse and
           combine this amount of data.
0          3) Proper motions in SAOC were derived from only two separate
           source positions per star. This lack of redundancy lead to a
           large number of coarse errors in that catalogue.  With more than
           two measurements per star such errors can be largely avoided.  In
           this way astronomers now get a more reliable astrometric tool.
0          PPM South is the southern-hemisphere complement to the PPM Star
           Catalogue (Roeser and Bastian, 1991), which covers the northern
           hemisphere, plus a strip between the equator and about -2.5
           degrees declination.  At the border line a continuous transition
           between the northern and southern part was tailored in such a way
           that no overlap, nor gaps, nor double entries occurred.
0          The star density of PPM South is slightly higher than that of its
           northern counterpart. The accuracy of the present-epoch positions
           is roughly twice that in the north.  In fact, all of PPM South is
           as precise as the "High-Precision Subset" of PPM (north). So, for
           the first time in the history of astronomy, the practical
           coordinate system is denser and more precise on the southern than
           on the northern hemisphere.
0          Compared to SAOC the mean star density is higher by a factor of
           1.5, but between the equator and -20 degrees declination it is
           higher by a factor of 2.  The accuracy of present-epoch positions
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                                                                      Page 4
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           and proper motions is higher by a factor of 6 to 10, depending on
           declination.
0          The high present-epoch accuracy of PPM South is due to the
           inclusion of the recently completed FOKAT-S and CPC-2 catalogues.
           FOKAT-S (Yagudin et al., 1993) is a fourfold coverage of the
           southern sky, photographed around 1984 in a Soviet-Bolivian
           cooperation.  CPC-2 (Zacharias et al, 1992) also is a fourfold
           coverage of the southern sky, photographed around 1966 at the
           Cape of Good Hope.
0          The data files following this Introduction to PPM South are
           analogous and complementary to the resp. files of PPM (north).
           Combining the corresponding files will provide the user with a
           catalogue of 378910 reference stars on the whole sky.
-
-
           2. Construction of the catalogue.
           =================================
0          The construction of the catalogue proceeded in much the same way
           as described in the Introduction to PPM (north). Only few, yet
           important changes to that procedure were made, and will be
           mentioned below.
-          Step 1: Compilation of the star list.
0          The star list for PPM South was constructed starting from the
           preliminary version of FOKAT-S (Bystrov et al., 1989) which
           contains 203135 stars.  All stars of FK5 (Basic FK5 plus Bright
           Extension), SRS and SAOC south of -2.5 degrees declination were
           added, if not already included.  In the course of the work a few
           thousand stars had to be deleted (because either they are
           non-existent or already in PPM North, or else have no
           satisfactory observational history). On the other hand, a number
           of close companions to FOKAT-S stars and a small list of stars of
           special interest were added.  This gave the final list of 197179
           stars.
-          Step 2: Identification of stars in the source catalogues
0          The complete list of source catalogues is given in Chapter 3,
           below, along with an explanation of their abbreviations, with
           bibliographic references and some statistics.
0          The stars in each of the source catalogues were identified with
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                                                                      Page 5
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           the objects of the star list.  This was done in a fully automatic
           process.  Problem cases recognized in this process were
           investigated manually to detect typing errors in the source
           catalogues, to correctly identify double star components, to
           avoid the effect of grossly incorrect positions in the star list
           etc.
0          Prior to the identification of Astrographic Catalogue data (given
           as original x,y plate coordinates) a plate reduction had to be
           performed, see step 4, below.
-          Step 3: Construction of a preliminary system of positions and
                   proper motions.
0          A preliminary system of positions and proper motions is necessary
           to eliminate systematic deviations between the individual source
           catalogues. For this purpose we used the SRS catalogue (Smith et
           al., 1989) with the preliminary proper motions given there.
           Nominally it is a representation of the FK4 system.  For
           observational epochs before 1920 this turned out to be too sparse
           and too inaccurate. Therefore the GC (Boss, 1936) was added,
           after removal of the systematic deviations between SRS and GC,
           both in positions and proper motions.
-          Step 4: Reduction of source catalogues to the preliminary system
0          Zonal systematic deviations as well as magnitude- and colour-de-
           pendent systematic deviations between each of the source
           catalogues and the preliminary system were determined and
           eliminated. The zonal corrections were done by a two-dimensional
           moving-average filter technique, as sketched by Roeser (1990).
0          For the reduction of the Astrographic Catalogue plates an
           intermediate compilation catalogue of 144 787 stars was
           constructed from all source catalogues except AC. Two versions of
           it were published as "Preliminary PPM South" (Bastian et al.,
           1990) and "Preliminary PPM South, Version 4/91" (on the CD-ROM of
           NASA's Astronomical Data Center, 1991).  But even with this
           catalogue it was not possible to fully exploit the high inherent
           quality of the raw AC data in a normal single-plate astrometric
           reduction.
0          A three-stage procedure was applied, therefore:
            - 1) A first-order single-plate reduction is performed.  The
           resulting celestial coordinates are used to cross-identify the
           stars on overlapping plates.
            - 2) A first-order plate-overlap solution follows as second
           stage.  Each plate is connected to all immediately overlapping
           plates. This gives a more rigid and more precise plate-to-sky
           transformation.  The accuracy of the resulting celestial
1
                                                                      Page 6
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           coordinates is no longer dominated by the reference catalogue,
           but by the inherent accuracy of the plate measurements.
            - 3) The residual differences, both to the reference catalogue
           and to the overlapping plates, are investigated thoroughly.
           Systematic defects of the measured plate coordinates (such as
           magnitude equations, higher-order distortions, coma, or colour
           equations) can be detected and corrected in this way.  If
           necessary, stages 2 and 3 were repeated.
-          Step 5: Determination of weights for the source positions
0          In any least-squares adjustment, weights have to be assigned to
           individual measurements, according to their mean errors.
           Magnitude-dependent mean errors of the positions were determined
           for each source catalogue. Different approaches were used,
           according to need. The following paragraph gives but a few
           examples.
0          For early-epoch catalogues the mean errors were preferentially
           taken from Eichhorn (1974). However, investigation of the Yale
           zone catalogues yielded that some of them, especially the latest
           ones, were in fact much better than estimated by Eichhorn.  For
           the Carlsberg Meridian Circle catalogues (CMC 1985-1991) the
           differences to FK4 were investigated by R. Bien (1988).
           Extrapolation to fainter magnitudes was possible using
           information given within the CMC catalogues.  For Astrographic
           Catalogue zones the differences between positions of the same
           star measured on different (overlapping) plates were
           investigated.  For SRS the mean errors given by its authors
           (Smith et al. 1989) were used, with some modification for the
           bright stars.
0          All weights were chosen to be conservative estimates, in order to
           ensure that the accuracy of PPM South will not be overestimated.
-          Step 6: Least-squares adjustment
0          A standard weighted least-squares adjustment of the mean
           positions and proper motions was performed for each star -
           separately for right ascensions and declinations. Automatic tests
           for unduly large scatter among the measurements (based on the
           chi-square sum) and automatic elimination of obvious outliers
           (based on appropriately normalized individual residues) were
           implemented. All stars having bad chi-square sums beyond a
           certain significance limit, but still not showing obvious
           outliers, were marked as "problem cases" (see flag 'P' in
           byte 127 of the machine-readable catalogue). This occurred in
           about 1500 cases.
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           Step 7: Manual treatment of difficult cases
0          The automatic outlier elimination deleted about 9000 measured
           coordinates (out of more than 2.5 million).  Tight restrictions
           however, were imposed on this automatic process in order to avoid
           spuriously "good" results. This created almost 1000 "difficult
           cases" that were treated manually. A majority of these turned out
           to be coarse errors in the source catalogues, mixed-up double
           star components etc.  For about 200 objects no satisfactory
           solution could be found.  These were added to the "problem cases"
           of step 6, giving a total of 1724 PPM stars with flag 'P'.
-          Step 8: Transformation from the preliminary to the final system
0          The positions and proper motions derived so far had to be
           transformed from the preliminary system (described above) to the
           new IAU (1976) coordinate system, as defined by FK5.
0          Comparison of our preliminary system with final IRS (Corbin
           1991), on the system of FK4, showed that there were almost no
           relevant differences. The sole exception are the proper motions
           in right ascension south of -70 degrees declination.
           Incidentally, however, the preliminary SRS system is closer to an
           undisturbed sphere than the final IRS system for present epochs.
           This follows from the comparison of preliminary PPM South with
           provisional HIPPARCOS results (Lindegren, 1992).
0          Therefore we decided to apply no changes at all to the
           preliminary system. The plots of Lindegren (1992) thus give a
           good indication of the regional deviations of the PPM system from
           a perfect coordinate sphere for present epochs. They also show
           that the PPM system is indeed very close to the FK5 system, both
           on the southern and on the northern celestial hemisphere.
0          The transition from FK4 system to FK5 system followed exactly the
           same procedure as was used in the construction of FK5 (Fricke et
           al., 1988).
-          Step 9: Introduction of FK5 data for FK5 stars
0          For the stars contained in FK5 Part I (the Basic Fundamental
           Stars) and in FK5 Part II (the Bright Extension Stars), PPM gives
           the original FK5 data. These were introduced by simply copying
           them from the machine-readable version of FK5.
-          Step 10: Provision of cross-references and auxiliary data
0          In addition to the astrometric data PPM gives cross-references to
           other star catalogues, magnitudes, spectral types and a number of
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                                                                      Page 8
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           flags for each star.
0          Cross-references were determined by different methods, ranging
           from direct cross-identification (based on positions only) to
           simply copying historic work done by others (in the cases of
           catalogues having low positional accuracy such as DM and HD).
           Cross-references are given explicitly for six catalogues: Bonner
           Durchmusterung and Cordoba Durchmusterung (abbreviated DM), SAO
           Catalogue, Henry Draper Catalogue (HD) and Cape Photographic
           Durchmusterung (CPD).  Three more cross-references are given
           implicitly by flags (see chapter 7, explanation of the
           machine-readable version):
0          Flag 'F' in byte 130 denotes the stars contained in FK5 (Part I
           plus the Bright Extension).
0          The double star flag 'D' (byte 128) was created by
           cross-referencing PPM with the Catalogue of Components of Double
           and Multiple Stars (Dommanget, 1988).
0          The magnitudes given are mostly V magnitudes, copied from CPC-2.
           They are indicated by flag 'V' in byte 131. V magnitudes from FK5
           are given for the FK5 stars (flag 'F'). The magnitudes for the
           remaining 33 000 stars of PPM South are an inhomogeneous
           collection from various sources.
0          The majority of spectral types are HD data. Again, FK5 data were
           copied for FK5 stars.
0          Various sorts of auxiliary information are given in the List of
           Critical Comments and in the List of Remarks (see Chapters 5 and
           6) and indicated by the 'C' and 'R' flags.
-
-
           3. Properties of PPM South
           ===========================
-
           Random errors
+          _____________
0          The table below shows a summary of the error budget of PPM South.
           Each line of the table gives the following data for different
           declination zones: The number of stars in the zone, the average
           number of source positions per star, the average number of stars
           per square degree, the average of the mean epochs (for right
           ascension and declination), the average of the mean errors of
           proper motion (for right ascension and declination) and the
1
                                                                      Page 9
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           average of the mean errors of position at epoch 1990 (again for
           right ascension and declination). Units are seconds of arc and
           seconds of arc per century, respectively. At the bottom of the
           table the corresponding values for SAOC are given for comparison.
0          Note that the accuracy of all PPM South is as high as that of the
           High-Precision Subset of PPM (north).
-
                     Table 1: Error budget of PPM South
0             Zone      No.   No.  Dens. mean ep.  mean err.   mean err.
                       stars  obs. /sq.d. 1900+    prop. mot.  pos. 1990
0           -2.5- -20  60657  5.6 10.2  62.3 62.1  0.28 0.28   0.11 0.11
            -20 - -40  62048  6.6 10.3  63.8 62.4  0.32 0.31   0.11 0.11
            -40 - -60  47121  5.8 10.5  60.5 60.4  0.31 0.32   0.12 0.12
            -60 - -90  27353  7.0 10.2  58.6 60.9  0.27 0.30   0.11 0.11
0             total   197179  6.1 10.3  61.8 61.6  0.30 0.30   0.11 0.11
0          SAOC,south 126000  2.0  6.5  30   30    1.5  1.5    1.2  1.2
-          Note that (on average) more than 6 measured positions are
           available per star. This redundancy allowed us to discover (and
           avoid) a large number of gross errors in the source catalogues.
           It ensures that PPM South contains very few coarse errors for
           stars with 4 or more positions (more than 90 percent of all
           stars).  For 1801 PPM South stars the redundancy was not
           sufficient to resolve discrepancies between the source positions.
           They are indicated as unreliable by the 'P' or 'C' flags
           mentioned above. We kept these stars in PPM South, because for
           the majority of them the PPM data will still be correct to a few
           tenths of an arcsec. And even the rest will be within a few
           arcsec at most.
-
           Source catalogues
+          _________________
0          More than 1 250 000 source positions (i.e. right ascensions and
           declinations) entered into the least-squares adjustments for PPM
           South.  The following table lists the various groups of source
           catalogues used and the total number of positions taken from each
           group. More information on many of the catalogues as well as
           bibliographic references are given in the book by Eichhorn
           (1974).
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                    Table 2: Source Catalogues
0               Astrographic Catalogue         482 000
                FOKAT-S                        203 000
                CPC-2                          172 000
                Yale zone catalogues           128 000
                "AGK1"                         126 000
                CPC                             62 000
                Sydney SSC                      22 000
                CMC4, CMC5                      20 000
                SRS                             19 000
                Perth Cat. of Astrogr. Ref. St.  9 000
                Melbourne Gen. Cat. 3 to 5       8 000
0               Total                        1 251 000
0          Here, "AGK1" stands for the different catalogues of the "Catalog
           der Astronomischen Gesellschaft, Zweite Abtheilung" and its South
           American extension, the catalogues Cordoba A to D and La Plata A
           to F.
-          Numbering.
+          __________
0          The assignment of running numbers to the stars is a straightfor-
           ward continuation of that for PPM (north). It starts with number
           181732 for the first star and ends with number 378910. As in PPM
           (north) the stars are arranged in bands of 10 degrees width in
           declination. Within each of these bands they are ordered
           according to right ascension.  This arrangement was also used in
           the SAO Catalogue.
0          As a side remark we mention that in Preliminary PPM South the
           stars had running numbers starting with 500001.  This was to
           ensure that no confusion with the final PPM number can arise.
           Furthermore, it ensures that any data taken from the preliminary
           catalogue can be easily recognized as such.
-
           Systematic Errors
+          _________________
0          We did our very best to ensure that PPM is on the system of FK5.
           Such a goal, however, can be reached to a certain accuracy only.
           We estimate that the residual systematic deviations between PPM
           South and the FK5 system have a typical size of 0.05 arcsec for
           the positions at mean epoch and of 0.2 arcsec per century for the
           proper motions.
0          These numbers do not hold, however, for a few special groups of
           objects: The very blue stars (spectral types B2 and earlier), the
           very faint stars (fainter than about 11.5 in photographic
           magnitude) and those very bright stars (brighter than about 7)
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           that are not in FK5.  Because these groups are very small by
           number it was neither possible to check our preliminary system to
           the desired accuracy, nor could we correct the individual source
           catalogues to this system with the desired accuracy. So we just
           do not know anything about possible systematic errors for these
           small groups.
-
           Missing bright stars
+          ____________________
0          PPM and PPM South are not intended to be an inventory of the sky,
           but to provide a practical coordinate system on the sphere. This
           is why no special efforts were taken to make them complete to
           some limiting magnitude. Nevertheless, it would clearly be
           advantageous if all bright stars were included. We plan,
           therefore, to produce a supplementary star list, containing the
           few hundred objects brighter than magnitude 8.0 which are missing
           now.
-
           Some Statistics
+          _______________
0          PPM South gives 125 420 SAOC numbers. This corresponds to more
           than 99 percent of all SAOC stars in the celestial region covered
           by PPM South. It gives 121 817 HD numbers, corresponding to
           roughly 75 percent of all HD stars in the region. 190 061 stars
           carry either a BD or a CoD number, 136 586 stars have a CPD
           number and 151 018 have a spectral type.
0          There are 12 376 double star flags ('D'), 1724 problem cases ('P'
           flags), 77 critical comments ('C' flags) and 33 less important
           remarks ('R' flags). The 'R' flags refer to double star
           companions and to variable stars mostly. They are not in any way
           intended to be exhaustive or complete.
0          The number of FK5 stars ('F' flags) in PPM South is 1160. In
           passing, we note that in PPM (north) inadvertantly no 'F' flags
           and no FK5 data were given for two stars: FK5 3942 = PPM 161 and
           FK5 1270 = PPM 178197.
1
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           4. Practical usage
           ==================
0          PPM South gives positions for a standard epoch (J2000) and a
           standard coordinate system (mean equator and equinox for J2000 in
           the new IAU (1976) system of astronomical constants.
0          To apply the catalogue as astrometric reference at a different
           observational epoch, but still in the J2000 coordinate system,
           proper motions must be taken into account. For most purposes a
           simple linear formula (position difference equals epoch
           difference times proper motion) is sufficient. But note that this
           procedure will give inaccurate results close to the pole. Better
           formulae are given e.g. by Murray (1983) and in the introduction
           to FK5.
0          To apply PPM South as astrometric reference for a different
           equator and equinox, but still in the IAU (1976) system of
           astronomical constants, precession has to be taken into account.
           The relevant formulae and numerical values are given e.g. by
           Lieske (1979) and in the introduction to FK5.
0          Note that simply precessing from J2000 to B1950 will still not
           give results in the old (FK4) astronomical coordinate system.
           This differs from the new IAU (1976) system by a correction to
           the precessional constant, a correction to the position of the
           vernal equinox, by the treatment of elliptical aberration and by
           complicated zonal corrections. In general, this adds up to about
           an arcsec in position and several tenths of an arcsec per century
           in proper motion. In the region between -60 and -80 degrees
           declination the difference between the FK4 and the FK5 system is
           especially large. It amounts to 1.6 arcsec in right ascension at
           epoch 2000, and to about 1 arcsec/century for the proper motion
           in right ascension.
0          In File 3 of the machine-readable version we therefore publish
           positions and proper motions for equinox and epoch B1950 on the
           system of FK4, as we did for PPM (north).
0          Application of proper motion and precession still gives mean
           positions. In order to derive apparent positions for PPM objects
           one has to apply nutation, aberration, stellar parallax, and
           relativistic light bending, in addition (see e.g. Murray, 1983).
           For most practical uses of PPM these effects can be ignored. But
           PPM South contains a small number of stars with fairly large
           parallaxes.  They are not indicated in the catalogue.
0          For each star PPM South gives mean errors for right ascension and
           declination at their respective mean epochs T. Standard error
           propagation calculus can be used to calculate the mean error PPM
           position for an epoch t different from the mean epoch: Denoting
           the mean error of one coordinate at mean epoch by E(T), the mean
1
                                                                     Page 13
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           error of proper motion by E(PM), the mean error of position at
           epoch t is given by
0                      2            2            2            2
                   E(t)    =    E(T)    +   E(PM)    *   (T-t)
0          Using more PPM stars in an application will usually give better
           results because of the partial cancellation of the purely
           accidental errors of the PPM data.  However, this improvement
           will never get beyond the systematic errors of PPM, as discussed
           in the previous chapter.
-
-
           5. List of Critical Comments on Individual Stars
           ================================================
0          The following list gives, for each star included: The PPM number
           and a critical comment.
0          All stars included in this list carry the 'C' flag. Their
           astrometric data should be regarded as unreliable.
-          187259      See remark to PPM 187260.
0          187260      Double star. Companion is PPM 187259. Components
                       may be mixed up.
0          198815      Northern component of ADS 9728. Proper motion
                       derived from 3 positions around 1900 and a re-
                       constructed one for the CPC-2 epoch. The position
                       of this star in Yale16 is wrong. CPC-2 contains
                       the southern component in duplicate.
0          206258      Seems to be double. Probably there is another
                       star a few arcsec to the south east.
0          209551      Double star SAO 147542 / SAO 147543. Components
                       possibly mixed up in photographic source
                       catalogues.
0          218925      Double star, photographic source catalogues
                       measured combined image.
0          219535      Western component of a 3 arcsec double. SAO data
                       grossly wrong due to mixing of components.
0          220938      Companion to PPM 220939
1
                                                                     Page 14
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0          220939      Companion to PPM 220938. Not properly resolved
                       in the photographic source catalogues.
0          221658      Double star ADS 7423. Bright component is SAO
                       155267. Fainter companion, about 9 mag, 5 arcsec
                       to the south. Not properly resolved in the
                       photographic source catalogues.
0          222456      Double star. Companion is PPM 222457.
                       Components may be mixed up.
0          232367      Double star. Companion is SAO 160197.
                       Components may be mixed up.
0          236431      Seems to be double, with a separation of 2 to 3
                       arcsec.
0          240280      Double star SAO 165078 / SAO 165077. Components
                       possibly mixed up in photographic source
                       catalogues.
0          241502      Double star ADS 16688. Separation around 5
                       arcsec. All photographic source catalogues
                       measured a combined image.
0          252684      Double star. Companion is PPM 252685. Components
                       may be mixed up.
0          252685      Double star. Companion is PPM 252684. Components
                       may be mixed up.
0          252900      Close companion to SAO 174237. SAO 174237 is not
                       in PPM, is about 1 mag brighter than PPM 252900 and
                       situated about 5 arcsec to the north of PPM 252900.
0          254989      Seems to be double. Separation 3 to 4 arcsec.
                       SAO proper motion grossly wrong.
                       Components mixed up in the source catalogues.
0          259116      Double star. Companion is PPM 259117. Components
                       may be mixed up.
0          259117      See remark to PPM 259116.
0          261849      Double star, photographic source catalogues
                       measured combined image.
0          263277      South-eastern component of a 4 arcsec pair
                       having roughly equal magnitudes.
0          263375      Double star. Companion is PPM 263376. Components
                       may be mixed up.
1
                                                                     Page 15
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0          263376      Double star. Companion is PPM 263375. Components
                       may be mixed up.
0          265426      Double star. Companion is SAO 159864. Components
                       may be mixed up.
0          266532      May be double. Suspected separation 2 to 3 arcsec
                       in right ascension.
0          266613      Double star. Companion is SAO 185199. Components
                       may be mixed up.
0          268784      Double star. Companion to PPM 268785. SAO 187168.
                       SAO data wrong due to mixing of components.
0          268785      Double star. Companion to PPM 268784. SAO 187168.
                       SAO data wrong due to mixing of components.
0          268984      Double star. Companion is PPM 268985. Components
                       may be mixed up.
0          268985      See remark to PPM 268984.
0          275452      Double star. Companion is SAO 192230. Components
                       may be mixed up.
0          278376      Double star. Companion is SAO 193927. Components
                       may be mixed up.
0          283089      Double star. Companion is SAO 197176. Components
                       may be mixed up.
0          283868      Double star. Companion is PPM 283869. Components
                       may be mixed up.
0          283869      See remark to PPM 283868.
0          286548      This is SAO 200445, the brighter, north-eastern
                       component of a double. The companion is
                       SAO 200444. Separation about 8 arcsec.
0          286920      Double star. Companion is SAO 200759. Components
                       may be mixed up.
0          291906      Double star, photographic source catalogues
                       measured combined image.
0          293743      Double star. Companion is SAO 206544. Components
                       may be mixed up.
1
                                                                     Page 16
-
           294532      Double star. Companion is PPM 294533. Components
                       may be mixed up.
0          294533      See remark to PPM 294532.
0          294735      Double star. Companion is PPM 294737. Components
                       may be mixed up.
0          294872      Double star. Companion is SAO 207516. Components
                       may be mixed up.
0          297036      Double star Co 222. Magnitudes 8 and 9, separation
                       about 3.5 arcsec in p.a. 120 degrees. Photographic
                       source catalogues measured combined images.
0          297085      Double star, photographic source catalogues
                       measured combined image
0          297133      Seems to be double, with a separation of 2 to 3
                       arcsec.
0          298436      See remark to PPM 298437.
0          298437      Double star. Companion is PPM 298436. Components
                       may be mixed up.
0          310971      Double star. Companion is PPM 310972. Components
                       may be mixed up.
0          310972      Double star. Companion is PPM 310971. Components
                       may be mixed up.
0          312674      Double star. Companion is SAO 219509. Components
                       may be mixed up.
0          313226      Double star, identity of components unclear.
                       Therefore the proper motion, both in PPM and
                       in SAO, may be wrong.
0          314660      Double star. Companion is SAO 221478. Components
                       may be mixed up.
0          320653      Double star. Companion is SAO 225845. Components
                       may be mixed up.
0          322346      See remark to PPM 322347.
0          322347      In star cluster NGC 6231.
                       Double star. Companion is PPM 322346. Components
                       may be mixed up.
0          323229      Double star. Companion is SAO 228247. Components
                       may be mixed up.
1
                                                                     Page 17
-
0          323811      See remark to PPM 323812.
0          323812      Double star. Companion is PPM 323811. Components
                       may be mixed up.
0          326265      Double star. Companion is SAO 230259. Components
                       may be mixed up.
0          328272      Double star, the companion is PPM 328273.
                       Not well separated, some photographic
                       source catalogues measured combined images.
0          328273      See remark to PPM 328272.
0          330419      Seems to be a close double, components mixed up.
0          335814      Double star. Companion is PPM 335815. Components
                       may be mixed up.
0          335815      See remark to PPM 335814.
0          339408      Eta Carinae complex
0          342157      Double star. Companion is SAO 241075. Components
                       may be mixed up.
0          343102      Double star. Companion is SAO 241950. Components
                       may be mixed up.
0          345433      Double star. Companion is SAO 227281. Components
                       may be mixed up.
0          350797      Double star Dunlop 246, SAO 247739 and SAO
                       247738. Magnitudes 6 and 7, separation about
                       9 arcsec in p.a. 260 degrees. Photographic
                       source catalogues measured combined images.
0          352179      Double star. Companion is PPM 352180. Components
                       may be mixed up.
0          352180      Double star. Companion is PPM 352179. Components
                       may be mixed up.
0          354885      30 Doradus nebula and cluster, NGC 2070
0          358676      Double star. Companion is SAO 251382. Components
                       may be mixed up.
0          367144      Globular cluster Dunlop 62, NGC 362.
1
                                                                     Page 18
-
-
-          6. List of Remarks on Individual Stars
           ======================================
0          The following list gives, for each star included: The PPM number
           and a remark.  In contrast to the Critical Comments these remarks
           are not of direct relevance to astrometry.
0          All stars included in this list carry the 'R' flag.
0          184482      Omikron Ceti, 2-10 mag
0          188303      Sigma Ori A, 4.0-6.0 mag
0          191848      T Hya, 7.3-13.8 mag
0          198814      Southern component to PPM 198815. 5 measured
                       positions, somewhat discordant in declination.
0          218852      Spectral type K5 + M3ep
0          219584      Northern component of ADS 6553. Companion of
                       similar brightness 5 arcsec to the south.
0          223226      U Hya, 4.8-5.9 mag
0          223323      The cross-identifications given are from SIMBAD
                       data base. But according to SAOC this star is
                       BD -13 3193 = HD 92677.
0          225675      R Crv, 5.9-14.0 mag
0          236273      Double star ADS 12699; a fainter companion
                       lies about 5 arcsec to the north west.
0          239702      Double star. The companion is SAO 164830,
                       about 5 arcsec to the north east.
0          243352      Double star. Companion is SAO 166652, 5 arcsec
                       to the north.
0          259064      SAO 179935, brighter component of double ADS 8183.
                       The fainter component is PPM 259065.
0          259065      Companion to PPM 259064 = SAO 179935.
                       SAO data grossly wrong due to mixing of components.
0          283489      Double star. Companion is SAO 197558.
1
                                                                     Page 19
-
0          295347      SU Sco, 11.5-14 mag
0          311594      variable, 3.4-6.2 mag
0          320951      Double star. Companion is SAO 226131.
0          321275      Double star. Companion is SAO 226443.
0          329505      Double star. Companion is SAO 231718.
0          339070      YZ Car, 9.0-10.7 mag
0          339090      UX Car, 8.1-9.1 mag
0          339405      SV Vel, 8.8-10.8 mag
0          344085      U Nor, 8.6-9.2 mag
0          349722      Double star. Companion is SAO 247198.
0          352298      Double star. Companion is SAO 248345.
0          354005      Double star. Companion is SAO 248985.
0          356979      SAO proper motion for this star is grossly wrong.
0          357553      Double star. Companion is SAO 250696.
0          358986      Southern component of an 8 arcsec pair.
0          359025      UU Mus, 9.4-10.3 mag
0          365147      Y Pav, 5.7-8.5 mag
0          377688      Double star. Companion is SAO 257158.
1
                                                                     Page 20
-
           7. Explanation of the machine-readable version of PPM South
           ===========================================================
0          The machine-readable version of PPM South contains 3 physical
           files.
0          The three files are:
0           - File 1: The text of this introduction to PPM South
0           - File 2: The catalogue as an easily readable table, 197179 records,
                      in the same format as PPM (north).
0           - File 3: The catalogue in the format in which the preliminary
                      version of PPM (north) was delivered in 1988.
0          The remainder of this chapter gives very short descriptions of
           these three files. It describes the formats of the files together
           with a short description of the contents.
-          The tables defining the individual files give the following
           information for each data item:
0           - name of the item (mnemonic)
            - position of the item within each record (first and last byte)
            - FORTRAN format
            - explanation
            - maybe a remark
0          In addition there is information on record length etc. at the top
           of each table.
-          File 1: The Introduction to PPM South
+          _____________________________________
0          This is a text file, given in exactly the same format as the
           printed Introduction to PPM South. Record length is 133 bytes,
           but only 76 bytes are actually used (the remaining being always
           blank).  This file can be used to produce printed versions of the
           introduction on any printer able to interpret the paper feed
           characters '1' (form feed), ' ' (single line feed), '0' (double
           line feed), '-' (triple line feed) and '+' (no line feed).  Page
           headings, page numbering etc. appear as in the printed
           introduction.  Just submit the file to your printer. The printed
           pages contain 66 lines at maximum.
1
                                                                     Page 21
-
           File 2: PPM South as an easily readable table
+          _____________________________________________
0          This is the main file giving the catalogue proper. Record length
           is 133 bytes. The stars are arranged in bands of 10 degrees width
           in declination. Within each of these bands they are ordered
           according to right ascension. This arrangement was also used in
           the SAO catalogue. You can use this file to produce a rough
           printed version of PPM South by just submitting it to a printer
           capable of printing 133 characters per line.  No page headings,
           form feed characters etc. are included, of course.
0           PPM     2 -   7   I6  designation of the star in PPM South
                                    starting with No. 181732, see chapter 3.
            DM     10 -  18   A9    designation of the star in the Bonner
                                    Durchmusterung (for zones from -02
                                    to -22 degrees) or in the Cordoba Durch-
                                    musterung (zones -23 to -89 degrees).
            Mag    20 -  23   F4.1  magnitude, see chapter 3.
            Sp     25 -  26   A2    spectral type, see chapter 3.
            R.A.   28 -  39   F2.0,1X,F2.0,1X,F6.3
                              Right Ascension for the equinox and epoch
                              J2000.0, on the system of FK5, given in
                              hours, minutes and seconds of time.
            Sign   42 -  42   A1  Sign of declination ('+' or '-').
            Dec.   43 -  53   F2.0,1X,F2.0,1X,F5.2
                              Declination for the equinox and epoch
                              J2000.0, on the system of FK5, given in
                              degrees, minutes and seconds of arc.
            PMA    56 -  62   F7.4
                              proper motion in right ascension for epoch
                              and equinox J2000.0, on the system of FK5,
                              given in seconds of time per Julian year.
            PMD    64 -  69   F6.3
                              proper motion in declination for epoch and
                              equinox J2000.0, on the system of FK5,
                              given in seconds of arc per Julian year.
            N      71 -  72   I2
                              number of individual published positions
                              used for the derivation of the position
                              and proper motion given
            SA     74 -  75   F2.0
                              mean error of right ascension at the mean
                              epoch of right ascension, multiplied by the
                              cosine of declination, given in units of
                              0.01 seconds of arc.
            SD     77 -  78   F2.0
                              mean error of declination at the mean epoch
                              of declination, given in units of
                              0.01 seconds of arc.
            SPMA   80 -  83   F4.1
                              mean error of the proper motion in right
                              ascension, multiplied by the cosine of
1
                                                                     Page 22
-
                              declination, given in units of 0.001 seconds
                              of arc per Julian year
            SPMD   85 -  88   F4.1
                              mean error of the proper motion in declination
                              given in units of 0.001 seconds of arc per
                              Julian year
            EPA    90 -  94   F5.2
                              weighted mean epoch of the measured positions
                              used for the derivation of R.A. and PMA,
                              given in years since 1900.0
            EPD    96 - 100   F5.2
                              weighted mean epoch of the measured positions
                              used for the derivation of Dec. and PMD,
                              given in years since 1900.0
            SAO   102 - 107   I6    designation of the star in the SAO
                                    Catalogue
            HD    109 - 114   I6    designation of the star in the Henry
                                    Draper Catalogue
            CPD   117 - 125   A9    designation of the star in the Cape
                                    Photographic Durchmusterung
            Flags 127 - 131   5A1   Five flags  -  possible values:
                        127         P  problem case, preferably not to be
                                       used as astrometric reference star.
                        127         C  a critical comment is given in the
                                       List of Critical Comments. Not to be
                                       used as astrometric reference star.
                        128         D  double star, preferably not to be
                                       used as astrometric reference star.
                        129         -  Not used, void for consistency with
                                       PPM (north).
                        130         F  member of FK5, mostly bright stars,
                                       original FK5 data are given.
                        131         R  a remark is given in the List of
                                       Remarks on Individual Stars.
                        131         V  the magnitude is a photographic V
                                       magnitude copied from CPC-2.
0          Be careful not to miss the sign of the declination (byte 42)
           while transforming this formatted file into a numeric file on
           your computer.
-          File 3: The catalogue in the format of the preliminary PPM
+          __________________________________________________________
0          File 3 gives a version of PPM South for equinox and epoch
           B1950.0, FK4 system (see items RA50, Dec50, PMA50 and PMD50 in
           the table below). It contains the J2000.0 version also. This file
           was added for the convenience of those users that received the
           preliminary PPM (north) on tape. To transfer File 3 to their home
           computer they can use exactly the same reading routine as for the
           preliminary PPM (north).
1
                                                                     Page 23
-
           Record length is 138 bytes.
0                   2 -   4   A3    3 characters 'PPM'
            PPM     5 -  10   I6
            Mag    11 -  16   F6.1
            Sp     19 -  20   A2
            Flag   22 -  22   A1    problem flag, see description of File 2,
                                    byte 127
            RA50   24 -  38   D15.8   radians
                                      Right ascension for equinox and
                                      epoch B1950, FK4 system
            Dec50  40 -  54   D15.8   radians
                                      Declination for equinox and epoch
                                      B1950, FK4 system
            PMA50  56 -  67   D12.5   radians/tropical century
                                      Proper motion in R.A. for equinox and
                                      epoch B1950, FK4 system
            PMD50  69 -  80   D12.5   radians/tropical century
                                      Proper motion in Dec. for equinox and
                                      epoch B1950, FK4 system
            R.A.   82 -  96   D15.8   radians
                                      Right ascension for equinox and
                                      epoch J2000, FK5 system
            Dec.   98 - 112   D15.8   radians
                                      Declination for equinox and
                                      epoch J2000, FK5 system
            PMA   114 - 125   D12.5   radians/julian century
                                      Proper motion in R.A. for equinox
                                      and epoch J2000, FK5 system
            PMD   127 - 138   D12.5   radians/julian century
                                      Proper motion in Dec. for equinox
                                      and epoch J2000, FK5 system
-
-
           References.
           ===========
0          Boss, B. (1936): General Catalogue of 33342 Stars for the Epoch
                  1950. Vols. I to V. Carnegie Institution of Washington,
                  Washington 1936.
0          Bystrov, N.F., Polozhentsev, D.D., Potter, Kh.I., Zalles, R.F.,
                  Zelaya, J.A. and Yagudin, L.I. (1989): On the
                  FOKAT catalog. Astron. Zh. 66, 425.
0          CMC (1985-1991): Carlsberg Meridian Catalogue La Palma,
                  Numbers 1 to 5. Copenhagen University Observatory,
                  Royal Greenwich Observatory and Real Instituto y
1
                                                                     Page 24
-
                  Observatorio de la Armada, San Fernando.
0          Corbin, T. (1991): International Reference Stars Catalog,
                  Washington, US Naval Observatory, 1991.
0          Eichhorn, H. (1974): Astronomy of Star Positions, Frederick
                  Ungar Publ. Co., New York.
0          Fricke, W., Schwan, H., Lederle, T. (1988): Fifth Fundamental
                  Catalogue (FK5). Part I. The Basic Fundamental Stars.
                  Veroeff. Astron. Rechen-Institut Heidelberg Nr.32.
0          IAU (1976): IAU Transaction XVI B, Reidel Publ., Dordrecht 1977.
0          Lieske, J. (1979): Precession matrix based on IAU(1976) system
                  of astronomical constants, Astron. Astrophys. 73, 282.
0          Murray, C.A. (1983): Vectorial Astrometry, Adam Hilger Ltd.,
                  Bristol, UK.
0          Roeser, S.  The System of the PPM Catalogue. Proc. IAU-Symp. 141
                     Inertial Coordinate System on the Sky. Ed.: J.H. Lieske
                     and V.K. Abalakin. p. 469. Kluwer,Dordrecht, 1990.
0          Roeser, S., Bastian, U. (1991): PPM Star Catalogue, Astronomi-
                  sches Rechen-Institut, Heidelberg, Vols. I and II, printed
                  by Spektrum Akademischer Verlag, Heidelberg
0          Roeser, S. et al. (1993): The Construction of PPM South, in
                  preparation.
0          Smith, C.A., Corbin, T.E. Hughes, J.E., Jackson E.S.,
                  Khrutskaya, E.V, Polozhentsev, A.D., Polozhentsev, D.D,
                  Yagudin, L.I., Zverev, M.S. (1989): The SRS catalog
                  of 20488 star positions: culmination of an international
                  cooperative effort, in: IAU Symp. No. 141, Inertial
                  Coordinate System on the Sky, Leningrad, Oct. 17-21,
                  1989.
0          Yagudin, L.I. et al. (1993): The FOKAT-S Star Catalogue, in
                  preparation.
0          Zacharias, N., de Vegt, C., Nicholson, W., Penston, M., 1992:
                  CPC-2 - the Second Cape Photographic Catalogue.
                  Astron. Astrophys. 254, 394.
1
                                                                     Page 25
-
           Acknowledgements
           ================
0          This work was supported by Deutsche Forschungsgemeinschaft,
           Academy of Sciences of the USSR, Russian Academy of Sciences
           and Ukrainian Academy of Sciences in the framework of the
           collaboration project "Astrometric Star Catalogues".
0          We gratefully acknowledge help from our colleagues Wayne Warren,
           Heiner Schwan, Maria Erbach and Eberhard Roehl.
