- - 0 0 *********************************************** * * * * * Introduction to PPM * * * * * *********************************************** - - - Contents ======== - 1. Scope of PPM 1 0 2. Construction of PPM 2 0 3. Properties of PPM 6 0 4. Practical Usage of PPM 9 0 5. List of Critical Comments on Individual Stars 10 0 6. List of Remarks on Individual Stars 12 0 7. Short Explanation of the Magnetic Tape Version of PPM 21 0 8. Short Explanation of the Printed Catalogue 24 0 References 26 0 Acknowledgments 27 Preface ======= 0 The idea of this Introduction to PPM is to deliver a short explanation together with the catalogue itself. It should not be understood as a detailed description of the work performed in the construction of PPM. This will be given in a forthcoming paper (Bastian and Roeser 1990). S. Roeser and U. Bastian Astronomisches Rechen-Institut Heidelberg, June 1989 1 (Introduction to PPM) Page 1 - 1. Scope of PPM =============== 0 PPM gives positions and proper motions of 181731 stars north of -2.5 degrees declination. Its main purpose is to provide a convenient, dense and accurate net of astrometric reference stars on the northern 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 the FK5 system at higher star densities and fainter magnitudes. 0 Two older catalogues of similar character have served the same purpose in the past decades: AGK3 and the SAO Catalog. There are three major reasons to replace these now: 0 1) SAOC and AGK3 are representations of the now obsolete FK4 system of positions and proper motions. Astronomers should have direct access to the FK5 system. 0 2) The accuracy of positions and proper motions in AGK3 and 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 quantity of data. 0 3) Proper motions in AGK3 and SAOC were derived from only two separate source positions per star. This lack of redundancy leads to a large number of coarse errors in those catalogues. 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 For purely practical reasons PPM presently covers only the northern celestial hemisphere plus the strip between the equator and -2.5 degrees declination. For the time being, a southern hemisphere portion of the SAO Catalogue, transformed to the system of FK5 (J2000), is appended to the magnetic tape version of PPM. In this way the magnetic tape users are provided with a star catalogue on the system of FK5 (J2000) on the southern hemisphere also. 0 An extension of PPM to the south pole is obviously necessary. It has to be provided in the near future. 1 (Introduction to PPM) Page 2 - 2. Construction of PPM ====================== - In principle, the construction of PPM proceeded in the same way as for other astrometric compilation catalogues in the past: For each star, a mean position and a proper motion are derived from a number of measured positions (found in published source catalogues) by a least-squares adjustment. In detail, however, quite a number of new methods and concepts were used which greatly reduced the effort for this undertaking. PPM was constructed in several steps, each of which will now be explained very briefly. - Step 1: Compilation of the star list. 0 The star list for PPM was constructed starting from the magnetic tape version of AGK3, which contains 181581 stars. All FK5 stars (Basic FK5 plus Bright Extension) north of -2.5 degrees declination were added, if not already included. In the course of the work six AGK3 stars had to be deleted (because they are non-existent) and five close companions to AGK3 stars were added. This gave the final list of 181731 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 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 effects of grossly incorrect positions in the star list etc. 0 Prior to the identification of Astrographic Catalogue data (given as x,y plate coordinates originally) a rough plate reduction was performed, using published approximate plate constants. - 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 AGK3, but with its positions and proper motions corrected to the system of NIRS (Corbin, 1978), the latter being regarded as a representation of the FK4 system. This correction was done using the systematic differences between AGK3 and NIRS given by Schwan (1985). - 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 1 (Introduction to PPM) Page 3 - catalogues and the preliminary system were determined and eliminated. For Astrographic Catalogue zones we performed second-order plate reductions, using the preliminary system as reference. The resulting star positions were further corrected for magnitude- and colour-dependent deviations and for effects of higher-order distortion ("coma"). - Step 5: Determination of weights for the source positions 0 In a least-squares adjustment weights have to be assigned to the individual measurements, according to their mean errors. Magnitude-dependent mean errors of the positions were determined for each source catalogue. For Astrographic Catalogue zones this was achieved by investigating the differences between positions of the same star measured on different (overlapping) plates. For Yale and AGK1 zone catalogues the differences between the source positions and a preliminary version of PPM (Roeser and Bastian, 1988) were investigated. For the Carlsberg Meridian Circle catalogues (CMC 1985-1988) the differences from FK4 were investigated by R. Bien (1988). For AGK3R the mean errors given by Eichhorn (1974) were used. - 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 column 19.1 of the printed catalogue). This occurred in about 950 cases. - Step 7: Manual treatment of difficult cases 0 The automatic outlier elimination deleted about 5500 measured coordinates (out of more than 2 million). Tight restrictions, however, were imposed on this automatic process in order to avoid spuriously "good" results. This created about 800 "difficult cases" that were treated manually. A majority of these turned out to be coarse errors in AGK3, the rest were caused by errors in other source catalogues, mixed-up double star components etc. For about 180 objects no satisfactory solution could be found. These were added to the "problem cases" of step 6, giving a total of 1120 PPM stars with flag 'P'. 0 Another group of stars was subject to manual checks: Those AGK3 stars not found in any source catalogue except AGK2 and AGK3 (about 60 cases). We checked these for coarse errors of AGK3 by locating the stars on Palomar Sky Survey prints - with a precision of a few arcsec. In most cases they were found at the predicted positions. Nine cases were indeed caused by errors in both AGK2 and AGK3. We kept the data for these nine objects, but marked them as severe problem cases (see flag 'C' in column 19.1 of the printed catalogue). 1 (Introduction to PPM) Page 4 - - Step 8: Transformation from the preliminary to the final system 0 The positions and proper motions derived thus far were transformed from the preliminary system (described above) to the new IAU (1976) coordinate system, as defined by FK5. This step had two major parts: First, a transformation from the preliminary system to a presumably better representation of the FK4 system was performed. Then a standard transformation from the FK4 system (B1950) to the FK5 system (J2000). 0 The first part became necessary because of the discovery of two sorts of systematic deviations between the preliminary system and the FK4 system: - Uncorrected atmospheric dispersion in the original AGK2 and AGK3 positions had caused a strong colour-dependent and declination-dependent systematic error. This was corrected. No other colour or magnitude equations were applied to the preliminary system. In other words: The colour and magnitude system of PPM is identical to that of AGK3 (except for the dispersion effect, of course). - In the course of the work we found indications for zonal errors of our preliminary proper-motion system. Therefore we did not keep this for the final system of PPM. Instead we constructed a new system of positions and proper motions from the systems of AGK3R (unchanged) and the CMC catalogues (after transformation to the FK4 system). 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). 0 More details on the construction and properties of the system of PPM will be given by Roeser (1989). - 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 flags for each star. 0 Much manual labour went into the provision of cross-references. They 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 four catalogues: Bonner Durchmusterung (abbreviated DM), SAO Catalog, Henry Draper Catalogue (HD) and AGK3. Three more cross-references are given implicitly by flags (see columns 19 of the printed catalogue): Flag 'F' in column 19.4 denotes the stars contained in FK5 (Parts I and II). 1 (Introduction to PPM) Page 5 - Flag 'H' in column 19.3 indicates stars that are contained in AGK3R and/or one of the CMC catalogues. The double star flag 'D' (column 19.2) was created by cross-referencing PPM with the Catalogue of Components of Double and Multiple Stars (Dommanget 1988). 0 The magnitudes and spectral types were copied either from AGK3 or from FK5 (see Chapter 8 for details). 0 Various sorts of auxiliary information are given in the List of Critical Comments and in the List of Remarks (Chapters 5 and 6), and indicated by the 'C' and 'R' flags. 1 (Introduction to PPM) Page 6 - 3. Properties of PPM ==================== - 0 Random Errors + _____________ - The table below shows a summary of the error budget of PPM. Each line of the table gives the following data for the particular set of stars indicated: The number of stars in the set, the average number of source positions per star, 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 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 AGK3 and SAOC are given for comparison (a more complete comparison of PPM with SAOC, AGK3 and the - future - HIPPARCOS catalogue is given by Roeser and Bastian 1989, Fig. 3). - Table 1: Error budget of PPM - set of stars No. No. mean epochs mean err. mean err. stars obs. prop. mot. pos. 1990 0 PPM, all stars 181731 6.2 1931.5 1930.7 0.43 0.42 0.27 0.27 PPM, HPS stars 31841 7.8 1950.3 1948.0 0.24 0.25 0.12 0.12 PPM, FK5 stars 1365 --- 1954.2 1945.2 0.08 0.10 0.04 0.05 0 AGK3 181581 2.0 1945 1945 0.95 0.95 0.45 0.45 SAOC, north 133000 2.0 1930 1930 1.5 1.5 0.9 0.9 0 Three subsets of PPM are shown in the table: The first line refers to the entire catalogue, the last line to the 1365 FK5 stars and the second line to the High-Precision Subset (HPS) of PPM. This subset will be briefly discussed now. 0 PPM essentially was constructed by combining AGK3 with early-epoch catalogues. So the mean epochs of PPM are quite early and the present-day accuracy is dominated by the accuracy of the proper motions. Therefore it would be highly desirable to have a repetition of AGK3 at present epoch. This not being available, we decided to introduce the Carlsberg Meridian Circle (CMC) catalogues, nos. 1 to 4 (CMC 1985 -1988). In addition, we introduced AGK3R because of its higher accuracy compared to AGK3. The High-Precision Subset of PPM is defined as the set of PPM stars for which either CMC or AGK3R observations are available. Its superior precision in present-day positions is mainly due to the fine work done at the Carlsberg Meridian Circle. 0 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 coarse errors in the source catalogues. It ensures that PPM contains very few coarse errors. For 1064 PPM stars the redundancy was not sufficient to resolve discrepancies between the source positions. They carry the 'P' flag mentioned above. 1 (Introduction to PPM) Page 7 - Source Catalogues + _________________ 0 More than 1.1 million source positions (i.e. right ascensions and declinations) were used for the construction of PPM. The following table lists the various groups of source catalogues used and the total number of positions derived from each group. More information on the catalogues as well as bibliographic references are given in the book by Eichhorn (1974), except for the CMC catalogues. - Table 2: Source Catalogues - Astrographic Catalogue zones 466 278 AGK3 181 581 AGK2 181 581 AGK1 141 146 Yale zone catalogues 80 574 Gyllenberg, 1926 11 498 Prager, 1923 8 602 0 CMC 1, 2, 3, 4 25 656 AGK3R 20 581 0 Total 1 117 497 - 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 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 12 in photographic magnitude) and the very bright stars (brighter than about 7, but not in HPS or 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. 0 Another possible systematic error stands out clearly from our data, but still cannot be removed. It is a magnitude equation in right ascension, affecting stars fainter than about 10.5 mag (photographic). It shows up as a systematic difference between PPM and the CMC catalogues (remember that, by definition, the magnitude dependence of the proper-motion system of PPM is that of AGK3. The CMC catalogues were transformed to that system before inclusion into PPM). It has a mean value of about 0.08 1 (Introduction to PPM) Page 8 - arcsec for stars between 10.6 and 11.0 mag, and 0.15 arcsec for stars fainter than 11.0 mag. The cause of this systematic difference cannot be identified with existing astrometric data. Therefore, it cannot be removed in a reasonable way. More details will be given by Roeser (1989). 1 Some Statistics + _______________ 0 PPM contains 131502 SAOC stars, which corresponds to almost 99 percent of all SAOC stars in the celestial region covered by PPM. It contains 85357 HD stars, corresponding to about 70 percent of all HD stars in the region. There are 16031 double star flags ('D'), 1120 problem cases ('P' flags), 22 critical comments ('C' flags) and 228 less important remarks ('R' flags). The 'R' flags refer to peculiar DM designations and variable-star designations mostly. 1 (Introduction to PPM) Page 9 - 4. Practical Usage of PPM ========================= 0 PPM 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 PPM 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 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. All this adds up to several tenths of an arcsec in position and a few tenths of an arcsec per century in proper motion. 0 Application of proper motion and precession still gives mean positions. In order to derive apparent positions for PPM objects one also has to apply nutation, aberration, stellar parallax, and relativistic light-bending (see e.g. Murray, 1983). For most practical uses of PPM these effects can be ignored. But PPM contains a small number of stars with fairly large paral- laxes. They are not indicated in the catalogue. 0 For each star PPM 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 of a 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 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. 0 Applications demanding utmost accuracy rather than high star density should use HPS stars only. 1 (Introduction to PPM) Page 10 - 5. List of Critical Comments on Individual Stars ================================================ 0 The following list gives, for each star included: The PPM number, the AGK3 number (if any) and a critical comment. Any positions given in the comment refer to equinox J2000.0. 0 All stars included in this list carry the 'C' flag. 0 20679 +66 0812 : Planetary nebula NGC 6543 0 42555 +45 0003 : An orbital double star. There is also +45 0002 in AGK2, but not in AGK3. A difficult problem, which cannot be solved at the moment. 0 43225 +40 0059 : BD +40 147. Centre of M32 according to SIMBAD(CDS). 0 43228 +40 0060 : BD +40 148. Centre of M31 according to SIMBAD(CDS). 0 50954 +41 0889 : FK5 339. This is an orbital double star. FK5 data are given referring to centre of gravity. 0 56062 +43 1399 : Globular cluster NGC 6341 = M92 0 72938 +31 0789 : FK5 287. This is an orbital double star. FK5 data are given referring to centre of gravity. 0 76814 +38 1224 : Companion to FK5 485. AGK2 and AGK3 are wrong. In our opinion GC gives the correct position and proper motion. Difficult case in photographic astrometry. PPM position and proper motion is derived from the the GC mean position and one CMC observation. 0 86045 +38 2138 : see 86047 and 86049. 0 86047 : FK5 793. The centre of gravity of 61 Cyg. Data copied from FK5. See also 86049. 0 86049 +38 2136 : 86045 and 86049 are the components of 61 Cyg. see also 86047. Both stars are of poor quality in PPM, because positions and proper motions are derived neglecting the large parallax of these stars. 0 112552 +21 2332 : Inspection on POSS shows: This star does not exist. The companion AGK3 +21 2333 is a double star with approximate separation 15 arcsec. AGK3 data are copied. Do not use them. 1 (Introduction to PPM) Page 11 - 150880 +5 0838 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. Positions and proper motions are derived from two AC measurements. There is another star at position: 6 37 17.19 +5 7 57.6, Epoch 1915.0. 0 150973 +08 0809 : This is NGC 2261 0 151210 +2 0793 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. There is a star in the AC at position: 6 46 27.50 +2 9 42.8, Epoch 1910.0 AGK3 data are copied. Do not use them. 0 151371 +3 0869 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. This star is n o t BD +3 1431. The position of BD +3 1431 is 6 50 54.36 +3 27 23.9, Epoch 1910.2. AGK3 data are copied. Do not use them. 0 152571 +8 973 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. Positions and proper motions are derived from two AC measurements. AGK3 claims that AGK3 +8 973 is BD +8 1757, but according to the coordinates given in the Bonner Durchmusterung the the BD star is about 4 arcmin south and at the same R.A. as given in AGK2/3. This star is in AC at position: 7 24 20.78 +8 19 15.9, Epoch 1920.12. This is the BD star. The declination difference suggests an error in the AGK2/3 measurements of 2 mm. 0 153068 +05 1072 : FK5 291. This is an orbital double star. FK5 data are given referring to centre of gravity. This star is omitted in the printed version of AGK3. 0 159607 +2 1655 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. There is a star in AC at position: 13 15 56.82 +2 40 39.4, Epoch 1910.4. AGK3 data are copied. Do not use them. 0 165440 +9 2185 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. Positions and proper motions are derived from two AC measurements. It is a companion to AGK3 +9 2184. 0 166000 +2 2269 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. There is a star in the Astrographic Catalogue (AC) at position: 18 30 53.79 +2 5 27.6, Epoch 1910.0 AGK3 data are copied. Do not use them. 0 168632 +4 2602 : Inspection on POSS shows: Both AGK2 and AGK3 are wrong. Positions and proper motions are derived from the measurements in AC and by Lopez (1987). 1 (Introduction to PPM) Page 12 - 6. List of Remarks on Individual Stars ====================================== 0 The following list gives, for each star included: The PPM number, the AGK3 number (if any) and a remark. In contrast to the Critical Comments these remarks are not of direct relevance to astrometry. Most remarks refer to peculiar DM designations and to variable-star designations. Any positions given in the comment refer to equinox J2000.0. 0 All stars included in this list carry the 'R' flag. - 736 +85 0058 BD +85 0059 austr 0 737 +85 0059 BD +85 0059 bor 0 4213 +85 0399 BD +84 0540 bor 0 5978 +70 0252 BD +70 0353 bor 0 5979 +70 0253 BD +70 0353 austr 0 6564 +73 0195 BD +73 0362 bor 0 6565 +73 0194 BD +73 0362 austr 0 8570 +71 0401 BD +71 0677 bor 0 8571 +71 0402 BD +71 0677 austr 0 10800 +76 0836 BD +75 0780 austr 0 10801 +76 0837 BD +75 0780 bor 0 11191 +70 0777 BD +70 1233 austr 0 11426 +78 0551 BD +77 0879 austr 0 11427 +78 0551a BD +77 0879 bor 0 12044 +62 0026 BD +62 0029 austr 0 13092 +61 0153 BD +60 0272 bor(AGK2) 0 13093 +61 0154 BD +60 0272 austr(AGK2) 0 14737 +64 0258 BD +63 0489s1 0 14738 +64 0259 BD +63 0489s2 0 16337 +65 0408 BD +65 0592 bor 0 19128 +61 0873 BD +61 1454 bor 0 19129 +61 0872 BD +61 1454 austr 0 19225 +67 0640 BD +67 0857 austr 0 19226 +67 0639 BD +67 0857 bor 1 (Introduction to PPM) Page 13 - 22874 +60 1381 BD +60 2239 bor 0 22875 +60 1382 BD +60 2239 austr 0 22923 +65 1105 BD +64 1552s1 0 24229 +64 1186 BD +64 1764 austr 0 24230 +64 1187 BD +64 1764 bor 0 24348 +68 1014 BD +68 1366 austr 0 24349 +68 1013 BD +68 1366 bor 0 24660 +62 1473 BD +61 2506 bor 0 24661 +62 1474 BD +61 2506 austr 0 25060 +51 0012 SS Cas. On one AC plate it has a companion (also variable? ) at position 0 9 36.63 +51 33 58.2 . 0 25788 +56 0096 BD +55 0191D 0 25791 +56 0097 BD +55 0191ABC 0 26075 +50 0132 BD +50 0228Aa according to AGK2 0 27500 +54 0285 BD +53 0509 austr 0 27501 +54 0286 BD +53 0509 bor 0 28515 +55 0346 BD +54 0684s2 0 29017 +57 0457 This AGK2 star was omitted in the printed version of AGK3. 0 29111 +50 0459 BD +50 0985 bor 0 29236 +52 0443 BD +52 0848 bor 0 29237 +52 0444 BD +52 0848 austr 0 30659 +58 0568 This star is wrongly identified in AGK3 to be BD +58 961a. The correct identification is +58 961. The star is HD 237537 and has spectral type K2 according to HD. Consequently, spectral type M9, given in AGK3, is wrong. This spectrum belongs to BD+58 961a = HD 47929, a star not contained in PPM. 0 36165 +59 1134 BD +59 1842 bor 0 36166 +59 1133 BD +59 1842 austr 0 36357 +50 1269 BD +50 2520 austr 0 36358 +50 1268 BD +50 2520 bor 0 37314 +53 1220 BD +53 2228 bor 0 37315 +53 1221 BD +53 2228 austr 1 (Introduction to PPM) Page 14 - 0 37610 +52 1296 BD +51 2645p2 0 37611 +52 1297 BD +51 2645p1 0 37667 +51 1344 BD +51 2661 bor 0 37668 +51 1345 BD +51 2661 austr 0 38331 +51 1432 BD +51 2821p2 0 38332 +51 1433 BD +51 2821p1 0 38663 +52 1418 BD +51 2898 bor 0 38664 +52 1417 BD +51 2898 austr 0 41324 +57 1624 BD +57 2657 austr 0 41350 +52 1707 BD +52 3341 bor 0 41950 +55 1690 BD +55 2981s1 0 42988 +48 0047 BD +48 0141 bor 0 42989 +48 0048 BD +48 0141 austr 0 43816 +40 0119 BD +40 0260a seq 0 44379 +43 0208 BD +43 0356 bor 0 44469 +47 0208 BD +47 0508s1 0 45477 +46 0288 BD +46 0633p1 0 45582 +44 0291 BD +44 0589 bor 0 45583 +44 0292 BD +44 0589 austr 0 47415 +44 0472 BD +44 1036p1 0 48885 +44 0639 BD +44 1402 austr 0 48886 +44 0640 BD +44 1402 bor 0 50828 +49 0822 BD +50 1575 bor 0 50829 +49 0821 BD +50 1575 austr 0 55572 +48 1261 BD +48 2421a prec 0 55574 +48 1263 BD +48 2421a seq 0 58003 +49 1511 BD +49 2959b seq 0 58005 +44 1577 BD +44 3078 bor 0 58006 +44 1578 BD +44 3078 austr 0 58174 +44 1594 BD +44 3107s1 1 (Introduction to PPM) Page 15 - 58554 +39 1976 BD +39 3832 bor 0 58555 +39 1975 BD +39 3832 austr 0 58885 +44 1669 BD +44 3261p1 0 58886 +44 1670 BD +44 3261p2 0 59824 +43 1820 UW Cyg 0 63398 +44 2119 This AGK2 star was omitted in the printed version of AGK3. 0 63400 +44 2118 CMC has observed AGK2 +44 2119. +44 2119 = BD +43 4305 = LHS 3853 = EV Lac. It is a flare star and astrom. binary, P=28y, a= 0.04". 0 64939 +39 2543 BD +38 5114 bor 0 64941 +39 2544 BD +38 5114 austr 0 66259 +35 0130 BD +35 0266 austr 0 66260 +35 0129 BD +35 0266 bor 0 67031 +33 0203 BD +32 0390 austr 0 67032 +33 0204 BD +32 0390 bor 0 67168 +37 0259 BD +36 0453AB 0 67839 +34 0295 BD +33 528B in AGK3 0 68514 +35 0353 R Per 0 68820 +34 0408 BD +34 0744 bor, but austr according to AGK2 0 69837 +38 0522 BD +38 1001s1 0 76100 +36 1089 BD +37 2218 bor 0 76101 +36 1090 BD +37 2218 austr 0 78728 +36 1364 BD +36 2626CD 0 82523 +34 1814 BD +34 3463 austr 0 82668 +35 1753 BD +34 3494s1 0 83206 +35 1822 BD +35 3703AB 0 83207 +35 1823 BD +35 3703s1 0 83534 +39 2011 BD +39 3910s1 0 83538 +39 2012 BD +39 3910s2 0 83664 +32 1842 A faint double star not measured in AC. 0 83719 +37 1855 BD +37 3651 bor 1 (Introduction to PPM) Page 16 - 0 83720 +37 1856 BD +37 3651 austr 0 85463 +30 2192 BD +29 4160 austr 0 87076 +34 2235 BD +33 4359 austr 0 87077 +34 2236 BD +33 4359 bor 0 87448 +30 2471 BD +30 4617 bor 0 87449 +30 2472 BD +30 4617 austr 0 87475 +31 2276 BD +30 4622 austr 0 87962 +39 2417 BD +38 4808 austr 0 87963 +39 2418 BD +38 4808 bor 0 88329 +32 2277 BD +32 4546 bor 0 88330 +32 2276 BD +32 4546 austr 0 91866 +28 0295 BD +28 0448 bor 0 91867 +28 0294 BD +28 0448 austr 0 91890 +26 0264 BD +26 0443 austr 0 91891 +26 0265 BD +26 0443 bor 0 92457 +24 0288 BD +23 0449 austr 0 92458 +24 0287 BD +23 0449 bor 0 92765 +25 0331 BD +25 0593 austr 0 92766 +25 0332 BD +25 0593 bor 0 94304 +20 0496 BD +19 0905 bor 0 94305 +20 0497 BD +19 0905 austr 0 94779 +28 0546 BD +28 0868 austr 0 95670 +27 0624 BD +27 1035 austr 0 96431 +27 0713 BD +27 1206 austr 0 96432 +27 0712 BD +27 1206 bor 0 96463 +23 0713 BD +23 1477 austr 0 96464 +23 0712 BD +23 1477 bor 0 97653 +22 0897 BD +23 1744 austr 0 97654 +22 0898 BD +23 1744 bor 0 97837 +28 0827 BD +28 1440 bor 1 (Introduction to PPM) Page 17 - 97991 +28 0845 BD +28 1474 austr 0 99247 +26 0987 BD +26 1885 bor 0 99248 +26 0988 BD +26 1885 austr 0 99374 +28 0979 BD +28 1707 austr 0 99455 +24 1065 BD +24 2067 bor 0 100883 +27 1117 Double star in AGK2: +27 1117 and +27 1118. The AGK3 measurement refers to the centre and was not used for PPM. 0 100884 +27 1118 This AGK2 star was omitted in the printed version of AGK3. 0 101958 +24 1314 BD +25 2518 bor 0 101975 +21 1297 BD +21 2429 bor 0 102684 +23 1318 BD +23 2584 bor 0 102685 +23 1319 BD +23 2584 austr 0 104347 +25 1597 BD +25 2973 bor 0 104348 +25 1598 BD +25 2973 austr 0 105039 +25 1673 BD +25 3108 bor 0 105040 +25 1674 BD +25 3108 austr 0 105654 +21 1678 BD +21 3063 bor 0 106982 +25 1901 BD +25 3473 austr 0 106983 +25 1902 BD +25 3473 bor 0 109767 +21 2053 BD +21 3927 bor 0 110507 +21 2112 BD +21 4073s1 0 110508 +21 2113 BD +21 4073s2 0 111510 +20 2287 In printed AGK2/3 BD +19 4464p1 0 111960 +20 2329 BD +19 4525 austr 0 112396 +20 2371 BD +20 4822 bor 0 112397 +20 2372 BD +20 4822 austr 0 113400 +28 2523 BD +27 4131 austr 0 114011 +28 2614 BD +28 4282 bor 0 114012 +28 2615 BD +28 4282 austr 0 115008 +27 2697 BD +26 4540 austr 1 (Introduction to PPM) Page 18 - 115977 +22 2581 BD +21 4999 bor 0 116009 +24 2583 BD +23 4830p2 0 116010 +24 2584 BD +23 4830p1 0 126928 +10 1274 BD +10 2072p1 0 126930 +10 1275 BD +10 2072p2 0 129303 +10 1567 BD +10 2466p1 0 129304 +10 1568 BD +10 2466p2 0 133569 +12 1829 BD +12 3253s1 0 133571 +12 1830 BD +12 3253s2 0 134095 +19 1680 RY Her 0 134248 +11 1993a This star is a close companion to 134249. In AGK3 this pair had only one entry (centre of light?). It is unclear which of the companions is HD 165475. 0 134249 +11 1993 This star is a close companion to 134248. In AGK3 this pair had only one entry (centre of light?). It is unclear which of the companions is HD 165475, but from a remark in GC it is clear that 44864 = SAO 103373 = GC 24655 0 134415 +10 2192 BD +10 3434s1 0 134416 +10 2193 BD +10 3434s2 0 136159 +19 1867 This AGK2 star was omitted in the printed version of AGK3. 0 136160 +19 1866 Double star in AGK2: +19 1866 and +19 1867. The AGK3 measurement refers to +19 1867 and not to +19 1866. 0 148223 +05 0540 BD +05 0776p1 0 148226 +05 0541 BD +05 0776p2 0 149628 +05 0689 BD +05 1043p1 0 149631 +05 0690 BD +05 1043p2 0 150058 +1 0662 This AGK2 star was omitted in the printed version of AGK3. 0 151093 +05 0860 BD +05 1373p1 0 151095 +05 0861 BD +05 1373p2 0 151096 +05 0862 BD +05 1373s1 0 151097 +05 0863 BD +05 1373s2 1 (Introduction to PPM) Page 19 - 151581 +03 0887 BD +03 1471p1 0 151582 +03 0888 BD +03 1471p2 0 151709 +00 0825 BD +01 1635p1 0 152202 +03 0956 BD +03 1609p1 0 152207 +03 0957 BD +03 1609p2 0 152338 +04 0950 BD +04 1652p1 0 152339 +04 0951 BD +04 1652p2 0 152441 +03 0987 BD +03 1651s1 0 152442 +03 0988 BD +03 1651s2 0 154155 +02 1086 BD +02 1916s1 0 154161 +02 1089 BD +02 1916s2 0 159258 +07 1684 BD +08 2654s1 0 159259 +07 1685 BD +08 2654s2 0 159970 +07 1756 BD +08 2747s1 0 159973 +07 1757 BD +08 2747s2 0 161865 +05 2052 BD +05 3070s1 0 161866 +05 2053 BD +05 3070s2 0 163056 +06 1957 BD +06 3288p1 0 163059 +06 1958 BD +06 3288p2 0 164086 +08 2122 BD +08 3427s2 0 165886 +07 2419 possibly BD +7 3700 0 167690 +06 2469 BD +06 4103s1 0 167691 +06 2470 BD +06 4103s2 0 168472 +08 2604 BD +08 4190p1 0 168475 +08 2605 BD +08 4190p2 0 168783 +08 2638 BD +08 4237s1 0 168787 +08 2639 BD +08 4237s2 0 169828 +09 2732 BD +09 4492p1 0 169830 +09 2733 BD +09 4492p2 0 171945 +07 3164 BD +06 4855s1 0 171946 +07 3165 BD +06 4855s2 1 (Introduction to PPM) Page 20 - 0 173580 +6 3146 Inspection on POSS shows: Both AGK2 and AGK3 are correct. This star is not measured in AC, but there is a star in AC nearby at position: 22 56 41.10 +6 36 36.4, Epoch 1918.77. On POSS the AC star has a faint companion. 0 173772 +06 3158 BD +05 5135p2 0 173773 +06 3157 BD +05 5135p1 1 (Introduction to PPM) Page 21 - 7. Short Explanation of the Magnetic Tape Version of PPM ======================================================== - The PPM magnetic tape contains 5 physical files. The records within each file have constant length. They are grouped into physical blocks of various constant lengths depending on how the tape has been prepared. 0 The five files are: 0 - File 1: The text of this Introduction to PPM, in exactly the same format as the printed Introduction. - File 2: The catalogue as an easily readable table, very similar to the format of the printed catalogue. - File 3: The catalogue in the format in which the preliminary version of PPM was delivered in 1988. - File 4: The southern part of the SAO Catalogue, in the same format as file 2. - File 5: The southern part of the SAO Catalogue, in the same format as file 3. 0 The remainder of this chapter gives very short descriptions of these five files. It describes only the formats of the files. The precise meaning of the individual data items is not described here, but in the Explanation of the Printed Catalogue (Chapter 8, below). In the present chapter the individual data items are denoted by mnemonic abbreviations which are the keys to the explanations in Chapter 8. 0 The tables defining the individual files give the following information for each data item: - name of the item (mnemonic) - position of the item within each record (first and last byte) - FORTRAN format - physical unit, if any - 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 + _______________________________ 0 This is a text file, given in exactly the same format as the printed Introduction to PPM. Record length is 80 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 to PPM 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 (Introduction to PPM) Page 22 - File 2: The PPM catalogue as an easily readable table + _____________________________________________________ 0 This is the main file giving the catalogue proper. Record length is 133 bytes. The format is very similar to that of the printed catalogue. You can use this file to produce a rough printed version of PPM 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 DM 10 - 18 A9 Mag 20 - 23 F4.1 Sp 25 - 26 A2 R.A. 28 - 39 F2.0,1X,F2.0,1X,F6.3 hours, minutes, seconds Sign 42 - 42 A1 Sign of declination ('+' or '-'). Dec. 43 - 53 F2.0,1X,F2.0,1X,F5.2 degrees, arcmin, arcsec PMA 56 - 62 F7.4 sec/year PMD 64 - 69 F6.3 arcsec/year N 71 - 72 I2 SA 74 - 75 F2.0 0.01 arcsec SD 77 - 78 F2.0 0.01 arcsec SPMA 80 - 83 F4.1 0.001 arcsec/year SPMD 85 - 88 F4.1 0.001 arcsec/year EPA 90 - 94 F5.2 years since 1900.0 EPD 96 - 100 F5.2 years since 1900.0 SAO 102 - 107 I6 HD 109 - 114 I6 AGK3 117 - 125 A9 Notes 127 - 131 5A1 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 PPM catalogue in the format of the preliminary PPM + ______________________________________________________________ 0 File 3 again contains the catalogue proper. It was added to the PPM tape just for the convenience of those users that received the preliminary PPM on tape. To transfer File 3 from the tape to their home computer they can use exactly the same reading routine as for the preliminary PPM. The only difference is in bytes 2 to 10, which now contain the PPM number, but contained the AGK3 number in the preliminary PPM. 0 Note that some information contained in File 2 is missing. On the other hand, File 3 gives a version of PPM for equinox and epoch B1950.0, FK4 system (see items RA50, Dec50, PMA50 and PMD50 in the table below). 0 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 Note 22 - 22 A1 Problem flag. May be blank, 'P' or 'C'. For further explanations see column 19.1 of the printed catalogue. RA50 24 - 38 D15.8 radians Right ascension for equinox and epoch B1950, FK4 system 1 (Introduction to PPM) Page 23 - 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 - File 4: Southern part of SAO Catalog in the format of File 2 + ____________________________________________________________ 0 We are well aware of the fact that any user of an astrometric catalogue such as PPM needs the entire sky. File 4 is intended to provisionally satisfy this need because a southern hemisphere extension of PPM is not yet available. 0 The file contains a J2000 version of the southern portion of the SAO Catalog. This portion was selected from the original SAO Catalog in such a way that there is neither a gap nor an overlap with PPM on the sky. The machine-readable version of the SAO Catalogue provided by Roman and Warren (1984) was used for this purpose. The SAO coordinates and proper motions were transformed to the equinox and epoch J2000 (FK5 system) in the standard way. 0 Basically, the format of File 4 is the same as that of File 2. But the following data items are always blank: PPM, N, SA, SD, EPA, EPD, AGK3, and all Notes except the last one. The last of the five Notes, corresponding to column 19.5 of the printed catalogue, is always set to 'S'. - File 5: Southern part of SAO Catalog in the format of File 3 + ____________________________________________________________ 0 File 5 provides the same subset of the SAO Catalog as File 4, but in a different format. The format of File 5 is the same as that of File 3, except for the first two data items. Bytes 2 to 4 contain the 3 characters 'SAO' instead of 'PPM' and bytes 5 to 10 contain the SAO number instead of the PPM number. 1 (Introduction to PPM) Page 24 - 8. Short Explanation of the Printed Catalogue ============================================= 0 The stars are arranged in bands of 10 degrees width in decli- nation. Within each of these bands they are ordered according to right ascension. This arrangement was also used in the SAO Catalog. 0 Column 1, PPM Serial no. of the star in PPM. 0 Column 2, DM Designation of the star in the Bonner Durchmusterung. Doubtful identifications are omitted (blank). The character 'x' denotes peculiar DM suffixes, which are given in the List of Remarks on Individual Stars. 0 Column 3, Mag Photographic magnitude, copied from AGK3. Visual magnitude for FK5 stars, copied from FK5 0 Column 4, Sp Spectral type, copied from AGK3; for FK5 stars copied from FK5. 0 Column 5, R.A. Right Ascension for the equinox and epoch J2000.0, on the system of FK5, given in hours, minutes and seconds of time. For FK5 stars original FK5 data are given. 0 Column 6, Dec. Declination for the equinox and epoch J2000.0, on the system of FK5, given in degrees, minutes and seconds of arc. For FK5 stars original FK5 data are given. 0 Column 7, PMA Proper Motion in Right Ascension for epoch and equinox J2000.0, on the system of FK5, given in seconds of time per Julian year. For FK5 stars rounded FK5 data are given. 0 Column 8, PMD Proper Motion in Declination for epoch and equinox J2000.0, on the system of FK5, given in seconds of arc per Julian year. For FK5 stars rounded FK5 data are given. 0 Column 9, N Number of individual published positions used for the derivation of the position and proper motion given (cols. 5 to 8). For FK5 stars N is set to zero. 0 Column 10, SA 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. For FK5 stars rounded FK5 data are given. 0 Column 11, SD Mean error of declination at the mean epoch of declination, given in units of 0.01 seconds of arc. For FK5 stars rounded FK5 data are given. 0 Column 12, SPMA Mean error of proper motion in right ascension, multiplied by the cosine of declination, given in milliseconds of arc per Julian year. For FK5 stars rounded FK5 data are given. 1 (Introduction to PPM) Page 25 - 0 Column 13, SPMD Mean error of proper motion in declination, given in milliseconds of arc per Julian year. For FK5 stars rounded FK5 data are given. 0 Column 14, EPA Weighted mean epoch of the individual published positions used for the derivation of right ascension and proper motion (cols. 5 and 7), given in years since 1900.0. For FK5 stars original FK5 data are given. 0 Column 15, EPD Weighted mean epoch of the individual published positions used for the derivation of decli- nation and proper motion (cols. 6 and 8), given in years since 1900.0. For FK5 stars original FK5 data are given. 0 Column 16, SAO Designation of the star in the SAO Catalog. Doubtful identifications are omitted. 0 Column 17, HD Designation of the star in the Henry Draper Catalogue. Doubtful identifications are omitted. 0 Column 18, AGK3 Designation of the star in AGK3. Doubtful identifications are omitted. 0 Column 19, Notes A number of notes on the individual stars are given in these columns. Notes P, C and D mark objects that should preferably not be used as astrometric reference stars. 0 Column 19.1 P problem case, preferably not to be used as astrometric reference star. Column 19.1 C a critical remark on this object is given in the List of Critical Remarks, it should not be used as astrometric refe- rence star. Column 19.2 D double star, preferably not to be used as astrometric reference star. Column 19.3 H member of the High-Precision Subset (HPS) of PPM. Column 19.4 F member of FK5, high precision stars, mostly very bright stars. Column 19.5 R a remark on this star is given in the List of Remarks on Individual Stars. 1 (Introduction to PPM) Page 26 0 References ========== 0 Bastian, U., Roeser, S. (1990): in preparation. 0 Bien, R. (1988): private communication. 0 CMC (1985-1988): Carlsberg Meridian Catalogue La Palma, Numbers 1 to 4. Copenhagen University Observatory, Royal Greenwich Observatory and Real Instituto y Observatorio de la Armada, San Fernando. 0 Corbin, T. (1978): The proper motions of the AGK3R and SRS stars. IAU Colloquium No. 48, Eds. F.V Prochazka and R.H. Tucker, 515. 0 Dommanget, J. (1988): in HIPPARCOS, Scientific Aspects of the Input Catalogue Production II, Proceedings of a Colloquium held at Sitges, Spain, 1988, eds. J. Torra and C. Turon, page 191. 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 Lopez, C. (1987): The Proper Motions of AGK3 Stars. IAU Colloquium No. 100, Fundamentals of Astrometry, Beograd, Sep. 8-11, 1987, in press. 0 Murray, C.A. (1983): Vectorial Astrometry, Adam Hilger Ltd., Bristol, UK. 0 Roeser, S. (1989): The System of PPM. IAU Symposium No. 141, Inertial Coordinate System on the Sky, Leningrad, Oct. 17-21, 1989. 0 Roeser, S. and Bastian, U. (1988): A New Star Catalogue of SAO Type, Astronomy and Astrophysics Suppl. 74, 449. 0 Roeser, S. and Bastian, U. (1989): Compilation of the PPM Catalogue, in: Star Catalogues, A Centennial Tribute to A.V. Vyssotsky, eds. A.G.D. Philip, A.R. Upgren, L. Davis press, Schenectady, N.Y., 1989. 0 Roman, N.G. and Warren, W.H. Jr. (1984): Documentation for the Machine-Readable Version of the SAO Star Catalog, Version 1984, Astronomical Data Center, National Space Science Data Center, Greenbelt, Maryland 0 Schwan, H. (1985): The systems of the positions and proper motions in star catalogues AGK3, AGK3RN, and N30. Astron. Astrophys. 149, 50. 1 (Introduction to PPM) Page 27 - Acknowledgments ================ 0 Generations of careful and patient observers and plate measurers have laid the base for the present work. Compared to their labour all other efforts that went into the preparation of PPM - inclu- ding our own - are small. 0 We gratefully acknowledge the help of Hamburger Sternwarte (C. de Vegt and H. M. Steinbach) and of Observatoire de Strasbourg (D. Egret and A. Fresneau) in providing the raw Astrographic Catalogue on punched cards. Several tons of cards were moved with the help of many hands in Strasbourg. Also we thank T. Corbin of US Naval Observatory for providing a magnetic tape containing part of the Strasbourg punched data already. 0 Heidelberger Druckmaschinen AG is gratefully acknowledged for technical help in the reading of the punched cards. 0 We thank the CMC group at La Palma for giving the CMC 4 catalogue to us prior to publication. 0 Last but not least we have to thank many people at our institute, especially E. Roehl and E. Mueller for careful checks and completion of the Astrographic Catalogue data, M. Erbach, M. Fleischer and T. Lederle for much valuable information on source catalogues, H. Schwan for many fruitful discussions and for his data on systematic differences between several catalogues, R. Bien for the determination of weights for the CMC catalogues and H. Bernstein for advice on mathematical statistics. Finally we want to thank R. Wielen, director of ARI, for giving us the opportunity to do this work.