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I/80        Catalog of 5268 Standard Stars, Normal System N30 (Morgan 1952)

Catalog of 5,268 Standard Stars Based on the Normal System N30 Morgan H.R. <Astron. Papers Amer. Ephemeris 13, Part III (1952)>
ADC_Keywords: Positional data ; Proper motions ; Stars, fundamental ; Fundamental catalog Description: The catalog was constructed primarily to assist in the reduction and interpretation of planetary observations, particularly those made in the nineteenth century. The new catalog was considered necessary because the only fundamental catalogs available at the time (FK3, GC) have mean epochs around 1900, and over the period of approximately fifty years, positional accuracies had deteriorated from cumulative effects of proper motion inaccuracies. The ADC version of the data file was prepared from the original file by reformatting and incorporating changes to effect uniformity in the data fields. The notes file was created at the ADC by keying the information directly to disk storage. Cross checks were performed to assure that all stars flagged as having notes have entries in the notes file and that all notes are flagged in the data file. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file n30.dat 90 5268 The N30 catalog of 5268 standard stars remarks.dat 80 277 Remarks
See also: I/113 : General Catalogue of 33342 stars (GC) (Boss 1937) Byte-by-byte Description of file: n30.dat
Bytes Format Units Label Explanations
1- 4 I4 --- N30 N30 running number 5- 12 A8 --- DM !DM number (Present for all stars) 13- 17 I5 --- GC [1/33342]? GC number (blank if not present) 18- 21 I4 0.01mag HPmag *Harvard photometric magnitude 22- 25 A4 --- HDSp *Henry Draper (HD) spectral type 26- 27 I2 h RAh *Right ascension (equinox B1950.0) in hours 28- 29 I2 min RAm *RA in minutes 30- 35 F6.3 s RAs *RA in seconds 36- 42 I7 0.01s RA3rd *Third term in right ascension 43- 47 I5 0.01s/ha pmRA Centennial proper motion in RA 48- 54 I7 0.01s/ha D(pmRA) ? Centennial secular variation in pmRA 55- 57 I3 0.1yr EpRA-1900 Mean epoch of RA (0.1 yr) (1900+) 58- 60 I3 --- w_RAs *weight of RA 61 A1 --- DE- sign 62- 63 I2 deg DEd *Declination (equinox B1950.0) in degrees 64- 65 I2 arcmin DEm *DEC in arcminutes 66- 70 F5.2 arcsec DEs *DEC in arcseconds 71- 75 I5 0.1arcsec DEC3rd *Third term in declination 76- 80 I5 marcsec/a pmDE Centennial proper motion in declination 81- 83 I3 marcsec/a D(pmDE) ? Centennial secular variation in pmDE 84- 86 I3 0.1yr EpDE-1900 Mean epoch of DEC (0.1 yr) (1900+) 87- 89 I3 --- w_DEs *weight of DEC 90 A1 --- rem [* ] "*" if there is a remark in remarks.dat
Note on HPmag: For double stars, if the position is for one component, the magnitude of that component is given and the magnitude, distance and position angle of the companion are given in the notes (remarks.dat). If the position is for the mean, center of light, or center of gravity, the combined magnitude is given and the magnitudes, distance and position angle of the components are given in the notes. Where the position is for the center of gravity, the orbital corrections used in the reduction of the observation were taken from the GC, Vol. I, Ap. II. For double stars of distances 1" to 2", there is an uncertainty as to part observed, depending upon the relative magnitudes of the components. If the components are separated and differ considerably in magnitude, then the use of screens cuts out the fainter star. There are a number of such stars and in older work the observations were reduced as the mean, or center of light. Where it seems probable that the new position is for the brighter star and the GC gives a mean, a note is given. The magnitudes of variable stars are given as a blank followed by three zeroes. Note on HDSp: Composite spectra are given as combinations; e.g. KOAO or KO+A. A few peculiar composite spectra require > 4 characters and the p's are omitted in the fields, but given in the notes. Note on RAh, RAm, RAs, DEd, DEm, DEs: Right ascension for equinox and epoch 1950.0 were brought up from epoch of observation using Newcomb's precession and the proper motions in this catalog. Note on RA3rd, DEC3rd: The first and second terms are not included on the original tape. Note on w_RAs: Sum of combining weights used in forming the normal position in RA. Note on w_DEs: Sum of combining weights used in forming the normal position in Dec.
Byte-by-byte Description of file: remarks.dat
Bytes Format Units Label Explanations
1- 4 I4 --- N30 N30 running number 5 A1 --- --- [.] A period (.) 7- 80 A74 --- rem Remark(s)
Remarks and Modifications: The catalog was received on magnetic tape from the Centre de Donnees Stellaires de Strasbourg. The following modifications were made to the format in order to make the records appear more similar to the published catalog, to make them easier to read when listed, and to simplify processing to produce printed and microform versions closely approximating the published catalog in appearance: 1. Data were read and rewritten to discard leading zeroes, which make the numbers difficult to read when listed. 2. All positive Durchmusterung numbers had zeroes in the zone numbers where + signs would ordinarily be. The zeroes were changed to + signs. 3. The GC numbers and secular variations in R.A. and Dec. were changed to blank fields if not present. They were zeroes on the tape as received. 4. Several modifications were made to the spectral types: (a) Peculiar and emission symbols (p, e) were changed to lower case to conform to standard usage. (b) Composite spectra are indicated by two spectral types which run together in the 4-byte field. For types of the form K0A, a change was made to the form K0+A. (c) Peculiar HD O-star types were coded numerically; they were decoded by replacing O1 by Ob, O3 by Od, O4 by Oe5, and O0P by Oap. 5. Plus (+) signs were added to the first byte of the declination field where blanks had been previously. 6. The note indicator (byte 88) was an asterisk (*) in many cases, but for more than half of the stars having notes, a peculiar code was found which printed as b on an extended chain printer. Since there should have been no varying note characters, the latter codes were changed to asterisks for uniformity. The notes file was created and added to the machine-readable catalog. Checks were made to ensure that all records containing an * have corresponding notes and vice versa. Acknowledgements: The original ADC documentation by Wayne H. Warren, Jr. (1981) was used to create this ReadMe file. He also did the reformatting discussed above. References: Morgan, H. R. (1952). Catalog of 5,268 Standard Stars for the Equinox and Epoch 1950.0 Based on the Normal System N30, Astron. Papers Amer. Ephemeris 13, Part III.
(End) C.-H. Joseph Lyu [Hughes STX/NASA] 08-Mar-1996
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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