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I/80 Catalog of 5268 Standard Stars, Normal System N30 (Morgan 1952)
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Catalog of 5,268 Standard Stars Based on the Normal System N30
Morgan H.R.
<Astron. Papers Amer. Ephemeris 13, Part III (1952)>
=1952N30...C......0M
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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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
stndstrs.dat 90 5268 The N30 catalog of 5268 standard stars
remarks.dat 80 277 Remarks
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Byte-by-byte Description of file: stndstrs.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID N30 running number
5 A1 --- DMsign DM sign
6- 7 I2 --- DMzone DM zone
8- 12 I5 --- DM DM number (Present for all stars)
13- 17 I5 --- GC ? GC number (blank if not present)
18- 21 I4 0.01mag HarvaP *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 v(pmRA) ? Centennial secular variation in pmRA
55- 57 I3 0.1yr mEpRA Mean epoch of RA (0.1 yr) (1900+)
58- 60 I3 --- w_mEpRA *weight of RA
61 A1 --- DE- sign
62- 63 I2 deg DEd *Declination (equinox 1950.0) 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 mEpDE Mean epoch of DEC (0.1 yr) (1900+)
87- 89 I3 --- w_mEpDE *weight of DEC
90 A1 --- rem [* ] "*" if there is a remark in
remarks.dat
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Note on HarvaP:
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_mEpRA:
Sum of combining weights used in forming the normal position in RA.
Note on w_mEpDE:
Sum of combining weights used in forming the normal position in Dec.
Byte-by-byte Description of file: remarks.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID N30 running number
5 A1 --- Dot [.]A period (.)
7- 80 A74 --- rem Remark(s)
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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.
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(End) M.C. Larkin [SSDOO/ADC] C.-H. Joseph Lyu [Hughes STX/NASA] 08-Mar-1996