Standards for Astronomical Catalogues, Version 2.0 (pdf)
(February 2000)

3.1  Structure of the ReadMe File

The Description File, named ReadMe, is aimed to provide all necessary information to locate the catalogue (authors, title, references, summary, etc...) and to interpret its contents by automatic procedures.

I/221               The Magellanic Catalogue of Stars - MACS (Tucholke+ 1996)
The Magellanic Catalogue of Stars - MACS
     Tucholke H.-J., de Boer K.S., Seitter W.C.
    <Astron. Astrophys. Suppl. Ser., 119, 91-98 (1996)>
    <The Messenger 81, 20 (1995)>
ADC_Keywords: Magellanic Clouds ; Positional data

    The Magellanic Catalogue of Stars (MACS) is based on scans of ESO
    Schmidt plates and contains about 244,000 stars covering large areas
    around the LMC and the SMC. The limiting magnitude is B<16.5m and the
    positional accuracy is better than 0.5" for 99% of the stars. The
    stars of this catalogue were screened interactively to ascertain that
    they are undisturbed by close neighbours.

File Summary:
 FileName    Lrecl    Records    Explanations
ReadMe          80          .    This file
lmc.dat         52     175779    The Large Magellanic Cloud
smc.dat         52      67782    The Small Magellanic Cloud

Byte-by-byte Description of file: lmc.dat smc.dat
   Bytes Format  Units   Label    Explanations
   1- 12  A12    ---     MACS     Designation
  14- 15  I2     h       RAh      Right Ascension J2000 , Epoch 1989.0 (hours)
  17- 18  I2     min     RAm      Right Ascension J2000 (minutes)
  20- 25  F6.3   s       RAs      Right Ascension J2000 (seconds)
      27  A1     ---     DE-      Declination J2000 (sign)
  28- 29  I2     deg     DEd      Declination J2000 , Epoch 1989.0 (degrees)
  31- 32  I2     arcmin  DEm      Declination J2000 (minutes)
  34- 38  F5.2   arcsec  DEs      Declination J2000 (seconds)
      40  I1     ---     Npos     Number of positions used
  42- 46  F5.2   mag     Mag      ?=99.00 Instrumental Magnitude
                                        (to be used only in a relative sense)
      48  I1     ---     PosFlag  [0,1] Position Flag   (0: ok,
                                        1: internal error larger than 0.5")
      50  I1     ---     MagFlag  [0,1] Megnitude Flag  (0: ok,
                                        1: bad photometry or possible variable)
      52  I1     ---  BochumFlag *[0] Bochum Flag
Note on BochumFlag: 1 if in Bochum catalog of astrophysical information
    on bright LMC stars) (yet empty)

Author's address:
    Hans-Joachim Tucholke    <>

(End)            Hans-Joachim Tucholke [Univ. Bonn]                  20-Nov-1995

The ReadMe file of a catalogue

An example of the ReadMe file of the catalogue I/221 is given in the ReadMe. The description file contains severals sections; as a general rule, only section headers are left flushed, while the text is indented — with the noticeable exceptions of the title, the file names in the File Summary section, and of Note headers (section 3.5). No line in this description file can exceed 80 characters; it is moreover suggested to limit the textual parts to 70 characters, such that a conversion to FITS could keep the text as COMMENT cards.

The description file contains the following parts:

  1. First line: catalogue designation, an abbreviated title followed within parenthesis by the last name of the first author, a + sign if there are multiple authors, and the year — this information has to be condensed in a single line of 80 characters or less;

  2. Full title(s), authors, and reference(s) of the catalogue. Each title is left-adjusted (no indentation); the line(s) containing the authors' names are indented (at least two blanks), and the bibliographic reference is enclosed between angle brackets. The standard SIMBAD/NED/ADS 19-byte bibliographical reference code(s) named BibCode ( see e.g.a description in the SIMBAD User's Guide, page 65, or on the WWW page is introduced by an equal sign, as a word without embedded blank of exactly 20 characters (with the equal sign).

  3. The Keywords.

    There are three categories of keywords:

    Whatever the category, multiple keywords are separated by a semicolon (;) or a dash (-) embedded in blanks.

  4. A short description of the contents, the purpose and remarks of special importance of the catalogue introduced by Description:  and/or Abstract:   section headers;

    This description contains a plain ascii text; special symbols are written with the the following conventions shared with data-base:

  5. (optional)  The list of observed objects introduced by Objects:   only in the case where no data table contains the list and position of the astronomical objects observed or studied, as for example in the study of a high-resolution spectrum of a single star. Such a list is normally restricted to very few objects – less than 10 or 20 typically; when the list of objects is large, it is suggested to store the list of objects with their positions in a dedicated file named objects.dat or stars.dat described in a standard way.

    The structure for this list must follow the following template:

          RA  (equinox)  DE     Name(s)
        hh mm ss.s +dd mm ss    Name1 = Name1

    The header line (the one with RA, DE, and the equinox) should be aligned with the data, in order to give a measure of the starting byte of the object designations (names).

    When each object in this list is related to a file, the name of this file can be put within brackets at the end of each line, as for instance in catalogue J/MNRAS/301/1031.

  6. A list of the files making up the catalogue is introduced by the File Summary:  section header. This list includes the following basic information for each file: its name, its record length (length of the longest line), the number of records, and a short title (caption).

  7. (optional)  The list of related catalogues, data sets or services are introduced by the See also:  header. In this section, each catalog or service starts on a new line, and is followed by a colon embedded in blanks, e.g.:

    See also:
        J/A+AS/97/729 : O-rich stars in 1-20um range
        http://machine/description.html : Detailed Description

  8. (optional)  Due to the frequent difficulties encountered the the nomenclature of astronomical objects, a dedicated section introduced by the Nomenclature Notes:  header provides the necessary explanations in the peculiar conventions used in this matter.

  9. A description explaining which are the columns of the tables, how to get the values stored in these columns, and what is their meaning is introduced by the Byte-by-byte Description of file:  section header. This line may specify that data files include header lines which are not part of the data (see section 2.4); the existence of header lines can be specified either by a number (i.e. the first n lines of the files are not data), or by a character which introduces a comment (usually a hash #). The existence of header lines is specified in parentheses as e.g.
    Byte-by-byte Description (12 headlines):   or when header lines are introduced by a has sign:
    Byte-by-byte Description (# headlines):  

    The description is presented as a five-column table with the following elements:

    1. the starting (from 1) and ending byte of a column, separated by a dash -; this dash is however not required for a single-byte column .

    2. à la FITS format which specifies how to interpret numbers or symbols, composed of
      • a letter A, I, F or E indicating to intrepret the data as Ascii text, Integer number, Floating-point number with a fixed number of decimals, or a floating-point number written in Exponential notation
      • followed by a number indicating the width of the column in bytes,
      • eventually followed by a dot and a number indicating the number of decimal digits (for F and E notations)
      This format could be preceded by an iteration factor to designate an array of values all written with the same format.

    3. the Unit in which the value is expressed; unit standards are detailed below (section 3.2). The symbol indicates unitless values, and the square brackets [unit] indicates values tabulated as decimal logarithmic values.

    4. a label or column header. Standard names and name building rules are detailed in section 3.3.

    5. a short explanation of the contents of the column. This last field may also specify:
      • a set of valid characters for an alphabetical column, or limits for numeric columns: see section 3.4.
      • whether the column is ordered: see section 3.4
      • whether blank (unspecified) numbers are allowed: see section 3.4
      • a key to more detailed notes: see section 3.4

  10. (optional)  Global notes — notes which apply to several tables — are introduced by Note (Gn):   n being the number of the global note referenced in the Byte-by-byte Description of file:  sections.

  11. (optional)  some other sections may exist when required, e.g. History;  introduces notes about the modification history, Acknowledgements:  etc...

  12. (optional)  The list of references is introduced by the References:  header; the 19-character BibCode is used when possible, to enable an automatic link to the existing Abstract Services like ADS.

  13. the very last line includes just the left-flushed word (End), the name of the person who took care of the standardisation, and the date of the last modification.