The Description File introduced in Chapter intro(Alternative: The alternative name 0readme is proposed in Chapter intro) 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)
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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)>
=1996A&AS..119...91T =1995Msngr..81...20D
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ADC_Keywords: Magellanic Clouds ; Positional data
Description:
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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
lmc.dat 52 175779 The Large Magellanic Cloud
smc.dat 52 67782 The Small Magellanic Cloud
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Byte-by-byte Description of file: lmc.dat smc.dat
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Bytes Format Units Label Explanations
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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
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Note on BochumFlag: 1 if in Bochum catalog of astrophysical information
on bright LMC stars) (yet empty)
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Author's address:
Hans-Joachim Tucholke <tucholke@astro.uni-bonn.de>
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(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 description file contains the following parts:
Objects:
\makebox[2em][c]
-----------------------------------------------—
\makebox[3.2em][c]
RA (equinox) DE
\makebox[1.5em][c]
Name(s)
\makebox[2em][c]
-----------------------------------------------—
\makebox[2em][c]
hh mm ss.s ±dd mm ss Name1 =
Name2...
\makebox[2em][c]
-----------------------------------------------—
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).
See also:
\makebox[1.5em][c]
J/A+AS/97/729 : O-rich stars in 1-20um range
\makebox[1.5em][c]
http://machine/description.html : Detailed Description of
the experiment
Special care has been taken to try to use the standard SI units, and to convert if necessary the unit to such standards: for instance, we use the string 0.1nm to express Angströms (Å=10–10m), since the Angström is a non-standard unit. Another example is mW/m2 , the milliwatt per m2, which is identical to the CGS erg/cm2/s unit, which is not used outside our discipline.
The standard adopted here differs from the OGIP ones ( OGIP memo 93-001 about ``Specification of Physical Units within OGIP FITS files" by Ian M. George & Lorella Angelini, August 1993) for the syntax of composite units (operator symbols), and in the usage of math functions and obsolete CGS units which are rejected here; the basic symbols however agree.
Only simple power functions or decimal logarithm of physical units are accepted, which means that e.g. solMass3/2 (solar mass at a 3/2 power) cannot be a valid unit; [solMass] indicates logModot unit, i.e. a value representing solar masses expressed on a logarithmic scale.
The numerical factor may include the letter x for the multiplication, as 1.5x10+11 to express the number 1.5×1011
Among several possible expressions of a unit, it is preferable to choose the shortest one; this leads also to prefer the division (/) to the multiplication of the inverse, e.g. prefer km/s to km.s-1.
The basic symbols listed in
The standard SI multiple and submultiple prefixes can be used;
these are summarized in
Remember that a label is always a single word: it cannot
contain any embedded blank. Other characters are in principle
accepted, e.g. parentheses or other punctuation signs.
A parameter has frequently associated values, and we have adopted
the rule of association with the one-letter underscore prefix:
if a column is obviously associated to another one — typically
mean errors or uncertainty flags — we use one of the
underscore prefixes listed in
Usual mathematical functions may be specified in the label,
with parentheses or a dot; for instance, the logarithm of the effective
temperature could be labelled log(Te) or log.Te.
The first word (i.e. set of characters followed by a blank)
of the explanation of a column
may specify validity checks to be performed about:
The three different checks have to be specified in this order:
range, NULL, order, without any embedded blank.
All these checks are performed by the standalone program anafile
detailed in section anafile.
Limits in a column can be specified in the explanation column,
with values enclosed within square brackets [ or ] (The square brackets are not part of the EBCDIC character set;
the angle brackets < > could eventually be used instead of the
square brackets.
); the square bracket must be the first
character of the explanation if present.
The only
exception arises when an asterisk is present before the first square
bracket to indicate the presence of extended notes (see section Notes).
As an example, the following specifies a parameter
350 < λ< 650 :
Both limits are not required: to express that a value has to be strictly
positive, use the expression ]0,]; the expression
[,0] specifies a negative or null value.
Writing [] is acceptable
when no range checking applies; this writing is required
if a not-NULL or a sorting order has to be specified.
When specified, limiting numbers should represent actual limits,
and not the
range of all possible values which can be inferred from the format
(e.g. [-999,9999] for an I4 number).
Some labels have implicit limits, listed in the column Limits
of
The default rule is the following:
The column Name of
Lengthy explanations can hardly be inserted in the
Byte-by-byte Description table;
such explanations are easier to read when they are
grouped at the end of the description table.
Two options are presently proposed:
Note on label: section header.
An example of this way is illustrated in
Note (n): section header.
An example of this way is illustrated in
The data files can be automatically transformed into FITS:
The transformation into FITS can also be performed directly
in the ftpd server at CDS —
the server which is used for remote copies.
Basic Unit Symbols (see section basic)
Symbol Explanation Definition (c) — Unitless value (c) % Unitless value, in percent 10–2 (a) a year (also yr) 365.25d = 31.5576×106s (b) A Ampere (a) AU astronomical unit 1.49598×1011m (a) arcmin minute of arc 1/60 deg (a) arcsec second of arc 1/60 arcmin (e) barn barn (cross-section) 10–28 m2 (c) bit binary information unit (computer storage) (c) byte byte (computer storage) 8 bit C Coulomb (electric charge) A⋅s (b) cd Candela (luminous intensity) (c) ct Count (events) D Debye 1/3×10–29 C⋅m (a) d day 24h = 86.4×103s (a) deg degree of arc π/180 rad (e) eV electron-Volt 1.602177×10–19 J F Farad (electric capacitance) C/V (b) g gram 10–3 kg (a) h hour of time (sideral if appropriate) 3600s H Henry (inductance) Wb/A Hz Hertz (frequency) s–1 J Joule (energy) N⋅m (a) Jy Jansky 10–26 W/m2/Hz (b) K Kelvin lm lumen (luminous flux) cd⋅sr lx lux (illuminance) lm/m2 (b) m metre (a) mag magnitudes (a) mas millisecond of arc (π/6.48)×10–8 rad (a) min minute of time (sideral if appropriate) (b) mol mole N Newton (force) kg⋅m/s2 Ohm (Ω) Ohm (electric resistance) V/A Pa Pascal (pressure) N/m2 (a) pc parsec 3.0857 ×1016m (c) pix pixel (image element) (b) rad radian (angle) (e) Ry Rydberg (energy)
1/2 (2πe2/hc)2mec2 = 13.60583 eV (b) s second of time S Siemens (electric conductance) A/V (c) solLum Solar luminosity 3.826×1026 W (c) solMass Solar mass 1.989×1030 kg (c) solRad Solar radius 6.9599×108 m (c) Sun Unit referring to the Sun (e.g. abundances) sr steradian (solid angle) T Tesla (magnetic field intensity) Wb/m2 V Volts (electric potential) W/A W Watt (power) J/s Wb Weber (magnetic flux) V⋅s (c) yr year (also a) 365.25d = 31.5576×106s 3.2.3 Multiples
Symbols used to express multiples and submultiples
Symbol Explanation Value d deci 10–1 c centi 10–2 m milli 10–3 u micro (µ) 10–6 n nano 10–9 p pico 10–12 f femto 10–15 a atto 10–18 z zepto 10–21 y yocto 10–24
Symbol Explanation Value da deca 10 h hecto 102 k kilo 103 M mega 106 G giga 109 T tera 1012 P peta 1015 E exa 1018 Z zetta 1021 Y yotta 1024 3.3 Labels
Symbol Explanation Default Limits RAh Part of the right ascension expressed in hours [0,24[ RAm Part of the right ascension expressed in minutes [0,60[ RAs Part of the right ascension expressed in seconds [0,60[ RAdeg (Alternative: RAhms could be envisaged for a right ascension expressed
in sexagesimal with no embedded blanks and leading zeroes, RAbhms
for sexagesimal values with embedded blanks.
Such extensions would however require special interpretation by
FITS readers.
)
Right ascension expressed in decimal degrees [0,360[ RArad Right ascension expressed in radians [0,2π[ DE- Sign of declination [+-] DEd Part of the declination expressed in degrees [0,90] DEm Part of the declination expressed in arc minutes [0,60[ DEs Part of the declination expressed in arc seconds [0,60[ DEdeg (Alternative: DEdms could be envisaged for a declination expressed
in sexagesimal with no embedded blanks and leading zeroes, DEbdms
for sexagesimal values with embedded blanks; questions similar to the
RAhms note have to be addressed.
)
Declination expressed in decimal degrees [–90,+90] DErad Declination expressed in radians
[–π/2,+π/2] ELON ecliptic longitude [0,360[ ELAT ecliptic latitude [0,360[ GLON galactic longitude [0,360[ GLAT galactic latitude [0,360[ plx Parallax pmRA Proper motion in Right Ascension pmDE Proper motion in Declination pmX Proper motion along X direction Diam Diameter >=0 PA Position Angle, normally North to East [0,360[ Rad Radius >=0 RV Radial velocity Sep Separation >=0 SpType Spectral type MType Morphological type
Symbol Explanation Default Limits a_label aperture used for
parameter label >=0 E_label mean error (upper limit)
on parameter label >=0 e_label mean error (σ)
on parameter label >=0 f_label flag
on parameter label l_label limit flag
on parameter label [<>] m_label multiplicity index
on parameter label to resolve ambiguities n_label note (remark)
on parameter label o_label number of observations
on parameter label >=0 q_label quality
on parameter label r_label reference (source) for parameter label u_label uncertainty flag
on parameter label [ :] w_label weight of parameter label >=0 x_label unit in which parameter label is
expressed 3.4 Data Checking
3.4.1 Limits
3 A1 --- u_lab [ :?] Uncertainty flag on parameter lab
The dash sign (-) may be used to specify consecutive characters,
e.g. [A-F] for any character of the set {A,B,C,D,E,F}.
75- 80 F6.2 nm lambda ]350,650[ Wavelength
3.4.2 NULL values
A NULL or unspecified value is always indicated by setting
all bytes of the column to blanks(Alternative: using out-of-range values to specify NULLs
— typically numbers made of 9's only —
is required by some FORTRAN users.
).
The range or character set specification may be followed by the characters
3.4.3 Order
Following the range, it is also possible to specify that this column
is increasing or decreasing throughout the table(Alternative:
An alternative way of defining the order is proposed in the
File Summary part described in section ReadMe
). If n is the
row number, the conventions are:
3.4.4 Notes
Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 5 A5 --- Cluster Abell cluster designation
7- 22 A16 --- Name *Galaxy name
24- 25 I2 h RAh Right Ascension 1950 (hours)
27- 28 I2 min RAm Right Ascension 1950 (minutes)
30- 33 F4.1 s RAs Right Ascension 1950 (seconds)
35 A1 - DE- Declination 1950 (sign)
36- 37 I2 deg DEd Declination 1950 (degrees)
39- 40 I2 arcmin DEm Declination 1950 (minutes)
42- 43 I2 arcsec DEs Declination 1950 (seconds)
47- 51 F5.2 mag B(0) []? Integrated magnitude
52 A1 --- n_B(0) *[RMCPHK] Origin of B(0)
55- 59 I5 km/s RV Velocity
62- 64 I3 km/s e_RV Mean error on RV
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Note on Name:
Names with RA given with five digits are normally from
Zwicky catalogues; the other (with four digits in RA,
starting or not with the letter A) are anonymous
galaxies.
Note on n_B(0):
C = CCD photometry (CfA redshift survey 1992)
H = Zwicky magnitude split by observers
K = Markarian catalogue of galaxies (1967)
M = MCG (Vorontsov-Velyaminov et al. 1962-68)
P = observer's eye estimate
R = RC1 (de Vaucouleurs & de Vaucouleurs 1964)
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A first alternative to write lengthy explanations
Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 5 A5 --- Cluster Abell cluster designation
7- 22 A16 --- Name Galaxy name (1)
24- 25 I2 h RAh Right Ascension 1950 (hours)
27- 28 I2 min RAm Right Ascension 1950 (minutes)
30- 33 F4.1 s RAs Right Ascension 1950 (seconds)
35 A1 - DE- Declination 1950 (sign)
36- 37 I2 deg DEd Declination 1950 (degrees)
39- 40 I2 arcmin DEm Declination 1950 (minutes)
42- 43 I2 arcsec DEs Declination 1950 (seconds)
47- 51 F5.2 mag B(0) []? Integrated magnitude
52 A1 --- n_B(0) [RMCPHK] Origin of B(0) (2)
55- 59 I5 km/s RV Velocity
62- 64 I3 km/s e_RV Mean error on RV
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Note (1): Names with RA given with five digits are normally from
Zwicky catalogues; the other (with four digits in RA, starting or
not with the letter A) are anonymous galaxies.
Note (2):
C = CCD photometry (CfA redshift survey 1992)
H = Zwicky magnitude split by observers
K = Markarian catalogue of galaxies (1967)
M = MCG (Vorontsov-Velyaminov et al. 1962-68)
P = observer's eye estimate
R = RC1 (de Vaucouleurs & de Vaucouleurs 1964)
--------------------------------------------------------------------------------
A second alternative to write lengthy explanations
3.5 Transformation to FITS
XTENSION= 'TABLE ' / Ascii Table Extension
BITPIX = 8 / Character data
NAXIS = 2 / Simple 2-D matrix
NAXIS1 = 58 / Number of bytes per record
NAXIS2 = 793 / Number of records
PCOUNT = 0 / Get rid of random parameters
GCOUNT = 1 / Only one group (isn't it obvious?)
TFIELDS = 7 / Number of data fields (columns)
EXTNAME = 'appendix' / JHKL'M of 37 sources
=======================================================================
TBCOL1 = 1 / ============== Start column +0
TFORM1 = 'A20 ' / Fortran Format
TTYPE1 = 'Name ' / ! Star designation
TBCOL2 = 22 / ============== Start column +21
TUNIT2 = 'd ' / Unit: day
TFORM2 = 'I7 ' / Fortran Format
TTYPE2 = 'JD ' / [2445597/2448375] Date
TAMIN2 = 2445597 / Allowed minimal value
TAMAX2 = 2448375 / Allowed maximal value
TBCOL3 = 30 / ============== Start column +29
TUNIT3 = 'mag ' / Unit: magnitude
TFORM3 = 'F5.2 ' / Fortran Format
TTYPE3 = 'J ' / 1.24mum
TBCOL4 = 36 / ============== Start column +35
TUNIT4 = 'mag ' / Unit: magnitude
TFORM4 = 'F5.2 ' / Fortran Format
TTYPE4 = 'H ' / 1.63mum
TBCOL5 = 42 / ============== Start column +41
TUNIT5 = 'mag ' / Unit: magnitude
TFORM5 = 'F5.2 ' / Fortran Format
TTYPE5 = 'K ' / 2.19mum
TBCOL6 = 48 / ============== Start column +47
TUNIT6 = 'mag ' / Unit: magnitude
TFORM6 = 'F5.2 ' / Fortran Format
TTYPE6 = 'L'' ' / 3.79mum
TBCOL7 = 54 / ============== Start column +53
TUNIT7 = 'mag ' / Unit: magnitude
TFORM7 = 'F5.2 ' / Fortran Format
TTYPE7 = 'M ' / 4.64mum
=======================================================================
END
The FITS extension header constructed from the ReadMe file
of