ACT Reference Catalog Format

File format from the CDROM format.txt file
CDROM format from the CDROM readme.txt file

Format of .dat files

Bytes    Format  Units      Explanations

   1- 2  I2      h          Right Ascension J2000.0 (hours)    
   4- 5  I2      min        Right Ascension J2000.0 (minutes)  
   7-13  F7.4    s          Right Ascension J2000.0 (seconds)  
     15  A1      ---        Declination J2000.0 (sign)   
  16-17  I2      deg        Declination J2000.0(degrees) 
  19-20  I2      arcmin     Declination J2000.0 (minutes)  
  22-27  F6.3    arcsec     Declination J2000.0 (seconds)  
  29-35  F7.5    s/yr       Proper Motion in RA, (sec of time/yr)  
  37-43  F7.4    arcsec/yr  Proper Motion in Dec, (arcsec/yr)  
  45-49  F5.1    mas        Stand. dev. of RA at 1991.25 (T14 in Tycho)  
  51-55  F5.1    mas        Stand. dev. of Dec at 1991.25 (T15 in Tycho)  
  56-61  F6.2    mas/yr     Stand. dev. of Proper motion (RA), in mas/yr  
  62-67  F6.2    mas/yr     Stand. dev. of Proper motion (RA), in mas/yr  
  69-74  F6.3    mag        Blue magnitude from Tycho (T32)  
  76-81  F6.3    mag        Visual magnitude from Tycho (T34)  
  83-88  F6.3    mag        Johnson B-V from Tycho (T37)  
  90-90  A1      ---        Astrometric Quality flag (T10)  
  91-91  A1      ---        Quality flag (T40)  
  92-92  A1      ---        Known variability flag (T47)  
  93-93  A1      ---        Variability from Tycho (T48)  
  94-94  A1      ---        Duplicity from Tycho (T49)  
 96-107  A12     ---        Tycho ID, embedded zeros for blanks 
109-115  I7      ---        AC 2000 Number  
117-125  A9      ---        BD identifier (T54)  
127-135  A9      ---        CD identifier (T55)  
137-145  A9      ---        CPD identifier (T56)  
147-152  I6      ---        Henry Draper Number (T53)  
154-159  I6      ---        Hipparcos number (T31)

Notes on Flags:

Flags are provided to give additional data to users. All are from the Tycho Catalogue. Brief meaning is given below. For more detailed description, consult SP 1200 Volume 1.

Astrometry Flag (T10 in Tycho): blank: a recommended astrometric reference star; X: a dubious astrometric reference star in Tycho
Quality flag (T40 in Tycho): 1 through 5: very high to medium astrometric quality; probably single stars; 6: perhaps non-single; 7: low astrometric quality; 8: perhaps non-stellar}; blank: unassigned, observed by Hipparcos, not Tycho
Known variability flag (T47 in Tycho): G: Star in General Catalogue of Variable Stars, 4th Edition; N: Star in New Catalogue of Suspected Variable Stars
Variability from Tycho (T48 in Tycho): U: Apparent variability in Tycho data; may be due to duplicity; V: strong evidence of variability in the Tycho data; W: variability suspected in the Tycho data
Duplicity from Tycho (T49 in Tycho): Y: Investigation of duplicity made, no indication of duplicity; Z: No investigation of duplicity was performed

Format of the CD-ROM

Due to the different storage capacities of computers, the data are on this CD twice. One set is divided into 4 files, each about 40 Mbytes in size. The other set contains 48 files, each approximately 5 Mbytes. The data contained within are exactly the same. The directory /data1 contains files containing the ACT catalog sorted in right ascension order and divided every 30 minutes of time (48 files in total). The directory /data2 contains the ACT catalog divided into 4 declination bands, then sorted in right ascension order within each band. The directory /intro contains the introduction to the data in several different types of formats, including Latex, postscript and .gif. The intoduction can be viewed with a Web browser by pointing it at intro.htm.

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 FileName         Lrecl       Records    Explanations
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readme.txt           80             .  This file
format.txt                             Format of the ACT data
/data1/             159       988,758  data directory, 48 files
/data2/             159       988,758  data directory, 4 files
/intro/                                introduction directory
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The ISO-9660 format used to create this disk limits the file names to 8 characters with a 3 character extension. All alphabetic characters are upper-case.