Fourth Catalog of Interferometric Measurements of Binary Stars: Format

The entries for each binary star system are comprised of two parts: an identification line containing designations from various catalogs, followed by individual measures sorted in order of observation date. Formats of these data are as follows:
Identification line:
Column   Format         Description

   1     t1,a18         Epoch-2000 coordinates, to 0.1s in RA, 1" in DEC when known

   2     t21,a26        Star name #1 (usually ADS or HR number, otherwise DM or 
                        other catalog designation)

   3     t47,a26        Star name #2 (discoverer designation, Bayer, Flamsteed, or 
                        variable star name, GJ number, or other catalog designation)

   4     t73,a13        HD or DM number. Formats are 'HD 123456', 'BD+12 1234', 
                        'CD-1212345', or 'CP-1212345'

   5     t86,a3,1x,a15  Hipparcos, SAO, Tycho-2, GSC, or other designation. The first
                        three characters indicate the catalog (G22 = GSC2.2, UC2 = UCAC2,

   6     t105,a10       WDS designation or epoch-2000 coordinates in the form of the 
                        WDS designation (HHMMM+DDMM)

   7     t116,a1        General flag:
                          I - uncertainty in catalog match for precise coordinates in 
                              column 1
                          N - note about object in notes file 
   8     t118,a1        Orbit flag. Pair has a published visual or astrometric orbit
                        in the Sixth Orbit Catalog.
Data lines:
Column   Format         Description

   1     t2,a1          Epoch flag:
                          : - epoch not given in paper; the date is estimated based on 
                              comments in the text.
                          < - no information on epoch in text. An upper limit to the date 
                              is given, based on the date of publication.

   2     t3,f9.4        Epoch of observation, given as fraction of the Besselian year 
                        (even though they may have been given in some other form in the 
                        original reference). The number of significant digits in the 
                        epoch reflects the accuracy in the time as quoted in the original 

   3     t14,a1         Position angle flag:
                          V - position angle is vector angle of a one-dimensional (e.g. 
                              occultation) measure
                          : - measure of lower accuracy
                          ? - questionable position angle value

   4     t15,f7.3       Position angle in degrees.  Position angles have occasionally been
                        adjusted to their "proper" quadrant; it should be remembered that
                        interferometry often yields position angle determinations with a
                        180-degree ambiguity.

   5     t23,a1         Position angle error flag:
                          < - quoted error is upper limit             
                          > - quoted error is lower limit  

                        Note: A very small number of measures give errors of 10 degrees
                        or more; hence a "1" or "2" in this column 

   6     t24,f5.3       Position angle error (if given in the original reference).

   7     t29,a1         Separation flag:
                          < - value given is the upper limit for an unresolved measure 
                              (usually the Rayleigh limit, a function of the telescope 
                              aperture and filter)
                          > - value given is a lower limit of the true separation
                          : - measure is of lower accuracy
                          ? - questionable measure or flag for possible duplicity
                          D - separation is in degrees
                          e - pair is elongated (along direction of position angle, if 
                          m - separation is in milliarcseconds
                          M - separation is in arcminutes
                          R - pair is noted as being resolved, but no separation is given
                          U - pair is unresolved, but no resolution limit is given

                        Hipparcos non-component double star solutions and suspected 
                        non-single stars are indicated by the following codes: 
                          G - Hipparcos non-component double star solution 
                              (acceleration solution)
                          O - Hipparcos non-component double star solution 
                              (orbit solution)
                          S - Hipparcos suspected non-single
                          V - Hipparcos non-component double star solution 
                              (variability-induced mover)
                          X - Hipparcos non-component double star solution 
                              (stochastic solution)

   8     t30,f10.6      Separation in arcseconds.  For one-dimensional measures this value 
                        is the vector, rather than true separation.  

   9     t41,a1         Separation error flag: 
                          V - published qualitative rating of very poor
                          P - published qualitative rating of poor
                          F - published qualitative rating of fair
                          G - published qualitative rating of good     
                          < - quoted error is an upper limit             
                          > - quoted error is a lower limit  

                        Note: occasionally a paper will quote a range in separation over 
                        which an object is unresolved. In this case (and if the upper 
                        limit is less than 10") columns 7 and 8 will indicate the lower 
                        limit of the separation range, while columns 9 and 10 will 
                        indicate the upper limit, with a ">" flag in column 9.

  10     t42,f8.6       Separation error (if given in the original reference).

  11     t51,a1         Primary magnitude flag. 
                          : - uncertain magnitude estimate
                          > - primary is fainter than indicated magnitude
                          t - value listed is combined magnitude of pair
                          v - primary is variable in magnitude

  12     t52,f6.3       Primary magnitude. 

  13     t59,a1         Primary magnitude error flag:
                          < - error is less than indicated value

  14     t60,f5.3       Primary magnitude error.

  15     t66,a1         Secondary magnitude flag:
                          : - uncertain magnitude estimate
                          < - secondary is brighter than indicated magnitude
                          > - secondary is fainter than indicated magnitude
                          q - author does not gives magnitude information, but notes
                              that reduction technique used (e.g., triple correlation)
                              yields unambiguous quadrant determination
                          s - magnitude is of secondary despite column 12 being blank
                          v - secondary is variable in magnitude

  16     t67,f6.3       Secondary magnitude or, if col 12 is blank, magnitude difference

  17     t74,a1         Secondary magnitude error flag:
                          < - error is less than indicated value
  18     t75,f5.3       Secondary magnitude or magnitude difference error.

  19     t83,f4.0       Filter effective wavelength (in nanometers unless otherwise noted)

  20     t87,f4.0       Filter FWHM (in nanometers unless otherwise noted)

  21     t91,a1         Filter flag:
                          a - average of two or more different filters. Filter columns now
                              indicate mean wavelength and sigma of the filters averaged.
                          c - filter effective wavelength and FWHM are in centimeters
                          m - filter effective wavelength and FWHM are in millimeters
                          M - filter effective wavelength and FWHM are in meters
                          n - no filter used in observation
                          u - filter effective wavelength and FWHM are in microns     
                          x - x-ray band 
                          ? - filter information is uncertain                       

  22     t93,f4.1,a1    Telescope aperture or baseline of multiple-aperture array
                        (in meters, unless noted)  

  23     t97,a1         Telescope aperture code: 
                          k - long-baseline interferometer, baseline in kilometers

  24     t99,i2         "Number of nights". Occasionally published measures are averages 
                        of more than one observation. This practice was more common in 
                        earlier publications; the inclusion of data obtained by eyepiece 
                        interferometry prompted the inclusion of this column. Relative 
                        weighting of measures is typically scaled by the square root of 
                        this value.

  25     t103,a8        Code for the original reference.  Code format is the WDS 
                        Discoverer Designation code (usually the first three letters of 
                        the first author's name), followed by the publication year. An 
                        "a", "b", ...  follow if necessary to differentiate publications
                        by more prolific authors. The list of references is given here.

  26     t112,a3        Technique code. Codes have been merged with those in the WDS and 
                        all other USNO double star catalogs. The list below includes all 
                        codes used in these catalogs, even if not in the interferometric 
                        catalog (old WDS and interferometric catalog codes are included as 

                        new old    description

                        A   U    = adaptive optics
                        Ac  Uch  = CHARA adaptive optics
                        Ad  Usd  = adaptive optics spectral deconvolution technique
                        Ag  Ula  = laser-guided AO
                        Al  Usi  = adaptive optics imaging, keeping only selected images 
                                   ("lucky imaging")
                        Am  Uam  = adaptive optics with aperture mask
                        Ao  Uco  = adaptive optics coronagraph
                        As  Uds  = AO + dark speckle coronagraph
                        Aw  Ucw  = adaptive optics with coronagraph and "well-corrected 

                        C   F    = CCD or other two-dimensional electronic imaging
                        Ca  W    = Area scanner                             
                        Cc  Fic  = IR coronagraph
                        Ce  L    = Electronographic camera                  
                        Ci  Fir  = IR direct imaging
                        Cl  Fsi  = short-exposure CCD imaging, keeping only selected 
                                   images ("lucky imaging")
                        Cp  Fip  = IR imaging polarimetry
                        Cs  Fss  = IR one-dimensional slit scanning
                        Cu  F    = USNO CCD imaging (speckle-style reduction)     

                        D   D    = Heliometer                               

                        E   E    = Wide-field CCD or other two-dimensional electronic 
                        E2  E2m  = 2MASS (Two Micron All-Sky Survey)
                        Ed  Ede  = DENIS (Deep Near-Infrared Survey)
                        Ek  Euk  = UKIDSS (UKIRT Infrared Deep Sky Survey)
                        Es  Esd  = SDSS (Sloan Digital Sky Survey)
                        Eu  Eu3  = UCAC3                              
                        Eu  Eu4  = UCAC4                          
                        Ey       = Yale SPM (Southern Proper Motion) Survey

                        H   T    = Hipparcos/Tycho, HST, or other space-based technique
                        H   Q    = Hipparcos/Tycho, HST, or other space-based technique
                        Ha  Qac  = HST + ACS
                        Hc  Ech  = Chandra
                        He  Eei  = Einstein
                        Hf  Qfg  = HST + Fine Guidance Sensor
                        Hg       = Gaia                            
                        Hh  Thp  = Hipparcos
                        Hi  Qir  = Spitzer Space Telescope + IRAC (Infrared Array Camera)
                        Hk       = Kepler
                        Hm  Qmi  = Spitzer Space Telescope + MIPS (Multiband Imaging 
                                   Photometer for Spitzer)
                        Hn  Qni  = HST + NICMOS IR direct imaging
                        Ho  Qfo  = HST + Faint Object Camera
                        Hp  Qpc  = HST + WFPC2 Planetary Camera or Wide Field Camera 3
                        Hs  Qst  = HST + STIS
                        Ht  Tty  = Tycho
                        Hw  Qwi  = WISE (Wide-field Infrared Survey Explorer) satellite 
                                   (IR imaging)
                        Hx  Qsx  = Spitzer Space Telescope + SpeX spectrometer and 
                                   slit-viewing camera
                        Hz       = XMM Newton satellite

                        I   P    = interferometric technique
                        Ig  Pgi  = phase grating interferometer  
                        Im  Pmi  = Michelson interferometer

                        J   J    = visual interferometer
                        Jm  Jmw  = Mount Wilson 100-inch telescope rotating interferometer 
                                   (Anderson, Merrill)
                        Jp  Jpe  = Mount Wilson 20-foot beam interferometer (Pease)

                        K   K    = long-baseline visual/IR/radio interferometer
                        K2  Kce  = CERGA 2-telescope interferometer
                        Ka  Kva  = VLTI/AMBER
                        Kb  Kbi  = BIMA 
                        Kc  Kch  = CHARA Array
                        Ke  Kev  = European VLBI network
                        Kf  Kcs  = CHARA Array (separated fringe packet data)
                        Kg  Kgl  = global VLBI array
                        Ki  Kio  = IOTA 
                        Kk  Kki  = Keck interferometer
                        Kl  Kvl  = VLA
                        Kl  Kvb  = VLBA
                        Km  Km3  = Mark III 
                        Kn  Knp  = NPOI (Navy Prototype/Precision Optical Interferometer)
                        Kp  Kpt  = PTI (Palomar Testbed Interferometer)
                        Kr  Kap  = radio/IR aperture synthesis technique
                        Ks  Ksu  = SUSI (Sydney University Stellar Interferometer)
                        Ku  Kpu  = Pulkovo Stellar Interferometer

                        M   A    = micrometry technique
                        Ma  A    = micrometer with refractor
                        Mb  B    = micrometer with reflector
                        Mc  C    = Comparison image micrometer
                        Md  N    = Visual measures with a double-image micrometer
                        Mg       = illuminated-reticle micrometer 
                                   (e.g. Celestron Micro-Guide)
                        Mr  R    = RGO use of micrometer plus comparison image micrometer 
                                   on same star        

                        O   O    = occultation 
                        O   Occ  = occultation 

                        P   G    = photographic technique
                        Pa  G    = photographic, with astrograph
                        Pb  G    = USNO-B astrograph data
                        Pc  Gac  = Astrographic Catalog 
                        Pe  G    = ESO Schmidt astrograph
                        Pk  Gag  = AGK Catalog
                        Po  H    = photographic, with medium or long-focus technique or 
                                   with ocular enlargement
                        Pp  Gp1  = Palomar Observatory Sky Survey (POSS-I)     
                                   1948-1958, 48in/1.2m Schmidt
                        Pp  Gp2  = Palomar Observatory Sky Survey (POSS-II)    
                                   1985-1999, 48in/1.2m Schmidt
                        Pu  Guk  = UK Schmidt Southern Survey                  
                                   1974-1987, 48in/1.2m Schmidt

                        S   Spe  = speckle interferometric technique
                        Sa  Sam  = aperture masking technique (MAPPIT, etc.)
                        Sb  Sbi  = bispectrum speckle interferometric technique
                        Sc  Sch  = CHARA speckle  
                        Si  Sir  = IR speckle  
                        Sp  Spo  = speckle polarimetry
                        Ss  Ssa  = shift-and-add technique
                        St  S    = Tokovinin speckle camera (SOAR)
                        Su  Sus  = USNO speckle  

                        T   M    = Transit circle / Meridian circle
                        Tm  I    = "Eyepiece micrometer" transit/chronometric technique

                        V        = visual estimate

                        X        = spectroscopic technique 
                        Xg  X    = Visual estimate made with an objective grating
                        Xh  Zhr  = high-resolution spectroscopy
                        Xl  Zlr  = low-resolution spectroscopy
                        Xr  Zre  = resolved spectroscopy
                        Xs  Zsp  = spectrophotometry      

                        Z   Z    = photometric technique
                        Z   Zpt  = photometer
                        Zc       = CCD photometry
                        Zd  V    = Photocell with diaphragm in focal plane
                        Zp  Z    = Visual photometry with a double-image or polarizing 
                        Zw  Y    = Wedge photometer