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 (HHMMSS.SS+DDMMSS.S) 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, etc.) 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 source. 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 given) 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 well): 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 subaperture" 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 imaging 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 photometer Zw Y = Wedge photometer