Version : 25 June 2012 DATA FROM THE WASHINGTON DOUBLE STAR CATALOGS (WDS) U.S. NAVAL OBSERVATORY WASHINGTON D.C. 20392 As a result of numerous changes in software and hardware, as well as the addition of new catalogs, information is now provided in a somewhat different format. It is hoped that this presentation is clearer; if it is in any way confusing, or there are omissions, please let us know. The WDS (and associated catalogs) are at present in a state of flux. At this point the following things have been done : General comments: 1. Data from all catalogs are referenced to a single note file and single reference file. 2. To facilitate those of you who make data requests on a regular basis I've added a "version number" to the top line so that it is know when this file is modified. Typically a user can just check these numbered notes and look for new ones. 3. Explanatory material from the WDS "intro.doc" added to this file, so that all explanatory WDS material is in a single file. WDS summary lines: 1. Arcsecond precise coordinates have been provided when available. 2. Secondary proper motions have been provided when available . 3. Duplicate discovery designations have been removed. Some numbers had been used more than once erroneously. In addition, some discovery designations were given unfortunate additional designations ("1/2", "a", and even the Struves' use of "App"). Some numbers were repeated due to the discoverer having more than one list (Herschel lists I-VI and N come to mind). To make the WDS discovery designation more clear all of these duplicate designations have been corrected. 4. The magnitude information in the WDS is a hodge-podge of data. Many systems with entries in the delta-m catalog inexplicably had little or no magnitude information available. These have been updated to be as consistent as possible, taking Tycho V magnitudes when available. 5. X codes have been added in column 109 of the summary line when the pair is questionable. Generally these are unconfirmed systems, which pairs may represent positional typos in the original publication (thus we're looking in the wrong location), optical doubles which have changed greatly in separation and/or angle due to radically different proper motions, plate errors, or may simply be not at the magnitude, separation, etc., where the first measure was added (too faint, too close, etc.). We would certainly like to know about circumstances where you have found or have ascertained the mystery behind these pairs. 6. The format of the WDS summary lines was changed slightly: a. The column for number of measures has been increased to four digits. Therefore, the 607 systems which previously had "99" measures (indicating N greater than or equal to this number) now have the actual number of measures. Ten systems have more than 1000 measures, with the largest being 70 Ophiuchus with 1640. b. The secondary proper motion, formerly at the end of each record, has been moved next to the primary proper motion. c. An additional notes column has been added. The actual notes codes have not changed, however, many cases have been found where a note has either been not included or put in the notes file. Adding the additional column will eventually decrease the size of the notes file. d. Precisions of coordinate have been improved by an order of magnitude in each digit, i.e., tenths of a second of arc and hundredths of a second of time. Nearly 99% of the pairs in the WDS now have coordinates to this precision. e. Spaces and decimals have been added where appropriate, for consistency and to improve readability. 7. The p code has been removed from the summary line codes in columns 108-111. This code referred to "Coordinates and proper motions from ACRS, PPM, IRS, FK5 catalogs". 8. Ambiguities with "P" coded proper motion (10x larger than listed) have been corrected. 9. Identification of pairs that could be physical or are certainly not physical are flagged, using one of several codes. See the list of summary catalog codes below. As of 2009.5 these were 2894 pairs with physical codes and 1552 with optical codes; this represents 2.77% and 1.49%, respectively, of the entire catalog. True natures of the vast majority of systems in the WDS are still undetermined. 10. At present the Durchmusterung catalogs (BD, CD, CPD) are still used as the primary cross-reference (in addition to the precise coordinates). It is anticipated that once it is complete, the more modern and deeper all-sky UCAC4 may be used in this role; alternatively, some combination of catalogs (Hipparcos, Tycho2, UCAC4, etc.) may be used for pairs of different magnitudes. In any event, a historical WDS <-> DD <-> BD cross reference will be available on the WDS website. WDS data lines: 1. The codes to the WDS data lines (columns 125 and 126) have been updated. Many codes have been removed, in favor of additional information included with the measures (for example, the "D" code, indicating that the separation is an upper limit, has been replaced with a "<" preceding rho). See the data line format table below. 2. Non-numeric position angles (N, NP, SF, etc.), have been converted to the nearest numeric position angle and a code (L) has been added indicating the change. 3. Measures which are likely to be in error, but cannot be corrected (code "X") are not included in the ensemble of data points for the summary line. Incomplete data (missing date, position angle and/or separation) are also not included in the summary line. 4. Our updating of measures, orbits, and discoveries continues. 5. Method files for all USNO double star catalogs have been combined. The new 1- and 2-letter codes (see below) provide considerably more detailed information about the technique than previously possible. 6. We are in the midst of correcting many errors in the WDS. This task included examining all measures containing old codes G, H, I, and J as well as large outliers in orbit or linear motion calculations. In most cases, this involves going back to the original reference and examining the observation to determine what errors can be ascertained (often a misidentification or a typo) and corrected. We have gone from these four codes to a more generic code "N" (corrected) or "X" (not corrected, while retaining the "I" (identification questionable) code. Code "X" data are not included in the summary line. 7. Sometimes you will find that the reference is listed as "unpublished". If you use such data, as a common courtesy dictates that you obtain the permission of the author if possible. This permission is implicitly given by us by inclusion of our own unpublished measures in the data base. Also, if you make use of data supplied by us, we would appreciate an acknowledgement in your published report or paper. Associated catalogs: 1. Data requests now include orbital information, ephemerides, and figures illustrating the orbits and all measures, all from the Sixth Orbit Catalog. See http://ad.usno.navy.mil/wds/orb6.html for more information. 2. Linear solutions from the "Linear Elements Catalog" as well as associated ephemeris and figures are now provided with data requests as well. 3. Data from the delta-m catalog (previously unavailable) are included in data requests. This is from the new, 3rd magnitude difference catalog, over 200% larger than the first magnitude difference catalog. See http://ad.usno.navy.mil/wds/dm3.html for more information. 4. The Fourth Interferometric Catalog is not currently checked by this program. However, virtually all relevant information from this catalog has been incorporated into the WDS database during the most recent reformat efforts. WDS technique codes were expanded to two characters in order to more complete technique descriptions in the Interferometric Catalog. ============================================================================= WDS SUMMARY CATALOG - note flags (columns 108-111): B Summary line gives blue (Johnson U or B, blue photographic, etc.) magnitudes C Orbit and Linear solution. A published orbit exists and this system has a Linear Solution as well. A "C" code, then, indicates both an "O" and an "L" code. D Has measure in Delta-M catalog I Identification uncertain. Match of object at precise position with WDS pair may or may not be correct. Currently under examination. K Summary line gives K-band or other infrared (>1 micron) magnitudes L Linear solution. Linear elements for this pair have been determined. M Magnitude modified. Magnitudes have been corrected to the Tycho-V scale based on other systems measured by the discoverer and Tycho. N Notes found in wdsnot.memo of the WDS. O Orbit, briefly described in WDSNOT MEMO and has entry in Orbit Catalog P 100 year proper motion in right ascension and declination. R Summary line gives red (Johnson R or I, red photographic, etc.) magnitudes. S Statistically different parallax and proper motion indicates that this pair is non-physical. T Statistically the same parallax within the errors and similar proper motion or other technique indicates that this pair is physical. U Proper motion or other technique indicates that this pair is non-physical. V Proper motion or other technique indicates that this pair is physical. X A "Dubious Double" (or "Bogus Binary"). This pair may represent a positional typo in the original publication (so we're looking in the wrong location), an optical double disappearing due to radically different proper motions, a plate flaw, or simply a pair not at a magnitude, separation, etc., sufficiently similar to those noted when the first measure was added (making it too faint, too close, etc.). We would certainly like to know about any circumstances where you have found or have ascertained the mystery behind these pairs. Y Statistically different parallax for the components indicates they are non-physical. Z Statistically the same parallax within the errors would indicate the components are physical. -------------------------------------------------------------------------------- WDS OBSERVATION CATALOG: data line format The format of the WDS data lines was greatly expanded May/June 2012, in order to accomodate more precise astrometry and photometry, as well as formal astrometric and photometric errors and filter information. During the process many old observation codes were eliminated, often by including additional information with the measure itself (for example, the "D" code, indicating that the separation is an upper limit, has been replaced with a "<" preceding rho). The new format is described below (note that in all cases the number of decimal places quoted in the catalog indicates the published precision): term columns format description wds 001-010 a10 WDS designation component 012-016 a5 component (e.g., "AB" or "Aa,Ab") date 018-027 f10.5 Observation date, in years. tflag 029-029 a1 Flag for theta (position angle) measure. Flags include: : = uncertain/estimated (old code U) L = originally published as nf, sp, etc. (old code L) Q = quadrant flipped 180deg from published value (old code Q) V = measure is vector separation along this angle vector (previously used only in interferometric catalog) theta 030-036 f7.3 position angle, in degrees terr 038-043 f6.3 published formal theta error, in degrees rflag 045-045 a1 Flag for separation (rho). Flags include: : = uncertain/estimated(old code U) < = separation is less than quoted value (old code D) E = pair elongated (old code E) U = pair unresolved/single (old code S) G, O, S, V, or X = Hipparcos non-component double star solutions or suspected non-single (codes previously used mostly in the interferometric catalog R = pair resolved bu no separation give (old code R) D = separation is in degrees (old code H) M = separation is in arcminutes (old code C) m = separation is in milliarcseconds (old code A) rho 046-054 f10.5 separation, in arcseconds (unless indicated otherwise by rflag) reflag 056-056 a1 Flag for separation error. Flags include: P, F, G, V = quality flags (poor, fair, etc.) > = error is lower limit to true value < = error is upper limit to true value rerr 057-063 f7.5 separation error, in same units as rho mflag1 065-065 a1 primary magnitude flag. Flags include: > = magnitude is lower limit to true value v = primary is variable mag1 066-071 f6.3 primary magnitude, in mag m1eflag 072-072 a1 primary magnitude error flag. Flags include: > = error is lower limit to true value < = error is upper limit to true value m1err 073-077 f5.3 primary magnitude error, in mag mflag2 079-079 a1 secondary magnitude flag. Flags include: > = magnitude is lower limit to true value s = mag2 is a magnitude rather than magnitude difference (only used if mag1 is blank; old code W) f = star is too faint (old code F) v = secondary is variable (old code V) mag2 080-085 f6.3 secondary magnitude, in mag. If mag1 is blank, mag2 is the magnitude difference. m2eflag 086-086 a1 secondary magnitude error flag. Flags include: > = error is lower limit to true value < = error is upper limit to true value m2err 087-091 f5.3 secondary magnitude error, in mag filter 093-100 2a4 filter effective wavelength and FWHM, in nm fflag 101-101 a1 filter flag. Flags include: a = value is average of multiple filters u = wavelength is in microns m = wavelength is in mm c = wavelength is in cm M = wavelength is in meters B = blue filter (old code B) R = red filter (old code R) K = IR filter (old code K) X = X-ray band n = no filter used ? = filter information is uncertain : =filter information is approximate tel 103-107 f5.1 telescope aperture, in meters teflag 108-108 a1 telescope aperture flag. Flags include: k = multiple aperture telescope, baseline in km a = average of multiple telescopes (old code M) nn 110-111 i2 number of nights averaged into mean measure ref 112-120 a8 reference code tech 122-123 a2 technique code. See table below. codes 125-126 2a1 additional codes. See table below. d.e. note 127-127 a1 data entry note. See table below. ----------------------------------------------------------------------------- WDS OBSERVATION CATALOG: method (data lines, columns 122-123) These same technique codes are now used for all our catalogs; the table below also lists the old codes used in the WDS and Interferometric Catalog, prior to the most recent reformat. 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 H T = Hipparcos/Tycho, HST, Spitzer, or other space-based technique H Q = Hipparcos/Tycho, HST, Spitzer, or other space-based technique Hc Ech = Chandra Ha Qac = HST + ACS He Eei = Einstein Hf Qfg = HST + Fine Guidance Sensor Hh Thp = Hipparcos Hi Qir = Spitzer Space Telescope + IRAC (Infrared Array Camera) 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 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 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/NOI [Navy (Prototype) 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 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 Pc Gac = Astrographic Catalog 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 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 Zd V = Photocell with diaphragm in focal plane Zp Z = Visual photometry with a double-image or polarizing photometer Zw Y = Wedge photometer Additional codes for references: mag = magnitude information in Second Delta M Catalog (codes not yet added) not = paper referenced in Notes file (codes not yet added) orb = orbit information in Sixth Orbit Catalog ----------------------------------------------------------------------------- WDS OBSERVATION CATALOG: codes (data lines, columns 125-126) F Too faint, not seen, or not located G This measure is not in the published paper but is a vector combination of measured pairs by this author for a pair already in the WDS. I Identification, or question about such L Original PA given as n, nf, f, sf, s, sp, p, or np (n = north, s = south, f = following, p = preceeding), and converted to 0, 45, 90, 135, 180, 225, 270, or 315, respectively. Also, a PA given as e (east) or w (west) is converted to 90 or 270 respectively. The PA is assumed accurate only to the nearest quadrant (i.e., +/- 45 deg). M Mean of multiple measures of same photographic plate or CCD. N Identification or position error, or misprint in publication, corrected. O Optical P Corrected by author V No. of nights varies 50% or more between angle and separation measures X Identification error, position error, or misprint in publication, NOT corrected. Code "X" data are not included in summary lines. The X code is also used to indicate measures superceded by later reductions of the same data (for example, reprocessing of Astrographic Catalog data for the WFC). Z Measurer other than author(s) ----------------------------------------------------------------------------- WDS OBSERVATION CATALOG: data entry notes (data lines, column 127) 0 Pre-IDS measure added by Burnham, Aitken, etc. 1 Post-IDS measure added by Lick Observatory 2 Post-IDS measure added by USNO 3 Measure prior to Lick punch-card collection, added by USNO 4 Post WDS (1984.0) measure added by USNO 5 Post WDS (1996.0) measure added by USNO 6 Post WDS (2001.0) measure added by USNO 7 Post WDS (2006.5) measure added by USNO ============================================================================== SIXTH ORBIT CATALOG - elements: P = Period of revolution pflag = units of period (c = centuries, d = days, h = hours, y = years) a = Semimajor axis of orbit aflag = units of semimajor axis (a = arcsec, m = milliarcsec, M = arcminutes, u = microarcsec) i = inclination, angle between plane of the sky and plane of the orbit, 0-180 degrees. The motion is direct (i.e., in direction of increasing position angles) if i < 90 and retrograde if i > 90. Node = Position angle of the line of intersection between the plane of the orbit and plane of the sky, in degrees. T = epoch of periastron passage tflag = units of T (y = years, d = MJD) e = orbital eccentricity omega = longitude of persiastron, in degrees G = orbit grade (1 = definitive, 2 = good, 3 = reliable, 4 = preliminary, 5 = indeterminate, 9 = unknown). The grading procedure is described in the introduction to the Sixth Catalog (see http://ad.usno.navy.mil/ad/wds/int6.html). Notes : In some cases more than one orbit will be provided. Cases like this fall into one of two categories: 1. More than one binary in a multiple system has an orbit calculated. 2. While the orbit grading algorithm grades orbits objectively on many categories, they sometimes can achieve approximately the same grade and the decision as to which orbit is better may be ambiguous. As a rule of thumb, following the time-honored precepts of van den Bos and Worley, and asking the question "Is this Orbit Really Necessary?" (see, for example, PASP, 74, 297; 1962 ), we answer in the negative, and retain the earlier orbit. However, there still remain cases where the orbits can be sufficiently different but ambiguous (for example, solutions with different quadrants selected for small magnitude difference systems). In this case, more than one orbit may be retained. 3. A grade 8 or 9 orbit (which was not provided in Worley & Heintz) is given when it is not possible to evaluate the orbit as no "classical double star" data are available. Interferometric orbits based solely on visibility data (i.e., no rho and theta provided) are given a grade of 8. Were complete data available these orbits (usually combined solutions with spectroscopic data) would undoubtedly have a very good grade. Astrometric orbits (derived from photocenter vs. barycenter shifts) are given a grade of 9. When resolved, systems of this type typically show rather large differences between the elements computed astrometrically and those based on differential measures. Further, the grades are only based on available visual double star data. If the solution to an orbit is based on a combined solution (e.g., with spectroscopic information), certain elements are certainly known better. Utilizers of the data are encouraged to thoroughly scan the "notes" section. ----------------------------------------------------------------------------- SIXTH ORBIT CATALOG - ephemerides: Each orbit above is provided with an ephemeris for the next five years. While many orbits may be of poor quality, short-term ephemerides are often quite good. ----------------------------------------------------------------------------- SIXTH ORBIT CATALOG - figures: In all orbit figures in this catalog, green plus signs indicate visual (micrometric) observations, violet asterisks photographic measures, and blue symbols various interferometric techniques (open circles, filled circles, and filled squares for eyepiece interferometry, speckle or other single-aperture techniques, and multi-aperture techniques, respectively). Finally, a red "H" or "T" indicates a measure from Hipparcos or Tycho. The dot-dash line indicates the line of nodes. Scales are in arcseconds, and the curved arrow at lower right indicates the direction of orbital motion. ============================================================================== RECTILINEAR ELEMENTS CATALOG - elements: The elements are defined by linear relationships relative to the closest approach x = -sin(theta) * rho y = cos(theta) * rho and let (x0,y0,t0) or (rho0,theta0,t0) define the relative location and time of closest approach Solve for: x = xa * (t-t0) + x0 y = ya * (t-t0) + y0 A standard weighted least squares fit is made, with weights of individual measures determined using the technique outlined in the Sixth Catalog of Orbits of Visual Binary Stars. RMS errors determine the errors of these parameters. ----------------------------------------------------------------------------- RECTILINEAR ELEMENTS CATALOG - ephemerides: Ephemerides for years 2010-2035 are provided with the elemental errors propagated into the rho and theta relative position. ----------------------------------------------------------------------------- RECTILINEAR ELEMENTS CATALOG - figures: Figures are also provided for each system, and are linked from the main catalog by the letter "P" in one of the righthand columns. The figures include all measures in the WDS, as well as the linear fits whose elements are given in the main catalog (shown as a solid black line). Individual measures in these figures are color-coded as in the Orbit Catalog; green, blue, and purple indicate micrometric, interferometric, and photographic measures, respectively, while a red "H" or "T" indicates a measure from Hipparcos or Tycho. Measures are connected to their predicted locations by "O-C" lines; measures given zero weight are indicates by dotted O-C's. For those pairs with two sets of proper motions in the WDS, a red line indicates the differential proper motion predicted by these values. Since most of these proper motions are from the Hipparcos or Tycho-2 catalogs, the red lines intersect the least-squares fit to the data at the Hipparcos epoch of 1991.25. The lengths of both the black and red lines correspond to a similar range of dates (usually roughly corresponding to the range of observation dates, unless T0 falls outside that range). ============================================================================== THIRD MAGNITUDE DIFFERENCE CATALOG - method The delta-m catalog is an eclectic collection of differential magnitude values collected over a long timebase. Many of them are visual estimates while others are photographic corresponding (approximately) to broadband V or B, respectively. More recent additions to the delta-m catalog include filter information (typically, central wavelength & FWHM) and errors. Also, the delta-m catalog gives information about components which have no differential measurements and are, thus, not found in the WDS. ============================================================================== Brian D. Mason Project Manager, Washington Double Star Program Astrometry Department U. S. Naval Observatory phone: 202-762-1412 3450 Massachusetts Avenue NW fax: 202-762-1516 Washington DC 20392-5420 email: bdm@usno.navy.mil ------------------------------------------------------------------------------ WDS web page: http://ad.usno.navy.mil/ad/wds/wds.html ==============================================================================