W2J00 Transit Circle Catalog


Full Paper:

The W2J00 Transit Circle Catalog (W2J00)
Holdenried, E.R. and Rafferty, T.J.
Publ. USNO, 2nd series, vol. XXVII (part 2), Washington (2016)


Abstract:

We present the result of observations made with the Six-inch Transit Circle in Washington, D.C. and the Seven-inch Transit Circle at the Black Birch station near Blenheim, New Zealand between April 1985 and February 1996. The catalog, called W2J00, contains mean positions of 44,395 globally distributed stars, 5048 observations of the planets, and 6518 observations of the brighter minor planets. Positions of stars are for mean epoch of observation, on equator and equinox J2000.0. Positions of solar system objects are apparent places. Error estimates are about 75 mas per coordinate for the majority of stars. 7-inch Transit Circle

Obtaining the Data:

The W2J00 data can be obtained via CDS (Strasbourg astronomical Data Center), catalog number I/334

Description:

The W2J00 is the result of observations made with the Six-inch Transit Circle in Washington, D.C., and the Seven-inch Transit Circle at the Black Birch station near Blenheim, New Zealand. It is named as such because it was the second (of two) transit circle catalogs to be referred to the Equinox of J2000.0, and reduced at the Washington D.C. headquarters of the U.S. Naval Observatory. It is sometimes referred to as the "Pole-to-Pole" program due to the fact that the telescopes were situated at latitudes such that a fundamental determination could be made of the azimuth using circumpolar stars of both the northern and southern sky. The observations were made between April 1985 and February 1996. The W2J00 project is the latest and largest of a long series of transit circle catalogs produced by the U.S. Naval Observatory. It is also, because of advancing technologies, certainly the last.

The observing program was structured to be absolute, in the sense that the reported positions were not to explicitly rely on previous observations. However, with the availability of Hipparcos observational data, it was decided to differentially adjust the observations to the ICRF using the Hipparcos star positions (ESA, 1997). A catalog on the ICRF was judged be more useful than one tied to the dynamical reference frame, as was the tradition.

The W2J00 contains mean positions of 44,395 globally distributed stars, 5048 observations of the planets, and 6518 observations of the brighter minor planets. The majority of stars are FK stars (Fricke, et al., 1988 and 1991) and International Reference Stars (IRS) (Corbin, 1991). The solar system objects include Mars, Jupiter, Saturn, Uranus, Neptune, twelve minor planets (Amphitrite, Eunomia, Flora, Hebe, Hygiea, Iris, Juno, Melphomene, Metis, Nemausa, Pallas, and Vesta), and the dwarf planet Ceres. Daytime observations of the Sun, Mercury, Venus, Mars, and bright stars were made but not included in the final catalog due to the problems inherent in reducing observations made in the daylight.

The W2J00 observing program used both the Six-inch Transit Circle and Seven-inch Transit Circle. Final positions are a combination of observations from both telescopes (for those stars in common). The authors have decided to present not only the combined positions, but the individual telescope's positions should future researchers decide to investigate the data based on which instrument was used.

See also:
The 6-inch Warner and Swasey Transit Cicle home page.


Characteristics of the W2J00 catalog:

Category Range Average
Magnitudes -1.6 to 9.91 6.84
RA standard errors of the mean 3 to 441 mas 68 mas
Dec standard errors of the mean 1 to 448 mas 76 mas
RA Number of observations / star 3 to 411 14
Dec Number of observations / star 2 to 418 14
Declination coverage -90 to +90 degrees  


File Summary:

--------------------------------------------------------------------------------
 FileName      Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe            80        .   This file
W2J00_stars.dat  197    44395   W2J00 star positions (means)
W2J00_solsys.dat  63    11566   W2J00 solar system object positions
--------------------------------------------------------------------------------

Byte-by-byte Description of file: W2J00_stars.dat

--------------------------------------------------------------------------------
   Bytes Format Units   Label    Explanations
--------------------------------------------------------------------------------
   1-  5  I5    ---     W2J00    W2J00 identifier
   7-  8  I2    h       RAh      Right Ascension ICRS, at Ep_RA (hours) (1)
  10- 11  I2    min     RAm      Right Ascension ICRS, at Ep_RA (minutes) (1)
  13- 18  F6.3  s       RAs      Right Ascension ICRS, at Ep_RA (seconds) (1)
  20- 22  I3    mas     e_RAs    Weighted standard error of the mean, RA
  24- 26  I3    ---     NumRA    Number of observations used for RA
  28- 35  F8.3  yr      Ep_RA    Mean epoch of RA
      37  A1    ---     DE-      Declination (ICRS) at Ep_DE (sign) (1)
  38- 39  I2    deg     DEd      Declination (ICRS) at Ep_DE (degrees) (1)
  41- 42  I2    arcmin  DEm      Declination (ICRS) at Ep_DE (minutes) (1)
  44- 48  F5.2  arcsec  DEs      Declination (ICRS) at Ep_DE (seconds) (1)
  50- 52  I3    mas     e_DEs    Weighted standard error of the mean, DE
  54- 56  I3    ---     NumDE    Number of observations used for DE
  58- 65  F8.3  yr      Ep_DE    Mean epoch of DE
  67- 70  F4.1  mag     Vmag     Visual magnitude (2)
  72- 77  I6    ---     HIP      Hipparcos Catalogue number (3)
  79- 80  I2    h       RA6h     RA ICRS from 6-inch, at Ep_RA6 (hours) (4)
  82- 83  I2    min     RA6m     RA ICRS from 6-inch, at Ep_RA6 (minutes) (4)
  85- 90  F6.3  s       RA6s     RA ICRS from 6-inch, at Ep_RA6 (seconds) (4)
  92- 94  I3    mas     e_RA6s   Weighted standard error of the mean, RA6
  96- 98  I3    ---     NumRA6   Number of observations used for RA6
 100-107  F8.3  yr      Ep_RA6   Mean epoch of RA6
     109  A1    ---     DE6-     Dec (ICRS) from 6-inch, at Ep_DE6 (sign) (4)
 110-111  I2    deg     DE6d     Dec (ICRS) from 6-inch, at Ep_DE6 (degrees) (4)
 113-114  I2    arcmin  DE6m     Dec (ICRS) from 6-inch, at Ep_DE6 (minutes) (4)
 116-120  F5.2  arcsec  DE6s     Dec (ICRS) from 6-inch, at Ep_DE6 (seconds) (4)
 122-124  I3    mas     e_DE6s   Weighted standard error of the mean, DE6
 126-128  I3    ---     NumDE6   Number of observations used for DE6
 130-137  F8.3  yr      Ep_DE6   Mean epoch of DE6
 139-140  I2    h       RA7h     RA ICRS from 7-inch, at Ep_RA7 (hours) (5)
 142-143  I2    min     RA7m     RA ICRS from 7-inch, at Ep_RA7 (minutes) (5)
 145-150  F6.3  s       RA7s     RA ICRS from 7-inch, at Ep_RA7 (seconds) (5)
 152-154  I3    mas     e_RA7s   Weighted standard error of the mean, RA7
 156-158  I3    ---     NumRA7   Number of observations used for RA7
 160-167  F8.3  yr      Ep_RA7   Mean epoch of RA7
     169  A1    ---     DE7-     Dec (ICRS) from 7-inch, at Ep_DE7 (sign) (5)
 170-171  I2    deg     DE7d     Dec (ICRS) from 7-inch, at Ep_DE7 (degrees) (5)
 173-174  I2    arcmin  DE7m     Dec (ICRS) from 7-inch, at Ep_DE7 (minutes) (5)
 176-180  F5.2  arcsec  DE7s     Dec (ICRS) from 7-inch, at Ep_DE7 (seconds) (5)
 182-184  I3    mas     e_DE7s   Weighted standard error of the mean, DE7
 186-188  I3    ---     NumDE7   Number of observations used for DE7
 190-197  F8.3  yr      Ep_DE7   Mean epoch of DE7
--------------------------------------------------------------------------------
Note (1): Mean positions are on the International Celestial Reference
    System (ICRS), differentially reduced using the Hipparcos
    Catalogue. The positions are a weighted mean of the Six-inch
    Transit Circle and Seven-inch Transit Circle observations, found
    in columns 79-197. The epochs for the right ascension and
    declination coordinates are found in the Ep_RA and Ep_DE fields
    respectively. 
Note (2): Visual magnitude for identification purposes.  
Note (3): Cross references to the Hipparcos Catalogue are provided
    for convenience of the user.
Note (4): Columns 1-65 give positions that are a weighted mean of the
    Six-inch Transit Circle and Seven-inch Transit Circle
    observations.  Columns 79-137 give the positions from the Six-inch
    Transit Circle only.
Note (5): Columns 1-65 give positions that are a weighted mean of the
    Six-inch Transit Circle and Seven-inch Transit Circle
    observations.  Columns 139-197 give the positions from the
    Seven-inch Transit Circle only.
--------------------------------------------------------------------------------


Byte-by-byte Description of file: W2J00_solsys.dat

Byte-by-byte Description of file: W2J00_solsys.dat
--------------------------------------------------------------------------------
   Bytes Format Units   Label    Explanations

 1- 10  A10   ---     Obj     Solar system object identifier
12- 13  I2    h       RAh     Right Ascen. (apparent) at Epoch (hours) (1, 2)
15- 16  I2    min     RAm     Right Ascen. (apparent) at Epoch (minutes) (1, 2)
18- 23  F6.3  s       RAs     Right Ascen. (apparent) at Epoch (seconds) (1, 2)
    25  A1    ---     DE-     Declination (apparent) at Epoch (sign) (1, 2)
26- 27  I2    deg     DEd     Declination (apparent) at Epoch (degrees) (1, 2)
29- 30  I2    arcmin  DEm     Declination (apparent) at Epoch (minutes) (1, 2)
32- 36  F5.2  arcsec  DEs     Declination (apparent) at Epoch (seconds) (1, 2)
38- 50  F13.5 day     Epoch   Julian date (UT1) of observation
52- 54  A3    ---     Obs     Observer (3)
    56  A1    ---     Clamp   Clamp orientation of instrument (4)
    58  A1    ---     RALimb  Limbs or center of light measured in RA (5)
    60  A1    ---     DELimb  Limbs or center of light measured in DE (5)
62- 63  A2    ---     Tel     Telescope used (6)
--------------------------------------------------------------------------------
Note (1): Positions are apparent places, reduced to be systematically
    consistent with the Hipparcos Catalogue.  An apparent place is a
    geocentric direction of an object that takes into account orbital
    motion, space motion, light-time, light deflection, and annual
    aberration.  Apparent place is given with respect to the true
    equator and equinox "of date"; in this case, it is the date of
    observation found in the Epoch field. 
Note (2): In some cases, an observation is made in only right
    ascension or declination.  If only the right ascension coordinate
    was observed, then the declination seconds field (DEs) will be
    blank, as will the DELimb.  If only the declination coordinate was
    observed, then the right ascension seconds field (RAs) will be
    blank, as will the RALimb.
Note (3): The Six-inch Transit Circle measurements were manual, in the
    sense that a person measured the position while looking through
    the instrument.  The Seven-inch Transit Circle's observations were
    automated, so the observer is not listed.  The observer code has
    the following meaning:
       CSC = C.S. Cole
       TEC = T.E. Corbin
       HEC = H.E. Crull
       SD  = S.J. Dick
       JCD = J.C. Doty
       RE  = R.   Etheridge
       FSG = F.S. Gauss
       MEG = M.E. Germain
       DMH = D.M. Hall
       GSH = G.S. Hennessy
       JH  = J.L. Hershey
       RBH = R.B. Hindsely
       ERH = E.R. Holdenried
       ESJ = E.S. Jackson
       IAN = I.   Jordan
       KAL = V.   Kallarakal
       JCM = J.C. Martin
       JMM = J.M. Muse
       RJM = R.J. Miller
       MDR = M.D. Robinson
       TJR = T.J. Rafferty
       CBS = C.B. Sande
       DS  = D.K. Scott
       CAS = C.A. Smith
       SEU = S.E. Urban
       GLW = G.L. Wycoff
       ZGY = Z.G. Yao
Note (4): Both transit circle telescopes were reversed (rotated 180
    degrees in azimuth) interchanging the east and west pivots
    approximately every 30 days. The orientation of the instrument was
    referenced to the location of the clamping device, which fixed the
    altitude of the instrument after it was pointed to a star, and
    thus referred to either as Clamp West or Clamp East.  The flag has
    the following meaning:
       W = Clamp West
       E = Clamp East
Note (5): Some planets subtend sizable disks in the instrument.
    Primarily depending on the object, either the limbs or the
    center-of-light were observed. The flag has the following meaning:
       L = limb was measured
       C = center of light was measured 
       R = ring was measured (Saturn only)
    Despite how an object was observed, the W2J00 positions refer to
    the center of the object.
Note (6): The observing program used two telescopes, the Six-inch
    Transit Circle in Washington DC, and the Seven-inch Transit Circle
    at Black Birch New Zealand. The "Tel" flag has the following
    meaning:
       6" = Six-inch Transit Circle, Washington D.C., USA
       7" = Seven-inch Transit Circle, Black Birch, New Zealand
--------------------------------------------------------------------------------


References:

    Corbin, T.E., 1991, "International Reference Stars", (Catalog I/172)

    Fricke, W., Schwan, H., & Lederle, T., et al.  1988, "Fifth
    Fundamental Catalogue (FK5), Part I. The Basic Fundamental Stars",
    Veroeff. Astron. Rechen-Institut Heidelb. No. 32  (Catalog I/149)

    Fricke, W., Schwan, H., Corbin, T., et al., 1991, Fifth
    Fundamental Catalogue FK5), Part II. The FK5 Extension, New
    Fundamental Stars, Veroeff. Astron. Rechen-Institut Heidelberg
    No. 33, (Catalog I/175)

    Holdenried, E.R. and Rafferty, T.J., 2016, "W2J00 Results of the
    USNO Pole-To-Pole Observations Made with the Six-inch and
    Seven-inch Transit Circles 1985-1996", 

    Perryman M.A.C., Lindegren L., Kovalevsky J., et al., 1997, "The
    Hipparcos Catalogue" (1997A&A...323L..49P) (Catalog I/239)

    Robertson, J. 1940, Astron. Papers, Vol. X. part II, Washington
  
    Rafferty, T.J., Holdenried, E.R., and Urban, S.E., 2016, "W1J00
    Results of the Observations Made with the Six-inch Transit Circle
    1977-1982"