The Third U.S. Naval Observatory CCD Astrograph Catalog (UCAC3)

Table of contents

  1. Introduction
  2. Summary of the project
    1. Observations and instrumentation
    2. Reductions of UCAC observations
    3. Computation of proper motions
  3. Properties of the catalog and important notes for the user
    1. Sky coverage
    2. Completeness
    3. Reference frame
    4. Magnitudes
    5. Additional photometry
    6. Non-stellar data
    7. Provided utility software
    8. Arrangement of the data files
    9. Star identification numbers
  4. Files contained on the DVD
    1. Main catalog data
    2. Other files
  5. Data formats
    1. Main catalog zone files
    2. Other files
  6. Description of utility software
  7. Acknowledgments
  8. References
  1. Introduction

    This is the "readme" file of the third U.S. Naval Observatory CCD Astrograph Catalog, UCAC3. This data release is available free of charge on a double sided DVD or through astronomical data centers.

    UCAC3 is a compiled, all-sky star catalog covering mainly the 8 to 16 magnitude range in a single bandpass between V and R. Positional errors are about 15 to 20 mas for stars in the 10 to 14 mag range. It is supplemented by proper motions and SuperCosmos and 2MASS photometric data, as well as various flags.

    The proper motions of bright stars are based on about 140 catalogs, including Hipparcos and Tycho, as well as all catalogs used for the Tycho-2 proper motion construction. Proper motions of faint stars are based on a re-reduction of early epoch SPM data (-90 to -10 deg Dec) plus Schmidt plate data from the SuperCosmos project (down weighted due to systematic errors of order 100 mas). The proper motions of faint stars (R >= 13.5) therefore should be used with caution. The unpublished plate measure data from the AGK2, the Hamburg Zone Astrograph, the USNO Black Birch Astrograph, and the Lick Astrograph have considerably contributed to improve proper motions for stars mainly in the 10 to 14 mag range (down to the UCAC3 limit for Lick data); however, these data do not cover all sky.

    UCAC3 features a number of major differences with respect to UCAC2:

    • complete sky coverage
    • re-reduction of the pixel data with better modeling
    • double stars are resolved to the limit of the data
    • significantly improved photometry from CCD data
    • slightly deeper limiting magnitude with larger number of stars/area
    • reduced systematic errors of CCD observations
    • the addition of several new catalogs for improved proper motions
    • photometry in the B, R, and I bands from the SuperCosmos project
    • minor planet observations have been sorted out
    • identification of more high proper motion stars
    • match with 2MASS extended sources and LEDA galaxies

    A UCAC4 release is anticipated in the future. The plan is to utilize a new reduction of the NPM plate material and benefit from global iterative solutions to further reduce possible systematic (zonal) errors and provide a strong link to the extragalactic reference frame. The UCAC4 release also might make individual positions at observational epochs public, and may serve pixel data as well.

    Additional details will be published in the upcoming release paper (Zacharias et al. 2009) and in several technical papers describing details of the reduction procedures and results. For the latest updates see . The release paper should be sited whenever UCAC3 data is utilized. Requests for the data DVD should be sent to, technical questions can be addressed to . The DVD will be sent to all addresses on the UCAC2 distribution list as soon as our resources allow.

  2. Summary of the Project

    1. Observations and Instrumentation

      The UCAC is an observational program, using the U.S. Naval Observatory Twin Astrograph and a 4k by 4k CCD camera, covering just over one square degree per frame with a scale of 0.9"/pixel. The red-corrected, 20 cm aperture, 5-element lens of the astrograph provides a 9 degree (diameter) field of view (designed for photographic plates), thus only a fraction is utilized with our CCD camera, centered on the optical axis.

      The CCD is a thick, Kodak device with 9 micrometer pixel size. The camera, made by Spectral Instruments, is Peltier cooled to -18 C. The raw data are severely affected by a low charge transfer efficiency (CTE) of our otherwise cosmetically excellent CCD chip. To mitigate this problem, a relatively warm operating temperature is used, causing a significant dark current.

      Observations started in January 1998 at Cerro Tololo Interamerican Observatory (CTIO) in Chile, where the entire southern sky and about half of the northern sky were observed. In October 2001 the instrument was moved to the Naval Observatory Flagstaff Station (NOFS) in Arizona where it completed the northern sky in 2004.

      A 2-fold, center-in-corner overlap pattern was adopted on a 0.5 degree grid, starting at the South Celestial Pole. Each field was observed with both a long (100 to 150 sec) and a short (20 to 30 sec) exposure. Extensive quality control routines led to the rejection of over 15% of the frames taken. All raw (pixel) data were saved and continue to be archived.

      Observations were made in a single bandpass (579-642 nm), thus the UCAC magnitudes are between Johnson V and R. No attempt has been made to obtain high quality, photometric data from the CCD observations. In fact, observations were made during nights with thin cirrus clouds.

      The telescope was actively guided with an ST-4 autoguider mounted behind the second, visually-corrected lens of the twin-astrograph. Operation was automated using a PC and a single board computer. An HP-Unix workstation was used for on-line reductions to obtain quality control statistics in near real-time.

    2. Reductions of UCAC Observations

      The UCAC3 positions of the CCD observations are based on the Tycho-2 reference stars, similar to the UCAC2 catalog. However, the 2MASS was utilized to probe for systematic errors in the CCD data, particularly magnitude equations and coma-like errors caused by the poor CTE of the detector. Image centroiding is based on a modified Lorentz profile model which matches the observed PSF better than a Gaussian function. For details, please see upcoming journal papers.

      Pixel processing included double star fits and real aperture photometry. "Flip" observations (telescope on West and East side of pier for same calibration field) were utilized to fix the overall magnitude equations.

      Saturated images of stars were propagated through the output catalog, so UCAC3 contains many more bright stars than UCAC2. However positional results are not as reliable as for unsaturated images and the user is urged to pay attention to flags and the meaning of various data columns.

    3. Computation of Proper Motions

      Proper motions of bright stars (R ~8 to ~12.5) were derived using a combination of ground-based photographic and transit circle catalogs, and included satellite observations from the Hipparcos and Tycho-2 catalogs. In addition, the U.S. Naval Observatory measured about 5000 astrograph plates on the StarScan machine to derive about 9 million positions for stars mainly in the 10 to 14 magnitude range, including the complete set of AGK2 (Bonn and Hamburg zones, +90 to -2.5 deg Dec).

      For the faint stars (~12.5 to ~16.5), data from the first epoch plates of the Yale Southern Proper Motions (SPM, van Altena et al. 1999) are utilized. These plates were measured on the Precision Measuring Machine at USNO Flagstaff Station by D. Monet. A complete re-reduction of the data were performed in a joint USNO - Yale University effort utilizing the StarScan pipeline for the pixel reductions and the Yale software to obtain RA,Dec coordinates. Because the re-reduction of the NPM data is still in progress, the SuperCosmos data (Hambly et al. 2001a,b,c) were included in UCAC3 to provide proper motion coverage of faint stars, particularly in the north. For this purpose stars with magnitude R <= 17 and all sky were extracted from a copy of the SuperCosmos "source" data. Due to zonal (plate pattern) systematic errors in the range of 50 to 200 mas, as compared to 2MASS data, the SuperCosmos positions at their mean epoch were downweighted with an additional 100 mas RMS error contribution. Other catalogs were handled similarly, with somewhat lower additional error contributions. The number of stars in UCAC3 which are also in major other catalogs used for the proper motions is as follows:

                  numb.stars  cat   ID and name
                      65392    1    Hipparcos
                    2386607    2    Tycho-2
                    4098873    3    AC2000
                     270823    4    AGK2 Bonn
                     960074    5    AGK2 Hamb
                    4320925    6    ZA
                    2970383    7    BY
                    1043857    8    Lick
                   85563642    9    SuperCosmos
                   51112855   10    SPM YSJ1
                      51297    -    high proper motion stars 
                                    from external catalogs
                   98114307    -    2MASS
                  100766420    -    all stars in UCAC3

      For more details please see the upcoming journal papers.

      It is hoped that this approach reduced systematic errors in UCAC3 proper motions of faint stars as compared to the procedures adopted for UCAC2.

      There are 51297 tagged previously known high proper motion stars in the UCAC3 release. While we have made an effort to identify previously known high proper motion stars, the list is not comprehensive. The high proper motion stars were identified by utilizing known proper motion catalogs to match with our UCAC3 positions. In all cases the proper motion given for each star come from the source catalog. In the North we used the LSPM-North Catalog (Lepine+ 2005) of 61977 new and previously known high proper motion stars having proper motions greater than 0.15"/yr. In the South we used many smaller surveys along with the Revised NLTT Catalog (Salim+, 2003), which produced 17730 unique high proper motion stars greater than 0.15"/yr. In chronological order, the smaller southern surveys used include: seven papers covering various portions of the southern sky by Wroblewski and collaborators (Wroblewski & Torres 1989, 1991, 1994, 1996, 1997; Wroblewski & Costa 1999, 2001), (2) UK Schmidt Telescope survey plates of 40 survey fields by Scholz and collaborators (Scholz et al. 2000), (3) The Calan-ESO survey (Ruiz et al. 2001) (4) SuperCOSMOS-RECONS proper-motion survey of the entire southern sky (Henry et al. 2004; Subasavage et al. 2005a, 2005b; Finch et al. 2007), (5) the Southern Infrared Proper-Motion Survey (SIPS; Deacon et al. 2005) and (7) Lepine's SUPERBLINK survey of a portion of the southern sky (L├ępine 2008).) Identified images of high proper motion stars in UCAC data were cut from the remaining pipeline and reduced separately. Results for those stars were then added in a later stage of the reductions. This avoids creating duplicate entries in UCAC3.

      The computation of proper motions is performed similarly to the procedure used for the UCAC2 and the Tycho-2 catalogs. All input catalogs were reduced to the ICRF utilizing Hipparcos data or some denser, interim catalog that follows the system of Hipparcos. Standard errors for each position are estimated. These error estimates are used as weights to compute a mean position and proper motion, which utilizes a weighted, least-squares adjustment procedure. Error estimates of UCAC3 astrometry are provided.

      Errors in proper motions of the bright stars (to R ~12) run from about 1 to 3 mas/yr mainly due to the large epoch spans involved. For the fainter stars using SPM data, typical errors are 2 to 3 mas/yr, while with SuperCosmos early epoch data alone proper motion errors are about 6 to 8 mas/yr (as a conservative estimate).

      Contrary to UCAC2, not all stars in UCAC3 have proper motions. Stars made it into the UCAC3 release catalog if any one of the following applies:

      • at least 2 matching positions from different CCD frames were obtained,
      • star was matched with a 2MASS entry,
      • star was matched with a SupeCosmos entry,
      • proper motions could be obtained in combination with any other early epoch data.

      A master list of exactly 139,134,800 mean positions from CCD data was matched against the various other catalogs, resulting in exactly 100,766,420 objects actually provided in this UCAC3 data release. Of these 51,297 are identified, known high proper motions stars.

  3. Properties of the catalog and important notes for the user

    1. Sky coverage

      UCAC3 is an all-sky catalog with at least about 40 stars per square deg anywhere on the sky. The average density of this catalog is over 2000 stars per square deg.

    2. Completeness

      UCAC3 is more complete than UCAC2, including previously omitted "problem" stars and double stars, many of which could be new discoveries. A paper is in preparation about a sample of new double stars found in UCAC3 and the rate of confirmation by speckle observations. The separation limit for double stars in UCAC3 varies as function of brightness of the components and brightness difference. However, some doubles with separations of only 1 arcsec in UCAC3 have been confirmed as real. Stars fainter than about R = 10 and separations larger than 2 arcsec are well covered.

      UCAC3 also contains observations of some bright stars, as they happened to make it through the pipeline. However, UCAC3 is not supplemented by a bright star catalog and is incomplete at around magnitude R=7.5 and brighter. Some positions are based on a center-of-mass centroiding when the least-squares fit did not succeed. The positions of those stars (number of used images, nu = 0) are not reliable and are given only to indicate a problem area in this area of the sky.

      If a star's proper motion was computed to be larger than 300 mas/yr in either coordinate, but it was not found in a high proper motion star catalog, the proper motion was set to zero and only the mean observed CCD position is given in UCAC3.

      Over 95 million stars in UCAC3 have a computed proper motion; for 45.4 million of these the proper motion is based on only 2 epochs, while for 49.5 million stars at least 3 epochs were available.

      If the computed position error of a star exceeds 500 mas in either coordinate it was set to 500 mas but the star was kept, if at least 2 observations from different CCD observations were matched or the star is either in the 2MASS, SPM or SuperCosmos data files. Similarly, the error in proper motion was truncated to 50 mas/yr but respective stars kept in UCAC3 by the same criteria as for large positional errors. Obviously all large error objects need to be handled with caution, and some of these will just be fake. This approach, different to UCAC2, was taken in order to drive up the completeness of UCAC3 at the expense of slightly greater contamination. In particular, the larger limits in errors deemed acceptable for UCAC3 accommodate the fainter limiting magnitude, which was possible mainly due to superior handling of dark subtraction in the pixel data. This allowed many low signal-to-noise, real stars to enter the catalog, although with expected larger random errors.

    3. Reference frame

      The astrometry provided in UCAC3 is on the Hipparcos system, i.e. the International Celestial Reference System (ICRS), as represented by the Tycho-2 catalog. Any possible deviations of the Tycho system with respect to Hipparcos or the extragalactic radio reference frame are under investigation for UCAC4.

      Positions in UCAC3 are given at the standard epoch of Julian date 2000.0, thus the UCAC3 is a compiled catalog. In order to be able to calculate positional errors at any epoch, the central epoch, i.e. the weighted mean epoch of the data (UCAC + early epoch) is given. At the central epoch (which varies from star to star and is also different for RA and Dec) the positional error has its smallest value, the one given in the catalog for "sigma position". In most cases this central epoch will be close to the UCAC observational epoch due to the relatively large weight given to the UCAC observations. However, a fair number of stars have a vastly different mean epoch, ranging back to about 1900.

      The proper motions are given at the central epoch. Positional errors of stars increase according to the errors in the proper motions when going forward or backward in time from the central epoch.

    4. Magnitudes

      UCAC3 covers the magnitude range of about R = 7.5 to 16.3 in a 579-642 nm bandpass. This is between visual (V) and red (R). The limiting magnitude can vary by about +-0.3 mag. The bright magnitude cut-off varies even more, depending on sky conditions at the time of observation.

      UCAC3 gives centroid fit-model magnitudes as well as aperture photometry derived from the new pixel data reductions. Systematic errors in these magnitudes are believed to be below 0.1 mag, which is a significant improvement over the UCAC2 release. Tycho-2 stars, except for the faint end, were used to perform differential photometric reductions, CCD frame by frame, including a zero-point and a linear color term. However, UCAC observations were performed in non-photometric sky conditions. Mean magnitudes were derived from CCD frames with indications of "good photometric quality", which is about 50% of the observations.

    5. Additional photometry

      For convenience to the user, the UCAC3 observational data are supplemented with plate photometry (B, R, I) from the SuperCosmos project (Hambly et al 2001), as well as with new, IR photometry from the Two Micron All Sky Survey, 2MASS (Scrutsky 2006). In addition to the J, H, and K_s magnitudes, rounded errors and some flags are provided as well. For more details see and .

    6. Non-stellar data

      The UCAC3 contains some galaxies, particularly at the faint end. No flag indicating a galaxy or star has been derived from the CCD pixel data; however, a cross reference to the LEDA galaxies (Paturel et al. 2005) and the 2MASS extended source catalog (Skrutskie et al. 2006) has been made and corresponding information is put into the UCAC3 release.

      Observations of asteroids have been identified and taken out of the main UCAC3 catalog. Individual epoch observations of about 1000 asteroids at multiple epochs have been prepared for publication, but are not part of the UCAC3 release. The observing schedule explicitly avoided all minor planets brighter than about R = 12, except for special observing campaigns to derive masses of asteroids.

    7. Provided utility software

      Only some basic access code is included with this release to illustrate the data format and allow conversion of the main binary files to ASCII tables. It is anticipated that 3rd party companies specialized in providing interfaces between various star catalogs and the user will integrate UCAC3 data into their products, as has been the case for UCAC2.

    8. Arrangement of the data files

      The main catalog data are arranged in declination zones of 0.5 degree width, with zone number 1 starting at the South Pole and increasing toward north. There is a separate file for each of the 360 zones. Records in the individual data files are sorted by right ascension. Each record contains the data for one star, 84 bytes of binary integers.

    9. Star identification numbers

      Official UCAC3 star ID numbers should be utilized for identification purposes and for communication with the UCAC team. The main identifier is the running star number in the CCD mean position data (MPOS number) which is provided on the UCAC3 individual star records as the last 4-byte integer item. This number spans the range of 3 to 140051297 but includes gaps for stars which did not make it into the release. MPOS numbers over 140 million identify high proper motion stars, which have been handled differently in the pipeline and were merged at a later stage into the release.

      Alternatively, a unique running star ID number without any gaps can be generated on the fly, counting stars along zones from south to north and along RA within each zone, similarly to what was recommended for UCAC2.

              ID = n0 + running star number in zone z

      where z is zone number where the star in question is located (1 to 360; zone 1: -90 to -89.5 decl., ...), n0 is the largest star ID number of the previous zone and ID is this official UCAC3 star ID number. A table is provided listing some statistics of zones, which include this n0 number.

      If needed, this 9-digit star ID number should be given in connection with the IAU sanctioned acronym of this project and this data release number, such as "3UCAC100200300". The star ID number runs from 000000001 to 100766420. Leading zeros are to be used to fill 9 digits in the star name.

  4. Files contained on the DVD

    The DVD does not contain sub-directories; all information is provided in files on the top level for each side of the double-sided DVD.

    1. Main catalog

      The main catalog data are contained in zone files "z001" to "z360". Each zone is 0.5 degree wide, beginning at the south celestial pole. The format of these binary data files is explained below.

    2. Other files

      readme_u3   = this file
      table_zones = table listing info for each zone
      u3index.asc = index file for each 0.1 hour in RA, ASCII text file
      u3index.unf = index file for each 0.1 hour in RA, unformatted binary 
      u3read.f    = Fortran code to read UCAC3 zone files
      u3read.dat  = sample data ASCII output file generated with u3read.f
  5. Data formats

    1. Main catalog zone data files

      sample code to illustrate data format (Fortran 77)

      * items to read from input files
            INTEGER*4 i, ra,spd, pmrac,pmdc, id2m, rn
            INTEGER*2 im1,im2,sigmag, sigra,sigdc, cepra,cepdc,sigpmr,sigpmd
           .         ,jmag,hmag,kmag, smB,smR2,smI
            INTEGER*1 objt,dsf, na1,nu1,us1,cn1, clbl,qfB,qfR2,qfI
            INTEGER*1 icqflg(3), e2mpho(3), catflg(10), g1,c1,leda,x2m
            OPEN (20,FILE=fnu3,ACCESS='direct',RECL=84) ! 1 record per star
            i = 0
              i = i + 1
              READ (20,REC=i,ERR=99)                    ! number of bytes
           .     ra,spd, im1,im2,sigmag, objt,dsf       !  8 + 6 +  2  = 16
           .    ,sigra,sigdc, na1,nu1,us1,cn1           !  4 + 4       =  8
           .    ,cepra,cepdc, pmrac,pmdc, sigpmr,sigpmd !  4 + 8 +  4  = 16
           .    ,id2m, jmag,hmag,kmag, icqflg, e2mpho   !  4 + 6 +  6  = 16
           .    ,smB,smR2,smI, clbl,qfB,qfR2,qfI        !  6 + 4       = 10
           .    ,catflg, g1,c1, leda, x2m, rn           ! 10 + 4 +  4  = 18
       99    WRITE (*,'(a,i9)') 'last record number on file = ',i-1
      num item   fmt unit        explanation                            remark
       1  ra     I*4 mas         right ascension at  epoch J2000.0 (ICRS)  (1)
       2  spd    I*4 mas         south pole distance epoch J2000.0 (ICRS)  (1)
       3  im1    I*2 millimag    UCAC fit model magnitude                  (2)
       4  im2    I*2 millimag    UCAC aperture  magnitude                  (2)
       5  sigmag I*2 millimag    UCAC error on magnitude (larger of sc.mod)(3)
       6  objt   I*1             object type                               (4)   
       7  dsf    I*1             double star flag                          (5)   
       8  sigra  I*2 mas         s.e. at central epoch in RA (*cos Dec)      
       9  sigdc  I*2 mas         s.e. at central epoch in Dec                 
      10  na1    I*1             total # of CCD images of this star
      11  nu1    I*1             # of CCD images used for this star        (6)
      12  us1    I*1             # catalogs (epochs) used for proper motions
      13  cn1    I*1             total numb. catalogs (epochs) initial match
      14  cepra  I*2 0.01 yr     central epoch for mean RA, minus 1900     
      15  cepdc  I*2 0.01 yr     central epoch for mean Dec,minus 1900  
      16  pmrac  I*4 0.1 mas/yr  proper motion in RA*cos(Dec)           
      17  pmdc   I*4 0.1 mas/yr  proper motion in Dec                    
      18  sigpmr I*2 0.1 mas/yr  s.e. of pmRA * cos Dec                   
      19  sigpmd I*2 0.1 mas/yr  s.e. of pmDec                            
      20  id2m   I*4             2MASS pts_key star identifier          
      21  jmag   I*2 millimag    2MASS J  magnitude                     
      22  hmag   I*2 millimag    2MASS H  magnitude                       
      23  kmag   I*2 millimag    2MASS K_s magnitude                     
      24  icqflg I*1 * 3         2MASS cc_flg*10 + phot.qual.flag          (7)
      25  e2mpho I*1 * 3         2MASS error photom. (1/100 mag)           (8)
      26  smB    I*2 millimag    SuperCosmos Bmag
      27  smR2   I*2 millimag    SC R2mag                                  (9)
      28  smI    I*2 millimag    SC Imag
      29  clbl   I*1             SC star/galaxy classif./quality flag     (10)
      30  qfB    I*1             SC quality flag Bmag                     (11)
      31  qfR2   I*1             SC quality flag R2mag                    (11)
      32  qfI    I*1             SC quality flag Imag                     (11)
      33  catflg I*1 * 10        mmf flag for 10 major catalogs matched   (12)
      34  g1     I*1             Yale SPM object type (g-flag)            (13)
      35  c1     I*1             Yale SPM input cat.  (c-flag)            (14)
      36  leda   I*1             LEDA galaxy match flag                   (15)
      37  x2m    I*1             2MASS extend.source flag                 (16)
      38  rn     I*4             MPOS star number; identifies HPM stars   (17)
               84 = total number of bytes per star record

      Note (1): Positions are on the International Celestial Reference System (ICRS) as represented by the Hipparcos / Tycho-2 catalogs. The epoch for the positions of all stars is J2000.0; the weighted mean catalog position was updated using the provided proper motions. The observational UCAC position is but one of several going into these values and is not given in the UCAC3, thus the original UCAC observation cannot be recovered from these data. The declination is given in south pole distance (spd) and can be converted back to a true declination by subtracting 324000000 mas.

      Note (2): Unknown, or unrealistic photometric results are set to magnitude = 18 (18000 mmag entry in catalog). Systematic errors are expected to be below 0.1 mag for im1, im2 photometric results obtained from the UCAC CCD pixel data. The aperture photometry is considered more robust, particularly for "odd" cases, while the model fit magnitude is expected to be more accurate for "well behaved" stars.

      Note (3): A value of -1 for error in magnitude means "unknown". For many stars a photometric error based on the scatter from individual observations of that star on different CCD frames could be obtained. A model error was also attempted to be assigned, based on the S/N ratio. The error quoted here is the larger of the 2. If that error exceeds 0.9 mag the error was set to 0.9 mag (900 mmag entry in catalog data).

      Note (4): The object type flag is used to identify possible problems with a star and has the following meaning:

          -2 = warning: object could be from possible streak
          -1 = warning: object is near overexposed star
           0 = good star
           1 = good star (data copied from another entry)
           2 = warning: contains at least 1 overexposed image
           3 = warning: all images are overexposed or "bad"

      Note (5): The dsf flag is a double star flag used to indicate the type/quality of double star fit with the following meaning:

           0 = single star
           1 = primary of pair with unreal secondary = single
           2 = forced separation, on same frame
           3 = blended image, some CCD frames show single star, some double
           4 = forced separation, 2 objects on same frame number
           5 = primary   component of real double
           6 = secondary component of real double
           7 = other "odd" case  

      Note (6): A zero for the number of used images indicates that all images have some "problem" (such as overexposure). In that case an unweighted mean over all available images (na) is taken to derive the mean position, while normally a weighted mean was calculated based on the "good" images, excluding possible problem images (nu <= na).

      Note (7): For each 2MASS bandpass a combined flag was created (cc_flg*10 + ph_qual) consisting of the contamination flag (0 to 5) and the photometric quality flag (0 to 8).

          0 =  cc_flg  2MASS 0, no artifacts or contamination
          1 =  cc_flg  2MASS p, source may be contaminated by a latent image
          2 =  cc_flg  2MASS c, photometric confusion
          3 =  cc_flg  2MASS d, diffraction spike confusion
          4 =  cc_flg  2MASS s, electronic stripe
          5 =  cc_flg  2MASS b, bandmerge confusion
          0 =  no ph_qual flag
          1 =  ph_qual 2MASS X, no valid brightness estimate
          2 =  ph_qual 2MASS U, upper limit on magnitude
          3 =  ph_qual 2MASS F, no reliable estimate of the photometric error
          4 =  ph_qual 2MASS E, goodness-of-fit quality of profile-fit poor
          5 =  ph_qual 2MASS A, valid measurement, [jhk]snr>10 AND [jhk]cmsig<0.10857
          6 =  ph_qual 2MASS B, valid measurement, [jhk]snr> 7 AND [jhk]cmsig<0.15510
          7 =  ph_qual 2MASS C, valid measurement, [jhk]snr> 5 AND [jhk]cmsig<0.21714
          8 =  ph_qual 2MASS D, valid measurement, no [jhk]snr OR [jhk]cmsig req.

      For example icqflg = 05 is decoded to be cc_flg=0, and ph_qual=5, meaning no artifacts or contamination from cc_flg and 2MASS qual flag = "A" .

      Note (8): The photometric errors from 2MASS were rounded by 1 digit here to fit into fewer bytes (1/100 mag instead of millimag).

      Note (9): The R magnitude from the second epoch Schmidt plates (R2) is used for UCAC3, as provided in the SuperCosmos source catalog.

      Note (10): clbl is a combination of the SuperCOSMOS "meanclass" and modified "blend" flag (meanclass + 10*blend) originally for each magnitude (B, R1, R2, I). The flag provided here is the maximum value over all bands for each of the 2 flags. The SuperCOSMOS mean class flag is an estimate of image class based on unit-weighted mean of individual classes from (B, R1, R2, I). The SuperCOSMOS modified blend flag indicates if blending is detected.

      The "meanclass" has the following meaning from SuperCOSMOS:

          1 = galaxy
          2 = star
          3 = unclassifiable
          4 = noise
      The modified "blend" flag has the following meaning:
          0 = no blending
          1 = possible blending detected

      Note (11): This is a modified quality flag from the "qualB", "qualR2", and "qualI" quality flag from SuperCOSMOS, which gives an indication of the quality of the image from the three bands (B, R2, I). The modified quality flag qfB, qfR2, and qfI have the following meaning:

          -1 = qual blank    in SuperCOSMOS, no flag given
           0 = qual zero     in SuperCOSMOS, no problems detected
           1 = qual < 128    in SuperCOSMOS, reliable image
           2 = qual < 65535  in SuperCOSMOS, problems detected
           3 = qual >= 65535 in SuperCOSMOS, spurious detection

      Note (12): The catflg provides reference to 10 major catalogs used in the computation of the proper motions and catalog matching. Each of the 10 numbers range from 0 to 6 and are the "mmf" (multiple match flag) with respect to each of the 10 following catalogs:

                 Hip, Tycho, AC2000, AGK2B, AGK2H, ZA, BY, Lick, SC, SPM
           catflg 1     2       3      4      5     6   7   8     9   10
      The value for each byte, the mmf flag, has the following meaning:
           0 = star not matched with this catalog
           1 = unique match,  not involving a double star
           2 = closest match, not involving a double, likely o.k. 
           3 = unique match,  and involving a double star
           4 = closest match, and involving a double, likely o.k.
           5 = maybe o.k. smallest sep. match in both directions
           6 = same as 5, but involving a double star

      Note (13): The g-flag from the Yale San Juan first epoch Southern Proper Motion data (YSJ1, SPM) has the following meaning:

           0 = no info
           1 = matched with 2MASS extended source list
           2 = LEDA  galaxy
           3 = known QSO

      Note (14): The c-flag from the Yale San Juan first epoch Southern Proper Motion data (YSJ1, SPM) indicates which input catalog has been used to identify stars for pipeline processing:

           1 = Hipparcos
           2 = Tycho2
           3 = UCAC2
           4 = 2MASS psc
           5 = 2MASS xsc (extended sources, largely (but not all!) galaxies)
           6 = LEDA  (confirmed galaxies, Paturel et al. 2005)
           7 = QSO   (Veron-Cetty & Veron 2006)

      Note (15): This flag is either 0 (no match) or contains the log of the apparent total diameter for I-band (object size) information copied from the LEDA catalog (galaxies). A size value of less than 1 has been rounded up to 1.

      Note (16): This flag is either 0 (no match) or contains the length of the semi-major axis of the fiducial ellipse at the K-band (object size) information copied from the 2MASS extended source catalog. If the size is larger than 127, the flag was set to 127.

      Note (17): MPOS running star numbers over 140 million indicate high proper motion stars which were identified in UCAC pixel data from matches with known HPM stars. The position given for those HPM stars is the unweighted mean of the CCD observations and the proper motion is copied from the literature catalog.

      The following table gives the total range of values present these data.

       # explanation                               unit   minimum    maximum
       1 right ascension     epoch J2000.0 (ICRS) [mas]         2 1295999990
       2 south pole distance epoch J2000.0 (ICRS) [mas]     57990  647908484
       3 UCAC fit model magnitude                [mmag]      2329      18000
       4 UCAC aperture  magnitude                [mmag]      2797      18000
       5 error on magnitude (larger of sc.model) [mmag]        -1        900
       6 object type                                           -2          3
       7 double star flag                                       0          7
       8 s.e. at central epoch in RA (*cos Dec)   [mas]         5        500
       9 s.e. at central epoch in Dec             [mas]         5        500
      10 total numb. of CCD images per star                     1         70
      11 number of CCD images used per star                     0         68
      12 numb. catalogs (epochs) used for proper motion         1         31
      13 total numb. of catalogs (epochs) initial match         0        113
      14 central epoch - 1900 for mean RA    [1/100 yr]      -477      10438
      15 central epoch - 1900 for mean Dec   [1/100 yr]      -938      10438
      16 proper motion in RA*cos(Dec)      [0.1 mas/yr]    -37060      67670
      17 proper motion in Dec              [0.1 mas/yr]    -58130     102770
      18 s.e. of pmRA * cos Dec            [0.1 mas/yr]       -10        500
      19 s.e. of pmDE                      [0.1 mas/yr]       -10        500
      20 2MASS pts_key star identifier                          0 1340037129
      21 2MASS J  magnitude                      [mmag]     -2652      30000
      22 2MASS H  magnitude                      [mmag]     -3732      30000
      23 2MASS K_s magnitude                     [mmag]     -4227      30000
      24 2MASS cc_flg*10 + phot.qual.flag J band                0         58
      25 2MASS cc_flg*10 + phot.qual.flag H band                0         58
      26 2MASS cc_flg*10 + phot.qual.flag K band                0         58
      27 2MASS error photom. J band         [1/100 mag]         0        127
      28 2MASS error photom. H band         [1/100 mag]         0        127
      29 2MASS error photom. K band         [1/100 mag]         0        127
      30 SC Bmag                                 [mmag]         0      30000
      31 SC R2mag                                [mmag]         0      30000
      32 SC Imag                                 [mmag]         0      30000
      33 SC star/galaxy classif./quality flag                   0         14
      34 SC quality flag Bmag                                  -1          2
      35 SC quality flag R2mag                                  0          2
      36 SC quality flag Imag                                  -1          2
      37 mmf flag Hipparcos catalog                             0          1
      38 mmf flag Tycho-2 catalog                               0          1
      39 mmf flag AC2000 catalog                                0          1
      40 mmf flag AGK Bonn catalog                              0          6
      41 mmf flag AGK Hamburg catalog                           0          6
      42 mmf flag ZA catalog                                    0          6
      43 mmf flag BY catalog                                    0          6
      44 mmf flag Lick catalog                                  0          6
      45 mmf flag SuperCosmos catalog                           0          6
      46 mmf flag SPM catalog                                   0          6
      47 Yale SPM object type (g-flag)                          0          3
      48 Yale SPM input cat.  (c-flag)                          0          7
      49 LEDA galaxy match flag    (size info)                  0        118
      50 2MASS extend.source flag  (size info)                  0        127
      51 MPOS star number                                       3  140051297
    2. Other files

      table_zones = table listing info for each zone

      This is a text file (ASCII) giving summary information about stars in each zone. There are 360 lines, 1 each for a 0.5 deg wide zone in declination, beginning at the South Celestial Pole. The meaning of the columns are:

        1  zn   = zone number (1 to 360)
        2  n1   = running star ID number of 1st star in this zone
        3  ns   = total number of stars in this zone
        4  dec  = upper limit of declination of this zone
        sample data:
         zn         n1         ns    dec
          1          1       1258  -89.5
          2       1259       3828  -89.0
          3       5087       6485  -88.5
        358  100759267       4104   89.0
        359  100763371       2132   89.5
        360  100765503        918   90.0  

      u3index.asc = index file for each 0.1 hour in RA, ASCII

      This is a text file (ASCII). Each line contains data for an area of sky (bin) 0.5 deg wide in declination (indexed by zone number from 1 to 360), and 0.1 h wide in RA (indexed from 1 to 240). So there are a total of 360 * 240 = 86400 lines on this file. The meaning of the columns are:

        1  n0   = running star number (index along the main data file)
                    of the star before the first one in this bin,
                    the sequence stars out with 0 at the beginning of
                    each new declination zone
        2  nn   = number of stars in this bin (which can be zero)
        3  zn   = zone number (1 to 360)
        4  j    = index for bins along RA (1 to 240) (divide by 10 = RA hour)
        5  dec  = declination corresponding to zn,
                    printed out only at the beginning of a new zone
        sample data:
               0         3   1   1 -89.5
               3         3   1   2
               6         6   1   3
              12         4   1   4
          304461       305 180 239
          304766       310 180 240
               0       318 181   1   0.5
             318       315 181   2
             913         1 360 238
             914         1 360 239
             915         3 360 240

      u3index.unf = index file for each 0.1 hour in RA, unformatted binary

      This file contains the same data as the u3index.asc, however as binary with the following access explanation (Fortran):

            INTEGER*4 n0(360,240), nn(360,240)  
            OPEN (15,FILE=fnidxu,ACCESS='direct',RECL=345600)  ! 360 * 240 * 4
            READ (15,REC=1) n0
            READ (15,REC=2) nn

      u3read.sample: This is the output of a run of the u3read code on zone z042 showing the first 20 records of that binary file. Exactly the same data as the corresponding binary file data are shown with columns in the same order as outlined above. However, the 3 items of "e2mpho" (error in 2MASS photometry) are separate columns, while the SPM g1 and c1 items are merged into a single column. Thus the ASCII table output of the sample data has 39 columns.

  6. Description of utility software

    u3read.f = sample Fortran code to read UCAC3 zone files

    This code reads a file from the main UCAC3 data (binary zone data) and outputs all the information into an ASCII table, star by star, 1 star per line. The user can select a range in RA, Dec and magnitude.

  7. Acknowledgments

    In a project such as this that has spanned a decade and two continents, many people have been involved. Here we list people and their main contributions to the project.

    • Norbert Zacharias - Principle Investigator, observer, responsible for UCAC position reductions (from pixels to positions on the sky), observing schedule, and external position comparisons, re-processing of pixel data and development of reduction pipeline, Star-Scan plate measure reductions.
    • Ted Rafferty - former project lead, instrumentation specialist, observer.
    • Charlie Finch - re-reduction of CCD x,y to RA,Dec, including systematic error control.
    • Gary Wycoff - proper motions data preparation, star identifications.
    • Marion Zacharias - quality control, observer, position reductions, extragalactic link program.
    • Terry Girard - SPM data reductions, from x,y plate data to RA,Dec, incl. systematic error handling (magnitude equations) and all related reduction pipeline development.
    • Bill van Altena - for many years of collaboration in astrometry.
    • Nigel Hambly - sharing of SuperCosmos source data for UACA proper motions.
    • Dave Monet - measurements of SPM and NPM plates on PPM at NOFS.
    • Sean Urban - proper motions of UCAC2 release, preparation of other position catalogs including systematic error removal.
    • Valeri Makarov - reduction of AGK2 and other StarScan plate measures from global x,y to individual RA,Dec positions.
    • Brian Mason - new double star speckle observations with USNO 26in and data reductions.
    • Bill Hartkopf - new double star speckle observations with USNO 26in and data reductions.
    • David Hall - verification of tape archive, data handling.
    • Marvin Germain - telescope control system software development, software-to-hardware interface including electronics.
    • Ellis Holdenried - telescope control system software maintenance and extension of user interface for telescope operation.
    • Lars Winter - basis for astrometric CCD reduction software.
    • Greg Hennessy - computer administration support (USNO-DC)
    • Danilo Castillo - observer, Cerro Tololo, Chile
    • Mauricio Martinez - observer, Cerro Tololo, Chile
    • Sergio Pizarro - observer, Cerro Tololo, Chile
    • Oscar Saa - telescope manager, Cerro Tololo, Chile
    • Trudy Tilleman - observer, U.S. Naval Observatory Flagstaff Station, assist with data reductions.
    • Stephanie Potter - observer, U.S. Naval Observatory Flagstaff Station
    • Dominic Marcello - observer, NOFS, joined the project in Jan. 2003
    • Gary Wieder - telescope upgrades, relocation, maintenance, and troubleshooting.
    • John Pohlman - telescope upgrades, maintenance, and troubleshooting
    • John Bowles - telescope upgrades and maintenance (USNO-DC)
    • Dave Smith - telescope upgrades and maintenance (USNO-DC)
    • Tie Siemers - telescope upgrades and maintenance (USNO-DC)
    • Mike Divittorio - telescope maintenance and troubleshooting (NOFS)
    • Steve Sell - telescope maintenance and troubleshooting (NOFS)
    • Albert Rhodes - telescope maintenance and troubleshooting (NOFS)
    • Blaize Canzian - network and computer system support (NOFS)
    • Sumit Dutta - summer student working on separating out minor planet observations and streak artifacts
    • Aleida Young - summer student working on identification of high proper motion stars
    • Danley Hsu - summer student working on UCAC3 release, and providing the UCAC3 access code included with this DVD

    Other Acknowledgments

    This project would not have been possible without support from the USNO administration. Special thanks are given to Thomas Corbin for under- standing the need for such a project, articulating it to those with resources, and administering the project in its early days. Thanks are given to the three USNO Astrometry Department Heads during the UCAC project. Without their continued support, it would not have come to fruition. They are F. Stephen Gauss, Ted Rafferty, and Ralph Gaume. Thanks are given to the USNO Scientific Director, Kenneth Johnston, for his approval and support of the project and for making USNO resources available.

    Our successful stay at the Cerro Tololo Interamerican Observatory would not have been possible without a memorandum of understanding, worked out by P. Kenneth Seidelmann, USNO, and the then director of CTIO, Malcolm Smith. The entire staff of CTIO is thanked for their generous support. The same holds for all the people at the Naval Observatory Flagstaff Station (NOFS) during the northern hemisphere observing of UCAC, in particular we want to thank the then director Jeff Pier.

    Also, we wish to thank Gary Sims from Spectral Instruments for building our 4k camera and providing outstanding support over the years. Finally, we wish to acknowledge the following for their important contributions; Bill Gray for custom updates to his GUIDE software regarding minor planet ephemerids, and Rae Stiening (Univ.of Mass.) for providing preliminary and pre-release 2MASS data to our project.

  8. References

    This list includes items relevant to UCAC even if they are not cited in the above text.

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    • ESA 1997, "The Hipparcos and Tycho Catalogues", European Space Agency, publication SP-1200
    • Finch,Charlie T., Henry,Todd J., Subasavage,John P., Jao,Wei-Chun, Hambly,Nigel C., 2007, "The Solar Neighborhood. XVIII. Discovery of New Proper-Motion Stars with 0.40" yr-1 > mu >= 0.18" yr-1 between Declinations -90d and -47d", AJ, 133, 2898
    • Gauss,F.S. Zacharias,N. Rafferty,T.J. Germain,M.E. Holdenried,E.R. Pohlman,J.W. and Zacharias,M.I., 1996, "A new astrometric survey of the Southern Hemisphere", Bull.AAS 28, No.4, p.1282
    • Girard,T. M., Platais,I., Kozhurina-Platais,V., van Altena, W. F., Lopez, C. E. 1998, "The Southern Proper Motion Program. I. Magnitude-Equation Correction", Astron. J. 115, 855.
    • Hoeg,E., Fabricius,C., Makarov,V.V., Urban,S., Corbin,T., Wycoff,G., Bastian,U., 2000, "The Tycho-2 Catalogue of the 2.5 million brightest stars", Astron.& Astroph. 355L, 27 (short paper)
    • Hoeg,E., Fabricius,C., Makarov,V.V., Bastian,U., Schwekendieck,P., Wicenec,A., Urban,S., Corbin,T., Wycoff,G., 2000, "Construction and verification of the Tycho-2 Catalogue", Astron.& Astroph. 357, 367 (long paper)
    • Hambly,N. C., MacGillivray,H. T., Read,M. A., Tritton,S. B., Thomson,E. B., Kelly,B. D., Morgan,D. H., Smith,R. E., Driver,S. P., Williamson,J., Parker,Q. A., Hawkins,M. R. S., Williams,P. M., Lawrence,A. 2001, "The SuperCOSMOS Sky Survey - I. Introduction and description", MNRAS, 326, 1279
    • Hambly,N. C., Irwin,M. J., MacGillivray,H. T. 2001, "The SuperCOSMOS Sky Survey - II. Image detection, parametrization, classification and photometry", MNRAS, 326, 1295
    • Hambly,N. C., Davenhall,A. C., Irwin,M. J., MacGillivray, H. T. 2001, "The SuperCOSMOS Sky Survey - III. Astrometry", MNRAS. 326, 1315
    • Henry,Todd J., Subasavage,John P., Brown,Misty A., Beaulieu,Thomas D., Jao,Wei-Chun, Hambly,Nigel C. 2004, "The Solar Neighborhood. X. New Nearby Stars in the Southern Sky and Accurate Photometric Distance Estimates for Red Dwarfs", AJ. 128, 2460
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    • Lepine, Sebastien, Shara, Michael M. 2005, "A Catalog of Northern Stars with Annual Proper Motions Larger than 0.15" (LSPM-NORTH Catalog)", AJ. 129, 1483
    • Lepine, Sebastien, 2008 "New High Proper Motion Stars from the Digitized Sky Survey. Iv. Completion of the Southern Survey and 170 Additional Stars with mu > 0.45" yr-1", AJ, 135, 2177
    • Paturel,G., Vauglin,I., Petit,C., Borsenberger,J., Epchtein,N., Fouque,P., Mamon,G. 2005, "A catalog of LEDA galaxies with DENIS measurements" Astron.& Astroph, 430, 751
    • Platais,I., Girard,T. M., Kozhurina-Platais,V., van Altena,W. F., Lopez,C. E., Mendez,R. A., Wen-Zhang Ma, Ting-Gao Yang, MacGillivray,H. T., Yentis,D. J. 1998, "The Southern Proper Motion Program. II. A Catalog at the South Galactic Pole", AJ, 116, 2556
    • Ruiz,Maria Teresa, Wischnjewsky,Marina, Rojo,Patricio M., Gonzalez,Luis E. 2001, "Calan-ESO Proper-Motion Catalog", ApJ 133, 199
    • Salim S., Gould A. 2003 "Improved astrometry and photometry for the Luyten catalog. II. Faint stars and the revised catalog.", AJ, 582, 1011
    • Scholz,R.-D., Irwin,M., Ibata,R., Jahreiss,H., Malkov,O. Yu. 2000, "New high-proper motion survey in the Southern sky", Astron.& Astroph, 353, 958
    • Skrutskie,M. F., Cutri,R. M., Stiening,R., Weinberg,M. D., Schneider,S., Carpenter,J. M., Beichman,C., Capps,R., Chester,T., Elias,J., Huchra,J., Liebert,J., Lonsdale,C., Monet,D. G., Price,S., Seitzer,P., Jarrett,T., J.D. Kirkpatrick, J. Gizis, E. Howard, T. Evans, J. Fowler, L. Fullmer, Hurt,R., Light,R., Kopan,E. L., Marsh,K. A., McCallon,H. L., Tam,R., Van Dyk,S., Wheelock,S. 2006, "The Two Micron All Sky Survey (2MASS)", AJ, 131, 1163
    • Subasavage,John P., Henry,Todd J., Hambly,Nigel C., Brown,Misty A., Jao,Wei-Chun 2005, "The Solar Neighborhood. XII. Discovery of New High Proper Motion Stars with mu >= 0.4" yr-1 between Declinations -90d and -47d", AJ, 129, 413
    • Subasavage,John P., Henry,Todd J., Hambly,Nigel C., Brown,Misty, A., Jao,Wei-Chun, Finch,Charlie T. 2005 "The Solar Neighborhood. XV. Discovery of New High Proper Motion Stars with mu >= 0.4" yr-1 between Declinations -47d and 00d", AJ, 130, 1658
    • Veron-Cetty & Veron 2006, A&A 455, 773
    • Wroblewski, H. and Torres, C. 1989 "New proper-motion stars south of declination -40d and right ascension between 00h and 04h 30m", Astron.& Astroph. 78, 231
    • Wroblewski, H. and Torres, C. 1991 "New proper-motion stars south of declination -40 deg and right ascension between 04h 30m and 16h 00m", Astron.& Astroph.91, 129
    • Wroblewski, H. and Torres, C. 1994 "New proper-motion stars south of declination -40deg and right ascension between 16h and 24h", Astron.& Astroph. 105, 179
    • Wroblewski, H. and Torres, C. 1996 "New proper-motion stars with declination between -5d and -30d and right ascension between 0h and 9h.", Astron.& Astroph. 115, 481
    • Wroblewski, H. and Torres, C. 1997 "New proper-motion stars with declination between -5d and -30d and right ascension between 9h and 13h 30m", Astron.& Astroph. 122, 447
    • Wroblewski, H. and Costa, E. 1999 "New high proper motion stars with declinations between -5(deg) and -30(deg) , and right ascensions between 13h 30m and 24h", Astron.& Astroph. 139, 25
    • Wroblewski, H. and Costa, E. 2001 "High proper motion stars with declinations between -30o and -40o, and right ascensions between 00 h and 10 h 40 m", Astron.& Astroph. 367, 725
    • Urban,S. E., Corbin,T. E., Wycoff,G. L., Martin,J. C., Jackson,E. S., Zacharias,M. I., Hall,D. M. 1998, "The AC 2000: The Astrographic Catalogue on the System Defined by the HIPPARCOS Catalogue" AJ, 115, 1212
    • Urban, S.E., Wycoff, G.L., Makarov, V.V., 2000, "Comparisons of Tycho-2 Catalogue Proper Motions with Hipparcos and ACT", AJ 120, 501
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    • van Altena, W. F., Girard, T. M., Platais, I., Kozhurina-Platais, V., Ostheimer, J., Lopez, C. E., and Mendez, R. A., 1999, "The Yale/San Juan Southern Proper Motion Program", AAS DDA meeting #31, #10.04
    • Winter, L. 1999 Ph.D thesis, University of Hamburg (in German)
    • Zacharias, N. 1997, "Astrometric Quality of the USNO CCD Astrograph (UCA)", AJ 113, 1925
    • Zacharias, N., Germain, M.E., Rafferty, T.J., 1997, "UCAC-S: a New High Precision, High Density Astrometric Catalog in the Southern Hemisphere", in: Proceedings "Hipparcos Venice 97", ESA publication SP-402, p.177
    • Zacharias, N. Zacharias, M.I., 1999, "Data Structure and Software of the UCAC-S Project", in: Proceedings of ADASS VIII, Eds. D.M.Mehringer, R.L.Plante and D.A.Roberts, ASP Conf.series 172, p.345, San Francisco
    • Zacharias, N., Urban, S.E., Zacharias, M.I., Hall, D.M., Wycoff, G.L., Rafferty, T.J., Germain, M.E., Holdenried, E.R., Pohlman, J., Gauss, F.S., Monet, D., Winter, L., 2000, "The first US Naval Observatory CCD Astrograph Catalog", AJ 120, 2131
    • Zacharias, N., Zacharias, M.I., Urban, S.E. and Hoeg, E., 2000, "Comparing Tycho-2 astrometry with UCAC1", AJ 120, 1148
    • Zacharias, N., 2002 "Astrometric surveys in support of large telescopes", Proceed. SPIE 4836, 279, Eds. T.A. Tyson & S. Wolff
    • Zacharias, N. 2003, "The USNO CCD Astrograph Catalog (UCAC) Project and Beyond", in "Small Telescopes in the New Millennium II. The Telescopes We Use.", ed. T Oswald, Kluwer Acad. Publ
    • Zacharias, N., Urban, S., Rafferty, T., Holdenried, E., and Winter, L., 2003, "First Results from AGK2 Plate Remeasurements", BAAS 35 #4, p.1036, abstract #6.01, 34th DDA meeting Ithaca, NY
    • Zacharias,N., Urban,S.E., Zacharias,M.I., Wycoff,G.L., Hall,D.M., Monet,D.G., Rafferty,T.J. 2004, "The Second US Naval Observatory CCD Astrograph Catalog (UCAC2)" AJ 127, 3043 (May)


    Norbert Zacharias for the UCAC team, USNO, Washington DC, July 2009