ACDS V10.0 - Detailed Description of IX/10A

ACDS V10.0 - Sun Jan 19 04:57:21 CET 2025

| # Detailed Description of IX/10A : ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999) |

Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.

    IX/10A              ROSAT All-Sky Bright Source Catalogue (1RXS) (Voges+ 1999)
    ================================================================================
    The ROSAT all-sky survey bright source catalogue.
        Voges W., Aschenbach B., Boller T., Braeuninger H., Briel U., Burkert W.,
        Dennerl K., Englhauser J., Gruber R., Haberl F., Hartner G., Hasinger G.,
        Kuerster M., Pfeffermann E., Pietsch W., Predehl P., Rosso C.,
        Schmitt J.H.M.M., Truemper J., Zimmermann H.U.
       <Astron. Astrophys. 349, 389 (1999)>
       =1999A&A...349..389V
    ================================================================================
    ADC_Keywords: X-ray sources

    Mission_Name: ROSAT

    Keywords: catalogs - surveys - X-rays: general

    Description:
        The ROSAT All-Sky Survey Bright Source Catalogue (RASS-BSC, revision
        1RXS) is derived from the all-sky survey performed during the first
        half year (1990/91) of the ROSAT mission. 18,806 sources are
        catalogued (five sources were removed compared to the 18,811 sources
        of the 1996 version), down to a limiting ROSAT PSPC count-rate of
        0.05cts/s in the 0.1-2.4keV energy band, with a detection likelihood
        of at least 15 and with at least 15 source photons. For 94% of the
        sources visual inspection confirmed the results of the standard
        processing with respect to existence and position; the remaining 6%
        were re-analysed and appropriately flagged. At a brightness limit of
        0.1cts/s (8,547 sources) the catalogue represents a sky coverage of
        92%. Broad band images are available for a subset of the flagged
        sources from http://www.rosat.mpe-garching.mpg.de/survey/rass-bsc .

        Questions or comments may be directed to
        <xray-info(at)mpe.mpg.de>

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × 1rxs.dat         185    18806   The 1RXS catalogue
    × 1rxs_cor.dat     225    18806   1RXS Correlation entries
    × cor_iras.dat     178     7972   1RXS Correlation to IRASPSC, IRASFSC
    × cor_ned.dat      196    38670   1RXS Correlation to NED
    × cor_nvs.dat      139    31674   1RXS Correlation to NVSS, FIRST
    × cor_pri.dat      214    54935   1RXS Correlation to PRI, RITTER, SIMBAD, TYCHO,
                                         EUVE
    × cor_hst.dat      214    26210   1RXS Correlation to HST_GSC
    × cor_wfc.dat      214      605   1RXS Correlation to ROSAT-WFC
    × cor_ros.dat      204    24355   1RXS Correlation to ROSATP3, ROSATWGA, ROSATHRI
    × cor_ver.dat      198     1935   1RXS Correlation Catalogue to VERON8 (VII/207)
    × refs.dat         137       79   References
    × 1rxscorr.txt     225   223982   The ROSAT All-Sky Survey Bright Source
                                     Correlation Catalogue in a single file
    × fields.ps         80     1725   Plot describing the field structure (postscript)
    × screen.ps         72    34684   Details about screening methods (postscript)

    See also:
      IX/11 : the ROSAT Source Catalogue (Voges+ 1995)
      IX/12 : the WGACAT version of the ROSAT PSPC Catalogue (White+ 1995)
      IX/28 : ROSAT HRI Pointed Observations (1RXH) (ROSAT Team, 1999)
      J/A+AS/114/465 :   ROSAT XUV Pointed Phase Source Catalogue (Kreysing+ 1995)
      J/MNRAS/274/1165 : The 2RE Source Catalogue (Pye+ 1995)
      http://www.xray.mpe.mpg.de/rosat/survey/rass-bsc : the WWW page

    Byte-by-byte Description of file:  1rxs.dat

       Bytes Format Units   Label     Explanations

       1-  4  A4    ---     ---       [1RXS]
       6- 21  A16   ---     1RXS      ROSAT All-Sky Survey Catalogue source name (1)
          22  A1    ---     n_1RXS    [*] Names modified from previous version
      24- 32  F9.5  deg     RAdeg     Right ascension (J2000), decimal degrees
      34- 42  F9.5  deg     DEdeg     Declination (J2000), decimal degrees
      45- 46  I2    arcsec  PosErr    ?=0 Total positional error
                                       (including 6" systematic error)
      48- 52  A5    ---     ScrFlags  [T_] screening flags (2)
      54- 57  A4    ---     NewFlag   [T._] 'new data' flags (3)
      60- 68  E9.3  ct/s    Count     ?=0 Source countrate (4)
      70- 78  E9.3  ct/s    e_Count   ?=0 Error on Count (4)
      80- 88  E9.3 ct/s/arcmin2 bgCt  ?=0 Background countrate (4)
      91- 95  I5    s       ExpTime   ?=0 Exposure time
      97-101  F5.2  ---     HR1       [-1/1]? Hardness ratio 1 (5)
     103-106  F4.2  ---     e_HR1     ? Error on HR1 (6)
     108-112  F5.2  ---     HR2       [-1/1]? hardness ratio 2 (5)
     114-117  F4.2  ---     e_HR2     ? Error on HR2 (6)
     121-123  I3    arcsec  Extent    Source extent, by which the source image
                                        exceeds the point spread function.
     125-128  I4    ---     L_Extent  ?=0 Likelihood of source extent (7)
     130-133  I4    ---     Ldetect   ?=0 Likelihood of
                                            source detection algorithm (7)
     135-139  I5    arcsec  ExtRad    ?=0 Extraction radius
     141-146  A6    ---    PrioFlags  [01] priority  flags (8)
         147  A1    ---     PHA       [ABCDb] PHA range of best detection (9)
     149-152  F4.2  ---    VigFactor  ?=0 Vignetting factor
     154-159  I6   "YYMMDD" IncDate   ?=0 Date when source was included (10)
     161-166  I6   "YYMMDD" UpdDate   ?=0 Date when source properties changed (11)
     168-170  I3    ---     Ncand     Number of identification candidates in the
                                       correlation catalogue
     173-180  I8    ---     SASS      Identification number of SASS field (12)
         181  A1    ---     ---       [_]
     182-185  I4    ---     MASOL     SASS source number (MASOL number)
                                      in SASS field (mainly for internal use)

    Note (1): The name includes the '1RXS' acronym, and is based
         on J2000 position (format JHHMMSS.S+DDMMSS).
         This name is used in the generation of a link to a broad band
         image if this image is available (see NewFlag, and Note (3))
         See the changes in sources compared to the 1996 version in the
         "History" section below
    Note (2): the flags are 'T' for 'true', 'F' or '_' for 'false'; '.' for not used
         n (byte 48) nearby sources affecting SASS flux determination
         p (byte 49) possible problem with position determination
         e (byte 50) source extended beyond SASS extraction radius
         d (byte 51) complex diffuse emission pattern
         m (byte 52) source missed by SASS
    Note (3): the flags are 'T' for 'true', 'F' or '_' for 'false'; '.' for not used
         r (byte 54) source counts and extraction radius recalculated
         i (byte 55) broad band image available (html link!)
         v (byte 56) variability flag (not yet filled)
         . (byte 57) dummy flag
    Note (4): Countrates are vignetting corrected

    Note (5): The hardness ratios are defined by:
         hr1 = ( B - A ) / ( B + A )  , where
                 A = countrate in PHA range  11 -  41 (~ 0.1-0.4 keV)
                 B = countrate in PHA range  52 - 201 (~ 0.5-2.0 keV)
         hr2 = ( D - C ) / ( D + C )  , where
                 C = countrate in PHA range  52 -  90 (~ 0.5-0.9 keV)
                 D = countrate in PHA range  91 - 201 (~ 0.9-2.0 keV)
         (PHA = Pulse Height Amplitude)
    Note (6): the true mean error is probably bigger, and
         values larger than 9.99 are set to 9.99
    Note (7): values larger than 9999 are set to 9999

    Note (8): the flags indicate the sliding window detection history
         using either the background map (M) or the local background (B),
         and take the values 0 = no detection, 1 = detection;
         The order of flags is:
         M-broad, L-broad, M-hard, L-hard, M-soft, L-soft
    Note (9): the PHA (Pulse Height Amplitude) range
         PHA range with highest detection likelihood is indicated by
             A =  PHA range 11-41  (~ 0.1-0.4 keV)
             B =  PHA range 52-201 (~ 0.5-2.0 keV)
             C =  PHA range 52-90  (~ 0.5-0.9 keV)
             D =  PHA range 91-201 (~ 0.9-2.0 keV)
             b or blank means 'broad'
    Note (10): a value "000000" for the date indicates a removed source

    Note (11): a value "000000" indicates not-applicable date

    Note (12): An overview of the field structure is available at URL
         http://www.xray.mpe.mpg.de/rosat/survey/rass-bsc/sup/psplit.ps.gz

    Byte-by-byte Description of file:  1rxs_cor.dat

       Bytes Format Units      Label     Explanations

       1-  4  A4    ---        ---       [1RXS]
       6- 21  A16   ---        1RXS      1RXS name
      23- 30  F8.4  deg        RAdeg     Right ascension (J2000)
      32- 39  F8.4  deg        DEdeg     Declination (J2000)
      43- 44  I2    arcsec     PosErr    Total positional error
      46- 48  I3    ---        Nid       Number of correlated sources
      50- 54  A5    ---        ---       Name of source catalogue (always 1RXS)
          61  A1    ---        bandPos   [x] origin of the source position
                                              (always x: X-ray)
      75- 80  F6.3  10+21cm-2  gal_Nh    Galactic HI column density
                                           (in 1021atoms/cm2)
      82- 89  F8.4  deg        GLON      Galactic longitude
      91- 98  F8.4  deg        GLAT      Galactic latitude
     105-109  F5.2  ---        HR1       Hardness ratio 1
     112-115  F4.2  ---        e_HR1     rms uncertainty on HR1
     117-121  F5.2  ---        HR2       Hardness ratio 2
     124-127  F4.2  ---        e_HR2     rms uncertainty on HR2
     129-131  I3    ---        Extent    Source extent
     133-135  I3    ---        L_Extent  Likelihood of source extent
     137-139  I3    ---        Ldetect   Likelihood of source detection algorithm
     141-145  I5    s          ExpTime   Exposure time
     147-154  E8.2  ct/s       Count     Source count rate
     156-163  E8.2  ct/s       e_Count   rms uncertainty on Count
     166-174  E9.3  mW/m2      Flux1     X-ray flux 1 in 0.1-2.4keV energy range
     176-184  E9.3  mW/m2      Flux2     X-ray flux 2 in 0.1-2.4keV energy range
     191-196  I6    "YYMMDD"   begDate   First date of observation
     197-199  F3.2  d         begDate.f  First date of observation (day fraction)
     201-206  I6    "YYMMDD"   endDate   Last date of observation
     207-209  F3.2  d         endDate.f  Last date of observation (day fraction)
     212-217  I6    "YYMMDD"   IncDate   Date when source was included
     219-224  I6    "YYMMDD"   UpdDate   ?=0 Date when source properties changed

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

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification (1)
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [i] Origin of the source position (i: IR)
      89- 98  A10   ---     Type       Type or class of object
     100-108  E9.3  Jy      F12um      Infrared flux in the 12µm band
     110-118  E9.3  Jy      F25um      Infrared flux in the 25µm band
     120-128  E9.3  Jy      F60um      Infrared flux in the 60µm band
     130-138  E9.3  Jy      F100um     Infrared flux in the 100µm band
     140-164  A25   ---     Com        Comments
     166-171  I6   "YYMMDD" IncDate    Date when source was included
     173-178  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): the IRASPSC numbers do not correspond to the usual IRAS designations.

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

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [giorx] Origin of the source position (1)
      89- 98  A10   ---     Type       Type or class of object
     101-105  F5.2  ---     fxfopt     ? Ratio of X-ray to optical flux f_X / f_opt
         107  A1    ---     l_vmag     Limit flag on vmag
     108-113  F6.3  mag     vmag       ? Visual magnitude
         114  A1    ---     n_vmag     [:/+] : => Uncertainty flag on vmag
                                             / => interval of magnitude
                                             + => 18+ ???
     115-116  I2    ---     vmag2      ? Second value of vmag when interval
         117  A1    ---     u_vmag2    [?] Uncertainty flag on vmag2
     119-124  F6.4  ---     z          ? Redshift
         126  A1    ---    l_NED-flux  Limit flag on NED-flux
     127-135  F9.2  mJy     NED-flux   ? Radio flux density or IR flux density
                                          in the band given in fl-band
     137-145  E9.3  mum     fl-band    ? Frequency band  or wavelength band
                                         used for flux given in NED-flux
                                         (Radio [GHz], IR [mJy] for NED)
         147  A1    ---     l_Size     Limit flag on Size
     148-154  F7.3  arcmin  Size       ? Size of object
         155  A1    ---     u_Size     Uncertainty flag on Size
     157-181  A25   ---     Com        Comments
     184-189  I6   "YYMMDD" IncDate    Date when source was included
     191-196  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): o: optical; x: X-ray; r: Radio; e: EUV; i: IR

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

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [orx] Origin of the source position (1)
      89- 98  A10   ---     Type       Type or class of object
     100-106  F7.1  kpc     dist       ? Distance
     108-115  F8.2  mJy     F20cm(I)   ? Radio integrated flux density in the
                                           20cm band
     117-125  F9.2  mJy     F20cm(P)   ? Radio peak flux density in the 20cm band
     127-132  I6   "YYMMDD" IncDate    Date when source was included
     134-139  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): o: optical; x: X-ray; r: Radio; e: EUV; i: IR

    Byte-by-byte Description of file:  cor_hst.dat  cor_pri.dat  cor_wfc.dat

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification (see also r_sourceID)
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [oexr] Origin of the source position (1)
      89- 98  A10   ---     Type       Type or class of object
     101-105  F5.2  ---     fxfopt     ? Ratio of X-ray to optical flux f_X / f_opt
         107  A1    ---     l_vmag     Limit flag on vmag
     108-112  F5.2  mag     vmag       ? Visual magnitude
     115-119  F5.2  mag     bmag       ? Blue magnitude
     122-126  F5.2  mag     rmag       ? Red magnitude
     129-133  F5.2  mag     b-r        ? (blue-red) colour
     135-139  F5.2  mag     b-v        ? (blue-visual) colour
     142-146  F5.2  mag     u-b        ? (ultraviolet-blue) colour
     149-150  A2    ---     var        Variability flag
         153  A1    ---     n_z        [*>] Note on z
     154-159  F6.4  ---     z          ? Redshift (from PRI or SIMBAD)
     161-165  I5    km/s    Vr         ? Radial velocity (from SIMBAD only)
     167-174  E8.3  kpc     dist       ? Distance
     176-200  A25   ---     Com        Comments
     202-207  I6   "YYMMDD" IncDate    Date when source was included
     209-214  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): o: optical; x: X-ray; r: Radio; e: EUV; i: IR

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

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [ex] Origin of the source position (1)
      89- 98  A10   ---     Type       Type or class of object
     100-104  F5.2  ---     HR1        ? Hardness ratio 1
     107-110  F4.2  ---     e_HR1      ? rms uncertainty on HR1
     112-116  F5.2  ---     HR2        ? Hardness ratio 2
     119-122  F4.2  ---     e_HR2      ? rms uncertainty on HR2
     124-126  I3    ---     Extent     ? Source extent
     128-130  I3    ---     L_Extent   ? Likelihood of source extent
     132-134  I3    ---     Ldetect    ? Likelihood of source detection algorithm
     135-140  I6    s       ExpTime    Exposure time
     142-149  E8.2  ---     Count      Source countrate
     151-158  E8.2  ---     e_Count    rms uncertainty on Count
     161-164  F4.1  arcmin  roff       Off-axis angle
     166-190  A25   ---     Com        Comments
     192-197  I6   "YYMMDD" IncDate    Date when source was included
     199-204  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): o: optical; x: X-ray; r: Radio; e: EUV; i: IR

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

       Bytes Format Units   Label      Explanations

       1-  4  A4    ---     ---        [1RXS]
       6- 21  A16   ---     1RXS       1RXS source name
      23- 25  I3    ---     Rank       Rank in correlation list for the source
      27- 47  A21   ---     sourceID   Source identification
      49- 56  F8.4  deg     RAdeg      [0/360] Right ascension (J2000)
      58- 65  F8.4  deg     DEdeg      Declination (J2000)
      68- 70  I3    arcsec  Sep        Separation
      72- 74  I3    deg     PA         [0/360] Position angle
      76- 85  A10   ---    r_sourceID  Source catalogue (see file "refs.dat")
          87  A1    ---     bandPos    [oAOR] Origin of the source position (1)
      89- 98  A10   ---     Type       Type or class of object
     101-105  F5.2  ---     fxfopt     ? Ratio of X-ray to optical flux f_X / f_opt
         107  A1    ---     l_vmag     Limit flag on vmag
     108-112  F5.2  mag     vmag       ? Visual magnitude
     114-118  F5.2  mag     rmag       ? Red magnitude
     120-124  F5.2  mag     b-v        ? (blue-visual) colour
     127-131  F5.2  mag     u-b        ? (ultraviolet-blue) colour
         133  A1    ---     n_z        [*>]Note on z
     134-138  F5.3  ---     z          ? Redshift
     141-148  F8.2  mJy     R-f6cm     ? R-f6cm in the 6cm band
     151-158  F8.2  mJy     R-f11cm    ? R-f11cm in the 11cm band
     160-184  A25   ---     Com        Comments
     186-191  I6   "YYMMDD" IncDate    Date when source was included
     193-198  I6   "YYMMDD" UpdDate    ?=0 Date when source properties were changed

    Note (1): o: optical; x: X-ray; r: Radio; e: EUV; i: IR

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

       Bytes Format Units   Label     Explanations

       1- 10  A10   ---     catal-id  Name of source catalogue
      12- 36  A25   ---     Aut       Author names
      38- 56  A19   ---     BibCode   BibCode
      58-137  A80   ---     Com       Comments

    History:
      * 15-Jul-1996 (Catalog IX/10):
        The catalog (Version 14-Jun-1996) was copied via FTP from
            ftp://ftp.rosat.mpe-garching.mpg.de/archive/survey/rass-bsc
      * 11-Oct-1999 (Catalog IX/10A):
        The catalog (Version 10-Jun-1999) was copied via FTP from
            ftp://ftp.xray.mpe.mpg.de/rosat/catalogues/rass-bsc
        Compared to the 14-Jun-1996 version:
        => five sources were removed:
           1RXS J050251.5-622744
           1RXS J054919.1-620511
           1RXS J055054.2-621454
           1RXS J055225.0-640206
           1RXS J055529.5-640618
        => 14 sources were renamed:
           1RXS J050531.2-614456 renamed 1RXS J050531.3-614456
           1RXS J050644.7-610943 renamed 1RXS J050644.8-610943
           1RXS J051545.5-643812 renamed 1RXS J051545.6-643812
           1RXS J051615.8-631319 renamed 1RXS J051615.9-631319
           1RXS J051934.0-604800 renamed 1RXS J051934.1-604800
           1RXS J052124.2-641851 renamed 1RXS J052124.3-641851
           1RXS J052630.7-602227 renamed 1RXS J052630.8-602227
           1RXS J052641.0-623959 renamed 1RXS J052641.1-623959
           1RXS J053431.8-601613 renamed 1RXS J053431.9-601613
           1RXS J053855.5-640457 renamed 1RXS J053855.6-640457
           1RXS J054053.0-614312 renamed 1RXS J054053.1-614312
           1RXS J054236.0-615414 renamed 1RXS J054236.1-615414
           1RXS J054513.1-595527 renamed 1RXS J054513.2-595527
           1RXS J181545.4+164043 renamed 1RXS J181545.4-164043
      * 07-Jun-2006: file "refs.dat" completed for TYCHO, WGA, GSC
           associated with pecularity notes.
      * 22-Jul-2008: New URLs for ROSAT. Catalog is now available at
           ftp://ftp.xray.mpe.mpg.de/rosat/catalogues/rass-bsc
    ================================================================================
    (End)                     Francois Ochsenbein, Patricia Bauer [CDS]  05-Nov-1999