CatWISE Catalog Output Table File Description (Rev. 2.2, Mar. 18, 2020) Based on WPHot Output Table File Description [pht12] Rev 1.5 Dec. 10, 2018 and on output from stf 1.7 B90210 run on IRSA table format files with -L option. Interface Name: CatWISE catalog table file for CatWISE2020 Processing Type of Interface: disk i/o Written By: J.Fowler, P.Eisenhardt Read By: CatWISE Software Team Description: Extension of Version 7 of WPHotpm for multiframe processing of two bands (unWISE W1 and W2 coadds) with additional table-file columns derived from: - merging the separate mdex files for ascending and descending scans of a tile - adding cc_flags from the AllWISE catalog - adding flags based on unWISE artifact bitmasks - adding primary source in tile designation flag (reject file only, not in catalog file) - adding unWISE catalog object ID since unWISE catalog is detection list for CatWISE2020 Catalog _______________________________________________________________________________________ Specification of output variables: Table Header information: -- # sources tabulated -- unWISE epoch coadds engaged (ascending and descending for option 1) -- WISE bands engaged (always bands 1 and 2 only for CatWISE) -- zero point mag used -- standard aperture radius in arcsec and pixel units (one line per band) -- circular aperture radii in arcsec and pixel units (one line per band) -- Modified Julian Date of the CatWISE coordinate epoch (MJD 57170.00 for CatWISE2020) -- CatWISE processing history (6 lines) Tabular data: Note that the first column in the width is occupied by a "pipe" or "bar" delimiter ("|") Field cols Width Units Type Format Name Description ---- ---- ----- ------- ---- ------- ------------ ------------------------------------ 1 1-21 21 -- char a21 source_name source hexagesimal designation 2 22-46 25 -- char a25 source_id tile name + processing code + wphot index 3 47-58 12 deg R*8 f12.7 ra right ascension (ICRS) 4 59-70 12 deg R*8 f12.7 dec declination (ICRS) 5 71-79 9 asec R*4 f9.4 sigra uncertainty in ra (arcsec) 6 80-88 9 asec R*4 f9.4 sigdec uncertainty in dec (arcsec) 7 89-97 9 asec R*4 f9.4 sigradec uncertainty cross-term (arcsec) # the following positions reflect the source xy position in the unWISE full depth coadd 8 98-106 9 pix R*4 f9.3 wx x-pixel coordinate 9 107-115 9 pix R*4 f9.3 wy y-pixel coordinate # The next set of columns are aperture/annulus measurements from the unWISE epoch coadds: 10 116-125 10 dn R*4 f10.3 w1sky frame sky background value, band-1 11 126-133 8 dn R*4 f8.3 w1sigsk frame sky background value uncertainty, band-1 12 134-141 8 dn R*4 f8.3 w1conf frame sky confusion based on the UNC images 13 142-151 10 dn R*4 f10.3 w2sky frame sky background value, band-2 14 152-159 8 dn R*4 f8.3 w2sigsk frame sky background value uncertainty, band-2 15 160-167 8 dn R*4 f8.3 w2conf frame sky confusion based on the UNC images # WPRO epoch coadd measurements: 16 168-174 7 asec R*4 f7.2 w1fitr fitting radius, band-1 (clipped at 999.99) 17 175-181 7 asec R*4 f7.2 w2fitr fitting radius, band-2 (clipped at 999.99) 18 182-188 7 -- R*4 f7.1 w1snr S/N ratio, band-1 19 189-195 7 -- R*4 f7.1 w2snr S/N ratio, band-2 20 196-207 12 dn R*4 1pe12.4 w1flux WPRO raw flux, band-1 21 208-221 14 dn R*4 1pe14.4 w1sigflux WPRO raw flux uncertainty, band-1 22 222-233 12 dn R*4 1pe12.4 w2flux WPRO raw flux, band-2 23 234-247 14 dn R*4 1pe14.4 w2sigflux WPRO raw flux uncertainty, band-2 24 248-254 7 mag R*4 f7.3 w1mpro WPRO flux in mag units, band-1 25 255-264 10 mag R*4 f10.3 w1sigmpro WPRO flux uncertainty in mag units, band-1 26 265-275 11 -- R*4 1pe11.3 w1rchi2 WPRO reduced chi^2, band-1 27 276-282 7 mag R*4 f7.3 w2mpro WPRO flux in mag units, band-2 28 283-292 10 mag R*4 f10.3 w2sigmpro WPRO flux uncertainty in mag units, band-2 29 293-303 11 -- R*4 1pe11.3 w2rchi2 WPRO reduced chi^2, band-2 30 304-314 11 -- R*4 1pe11.3 rchi2 reduced chi squared, total 31 315-318 4 -- int i4 nb number of blend components used in each fit 32 319-322 4 -- int i4 na number of actively deblended components 33 323-330 8 -- R*4 f8.5 w1Sat fraction of pixels saturated, band-1 34 331-338 8 -- R*4 f8.5 w2Sat fraction of pixels saturated, band-2 # full depth coadd measurements: WAPPco, standard aperture w/ aperture correction; # the standard (aperture corrected) aperture radius is 8.25 arcsec. 35 339-345 7 mag R*4 f7.3 w1mag standard aperture mag w/ correction applied 36 346-352 7 mag R*4 f7.3 w1sigm standard aperture mag uncertainty, band-1 37 353-358 6 -- int i6 w1flg standard aperture flag, band-1 38 359-366 8 -- R*4 f8.2 w1Cov mean coverage depth, band-1 39 367-373 7 mag R*4 f7.3 w2mag standard aperture mag w/ correction applied 40 374-380 7 mag R*4 f7.3 w2sigm standard aperture mag uncertainty, band-2 41 381-386 6 -- int i6 w2flg standard aperture flag, band-2 42 387-394 8 -- R*4 f8.2 w2Cov mean coverage depth, band-2 # full depth coadd measurements: WAPPco, circular apertures, no aperture correction is applied; # radii: 5.50 8.25 11.00 13.75 16.50 19.25 22.00 24.75 arcsec 43 395-404 10 mag R*4 f10.3 w1mag_1 Aper 1, aperture mag, band-1 44 405-414 10 mag R*4 f10.3 w1sigm_1 Aper 1, aperture mag uncertainty, band-1 45 415-422 8 -- int i8 w1flg_1 Aper 1, aperture flag, band-1 46 423-432 10 mag R*4 f10.3 w2mag_1 Aper 1, aperture mag, band-2 47 433-442 10 mag R*4 f10.3 w2sigm_1 Aper 1, aperture mag uncertainty, band-2 48 443-450 8 -- int i8 w2flg_1 Aper 1, aperture flag, band-2 49 451-460 10 mag R*4 f10.3 w1mag_2 Aper 2, aperture mag, band-1 50 461-470 10 mag R*4 f10.3 w1sigm_2 Aper 2, aperture mag uncertainty, band-1 51 471-478 8 -- int i8 w1flg_2 Aper 2, aperture flag, band-1 52 479-488 10 mag R*4 f10.3 w2mag_2 Aper 2, aperture mag, band-2 53 489-498 10 mag R*4 f10.3 w2sigm_2 Aper 2, aperture mag uncertainty, band-2 54 499-506 8 -- int i8 w2flg_2 Aper 2, aperture flag, band-2 55 507-516 10 mag R*4 f10.3 w1mag_3 Aper 3, aperture mag, band-1 56 517-526 10 mag R*4 f10.3 w1sigm_3 Aper 3, aperture mag uncertainty, band-1 57 527-534 8 -- int i8 w1flg_3 Aper 3, aperture flag, band-1 58 535-544 10 mag R*4 f10.3 w2mag_3 Aper 3, aperture mag, band-2 59 545-554 10 mag R*4 f10.3 w2sigm_3 Aper 3, aperture mag uncertainty, band-2 60 555-562 8 -- int i8 w2flg_3 Aper 3, aperture flag, band-2 61 563-572 10 mag R*4 f10.3 w1mag_4 Aper 4, aperture mag, band-1 62 573-582 10 mag R*4 f10.3 w1sigm_4 Aper 4, aperture mag uncertainty, band-1 63 583-590 8 -- int i8 w1flg_4 Aper 4, aperture flag, band-1 64 591-600 10 mag R*4 f10.3 w2mag_4 Aper 4, aperture mag, band-2 65 601-610 10 mag R*4 f10.3 w2sigm_4 Aper 4, aperture mag uncertainty, band-2 66 611-618 8 -- int i8 w2flg_4 Aper 4, aperture flag, band-2 67 619-628 10 mag R*4 f10.3 w1mag_5 Aper 5, aperture mag, band-1 68 629-638 10 mag R*4 f10.3 w1sigm_5 Aper 5, aperture mag uncertainty, band-1 69 639-646 8 -- int i8 w1flg_5 Aper 5, aperture flag, band-1 70 647-656 10 mag R*4 f10.3 w2mag_5 Aper 5, aperture mag, band-2 71 657-666 10 mag R*4 f10.3 w2sigm_5 Aper 5, aperture mag uncertainty, band-2 72 667-674 8 -- int i8 w2flg_5 Aper 5, aperture flag, band-2 73 675-684 10 mag R*4 f10.3 w1mag_6 Aper 6, aperture mag, band-1 74 685-694 10 mag R*4 f10.3 w1sigm_6 Aper 6, aperture mag uncertainty, band-1 75 695-702 8 -- int i8 w1flg_6 Aper 6, aperture flag, band-1 76 703-712 10 mag R*4 f10.3 w2mag_6 Aper 6, aperture mag, band-2 77 713-722 10 mag R*4 f10.3 w2sigm_6 Aper 6, aperture mag uncertainty, band-2 78 723-730 8 -- int i8 w2flg_6 Aper 6, aperture flag, band-2 79 731-740 10 mag R*4 f10.3 w1mag_7 Aper 7, aperture mag, band-1 80 741-750 10 mag R*4 f10.3 w1sigm_7 Aper 7, aperture mag uncertainty, band-1 81 751-758 8 -- int i8 w1flg_7 Aper 7, aperture flag, band-1 82 759-768 10 mag R*4 f10.3 w2mag_7 Aper 7, aperture mag, band-2 83 769-778 10 mag R*4 f10.3 w2sigm_7 Aper 7, aperture mag uncertainty, band-2 84 779-786 8 -- int i8 w2flg_7 Aper 7, aperture flag, band-2 85 787-796 10 mag R*4 f10.3 w1mag_8 Aper 8, aperture mag, band-1 86 797-806 10 mag R*4 f10.3 w1sigm_8 Aper 8, aperture mag uncertainty, band-1 87 807-814 8 -- int i8 w1flg_8 Aper 8, aperture flag, band-1 88 815-824 10 mag R*4 f10.3 w2mag_8 Aper 8, aperture mag, band-2 89 825-834 10 mag R*4 f10.3 w2sigm_8 Aper 8, aperture mag uncertainty, band-2 90 835-842 8 -- int i8 w2flg_8 Aper 8, aperture flag, band-2 # the following are "N of M" counters for WPRO measurements # w?M - The number of individual epochs for band ? that are # available to make a profile-fit measurement. # w?NM - The number of individual epochs for band ? on which # WPRO extracted a flux measurement that has snr>3. # w?mLQ - variability indicator mLogQ for the flux array 91 843-849 7 -- int i7 w1NM WPRO, N (of M), band-1 92 850-855 6 -- int i6 w1M WPRO, M , band-1 93 856-863 8 mag R*4 f8.3 w1magP WPRO repeatability mag; band-1 94 864-871 8 mag R*4 f8.3 w1sigP1 WPRO mag population sigma; band-1 95 872-879 8 mag R*4 f8.3 w1sigP2 WPRO mag uncertainty of the mean; band-1 96 880-891 12 -- R*4 f12.5 w1k Stetson k index for variability; band-1 97 892-897 6 -- int i6 w1Ndf No. degrees of freedom in var chi-square; band-1 98 898-903 6 -- R*4 f6.2 w1mLQ -log(Q), Q = 1-P(chi-square); band-1 99 904-921 18 -- R*8 f18.8 w1mJDmin minimum mJD; band-1 100 922-939 18 -- R*8 f18.8 w1mJDmax maximum mJD; band-1 101 940-957 18 -- R*8 f18.8 w1mJDmean mean mJD; band-1 102 958-964 7 -- int i7 w2NM WPRO, N (of M), band-2 103 965-970 6 -- int i6 w2M WPRO, M , band-2 104 971-978 8 mag R*4 f8.3 w2magP WPRO repeatability mag; band-2 105 979-986 8 mag R*4 f8.3 w2sigP1 WPRO mag population sigma; band-2 106 987-994 8 mag R*4 f8.3 w2sigP2 WPRO mag uncertainty of the mean; band-2 107 995-1006 12 -- R*4 f12.5 w2k Stetson k index for variability; band-2 108 1007-1012 6 -- int i6 w2Ndf No. degrees of freedom in var chi-square; band-2 109 1013-1018 6 -- R*4 f6.2 w2mLQ -log(Q), Q = 1-P(chi-square); band-2 110 1019-1036 18 -- R*8 f18.8 w2mJDmin minimum mJD; band-2 111 1037-1054 18 -- R*8 f18.8 w2mJDmax maximum mJD; band-2 112 1055-1072 18 -- R*8 f18.8 w2mJDmean mean mJD; band-2 # band-to-band sample correlation coefficients and their probabilities for adjacent bands 113 1073-1078 6 % int i4 rho12 W1W2 correlation coefficient 114 1079-1084 6 -- int i4 q12 -log10(1-P(rho12)) given no real correlation 115 1085-1091 7 -- int i7 nIters number of chi-square-minimization iterations 116 1092-1098 7 -- int i7 nSteps number of steps in all iterations # MDET-Related Parameters # p1 and p2 are clipped to the range (-99.99999, +99.99999) if necessary 117 1099-1105 7 -- int i7 mdetID SNR-sorted rank of unwise source 118 1106-1115 10 asec R*4 f10.5 p1 P vector component 1 119 1116-1125 10 asec R*4 f10.5 p2 P vector component 2 # Motion Fit Solution Parameters # ra_pm and dec_pm are in the ICRS frame at the CatWISE epoch # (MJD 57170.00 for the CatWISE2020 Catalog) based on PMRA and PMDec # PMRA and PMDec are clipped at +/-99.99999 120 1126-1138 13 MJD R*8 f13.6 MeanObsMJD mean observation epoch 121 1139-1150 12 deg R*8 f12.7 ra_pm right ascension (ICRS) 122 1151-1162 12 deg R*8 f12.7 dec_pm declination (ICRS) 123 1163-1171 9 asec R*4 f9.4 sigra_pm uncertainty in ra_pm 124 1172-1181 10 asec R*4 f10.4 sigdec_pm uncertainty in dec_pm 125 1182-1193 12 asec R*4 f12.4 sigradec_pm uncertainty cross-term 126 1194-1203 10 asec/yr R*4 f10.5 PMRA motion in ra 127 1204-1213 10 asec/yr R*4 f10.5 PMDec proper motion in dec 128 1214-1222 9 asec/yr R*4 f9.4 sigPMRA uncertainty in PMRA 129 1223-1231 9 asec/yr R*4 f9.4 sigPMDec uncertainty in PMDec 130 1232-1240 9 -- R*4 f9.1 w1snr_pm flux S/N ratio, band-1 131 1241-1249 9 -- R*4 f9.1 w2snr_pm flux S/N ratio, band-2 132 1250-1261 12 dn R*4 1pe12.4 w1flux_pm WPRO raw flux, band-1 133 1262-1275 14 dn R*4 1pe14.4 w1sigflux_pm WPRO raw flux uncertainty, band-1 134 1276-1287 12 dn R*4 1pe12.4 w2flux_pm WPRO raw flux, band-2 135 1288-1301 14 dn R*4 1pe14.4 w2sigflux_pm fit WPRO raw flux uncertainty, band-2 136 1302-1311 10 mag R*4 f10.3 w1mpro_pm WPRO flux in mag units, band-1 137 1312-1324 13 mag R*4 f13.3 w1sigmpro_pm WPRO flux uncertainty in mag units, band-1 138 1325-1335 11 -- R*4 1pe11.3 w1rchi2_pm WPRO reduced chi^2, band-1 139 1336-1345 10 mag R*4 f10.3 w2mpro_pm WPRO flux in mag units, band-2 140 1346-1358 13 mag R*4 f13.3 w2sigmpro_pm WPRO flux uncertainty in mag units, band-2 141 1359-1369 11 -- R*4 1pe11.3 w2rchi2_pm WPRO reduced chi^2, band-2 142 1370-1380 11 -- R*4 1pe11.3 rchi2_pm reduced chi squared, total # pmcode provides information that may correlate with the quality of the PM solution. # The format is ABCCC, where A is the number of components in the passive blend group # (including the primary) before any are removed or added, # B is "Y" or "N" to indicate "Yes" or "No" that a secondary blend component replaced the primary, # CCC is the distance in hundredths of an arcsec between the # PM position solution for the mean observation epoch and the stationary solution 143 1381-1387 7 -- char A5 pmcode quality of the PM solution 144 1388-1397 10 -- int i10 nIters_pm number of chi-square-minimization iterations 145 1398-1407 10 -- int i10 nSteps_pm number of steps in all iterations # Parameters Derived From Ascending-Descending Scan Differences 146 1408-1416 9 asec R*4 f9.3 dist radial distance between apparitions 147 1417-1423 7 mag R*4 f7.3 dw1mag w1mpro difference 148 1424-1430 7 -- R*4 f7.3 rch2w1 chi-square for dw1mag (1 DF) 149 1431-1437 7 mag R*4 f7.3 dw2mag w2mpro difference 150 1438-1444 7 -- R*4 f7.3 rch2w2 chi-square for dw2mag (1 DF) 151 1445-1455 11 deg R*8 f11.6 elon_avg averaged ecliptic longitude 152 1456-1466 11 asec R*4 f11.3 elonSig one-sigma uncertainty in elon 153 1467-1477 11 deg R*8 f11.6 elat_avg averaged ecliptic latitude 154 1478-1487 10 asec R*4 f10.3 elatSig one-sigma uncertainty in elat 155 1488-1498 11 asec R*4 f11.3 Delon desc-asce ecliptic longitude 156 1499-1509 11 asec R*4 f11.3 DelonSig one-sigma uncertainty in Delon 157 1510-1520 11 asec R*4 f11.3 Delat desc-asce ecliptic latitude 158 1521-1530 10 asec R*4 f10.3 DelatSig one-sigma uncertainty in Delat 159 1531-1541 11 -- R*4 f11.3 DelonSNR |Delon|/DelonSig 160 1542-1552 11 -- R*4 f11.3 DelatSNR |Delat|/DelatSig 161 1553-1562 10 -- R*4 1pE10.3 chi2pmra chi-square for PMRA difference (1 DF) 162 1563-1572 10 -- R*4 1pE10.3 chi2pmdec chi-square for PMRA difference (1 DF) 163 1573-1575 3 -- int i3 ka astrometry usage code 164 1576-1578 3 -- int i3 k1 W1 photometry usage code 165 1579-1581 3 -- int i3 k2 W2 photometry usage code 166 1582-1584 3 -- int i3 km proper motion usage code 167 1585-1595 11 asec R*4 f11.3 par_pm parallax from PM desc-asce elon 168 1596-1606 11 asec R*4 f11.3 par_pmSig one-sigma uncertainty in par_pm 169 1607-1617 11 asec R*4 f11.3 par_stat parallax estimate from stationary solution 170 1618-1628 11 asec R*4 f11.3 par_sigma one-sigma uncertainty in par_stat # Parameters Derived from AllWISE Artifact Flags 171 1629-1641 13 asec R*4 f13.6 dist_x distance between CatWISE and AllWISE source 172 1642-1657 16 -- char a16 cc_flags worst case 4 character cc_flag from AllWISE 173 1658-1670 13 -- int i13 w1cc_map worst case w1cc_map from AllWISE 174 1671-1690 20 -- char a20 w1cc_map_str worst case w1cc_map_str from AllWISE 175 1691-1703 13 -- int i13 w2cc_map worst case w2cc_map from AllWISE 176 1704-1723 20 -- char a20 w2cc_map_str worst case w2cc_map_str from AllWISE 177 1724-1728 5 -- int i5 n_aw number of AllWISE matches within 2.75 asec # Parameters Derived from unWISE Artifact Bitmasks 178 1729-1737 9 -- char a9 ab_flags Two character (W1 W2) artifact flag 179 1738-1746 9 -- int i9 w1ab_map w1 artifact code value 180 1747-1759 13 -- char a13 w1ab_map_str w1 artifact string 181 1760-1768 9 -- int i9 w2ab_map w2 artifact code value 182 1769-1781 13 -- char a13 w2ab_map_str w2 artifact string # Indexed Coordinates Derived from Stationary ra and dec 183 1782-1793 12 deg R*8 f12.6 glon galactic longitude 184 1794-1805 12 deg R*8 f12.6 glat galactic latitude 185 1806-1817 12 deg R*8 f12.7 elon ecliptic longitude 186 1818-1829 12 deg R*8 f12.7 elat ecliptic latitude # unWISE ID obtained by cross-matching SNR-sorted source number (mdetID) to unwise_objid in fbt2mdet 187 1830-1849 20 -- char a20 unwise_objid unWISE catalog object ID NOTES 1.) Delon may have a bias correction for a systematic error induced by residual PSF errors that manifest themselves in ascending-descending differences; see the "-pb" command line option of the mrgad program. 2.) Delon is defined as descending position minus ascending position in order to have the proper sign for parallax (~Delon/2). 3.) the usage codes ka, k1, k2, and km have values of 0 - 3 meaning 0: neither the ascending nor the descending scan provided a solution 1: only the ascending scan provided a solution 2: only the descending scan provided a solution 3: both scans provided solutions which were combined in the relevant way 4.) Delon is the straightforward difference in ecliptic longitude, ignoring the different effective observation epochs of ascending and descending scans; par_pm is computed from the motion-solution positions, which are translated by WPHotpmc to the standard epoch (MJD0), so except for estimation errors, par_pm is the parallax; the par_stat column is computed by using the motion estimate to move the ascending stationary-solution position from the ascending effective observation epoch to that of the descending solution, then dividing the ecliptic longitude difference by 2. 5.) Delon will be null unless ka = 3; par_pm will be null unless km = 3; par_stat will be null unless ka = 3 AND km > 0 AND all W?mJDmin/max/mean values are non-null in both ascending and descending mdex files. ____________________________________________________________________________________ N of M Statistics M == number of flux measurements for a given source N == number of M sources that have SNR >= 3 ____________________________________________________________________________________ Photometry Flags: Standard aperture measurement quality flag. This flag indicates if one or more image pixels in the measurement aperture for this band is confused with nearby objects, is contaminated by saturated or otherwise ususable pixels, or is an upper limit. The flag value is the integer sum of any of following values which correspond to different conditions. value Condition ----- ------------------------------------------------------ 0 nominal -- no contamination 1 source confusion -- another source falls within the measurement aperture 2 bad or fatal pixels: presence of bad pixels in the measurement aperture (bit 2 or 18 set) 4 non-zero bit flag tripped (other than 2 or 18) 8 corruption -- all pixels are flagged as unusable, or the aperture flux is negative; in the former case, the aperture magnitude is NULL; in the latter case, the aperture magnitude is a 95% confidence upper limit 16 saturation -- here are one or more saturated pixels in the measurement aperture 32 upper limit -- the magnitude is a 95% confidence upper limit combinations: 3 source confusion + bad pixels 5 source confusion + non-zero bit flag 6 bad pixels + non-zero bit flag 7 source confusion + bad pixels + non-zero bit flag 9 source confusion + corruption 10 bad pixels + corruption 11 source confusion + bad pixels + corruption 12 non-zero bit flag + corruption 13 source confusion + non-zero bit flag + corruption 14 bad pixels + non-zero bit flag + corruption 15 source confusion + bad pixels + non-zero bit flag + corruption 17 source confusion + saturation 18 bad pixels + saturation 19 source confusion + bad pixels + saturation 20 non-zero bit flag + saturation 21 source confusion + non-zero bit flag + saturation 22 bad pixels + non-zero bit flag + saturation 23 source confusion + bad pixels + non-zero bit flag + saturation 24 corruption + saturation 25 source confusion + corruption + saturation 26 bad pixels + corruption + saturation 27 source confusion + bad pixels + corruption + saturation 28 non-zero bit flag + corruption + saturation 29 source confusion + non-zero bit flag + corruption + saturation 30 bad pixels + non-zero bit flag + corruption + saturation 31 source confusion + bad pixels + non-zero bit flag + corruption + saturation ______________________________________________________________________________________________ Note about upper limits: threshold = 2 * RMS if ( f < threshold) then if (f < 0) then upper_limit = threshold else upper_limit = f + threshold where f is the flux of the source, RMS is the source flux uncertainty The upper limit is reported in the WPRO and standard aperture MAG columns; the reported uncertainty is set to 9.99 mag. ______________________________________________________________________________________________ Note: Null values are now indicated by the character string "null"