History of changes to NVSSlist 1 Sep 95: Initial version 1.0, B. Cotton. 5 Sep 95: version 1.1 B. Cotton Fixed bug in selection by minimum polarization; the percent polarization computed could go negative after bias correction. Faster search method, more compact output when searching for items in a list. Added "silent" window to tell if there were other sources in the area (i.e. the region was included in the catalog) if nothing was found in the search window. 8 May 96: version 1.2 B. Cotton Added an option to get "raw" values, i.e. flux densities with no bias corrections added. Also in this mode no errors are given as they are all derived. 1 June 96: version 1.4 B. Cotton Made minor changes in the treatment of "unresolved" sources; in particular, resolution on only one axis is treated differently. If a search position is given, then the orientation of the offset is now given and the offset is always in seconds. Output is generally more compact. The date the FITS file was written and number of entries is now given to specify the version of the table. 3 June 96: version 1.5 B. Cotton If the center of the search is below -40 deg., a warning message is given and the program continues. 13 June 96: version 1.5.1 B. Cotton Fixed error in rounding of position angle of position wrt the search center. 16 July 96: version 1.6 B. Cotton Changed to accept search and verification radii in arcseconds rather than degrees. 30 July 96: version 1.7 B. Cotton Changed to accept minimum flux density in mJy rather than Jy. 7 August 96: version 1.8 B. Cotton Fixed to cope with blanked polarization data. Also allow more than 8 characters in date string. 23 September 96: version 1.8 B. Cotton Fixed bug in PDBIAS which caused incorrect indexing of the bias correction table. CORERR no longer modifies the input value of the peak flux density and corrects the error in the "fitted" peak flux density if the source is determined to be unresolved. 7 October 96: version 1.8 B. Cotton Fixed bug which asked interactive user twice if they wanted to quit rather than telling the number of sources found. Also fixed default search radius; it was the entire sky rather than 15 arcsec as indicated by the prompt. 24 October 96: version 1.8 B. Cotton Fixed default search radius when reading a list, the default was 0.004" rather than 15" as advertised. Also cleaned up documentation. Also the option to list everything in a box was broken; this is now fixed. 11 November 96: version 1.10 B. Cotton Fixed bug in verification box logic; the width in RA was only the primary search radius. 5 December 96: version 1.11 B. Cotton Fixed bug which disabled the use of a search box (as opposed to a search radius). 7 January 97: version 1.12 B. Cotton Changed corerr to use 2% rather than 1% of the beam size as the calibration component of the size error. 25 February 97: version 1.13 B. Cotton Changed output format to give distance from the specified position up to 99999" rather than the previous limit of 10000". 25 August 1997: version 2.0 B. Cotton Changed corerr to use improved calibration values. An RA bias correction of -0.025" is added and a declination bias of 0.113" to force agreement with the USNOA1 optical (FK%) positions. The RA calibration error is now 0.45" and the declination calibration error is 0.56". The noise component of the position errors was increased by a factor of 1.4 into agreement with the FIRST positions. The amplitude bias was changed to +250 uJy - 250/peak. Fix bugs in dealing with entries in which the polarization data was blanked. 27 August 1997: version 2.1 B. Cotton Fixed bug which caused entries from which the bias corrected polarized flux was less than 0 not to be displayed if the default minimum polarized flux density was used. 4 October 1997: version 2.2 B. Cotton Routine corerr was correcting the image position bias even if DORAW was true. 6 October 1997: version 2.3 B. Cotton Modified corerr to use the polarized emission at the peak rather than the input integrated value as the measure of the source polarized amplitude. The polarized flux and error are now scaled by the ratio of source to beam areas if deconvolved values are returned. 13 October 1997: version 2.4 B. Cotton - Now only gives polarization angles if the probability of a false detection is less than 2%. - Several minor problems in the computation of flux density errors were corrected. - An error in the computation of the errors of deconvolved source sizes was fixed. The errors were being overestimated. 21 October 1997 version 2.5 B. Cotton - Added a calibration (0.3%) term into the decision about whether to give the polarization angle in calerr.FOR. 10 December 1997 version 2.6 B. Cotton - Fixed problem with the estimation of errors in the deconvolved axis size in DECONV. This was causing occasionally arithmetic exceptions and was overestimating the uncertainty in the source size. 10 December 1997 version 2.7 B. Cotton - "Raw" flux densities were having inappropriate corrections applied. The offset from the corrected position given in the output listing now includes any calibration correction applied to the position. 14 January 1998 version 2.8 B. Cotton - "Bad hair" (no polarization) entries were being listed improperly giving zero polarized flux density. Such entries are now "Blank". 8 February 1998 version 2.9 B. Cotton Cosmetic change only, the labeling for B1900 was messed up. 10 July 1998 version 2.10 B. Cotton Now entries with a peak value less that 3 times the postfit RMS residual are not displayed. This suppresses alot of the "junk" around very bright regions but should not affect real sources. Also modified the output to give the offending values of the residual RMS, peak or integral when the "R*", "P*", or "S*" flags are given. The values are in 100s of microJy. 21 January 1999 version 2.12 Correct error in reference to NVSS paper. 19 June 1999 version 2.13 Clip flux density and error at 99.99 to prevent overflows. 8 October 1999 version 2.14 B. Cotton Replace previous fix with a variable format for flux densities and errors. Values up to 10,000 Jy should be printed OK. 19 Janurary 2001 version 2.15 B. Cotton Allow selection by max as well as min flux and max and min galactic latitude. Fixed several bugs related to a selection box. 12 February 2001 version 2.16 B. Cotton, J. Condon Replaced fixed point source response (45" Gaussian) with one that depends on source peak flux density and declination. This is to compensate for the incomplete CLEANing which left a somewhat larger pedestal under each source. 6 March 2001 version 2.16 B. Cotton, J. Condon Separate the CLEAN bias correction for D and DnC data. 21 August 2001 version 2.17 B. Cotton Fix bug in coarse selection of RA range (missing / cos(dec)) 14 May 2004, version 0.1 B. Cotton Change survey name to VLSS. 18 May 2007: version 1.1 B. Cotton changes from A. Cohen: For the parameters that need to be changed, the new values are: CALERA = (2.8595") ** 2 CALEDE = (3.03324") ** 2 BIASRA = 0.0825713" BIASDE = 0.083267" CALAER = 0.10 Also, to correct for the clean bias, we need to add 1.39 times the local rms noise level to the peak brightness before calculating the integrated flux density. I believe the measured peak brighness should still be used for calculating rho.