SIMPLE = T / BITPIX = 16 / NAXIS = 4 / NAXIS1 = 1024 / NAXIS2 = 1034 / NAXIS3 = 3 / NAXIS4 = 1 / EXTEND = T /Tables following main image BLOCKED = T /Tape may be blocked OBJECT = 'C0000P40' TELESCOP= 'VLA ' INSTRUME= 'L-BAND ' OBSERVER= 'NVSS GRP' DATE-OBS= '15/12/93' DATE-MAP= '03/04/98' BSCALE = 9.99999974738E-05 /REAL = TAPE * BSCALE + BZERO BZERO = 0.00000000000E+00 / BUNIT = 'JY/BEAM ' EPOCH = 2.000000000E+03 /EPOCH OF RA DEC ALTRPIX = 1.000000000E+00 /ALTENATE FREQ/VEL REF PIXEL OBSDEC = 4.00000000000E+01 /ANTENNA POINTING DEC YSHIFT = -7.105427358E-15 /NET SHIFT OF PHASE CENTER INY DATAMAX = 1.246536493E+00 /MAX PIXEL VALUE DATAMIN = -1.483317930E-02 /MIN PIXEL VALUE CTYPE1 = 'RA---SIN' CRVAL1 = 0.00000000000E+00 / CDELT1 = -4.166666884E-03 / CRPIX1 = 5.120000000E+02 / CROTA1 = 0.000000000E+00 / CTYPE2 = 'DEC--SIN' CRVAL2 = 4.00000000000E+01 / CDELT2 = 4.166666884E-03 / CRPIX2 = 5.130000000E+02 / CROTA2 = 0.000000000E+00 / CTYPE3 = 'STOKES ' CRVAL3 = 1.00000000000E+00 / CDELT3 = 1.000000000E+00 / CRPIX3 = 1.000000000E+00 / CROTA3 = 0.000000000E+00 / CTYPE4 = 'FREQ ' CRVAL4 = 1.40000000000E+09 / CDELT4 = 1.000000000E+08 / CRPIX4 = 1.000000000E+00 / CROTA4 = 0.000000000E+00 / HISTORY ------------------------------------------------------------------------ HISTORY NRAO VLA Sky Survey HISTORY Copyright 1994 HISTORY Associated Universities, Inc. HISTORY National Radio Astronomy Observatory HISTORY 520 Edgemont Road HISTORY Charlottesville, VA 22903-2475 HISTORY HISTORY Permission is granted for publication and reproduction of this HISTORY material for scholarly, educational, and private non-commerical HISTORY use. Inquiries for potential commercial uses should be HISTORY addressed to: HISTORY NRAO HISTORY 520 Edgemont Road HISTORY Charlottesville, VA 22903-2475 HISTORY HISTORY ------------------------------------------------------------------------ HISTORY HISTORY HISTORY THE NRAO VLA SKY SURVEY HISTORY HISTORY J. J. Condon, W. D. Cotton, E. W. Greisen, and Q. F. Yin HISTORY National Radio Astronomy Observatory, 520 Edgemont Road HISTORY Charlottesville, VA 22903 HISTORY HISTORY R. A Perley HISTORY National Radio Astronomy Observatory, P. O. Box 0 HISTORY Socorro, NM 87801 HISTORY HISTORY J. J. Broderick HISTORY Physics Department HISTORY Virginia Polytechnic Institute and State University HISTORY Blacksburg, VA 24061 HISTORY HISTORY HISTORY Observations for the 1.4 GHz NRAO VLA Sky Survey (NVSS) began in 1993 HISTORY September and should cover the sky north of -40 deg declination (82% HISTORY of the celestial sphere) before the end of 1996. The principal data HISTORY products will be: HISTORY HISTORY (1) A set of 2326 continuum map "cubes," each covering 4 deg X 4 deg HISTORY with three planes containing Stokes I, Q, and U images. These maps HISTORY were made with a relatively large restoring beam (45 arcsec FWHM) to HISTORY yield the high surface-brightness sensitivity needed for completeness HISTORY and photometric accuracy. Their rms brightness fluctuations are HISTORY about 0.45 mJy/beam = 0.14 K (Stokes I) and 0.29 mJy/beam = 0.09 K HISTORY (Stokes Q and U). The rms uncertainties in right ascension and HISTORY declination vary from 0.3 arcsec for strong (S > 30 mJy) point HISTORY sources to 5 arcsec for the faintest (S = 2.5 mJy) detectable HISTORY sources. HISTORY HISTORY (2) Lists of discrete sources. HISTORY HISTORY The NVSS is being made as a service to the astronomical community, and HISTORY the data products are being released as soon as they are produced and HISTORY verified. HISTORY HISTORY ------------------------------------------------------------------------ HISTORY HISTORY HISTORY ADDITIONAL INFORMATION HISTORY HISTORY All large NVSS maps that have been verified are available by anonymous HISTORY FTP, as described below. The anonymous FTP directory also contains a HISTORY README file pointing to files, such as the postscript file "paper.ps", HISTORY giving a more detailed description of the NVSS. Careful users will HISTORY read these files before using the NVSS images. If you have any HISTORY questions or comments about the NVSS, please contact Jim Condon by HISTORY email at Internet address "jcondon@nrao.edu" or by telephone at (804) HISTORY 296-0322. HISTORY HISTORY ------------------------------------------------------------------------ HISTORY HISTORY HISTORY ANONYMOUS FTP DIRECTORY HISTORY HISTORY The large (4 deg X 4 deg) map cubes and total intensity only images HISTORY are stored as binary files in FITS format (see Grosbol et al. 1988, HISTORY Astronomy & Astrophysics Supplements, v. 73, p. 359 for a description HISTORY of the FITS format). Maps are stored in gzip compressed form but an HISTORY uncompressed form may be requested (see below). Each map is named by HISTORY the J2000 right ascension and declination of its center. Maps HISTORY containing the full (IQU) polarization cube have names beginning with HISTORY a "C" and those with total intensity only begin with an "I". For HISTORY example, C2230P84.gz is centered on right ascension = 22h 30m, HISTORY declination = +84 deg; "M" is used to denote negative declinations. HISTORY You can copy these maps by anonymous FTP. A typical FTP session might HISTORY go as follows: HISTORY HISTORY ftp nvss.cv.nrao.edu HISTORY login: anonymous HISTORY password: (type your name or email address here) HISTORY cd pub/nvss (to access the NVSS public directory) HISTORY ls (to list the directory contents) HISTORY get paper.ps (to get a postscript copy of the paper) HISTORY binary (to copy binary files) HISTORY cd MAPS (to go to the maps directory) HISTORY get C2230P84.gz (to get the map cube centered on 22h 30m, HISTORY +84 deg in compressed form) HISTORY get I2230P84 (to get the total intensity map centered on HISTORY 22h 30m, +84 deg in uncompressed form) HISTORY quit HISTORY HISTORY HISTORY You can also access the FTP directory via the VLA D-array NVSS Survey HISTORY item on the NRAO WWW home page: HISTORY HISTORY http://www.nrao.edu HISTORY HISTORY Compression: The images are stored as standard FITS files compressed HISTORY in GNU zip (gzip) format; the .gz at the end of the name denoting this HISTORY compression. If an uncompressed version is desired, omit the ".gz" when HISTORY requesting the file from ftp. Gzipped file are uncompressed using HISTORY gunzip which is available for most computer systems. For more details HISTORY see file pub/nvss/compress.txt. HISTORY ------------------------------------------------------------------------ ORIGIN = 'AIPSGorila Magilla 15JAN96' / DATE = '06/04/98' / File written on dd/mm/yy HISTORY AIPS IMNAME='C0000P40 ' IMCLASS='IQU ' IMSEQ= 1 / HISTORY AIPS USERNO= 101 / HISTORY AIPS / VDQTZ QUANTIZE AT 1.00000E-04 HISTORY AIPS CLEAN BMAJ= 1.2500E-02 BMIN= 1.2500E-02 BPA= 0.00 HISTORY AIPS CLEAN NITER= 1 PRODUCT=1 / NORMAL END