***** File BRWZINFO.TXT                                                       
                                                                              
     This directory contains uncompressed, subsampled browse images of both   
Halley's Comet and calibration objects; the data were obtained by the         
Large-Scale Phenomena Network.                                                
                                                                              
     In order to provide a uniform set of images which can be displayed       
quickly with the hardware currently available, a set of "browse images" has   
been generated of all L-SP comet and calibration digital data.  These images  
were created by the subsampling program MIDGET.FOR (refer to the SOFTWARE     
subdirectory), and have a maximum size of 256 by 256 pixels, a strategy       
adopted to permit a minimum simultaneous display of four images on many       
standard (512x512) display devices.  The digital data have been scaled into a 
numerical range of 0 to 255 (a single byte per pixel; the precision for most  
of the original images was 10 bits, or two bytes per pixel).                  
                                                                              
     The FITS headers for the browse images contain the information present in
the headers for the full-resolution images, but NAXIS1, NAXIS2, and the       
astrometric keywords have been updated to reflect changes in the pixel spacing
and scale of the images.  In other words, it is possible to perform (degraded)
astrometry directly using the FITS headers accompanying these browse images.  
Also, HISTORY keyword lines have been inserted into the FITS headers to       
document the linear scale and density scale changes.                          
                                                                              
     The filename extension for files of browse data (.IBG = image, .HDR =    
header, .LBL = label) follow the IHW filename conventions.  To reconstruct the
original FITS byte stream, the .HDR and the .IBG files for the the appropriate
observation must be concatenated.                                             
                                                                              
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NOTE                                                                          
----                                                                          
This file included in this presentation of the data set were taken from       
the SUMMARY/BROWSE directories of the original HAL_0018 CDROM volume.  They   
include not only all the data files, but also all the calibration             
observations comprising the complete data set.                                
                                                                              
-A.C.Raugh 2011-05-16