U.S. DEPARTMENT OF THE INTERIOR / U.S. GEOLOGICAL SURVEY
                                
                                
        U.S. GEOLOGICAL SURVEY DIGITAL DATA SERIES DDS-13
                                
              International Phase of Ocean Drilling
                Seismic Line 1 Demultiplexed Data
               Cape Hatteras to Mid-Atlantic Ridge
                                
                            DISC ¯26

Demultiplexed Seismic Data

     Each file of seismic data is the disc-image of a SEG-Y
format tape output during the demultiplexing of the original
field data.  The data were written to tape using the 32 bit IBM
floating point format (Barry, and others, 1975).  As the data
were copied bit-for-bit to the CD-ROM file, this format was
preserved.  Each file of sesimic data is named IPD{number}, where
{number} is the first shotpoint in the file.  NOTE: FFID
indicates the Field File Identification Number assigned each shot
as it was recorded.

             file:  ¯IPD21626.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1550
      data length:  ¯6200 msec
  bytes per trace:  ¯6440
    bytes in file:  ¯137478280
   traces in file:  ¯21347
      first trace:  ¯573/9 FFID/trace
       last trace:  ¯43/1 FFID/trace


             file:  ¯IPD21848.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯126889340
   traces in file:  ¯19715
      first trace:  ¯17/1 FFID/trace
       last trace:  ¯427/35 FFID/trace


             file:  ¯IPD22053.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯137547356
   traces in file:  ¯21371
      first trace:  ¯427/36 FFID/trace
       last trace:  ¯874/46 FFID/trace

                             1

             file:  ¯IPD22276.SGY
      sample rate:  4000.0 microsec
samples per trace:  ¯1549
      data length:  ¯6196 msec
  bytes per trace:  ¯6436
    bytes in file:  ¯136446800
   traces in file:  ¯21200
      first trace:  ¯874/47 FFID/trace
       last trace:  ¯317/30 FFID/trace




Observer Logs

     The following files are digitized versions of the original
observer's log sheets.  Each file is named OB{number}.{format},
where {number} is the first shot point on the page, and {format}
is the graphic format of the file: PCX, TIF, or GIF.  No {format}
extension is shown with the file names given below.

OB21621
OB21671
OB21721
OB21771
OB21821
OB21871
OB21921
OB21971
OB22041
OB22041G
OB22091
OB22141
OB22191
OB22241
OB22291
OB22341
OB22394
OB22441



REFERENCE

Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended
     standards for digital tape formats: Geophysics, v. 40, p.
     344-352.





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