Hi Elora - First, the simple. Below is the SEG-Y definition of key "scalco": Scalar to be applied to all coordinates specified in Standard Trace Header bytes 73-88 and to Standard Trace Header bytes 181-188 to give the real value. Scalar = 1, +/- 10, +/- 100, +/- 1000, or +/- 10,000. Positive=multiplier, Negative=divisor. A value of zero is assumed to be a scalar value of 1.
I put this here as a reminder to divide your sx, sy, gx(, gy) values by 1000 to get actual coordinates. Second, the SEG-Y textual header (3200 bytes) that by default is named "header" during SU import might have useful information. Also, you might contact anyone who processed the data or used the dataset for a publication to ask about geometry information.
Third, you seem to have valid "offset" values. I think using sx, sy, offset, and trigonometry, solve the problem of the direction to the gx value. That directly leads to the gy value. This is simple addition/subtraction for an east-west line but is complicated (requires trigonometry) for other orientations. If this is a land line, it could be center-spread, pushed, or pulled.. A look at the plotted gathers immediately shows whether the line is center-spread. A marine line is simpler. After you have the calculated gy values, you can use suggestions from Gerhard. However, remember to multiply your gy values by 1000 before putting them in trace headers to honor the scalco key.
Regards, David . . . . . . . . . . . . . .
On Tuesday, June 13, 2023 at 12:00:48 AM MDT, Gerhard Diephuis gdiephuis@xs4all.nl wrote:
Elora,
I am rather amazed about your question. The sushw program is very versatile in generating traceheaders for complicated geometry as well as using values from a textfile for traceheaders. If you have the values for sy in a simple textfile in one column, try a2b < your_text_file n1=1 > binary_file, followed by sushw < your_su_file infile=binary_file key=sx > your_amended_su_file.
Check results by applying sugethw < your_amended_su_file key=sx,sy,gx,gy output=geom > resulting_header_file.txt. That shoud result in a four-column text file
Good luck
Gerhard
From: Elora Afrin elora.afrin@students.tamuk.edu Date: Tuesday, 13 June 2023 at 00:41 To: SU-users seisunix@mailman.seismic-unix.org Subject: [Seisunix] Help with getting headerword
Hello Everyone,
Greetings. I have a su file where sy header is missing. How can I set a correcect sy values? I went through sushw and suchw and saw some basic information. I tried Key1=sy, key2=sx and key3=gx but noticed that I got gy values but gx and gy are same which is not supposed to be. I do not know the first value of gy. I request you to help me to set gy values.
Thank you.
Sincerely,
Elora
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