The file B.comp.ROT is a composite image of all of the clear
exposures taken with the HAO White Light Cononal Camera of the 
July 11 1991 eclipse in Mauna Loa, Hawaii.

The image is B/Bsun that has been multiplied by 1.e+10.
So to get back to true B/Bsun, multiply the data in the image by 1.e-10.
 
Where a 0 occurs in the image, the data could not be trusted, and
was thrown out.  (Data less than 319 is suspicious, as is data 
greater than 26218.)
 
You will notice discontinuities in the data where the exposures
merge.  In these areas, it is best to trust the lower value.
 
The data is probably reliable to 20%  -- ?
 
My biggest question with the numbers in the data come from whether
it needs to be corrected for sky transmission changes between
calibration day and eclipse day.

Right now (9/9/93) I do not think the white light coronal camera data 
requires any sky transmission corrections, as seeing on calibration 
day and eclipse day were very similar.  The possible factor to multiply
the coronal camera data by is: 236./206. = 1.14, but I wouldn't do it,
as it is just too uncertain...  We had previously thought it was necessary
to multiply the data by 1.0/0.45 = 2.222  -- I don't think this is
the right thing to do, but please let me know if you suspect such a
factor!

The image is straight binary, with no embedded record structure.

The data is 512 pixels in the x-direction, and 512 pixels in the
y- direction.  x-direction is east to west, y-direction is south to north.
that is:
the first 512 pixels go across in the x-direction, again east to west;
the next  512 pixels are further north (bigger y) 
                     go across in the x-direction, again east to west.
Etc.

Each pixel is a 16bit integer.  One pixel is 1.0/104.44 Rsun (solar
radii)  so 104.44 pixels = 1 solar radius.

The center of the sun in this image is x=255.5 y=249.5.  This
applies when the pixel counting begins with 0.

If you begin the pixel counting with 1, the center of the image is
at 256.5 250.5.

The image has been corrected for p-angle, so solar north is at the
very top of the image. 

 
Let me know if you have any questions, or if you notice anything odd
about the image!

Thank you,
Alice Lecinski  (phone 303-497-1523)
                (email alice@ncar.ucar.edu)



----------------------------- ftp info -----------------------------

1) ftp puu.hao.ucar.edu        (or ftp 128.117.16.39)
2) cd mk3/pub/eclipse/WLCC
3) ascii
4) get README.Bcomp.ROT
5) binary
6) get B.comp.ROT
7) get B.comp.ROT.fits
8) quit