3.4 IUE Label Files

  When each image is read down from the spacecraft, it is associated with a ``VICAR'' label or Science Image Header containing observation information, spacecraft data, and comments by the Telescope Operator. The IUESIPS (and NEWSIPS) software adds image processing information to this label. It is written primarily in EBCDIC, (i.e.,'s Extended Binary Coded Decimal Interchange Code). The label file can be converted to ASCII for display at your terminal by typing:

LABEL,'IMAGET',START-LINE,END-LINE 

A small portion of the label is written in IBM binary code and will not be properly converted using LABEL.

The VICAR label is also preserved in NEWSIPS files. The EBCDIC information however is converted to ASCII and stored as commentary keywords in the FITS header. Image processing information is stored in FITS ``HISTORY'' keywords, which are considered part of the label by our programs. The LABEL program can be used to extract the label from the FITS header and is a useful tool for identifying the contents of a NEWSIPS FITS file. The display will look nearly identical to that produced when reading an IUESIPS file except that lines originally containing binary data now appear as two lines containing hexadecimal ASCII characters. This should not worry the user as the doubled binary lines will not be assigned independent line numbers. Thus line 101 will still be the first line of the processing history. Examples of using LABEL to display information in the IUE science image header file are given in Table 3.3. Remember that 'IMAGET' assumes the file extension is specified for NEWSIPS FITS files but not for IUESIPS RDAF-format files.

 

 

Table 3.3: LABEL Examples

Expression	Definition
LABEL,'IMAGET',1,2	Displays the first 2 lines of the VICAR label.
LABEL,'IMAGET',3,9	Displays observer comments entered by telescope operator.
LABEL,'IMAGET',10,32	Displays the history of events associated with the image.
LABEL,'IMAGET',36,37	Displays target information from preplanned information, as updated by the telescope operator.
LABEL,'IMAGET',101,0	Displays the image processing history to end of label.
LABEL,'IMAGET',0,0	Displays entire label.