DADA Headers

The specification of “Distributed Acquisition and Data Analysis” (DADA) headers is part of the DADA software specification. In particular, its appendix B.3 defines expected header keywords, which we reproduce below. We separate those for which the meaning has been taken from comments in an actual DADA header from Effelsberg, as well as additional keywords found in that header that do not appear in the specification.

Keyword	Description
Primary (from appendix B.3 [Default])
HEADER	name of the header [DADA]
HDR_VERSION	version of the header [1.0]
HDR_SIZE	size of the header in bytes [4096]
INSTRUMENT	name of the instrument
PRIMARY	host name of the primary node on which the data were acquired
HOSTNAME	host name of the machine on which data were written
FILE_NAME	full path of the file to which data were written
FILE_SIZE	requested size of data files
FILE_NUMBER	number of data files written prior to this one
OBS_ID	the identifier for the observations
UTC_START	rising edge of the first sample (yyyy-mm-dd-hh:mm:ss)
MJD_START	the MJD of the first sample in the observation
OBS_OFFSET	the number of bytes from the start of the observation
OBS_OVERLAP	the amount by which neighbouring files overlap
Secondary (description from Effelsberg sample file)
TELESCOPE	name of the telescope
SOURCE	source name
FREQ	observation frequency
BW	bandwidth in MHz (-ve lower sb)
NPOL	number of polarizations observed
NBIT	number of bits per sample
NDIM	dimension of samples (2=complex, 1=real)
TSAMP	sampling interval in microseconds
RA	J2000 Right ascension of the source (hh:mm:ss.ss)
DEC	J2000 Declination of the source (ddd:mm:ss.s)
Other (found in Effelsberg sample file)
PIC_VERSION	Version of the PIC FPGA Software [1.0]
RECEIVER	frontend receiver
SECONDARY	secondary host name
NCHAN	number of channels here
RESOLUTION	a parameter that is unclear
DSB	(no description)