Description of Lyman Alpha Level1 Data
2/21/2011
Produced by Southwest Research Institute

Daily IDL savesets will be transferred to the SPDF through their ftp server at cdaweb.gsfc.nasa.gov.  The savesets will be gzipped and entitled TWINS#_YYYY_MM_DD_LAD.sav.gz where # is either 1 or 2 signaling which spacecraft's data is included in the saveset.  YYYY is the year, MM is month, and DD is the day of the month.

Within each saveset is a structure entitled Level1_Data_Array.

Level1_Data_Array = { 
	TIME:     			DOUBLE 	Array[N]
	LAD1_0_DATA:		DOUBLE 	Array[N]
	LAD2_0_DATA:		DOUBLE 	Array[N]
	LAD1_2_DATA:		DOUBLE 	Array[N]
	LAD2_2_DATA:		DOUBLE 	Array[N]	
	LAD1_DATA: 		DOUBLE 	Array[N]
	LAD2_DATA: 		DOUBLE 	Array[N]
	SECTOR_POSITION: 	DOUBLE 	Array[N]	
}


Time  is an array containing the timestamps of the LAD data in Modified Julian Date.

LAD1_0_DATA is an array of LAD photon intensities (in units of Rayleigh) from the Toward LAD sensor with 0 degree offset.  The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

LAD2_0_DATA  is an array of LAD photon intensities (in units of Rayleigh) from the Away LAD sensor with 0 degree offset. The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

LAD1_2_DATA is an array of LAD photon intensities (in units of Rayleigh) from the Toward LAD sensor with 2 degree offset. The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

LAD2_2_DATA is an array of LAD photon intensities (in units of Rayleigh) from the Away LAD sensor with 2 degree offset. The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

LAD1_DATA is an array of LAD photon intensities (in units of Rayleigh) from the Toward LAD sensor (sum of 0degree and 2degree offset). The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

LAD2_DATA is an array of LAD photon intensities (in units of Rayleigh) from the Away LAD sensor (sum of 0degree and 2degree offset). The LAD counters are read out every 0.67 seconds corresponding to 2 degrees at the nominal TWA rotation rate of 3degree per second.

SECTOR_POSITION is position of the actuator at the current timestamp.  The nominal TWA rotation rate of 3 degree per second and timestep of 1.333 seconds, means the actuator moves approximately 4 degrees between timestamps.

N will vary by day, but all of the arrays in a particular saveset will be the same size.