Integer Array Format Before January 2003

The size of each entry is 52 bytes. Each entry contains 13 elements. They are all of size 4 bytes and in network byte order. Thus they can simply be read as an array of integers on big-endian systems (e.g., 68k and SPARC). On little-endian systems (e.g., x86 and VAX), their byte order must be swapped.

Offset
(bytes)
Size
(bytes)
Type Description
+0 4 unsigned integer UTC modified Julian day at midnight
+4 4 unsigned integer #ticks from midnight (10 msec)
+8 4 booleans Flags (see below)
+12 4 unsigned integer Local apparent sidereal time (10 msec)
+16 4 unsigned integer Requested apparent right ascension (10 msec)
+20 4 signed integer Requested apparent declination (100 mas)
+24 4 signed integer Parallactic angle (100 mas)
+28 4 signed integer X offset (100 mas)
+32 4 signed integer Y offset (100 mas)
+36 4 signed integer Requested azimuth (100 mas)
+40 4 signed integer Requested elevation (100 mas)
+44 4 signed integer Error in azimuth (100 mas)
+48 4 signed integer Error in elevation (100 mas)

Right ascensions, declinations and parallactic angles are not valid if the CELESTIAL flag (see below) is not set, i.e., zero.

The 32-bit flag field is defined as follows:

Offset
(bytes)
b7 b6 b5 b4 b3 b2 b1 b0
+8 TTL
Input 8
TTL
Input 7
TTL
Input 6
TTL
Input 5
TTL
Input 4
TTL
Input 3
TTL
Input 2
TTL
Input 1
+9 TTL
Output 8
TTL
Output 7
TTL
Output 6
TTL
Output 5
TTL
Output 4
TTL
Output 3
TTL
Output 2
TTL
Output 1
+10             ON-beam Chopping
+11       Tracking Acquired Scanning Transited Celestial

The TRACKING flag in the telescope pointing information is different from the TTL TRACKING (/IDLING) signal. For historical reasons, the TTL TRACKING (/IDLING) signal is high when the TRACKING flag is true but the SCANNING flag is false.