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A history of the GSPC background is added to the GSPC CCF. The evolution of the background is given by 6 standard background spectra for individual periods from 1983-1986. The background spectra reside in the newly defined data type HB which consists of 20 records. For the moment only-the first 12 records are used.

Each background spectrum covers 2 records. Within a record, each pair of bytes gives the count rate in counts/1000 sec per energy channel in the corresponding channel. The accumulation time of the spectrum is given in the last 2 bytes of the second record of each spectrum in units of 8 sec.

Record 1

Bytes     0-1      c in #1
Bytes 2-3 c in #2
Bytes 254-255 c in #128

Record 2

Bytes     0-1      c in #129
Bytes 254-255 Accumulation time in units of 8 sec.

Record 1, 2:     Background (gain 2) for period prior day 300/84
3, 4: Background (gain 1) for period prior
5, 6: Background (gain 2) calculated around day 10/85
7, 8: Background (gain 2) calculated around day 160/85
9,10: Background (gain 1) calculated around day 180/85
11,12: Background (gain 2) calculated around day 1/86

The background spectra in record 1,2 and 3,4 are identical to the spectra in data type B1, B2. All 6 spectra have been smoothed (average over 3 bins).

The new effective areas as given on p.34 have been incorporated into the CCF (for the layout of data type EA, see Express No. 12 p.74). Also the parameters E*j, P1j, P2J, S1j, S2j in record 4 of data type EA for the transformation to burst length windows 89-107 and 89-104 have been improved and updated in the CCF.

M. Gottwald

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