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14.12 FCS Power Calibration


Description Parameter:	 Section 2.7, 5.2.4
Processing Level:	 SPD 
Usage in processing:	 Section 7.10
File Type:		 FITS Image
Units:			 mW 
File names:		 PP1FCSPOW, PP2FCSPOW,
			 PP3FCSPOW_01, PP3FCSPOW_02, 
			 PC1FCSPOW_01, PC1FCSPOW_02, 
			 PC2FCSPOW_01, PC2FCSPOW_02

The FCS power calibration tables give the electrical power in mW applied to the FCS as a function of filter, TRS, FCS and the index in the table listing the in-band power on the detector in regular logarithmic intervals. For a given filter, TRS, and FCS combination the indices and $P_{FCS}(i-1),~P_{FCS}(i)$ are retrieved from the Cal-G file. $P_{FCS}(i)$ is the first FCS power in the table higher than the actual FCS power $P_{FCS, meas}$ used in the FCS measurement. Once the indices have been determined Table 14.4 is used to convert these to in-band powers on the detector $P_{det}$ .

**Table 14.4:** *Conversion index of axis 1 to power in W for C100 and C200 or $\rm W~mm^{-2}$ for P1, P2, and P3.*
index	$P_{det}$	index	$P_{det}$	index	$P_{det}$
1	1.78E20	16	1.00E16	31	5.62E13
2	3.16E20	17	1.78E16	32	1.00E12
3	5.62E20	18	3.16E16	33	1.78E12
4	100.E19	19	5.62E16	34	3.16E12
5	1.78E19	20	1.00E15	35	5.62E12
6	3.16E19	21	1.78E15	36	1.00E11
7	5.62E19	22	3.16E15	37	1.78E11
8	1.00E18	23	5.62E15	38	3.16E11
9	1.78E18	24	1.00E14	39	5.62E11
10	3.16E18	25	1.78E14	40	1.00E10
11	5.62E18	26	3.16E14	41	1.78E10
12	1.00E17	27	5.62E14	42	3.16E10
13	1.78E17	28	1.00E13	43	5.62E10
14	3.16E17	29	1.78E13	44	1.00E09
15	5.62E17	30	3.16E13	45	1.78E09

The final in-band power obtained in OLP is derived from a linear interpolation in logarithmic space in between $log(P_{det}(i-1))$ and $log(P_{det}(i))$ based on $P_{FCS}(i-1),~P_{FCS}(i)$ and $P_{FCS, meas}$ .

The properties (FCS1,TRS2) altered between rev 93 and 94 due to unknown reasons. This event changed the FCS calibration for those detectors for which the (FCS1,TRS2) combination is used namely: P3, C100, and C200. For these detectors two calibration files are available: one for FCS measurements obtained before rev 94 (suffix _01) and one for rev 94 and higher (suffix _02).

During the ISO mission only specific FCS/TRS combinations were used. Entries in the Cal-G files that do not refer to these settings have been set to zero:

FCS1/TRS1: P1, P2
FCS1/TRS2: P3, C100, C200
FCS2/TRS1: P1, P2 chopped mode
FCS2/TRS2: P3, C100, C200 chopped mode

Example: for detector P2, settings FCS1/TRS2 and FCS2/TRS2 are not allowed and therefore set to zero in the corresponding table.

For all FCS power calibration tables, the following FITS keywords are common:

NAXIS = 4
TYPE = REAL*4

14.12.1 Product PP1FCSPOW: PHT-P1 FCS power calibration table


AXIS	Length	Description
1	45	Index for in-band optical power on detector
2	10	Filters ordered according to (see Section A.1):
		3.3, 3.6, 4.8, 7.3, 7.7, 10, 11.3, 12.8, 15, 12 m
3	2	Each TRS: TRS1, TRS2
4	2	Each FCS: FCS1, FCS2

14.12.2 Product PP2FCSPOW: PHT-P2 FCS power calibration table


AXIS	Length	Description
1	45	Index for in-band optical power on detector
2	2	Filters ordered according to: 20, 25 m
3	2	Each TRS: TRS1, TRS2
4	2	Each FCS: FCS1, FCS2

14.12.3 Product PP3FCSPOW_01/02: PHT-P3 FCS power calibration table


AXIS	Length	Description
1	45	Index for in-band optical power on detector
2	2	Filters ordered according to: 60, 100 m
3	2	Each TRS: TRS1, TRS2
4	2	Each FCS: FCS1, FCS2

14.12.4 Product PC1FCSPOW_01/02: PHT-C100 FCS power calibration table


AXIS	Length	Description
1	45	Index for in-band optical power on detector (see Section A.1)
2	7	Filters ordered according to (see Section A.1):
		90(backup), 65, 60, 80, 100, 105, 90 m
3	2	Each TRS: TRS1, TRS2
4	2	Each FCS: FCS1, FCS2

14.12.5 Product PC2FCSPOW_01/02: PHT-C200 FCS power calibration
table


AXIS	Length	Description
1	45	Index for in-band optical power on detector
2	5	Filters ordered according to (see Section A.1):
 		170, 200, 180, 150, 120 m
3	2	Each TRS: TRS1, TRS2
4	2	Each FCS: FCS1, FCS2