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## Combine Example

As an example of the use of a Association Table similar to the one displayed in Table 3.1. Let us create a master flat frame to be used for the reduction of the science frame susi0100.bdf. Suppose the Association Table contains the name of the master flat to be created: susi_140_142_143.bdf. Hence, three flats have to be combined, namely susi0140.bdf, susi0142.bdf, and susi0143.bdf. To combine these frames into the master flat field we enter:

SELECT/TABLE asso_tbl
COMBINE/CCD FF asso_tbl
The command will go the Association Table, checks the output name for the flat to be created for science frame susi0100, makes a list of single flats to be combined and does the combining. The output on the screen and stored in the MIDAS log file will look like (VERBOSE=YES):

```    Combining FLAT frames: Input=asso_tbl.tbl; output=susi_140_142_143.bdf

Statistics of frame no. 0:
area [@60,@10:@1070,@1020] of frame
minimum, maximum:                  5.560000e+02   8.654000e+03
mean, standard_deviation:          6.101316e+03   1.913127e+02

Statistics of frame no. 1:
area [@60,@10:@1070,@1020] of frame
minimum, maximum:                  8.390000e+02   1.276900e+04
mean, standard_deviation:          8.313817e+03   2.569877e+02

Statistics of frame no. 2:
area [@60,@10:@1070,@1020] of frame
minimum, maximum:                  4.220000e+02   1.046500e+04
mean, standard_deviation:          5.622723e+03   1.722370e+02

Method=avsigclip, low=  0.00, high=  0.00
lowclip=  3.00, highclip=  3.00
frame #        Ncomb   Exp_time   Mode   Scale   Offset   Weight
susi0140.bdf         1       1.00 571.878   1.093       -0    0.333
susi0142.bdf         1       5.00 862.392   0.725       -0    0.333
susi0143.bdf         1       5.00 441.692   1.416       -0    0.333
--------------------------------------------------------------------
Statistics of output frame susi_140_142_143.bdf:
area [@60,@10:@1070,@1020] of frame
minimum, maximum:                  6.045866e+02   1.023942e+04
mean, standard_deviation:          6.886717e+03   2.060752e+02

Ncomb   Exp_time   Mean    Mode  N_undef
susi0100_ff          3      3.933 6886.72 623.478        0
Undefined pixels, set to `null value' (=     0.000000)
--------------------------------------------------------------------
```

Petra Nass
1999-06-15