EG057 is a multi-phase center experiment. There are 27 IDI data sets created. 
The in-beam calibrator was inclued in the first data set eg057_1_1.IDI<1-6>. 
The rest data sets are made for the target sources. Their mapping relation is 
listed in the following table.

===================================
Source          IDI fits files
---------------------------------
J2229+0114	eg057_1_1.IDI<1-6>
J2228+0110	eg057_2_1.IDI<1-6>
FIRST-1		eg057_3_1.IDI<1-6>
FIRST-2		eg057_4_1.IDI<1-6>
FIRST-3		eg057_5_1.IDI<1-6>
FIRST-4		eg057_6_1.IDI<1-6>
FIRST-5		eg057_7_1.IDI<1-6>
FIRST-6		eg057_8_1.IDI<1-6>
VLA-1		eg057_9_1.IDI<1-6>
VLA-2		eg057_10_1.IDI<1-6>
VLA-3		eg057_11_1.IDI<1-6>
VLA-4		eg057_12_1.IDI<1-6>
VLA-5		eg057_13_1.IDI<1-6>
NVSS-1		eg057_14_1.IDI<1-6>
NVSS-2		eg057_15_1.IDI<1-6>
NVSS-3		eg057_16_1.IDI<1-6>
SDSS-G1		eg057_17_1.IDI<1-6>
SDSS-G2		eg057_18_1.IDI<1-6>
SDSS-G3		eg057_19_1.IDI<1-6>
SDSS-G4		eg057_20_1.IDI<1-6>
SDSS-G5		eg057_21_1.IDI<1-6>
SDSS-G6		eg057_22_1.IDI<1-6>
SDSS-G7		eg057_23_1.IDI<1-6>
SDSS-G8		eg057_24_1.IDI<1-6>
SDSS-Q1		eg057_25_1.IDI<1-6>
SDSS-Q2		eg057_26_1.IDI<1-6>
SDSS-Q3		eg057_27_1.IDI<1-6>
====================================
