| 1 | proportional counter array | PCA | 99 | 7 | 2.001334 | 9904391,9904123,etc |
| 2 | sunyaev zel'dovich | SZ | 171 | 5 | 1.00435 | 9904235,9904168,etc |
| 3 | wide field camera | WFC | 14 | 4 | 1.001897 | 9904385,9904114,etc |
| 4 | wide field planetary camera 2 | WFPC2 | 64 | 4 | 2.000657 | 9904032,9904114,etc |
| 5 | lyon meudon extragalactic database | LEDA | 22 | 4 | 1.000495 | 9904326,9904259,etc |
| 6 | all sky monitor | ASM | 26 | 4 | 1.001894 | 9904286,9904123,etc |
| 7 | ministry for university and research | MURST | 4 | 4 | 1.000051 | 9904101,9904203,etc |
| 8 | space telescope imaging spectrograph | STIS | 42 | 3 | 1.004165 | 9904032,9904161,etc |
| 9 | diffuse ionized gas | DIG | 105 | 3 | 1.002997 | 9904428,9904154,etc |
| 10 | kolmogorov smirnov | KS | 3 | 3 | 1.00003 | 9904374,9904149,etc |
| 11 | narrow field instrument | NFI | 9 | 3 | 1.002733 | 9904286,9904169,etc |
| 12 | planetary camera | PC | 44 | 3 | 2.001251 | 9904106,9904247,etc |
| 13 | compact steep spectrum | CSS | 18 | 3 | 1.001424 | 9904106,9904141,etc |
| 14 | period luminosity | PL | 26 | 3 | 2.000812 | 9904027,9904360,etc |
| 15 | high energy x ray timing experiment | HEXTE | 61 | 3 | 2.000505 | 9904123,9904244,etc |
| 16 | proportional counter unit | PCU | 6 | 3 | 1.000205 | 9904123,9904222,etc |