EVN baseline sensitivity
Assuming a total data rate of 128 Mbits/second (a bandwidth of 64 MHz and 1 bit-sampling) and coherent integrations times of 600 secs (18 cm), 350 secs (6, 5 & 3.6 cm), 80 secs (1.3 cm), the expected 7-sigma RMS noise level expected on EVN baselines (using Effelsberg, Eb, as the reference telescope) are:
| Baseline (to Eb) |
18 cm (mJy) |
6 cm (mJy) |
5 cm (mJy) |
3.6cm (mJy) |
1.3cm (mJy) |
|---|---|---|---|---|---|
| Jb-1 | 2.1 | - | - | - | - |
| Jb-2 | 5.6 | 7.5 | 20.9 | - | 69.9 |
| Cm | 4.5 | 4.9 | ?? | - | 62.2 |
| Wb7 | ?? | ?? | - | ?? | - |
| Wb | 1.7 | 3.2 | - | 4.6 | - |
| Mc | 7.5 | 7.2 | 20.8 | 6.9 | 76.5 |
| Nt | 8.7 | 6.7 | - | 11.6 | 115.9 |
| On85 | 6.1 | 10.2 | 26.9 | - | - |
| On60 | - | - | - | 16.9 | 86.1 |
| Sh | 10.5 | 10.7 | - | 12.4 | 92.9 |
| Ur | 4.8 | 7.9 | - | 8.3 | 125.9 |
| Tr | 4.7 | 6.6 | 12.0 | ?? | - |
| Sm | 12.5 | 22.9 | - | 14.5 | 126.9 |
| Mh | - | - | - | - | 118.4 |
| Yb | - | - | - | 13.4 | - |
| Ro63 | 2.0 | - | - | 2.0 | 23.2 |
| Ro65 | - | - | - | ?? | - |
| Wz | - | - | - | 11.5 | - |
| Hh | 6.6 | 11.1 | 19.6 | 12.8 | - |
The numbers above have been calculated using the EVN Calculator. The sensitivities quotes for the Wb array assume the use of 14 telescopes and an associated degradation factor (due to the 3-level phase-array adding process) of 0.89.
A target radio source must have a correlated flux density S_c at the levels shown above, if fringes are to be detected on these baselines. Typically the EVN can detect sources with correlated fluxes, S_corr > 10 mJy (18 and 6 cm), S_corr > 20 mJy (5 and 3 cm) and S_corr > 90 mJy (1.3cm). Below or around these flux levels EVN Users are encouraged to use the technique of phase referencing which allows much longer coherent integration times to be used.
EVN webmaster (jive@jive.nl)