Gain (K/Jy) is computed as: \(G(x) = DPFU \times (ax^2 + bx +c)\) K/Jy, where x is the source elevation.
| Receiver | a | b | c | DPFU | HPBW (arcmin) | Beam Efficiency |
|---|---|---|---|---|---|---|
| CC | -4.68E-05 | 6.24E-03 | 7.92E-01 | 0.160 | 7.4 | 0.75 |
| CH | -4.02E-05 | 4.85E-03 | 8.53E-01 | 0.139 | 6.8 | 0.71 |
| X | -7.24E-05 | 1.06E-02 | 6.10E-01 | 0.141 | 4.9 | 0.72 |
| K | -4.20E-05 | 5.90E-03 | 7.92E-01 | 0.114 | 1.76 | 0.53 |
T\(_{{\rm sys}}\) for the K band receiver is computed starting from the quantities reported in the "Opacity and \(T_m\) table" below.
| Elevation (deg) | T\(_{{\rm sys}}\) (K) CC band | T\(_{{\rm sys}}\) (K) CH band | T\(_{{\rm sys}}\) (K) X band |
|---|---|---|---|
| 10 | 44 | 104 | 52 |
| 15 | 43 | 103 | 48 |
| 20 | 42 | 102 | 46 |
| 25 | 40 | 100 | 43 |
| 30 | 38 | 98 | 42 |
| 35 | 36 | 96 | 41 |
| 40 | 34 | 94 | 39 |
| 45 | 33 | 93 | 39 |
| 50 | 31 | 91 | 38 |
| 55 | 31 | 91 | 38 |
| 60 | 29 | 89 | 38 |
| 65 | 28 | 88 | 38 |
| 70 | 28 | 88 | 38 |
| 75 | 28 | 88 | 38 |
| 80 | 28 | 88 | 38 |
| 85 | 28 | 88 | 38 |
\(T_{sys}\) for K band observations si computed by means of the formula:
\(T_{sys}= T_{atm} \eta_{f} (1 - e^{\frac{-\tau}{sin(El)}}) + (1 - \eta_{f})T_{gnd} + T_{ric}\)
where for the Medicina K band receiver \(T_{ric}=15\) K (from semester 2022B)
and \(\eta_{f}\) = 0.986 at 22 GHz.
| Season | \(\tau\) | \(T_{gnd}\) (K) | \(T_{atm}\) (K) |
|---|---|---|---|
| Spring | 0.1 | 290 | 275 |
| Summer | 0.2 | 290 | 300 |
| Autumn | 0.1 | 290 | 275 |
| Winter | 0.06 | 290 | 250 |
Gain Table
| Receiver | Ref. frequency (MHz) | HPBW (arcmin) | Gain K/Jy | Beam Efficiency |
|---|---|---|---|---|
| C-low | 4900 | 3.9 | 0.64 | 0.71 |
| C-high | 6700 | 2.7 | 0.60 | 0.75 |
| K | 22000 | 0.8 | 0.66 | 0.67 |
For the K-band receiver, gain (K/Jy) is computed as: \(G(x) = DPFU \times (ax^2 + bx +c)\) K/Jy, where x is the source elevation.
| Receiver | a | b | c | DPFU |
|---|---|---|---|---|
| K | -7.97817471e-05 | 1.08244713e-02 | 6.32844659e-01 | 0.66 |
T\(_{{\rm sys}}\) has been measured at 7 GHz with 680 MHz bandwidth for the C receiver.
T\(_{{\rm sys}}\) for the K band receiver is computed starting from the quantities reported in the "Opacity and \(T_m\) table" below.
| Elevation (deg) | T\(_{{\rm sys}}\) (K) C-low band | T\(_{{\rm sys}}\) (K) C-high band |
|---|---|---|
| 10 | 25 | 45 |
| 20 | 25 | 41 |
| 30 | 25 | 38 |
| 40 | 25 | 36 |
| 50 | 25 | 35 |
| 60 | 25 | 35 |
| 70 | 25 | 34 |
| 80 | 25 | 33 |
| 90 | 25 | 33 |
\(T_{sys}\) for K band observations si computed by means of the formulae:
\(T_{sys}= T_{atm} \eta_{f} (1 - e^{\frac{-\tau}{sin(El)}}) + (1 - \eta_{f})T_{gnd} + T_{ric}\)
and:
\(T_{atm} \approx 0.683 T_{gnd} + 77.919\)
where for the SRT K band receiver \(T_{ric}=15\) K and \(\eta_{f}\) = 0.9 at 22
GHz.
Opacity and ground temperature seasonal values are given in the following
table.
| Season | \(\tau\) | \(T_{gnd}\) (K) |
|---|---|---|
| Spring | 0.13352 | 289.15 |
| Summer | 0.17970 | 295.82 |
| Autumn | 0.13104 | 285.48 |
| Winter | 0.09763 | 281.32 |
| Send comments to: Alessandra Zanichelli | Last modified: |