UVIT Filters
Filters for the three channels are shown below. For an observed counts per second (CPS), the source Flux and its AB magnitude for a filter can be estimated using the following relations:
Ffilter = CPS x UC (ergs s-1 cm-2 A-1)
mAB = -2.5 log10 (CPS) + ZP
CPS : Counts per second, the source count-rate
UC : Unit Conversion for the filter (see the table below)
ZP: Zero point for the filter (see the table below)
NOTE: These are from the lab measurements and are shown here only for indicative purposes. Please refer to the ground calibration and the in-orbit updates for the latest values.
| Channel | Slot | Filter | Name | Mean λ (A) | Δ λ (A) | Zero Point (ZP) | Unit Conv. (UC) X 10-15 |
| FUV | 0 | Block | Block | ||||
| 1 | F148W | CaF2-1 | 1481 | 500 | 18.016 ± 0.01 | 3.09 ± 0.029 | |
| 2 | F154W | BaF2 | 1541 | 380 | 17.778 ± 0.01 | 3.55 ± 0.04 | |
| 3 | F169M | Sapphire | 1608 | 290 | 17.455 ± 0.01 | 4.392 ± 0.037 | |
| 4 | Grating-1 | ||||||
| 5 | F172M | Silica | 1717 | 125 | 16.342 ± 0.02 | 10.74 ± 0.16 | |
| 6 | Grating-2 | ||||||
| 7 | F148Wa | CaF2-2 | 1485 | 500 | 17.994 ± 0.01 | 3.28 ± 0.025 | |
| NUV | 0 | Block | Block | ||||
| 1 | N242W | Silica-1 | 2418 | 785 | 19.81 ± 0.002 | 0.222 ± 0.00065 | |
| 2 | N219M | NUVB15 | 2196 | 270 | 16.59 ± 0.02 | 5.25 ± 0.082 | |
| 3 | N245M | NUVB13 | 2447 | 280 | 18.50 ± 0.07 | 0.725 ± 0.0036 | |
| 4 | Grating | ||||||
| 5 | N263M | NUVB4 | 2632 | 275 | 18.18 ± 0.01 | 0.844 ± 0.0096 | |
| 6 | N279N | NUVN2 | 2792 | 90 | 16.50 ± 0.01 | 3.50 ± 0.035 | |
| 7 | N242Wa | Silica-2 |
Filter Effective Area
Effective area of various UVIT filters are listed below. These values may be updated as and when new data is available from ground (and later in-flight) calibrations.
FUV Filters
NUV Filters