# Groups & Integrations Calculator

This tool calculates the groups and integrations for an optimal transit observation. We require some information about your background star, transit, and planned use of JWST (instrument, subarray, and filter), in order to interpolate your planned transit observation to our nearest information from pandeia (which powers the JWST ETC.)

1. At present, this tool is likely to overestimate saturation on direct comparison to the ETC. (This means we may predict less groups -- and put the user in less danger of oversaturating your observation)
2. Users should be aware of data rates. There are maximum number of groups and integrations that each instrument (and APT) allows based on how much data JWST can store. Therefore, results of this tool should always be checked against the documentation and APT. More information can be found at the "JWST Data Rate and Data Volume Limits" JDox page.
3. For NIRCam, it is currently assumed that a 4-amplifier readout is needed. 1-amplifier readouts are currently not supported by this tool, but they are by, e.g., PandExo.
4. NIRSpec/PRISM mode is currently not supported, but we aim to support this mode in future versions.

The name of a target to resolve in ExoMAST

$$\small \text{mag}$$
The K-band vega magnitude of the target
Phoenix stellar atmosphere model that most closely matches your star

The length of the observation

Enter "0" to optimize the number of groups

The JWST instrument

The photometric bandpass or grism for your science observation
The filter for target acquisition

The full frame or subarray mode for your science observation
The subarray mode for target acquisition

How to measure the saturation.

The level of saturation
Some background on saturation levels to inform your decision: The following is the saturation cap built into the ETC, and the current estimates of max possible saturation (which is what we use when you opt for well fraction).

MIRI NIRCam NIRSpec NIRISS fullwell
193655.0 58100.0 65000.0 56000.0 [e-] JWST ETC recommendation
250000 60000 65500 75000 max possible saturation