UVOT's observations are not specified by filter and observing time but by an observing mode which divides the requested observing time appropriately among a group of filters. Modes can include grism observations, event mode and detector windowing.
The following page lists all of the observing modes for the UVOT instrument. Each mode is listed with the sequence of filters that will be used, the image field of view, the binning, the maximum exposure time and the weighting scheme for dividing the exposure time. Also listed are the number of times that mode has been used during the mission as well as comments that describe the subtleties of each mode.
Please note that proposals for Swift do not require you to select a UVOT mode. A detailed description of the requested observations should be sufficient for the UVOT team to pick or suggest an observing mode. Please also note that requested modes are always subject to change due to bright stars, science planning requirements and review by the UVOT team.
A few subtleties of observing with UVOT: Binning observations 2x2 is standard for UVOT observations, since 1x1 would be smaller than UVOT's spatial resolution. It is highly recommended that single-filter observations in the optical (white, V and B) and the grisms use modes that include "earth-limb protection." These short snapshots at the beginning and end of the observation can minimize the background sky level in the primary exposure. Observations requesting *only* optical filters should contain a strong justification since B and V data can be easily obtained from ground-based observatories.
Some of the more common modes in use are:
Modes that involve the grism, windowing the detector to shorten the read time or using event mode will generally be picked by the UVOT team depending on the specific needs and observation sequences.
To view a list of all UVOT modes, click here.