Solar Ultraviolet Observations from the Solar Maximum Mission/ Ultraviolet Spectrometer and Polarimeter (SMM/UVSP)

Data from the Ultraviolet Spectrometer and Polarimeter (UVSP) consist
of photon counts at selected UV wavelengths in the 1170 - 3500 A band
from detectors which are used in a variety of modes to build up solar
images with various spatial dimensions. Spectral resolution in some
observations is as good as 0.01 A.

Each observing sequence is termed an experiment, and given an
experiment number. A complete data base exists, in which all of the
experiments appear, and which may be searched according to fields that
identify experiment types. This data base is available on-line at the
Solar Data Analysis Center (SDAC). There are also various special
data sets (e.g. ozone experiments) at the SDAC.

Reformatted data from 1980 to the present are archived on optical disk.
Requests for data should be addressed to the SDAC.

The UVSP was designed to measure the relatively low-temperature
plasmas (5000 to 200,000 K) in flares, active regions and the quiet
Sun. The wavelength range given above could be scanned. Spatial
resolution in some observations is as good as 1 arc sec, and the field
of view could be varied by raster scanning to build up images as large
as 256 arc sec square. (Some larger images were made by adjusting the
spacecraft fine pointing between rasters.) Dopplergrams were possible
using two detectors, one on either side of a spectral line. Time
resolution could be as fast as 64 ms. Linear and circular polarimetry
were possible. Any combination of timing, slit size, spatial step
size, polarimetry and wavelength scanning in any order was possible.

Many of the various instrument modes have been utilised during its
operational life, so there is a great variety of kinds of data arrays
(with differing dimensionality in spatial, spectral and temporal
dimensions). There are fixed-wavelength image sequences of every size
from 3 x 3 pixels to full-scale 256 x 256 arc-sec-square rasters, and
any of these sequences may have been interspersed with similar ones at
other wavelengths. One common observing strategy was to obtain
small-scale images of the brightest area early in a flare, to maximize
time resolution during the impulsive phase, and to make larger-scale
rasters later in the flare when the gradual phase typically occurred.

Observations of stratospheric ozone have also been made, exploiting
the passage of sunlight through the Earth's atmosphere as SMM enters
or emerges from the Earth's shadow during its 90-minute orbit. These
observations have provided unique measurements of ozone concentration
in mid-latitudes.

For more information, see:
https://umbra.nascom.nasa.gov/smm/uvsp.html