Derived Data Records (DDR)

The DDR Date Set

The UVVS Derived Data Records consist of time ordered sequences of radiance values that are measured along lines of sight perpendicular to Mercury radius vectors. The viewing direction for each measurement is determined by specifying the latitude, longitude, and altitude of the spacecraft and the latitude, longitude, and altitude of the minimum ray

There are nine UUVS DDR data products per Mercury year. For each species (Na - the sum of Sodium D lines at 589.2 and 589.8 nm), (Mg - the emission line at 285.3 nm), and (Ca - the emission line at 422.8 nm) there are three observation categories (dayside limb altitude profile, dayside and nightside limb drift profile, and night side tail sweep profile).

For Example:
ud_01_ld_mg_dat (i.e. Magnesium Limb Drift)
ud_01_ns_ca_dat (i.e. Calcium Night Sweep)
ud_01_ls_na_dat (i.e. Sodium Limb Scan)

DDRs for each species and observation category consist of individual files spanning one Mercury year from true anomaly 0 to 360 degrees. Fractional years (including the beginning of the orbital phase and the end of mission) will not contain data for all true anomaly values. There are two types of data stored in each science file: RADIANCE versus WAVELENGTH (spectra) and TOTAL_RADIANCE in each observed emission line [total radiance integrated over the emission line(s) as measured at each tangent altitude].

The DDRs are in binary format and each is described by a detached PDS label . Detailed descriptions of the parameters in the label can be found in the label directory.

Also see and Section 5.2.2 of the DDR SIS for details of observations

A Master Science Index

A label and index are available that provides an overview of the data set has been derived from housed in the index directory

Accessing Binary Files

An IDL tool which translates the DDR binary files is available (See side bar)