VEX Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) Raw Data (EDR)

EDR – Experiment Data Record

Instrument: Visible and Infrared Thermal Imaging Spectrometer (VIRTIS)

PDS Data Set ID: VEX-V-VIRTIS-2-3-V3.0, VEX-V-VIRTIS-2-3-EXT1-V2.0, VEX-V-VIRTIS-2-3-EXT2-V2.0, VEX-V-VIRTIS-2-3-EXT3-V1.0, VEX-V-VIRTIS-2-3-EXT4-V1.0

For more information about VIRTIS raw data products, see the Venus Express-VIRTIS To Planetary Science Archive Interface Control Document.

The Venus Express Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) PDS formatted Raw Data (EDR) are in DN, derived from telemetry with decompression, quality checked, time ordered, and sorted by channel/FPA. This includes both observations and flight calibrations. File extension is .QUB. The raw data include decompressed science data, housekeeping selection, and geometry data.

All data products in the VIRTIS-VEx archive use the PDS Qube objects with 3 dimensions, and contain decompressed data in binary format. Data are located in the Qube core and housekeeping parameters are located in the Qube suffix (sideplane or backplane). In addition, all data files include an empty HISTORY object (PSA early requirement, maintained for consistency but unused). Finally, all files have an attached PDS label describing their content (e.g., timing information, operational mode, average instrument temperatures, viewing conditions, data dimensions, applied processing…). The labels are padded with ascii character 32 (space) to an integer number of records, while the data objects are padded with character 0.

Measurements are stored in the Qube core in the order in which they are transmitted. In particular, successive frames in the Qube core correspond to data acquired at successive time steps. Associated to each frame of the Qube core, a frame in the suffix gathers the HK parameters acquired during the corresponding period.

Basic data access is performed through the LecturePDS software included in the DOCUMENT directory. The software documentation provides more specific information about data handling and visualization (e.g. dark frame identification in M cubes, suffix decoding…)

Although the data area is designed to preserve ISIS formatting requirements, the files cannot be directly ingested into ISIS. This however only requires modifications in the label, which are not supported by the team.

The Virtis Venus-Express data set includes geometry files providing useful quantities such as coordinates and viewing angles for all observing sessions on a pixel basis. There is a one-to-one correspondence with the observation data files for Venus. File extension is .GEO. The format of the geometry files is described in details in document VIRTIS geometry files formatting [VIR-LES-SW-2268, version 1.2, July 2008]. Geometry parameters are stored in Qube objects with no sideplane. Please see more details in The VIRTIS PDS/IDL software library(lecturePDS).

 

VIRTIS EDR products have the following file names:

VFXXXX_NN.QUB, raw data files

VFXXXX_NN.GEO, geometry files (Preliminary geometry files (computed from predicted kernels) have extension .PRE. These files are normally replaced by *.GEO as soon as the reconstructed kernels are available.)

where:

V is a literal “V” character

F is the FPA/transfer mode identifier (one alpha character):

H: H image transfer mode (backup observation mode)

S: H spectrum transfer mode (including dark files in nominal mode)

T: H "64-spectra" transfer mode (nominal mode)

I: M-IR

V: M-Vis

XXXX is the orbit number coded on exactly 4 digits to encompass the duration of the extended mission.

NN is the subsession ID (ID of file produced by this FPA for this orbit).

In ODE, VIRTIS EDR products have the following product IDs:

VFXXXX_NN.QUB