UVES productsFITS files
The following FITS products exist in the data set (sorted along increasing reduction level):
The error products contain information based on the extraction process. They record, in each wavelength bin, the chi^2 value of the profile used for optimum extraction. Like the signal files, the error files come in two varieties: before flux calibration, and after flux calibration, if a final flux-calibrated product exists.
There is also the extracted sky background recorded which might become useful to assess data quality in cases of faint sources and high sky level (moon contamination, sky emission lines).top Relation between raw file and product files
The UVES spectra in a data set are always derived from a single raw file. There is always a set of 4 or 6 FITS products per CCD. The UVES blue arm has one CCD, the red arm two CCDs. Therefore all spectra from the red arm come as set of 8 or 12 FITS files, the blue products as set of 4 or 6 files:UVES FITS products
Dichroic: Most often UVES data have been measured in dichroic mode, delivering one blue and one red file almost simultaneously and covering a large part of the optical spectrum at once. Products from this pair of raw files are formally distinct (belong to 2 different data sets) but can be easily recognized from the product names.top Names of FITS products
UVES product fits files carry names which are intended to contain explicitly some useful information. This is why they are not optimized for brevity. A typical UVES product fits file has a name like:
UV_SRED is the product code and identifies a reduced but not fluxed spectrum. The next group is the OB (observing block) which might be helpful for a user e.g. to identify other data from the same OB. The next group (2002-05-02T06:22:50.057)is inherited from the raw file and is useful to uniquely describe this file (since an OB can produce more than one file of the same type). It also marks the timestamp of acqusition (actually of archiving the raw file). This timestamp is identical to the one of the data set.
The last part of the name consists of a setup string, describing: the CCD (BLUE | REDL | REDU); the central wavelength in nm; a short tag for the instrument mode (d1/d2 for the dichroic modes #1 or #2; bl for BLUE arm only, re for RED arm only). 2x2 marks the binning, 10 codes the slit width (10 stands for 1.0 arcsec).
The naming scheme facilitates grouping of similar files (e.g. all files from OB 118913), or e.g. of all files from that night taken with a particular setup. As mentioned above, files taken in dichroic mode are almost simultaneously acquired. In this example, there are in total three SRED files:
more on UVES SCIENCE naming scheme ...top Ancillary files
There is associated log and QC information available in the following text and graphical files in the data set:
All log files carry the data set ID, with a typical extension. The qc_report names include the data set ID, plus some additional tags which are used for technical reasons.