Final Datasets for BET-CAS
Notes. Range is in Å. Texp is the maximum monochromatic exposure (seconds), accounting for coadditions and splices. MJD is the earliest start time of the sequence. QF is a quality factor, approximately the average S/N per resel.
Preview. In the main panel, the spectrum is blue and its photometric error (1σ) is red. The flux density and error tracings were heavily smoothed for display. Fluxes are clipped at the photometric error level: for weak spectra, the error tracing dominates. The highly structured error curve tracks the rapidly varying echelle blaze sensitivity.
The right panel depicts the observation time line. Each exposure start is marked by a vertical bar spanning the λ range of the setting (bottom of the frame is 1000 Å; top, 3300 Å). Gray shading delimits FUV modes; upper unshaded zone, NUV. Color coding: orange E140M, blue E140H, green E230M, red E230H.
Data table. Dataset column drills down to the next layer, which holds the contributing exposures. Bottom-most level: o-type subexposures (if n>1). FITS returns a FITS file containing data products. EXTEN=0 is a header describing the target, observation, and processing history. EXTEN=1 contains arrays of wavelength, flux, photometric error, and data quality. If the dataset is an o-type with two or more subexposures, EXTEN=1 is the coadded spectrum, subexp 1 is in EXTEN=2, subexp 2 in EXTEN=3, and so forth. ETC returns an ASCII file of a heavily filtered version of the spectrum, suitable for use with one of the HST Exposure Time Calculators but not suitable for scientific analysis.