TCO Echelle Spectra of Hot Supergiants

The archive is integrated into the Kazakhstan National Virtual Observatory (KazVO) data services and optimized for the IVOA Simple Spectral Access Protocol (SSAP). **Data Specification:**

• Data Type: Medium-resolution optical echelle spectra.
• File Format: FITS (Flexible Image Transport System).
• Data Representation: 1D merged (stitched) spectra.
• Flux Calibration: Relative intensity, normalized to the continuum. **Observational Setup and Instrumentation:**
• Observatory: Three College Observatory (TCO), North Carolina, USA
• Telescope: 0.81-m Ritchey-Chretien telescope
• Instrument: Fiber-fed echelle spectrograph eShel
• Spectrograph Manufacturer: Shelyak Instruments **Spectral Characteristics:**
• Spectral Range: Approximately 3900 - 7800 Angstroms (precise wavelength boundaries are frame-dependent and fixed within individual FITS headers).
• Spectral Resolution: R approx 12,000.
• Wavelength Calibration: Executed using a Thorium-Argon (ThAr) reference lamp spectrum. **Data Reduction Pipeline:** Primary and scientific data reduction was performed within the IRAF (Image Reduction and Analysis Facility) environment using standard echelle spectroscopy packages. **Key Reduction Steps:** 1. Pre-processing: Bias frame subtraction. 2. Extraction: Localization and extraction of individual echelle orders. 3. Dispersion Relation: Wavelength calibration based on ThAr reference frames. 4. Order Merging: Stitching of discrete spectral orders into a continuous 1D array. 5. Kinematic Correction: Application of the heliocentric velocity correction (documented under the VHELIO FITS header keyword). 6. Continuum Normalization: Continuum flattening achieved via high-order polynomial fitting.