# Spectrophotometry of Very Bright Stars in the Southern Sky

## TL;DR

This study presents spectroscopic observations of 26 bright southern stars using a 1.5-m telescope, establishing a Sirius-based calibration system for stellar and extragalactic photometry.

## Contribution

It introduces a new Sirius-based spectrophotometric calibration system derived from observations of bright stars, improving upon previous methods using Vega.

## Key findings

- Spectra of 26 bright southern stars obtained and calibrated.
- A Sirius-based system established for stellar photometry.
- Potential for improved calibration standards in astronomy.

## Abstract

We obtained spectra of 26 bright stars in the southern sky, including Sirius, Canopus, Betelgeuse, Rigel, Bellatrix, and Procyon, using the 1.5-m telescope at Cerro Tololo Inter-American Observatory and its grating spectrograph RCSPEC. A 7.5 magnitude neutral density filter was used to keep from saturating the CCD. Our spectra are tied to a Kurucz model of Sirius with T = 9850 K, log g = 4.30, and [Fe/H] =+0.4. Since Sirius is much less problematic than using Vega as a fundamental calibrator, the synthetic photometry of our stars constitutes a Sirius-based system that could be used as a new anchor for stellar and extragalactic photometric measurements.