# Prospects of the multi-channel photometric survey telescope in the cosmological application of Type Ia supernovae

**Authors:** Zhenyu Wang, Ju-Jia Zhang, Xinzhong Er, Jinming Bai  
**arXiv:** [2404.07246](https://arxiv.org/abs/2404.07246)  
**Date:** 2024-04-10  
**Summary page:** https://www.summarizepaper.com/en/paper/2404.07246v1/

## Key points

- The Multi-channel Photometric Survey Telescope (Mephisto) is a cutting-edge, real-time, three-color photometric system designed for capturing the color evolution of stars and transients.
- Mephisto plays a crucial role in cosmological distance measurements of low-redshift Type Ia supernovae (SNe Ia) with redshift values below approximately 0.1.
- An extensive simulation study was conducted to optimize Mephisto's capabilities, considering factors such as atmospheric extinction, weather conditions, lunar phase, and instrumental features.
- The most effective strategy for SN Ia cosmology involves capturing images with an exposure time of 130 seconds and a cadence of 3 days.
- Mephisto can acquire high-quality SNe Ia observations leading to distance measurements with an accuracy better than 4.5% by collaborating with the Lijiang 2.4 m Telescope at the same observatory.
- While Mephisto may not outperform other large-scale survey telescopes in quantity for SN Ia discoveries, its observational capabilities are unmatched for detecting SNe Ia at lower redshifts.
- Mephisto prides itself on exceptional color calibration precision and conducting simultaneous observations across three spectral bands to mitigate systematic errors from variations in site weather conditions.
- A detailed simulation assessed the accuracy of cosmological parameter estimation under various observation strategies within a fixed observation duration covering 180 deg2 over 200 days, solidifying Mephisto's potential impact on advancing our understanding of supernovae and the universe's dynamics and evolution.

## Summary

The Multi-channel Photometric Survey Telescope (Mephisto) is a cutting-edge, real-time, three-color photometric system specifically designed to accurately capture the color evolution of stars and transients. This innovative telescope system plays a crucial role in cosmological distance measurements of low-redshift Type Ia supernovae (SNe Ia), with redshift values below approximately 0.1. In order to optimize the capabilities of this instrument, an extensive simulation study was conducted prior to its official operation commencement. The simulation study took into account various factors such as atmospheric extinction, weather conditions, and lunar phase at the observing site, while also considering instrumental features. By simulating the light curves of SNe Ia obtained by Mephisto under different conditions, it was determined that the most effective strategy for SN Ia cosmology involves capturing images with an exposure time of 130 seconds and a cadence of 3 days. This approach allows Mephisto to acquire hundreds of high-quality SNe Ia observations, leading to distance measurements with an impressive accuracy better than 4.5%. Furthermore, Mephisto's collaboration with the Lijiang 2.4 m Telescope at the same observatory enables on-time spectral classification and monitoring throughout its operation. This partnership significantly enriches the well-calibrated sample of supernovae at low redshifts and enhances the calibration accuracy of high-redshift SNe Ia. While Mephisto may not necessarily outperform other large-scale survey telescopes in terms of sheer quantity when it comes to SN Ia discoveries, its observational capabilities are unmatched when detecting SNe Ia at lower redshifts. The project prides itself on exceptional color calibration precision and its unique ability to conduct simultaneous observations across three spectral bands. These features prove instrumental in mitigating systematic errors stemming from variations in site weather conditions. A detailed simulation for Mephisto was carried out to assess the accuracy of cosmological parameter estimation under various observation strategies within a fixed observation duration covering 180 deg2 over a span of 200 days. The optimal observation strategy identified through this simulation study further solidifies Mephisto's potential impact on advancing our understanding of supernovae and contributing valuable insights into the dynamics and evolution of our universe.