Photometric Calibration on Lunar-based Ultraviolet Telescope for Its First Six Months of Operation on Lunar Surface

TL;DR

This paper details the photometric calibration of the Lunar-based Ultraviolet Telescope (LUT) during its first six months on the lunar surface, demonstrating its stable performance and consistent magnitude zero points across two spectral datasets.

Contribution

It presents the first calibration of a lunar-based ultraviolet telescope, establishing its stability and accuracy over initial operation months.

Findings

LUT's photometric performance remained highly stable during the first six months.

The magnitude zero points from two spectral datasets are consistent within uncertainties.

Calibration results confirm LUT's reliable operation on the lunar surface.

Abstract

We reported the photometric calibration of Lunar-based Ultraviolet telescope (LUT), the first robotic astronomical telescope working on the lunar surface, for its first six months of operation on the lunar surface. Two spectral datasets (set A and B) from near-ultraviolet (NUV) to optical band were constructed for 44 International Ultraviolet Explorer (IUE) standards, because of the LUT's relatively wide wavelength coverage. Set A were obtained by extrapolating the IUE NUV spectra ($\lambda<3200\AA$) to optical band basing upon the theoretical spectra of stellar atmosphere models. Set B were exactly the theoretical spectra from 2000\AA\ to 8000\AA\ extracted from the same model grid. In total, seven standards have been observed in 15 observational runs until May 2014. The calibration results show that the photometric performance of LUT is highly stable in its first six months of operation. The magnitude zero points obtained from the two spectral datasets are also consistent with each other, i.e., $\mathrm{zp=17.54\pm0.09}$mag (set A) and $\mathrm{zp=17.52\pm0.07}$mag (set B).