Photometric Redshifts and Galaxy Clusters for DES DR2, DESI DR9, and HSC-SSP PDR3 Data

Photometric redshift(photoz)is a fundamental parameter for multi-wavelength photometric surveys,while galaxy clusters are important cosmological probes and ideal objects for exploring the dense environmental impact on galaxy evolution.We extend our previous work on estimating photoz and detecting galaxy clusters to the latest data releases of the Dark Energy Spectroscopic Instrument(DESI)imaging surveys,Dark Energy Survey(DES)and Hyper Suprime-Cam Subaru Strategic Program(HSC-SSP)imaging surveys and make corresponding catalogs publicly available for more extensive scientific applications.The photoz catalogs include accurate measurements of photoz and stellar mass for about 320,293and 134 million galaxies with r<23,i<24 and i<25 in DESI DR9,DES DR2 and HSC-SSP PDR3 data,respectively.The photoz accuracy is about 0.017,0.024 and 0.029 and the general redshift coverage is z<1,z<1.2 and z<1.6,respectively for those three surveys.The uncertainty of the logarithmic stellar mass that is inferred from stellar population synthesis fitting is about 0.2 dex.With the above photoz catalogs,galaxy clusters are detected using a fast cluster-finding algorithm.A total of 532,810,86,963 and 36,566 galaxy clusters with the number of members larger than 10 is discovered for DESI,DES and HSC-SSP,respectively.Their photoz accuracy is at the level of 0.01.The total mass of our clusters is also estimated by using the calibration relations between the optical richness and the mass measurement from X-ray and radio observations.The photoz and cluster catalogs are available at Science DB(https://www.doi.org/10.11922/sciencedb.o00069.00003)and Paper Data Repository(https://doi.org/10.12149/101089).

A sodium laser guide star coupling efficiency measurement method

A large telescope＇s adaptive optics （AO） system requires one or more bright artificial laser guide stars to improve its sky coverage. The recent advent of a high power sodium laser is perfect for such application. However, besides the output power, other parameters of the laser also have a significant impact on the brightness of the generated sodium laser guide star, mostly in non-linear relationships. When tuning and optimizing these parameters it is necessary to tune based on a laser guide star generation performance metric. Although return photon fluxis widely used, variability of the atmosphere and sodium layer makes it difficult to compare results from different sites or even within a short time period for the same site. A new metric, coupling efficiency, is adopted in our field tests. In this paper, we will introduce our method for measuring the coupling efficiency of a 20W class pulse sodium laser for AO application during field tests that were conducted during 2013-2015.