Using THELI pipeline in order to reduce Abell 226 multi-band optical images

TL;DR

This paper reviews the THELI pipeline for reducing multi-band optical images, demonstrating its application to Abell 226 and emphasizing photometric calibration and data quality assessment.

Contribution

It presents a detailed application of the THELI pipeline to Abell 226 images, highlighting improvements in photometric calibration and data reduction strategies.

Findings

Successful reduction of multi-band images with THELI pipeline

Effective photometric calibration using cross-association with reference catalogues

High-quality deep co-added mosaic images achieved

Abstract

In this paper we review THELI (Erben & Schrimer, 2005), an image processing pipeline developed to reduce multi-pointing optical images taken by mosaic CCD cameras. This pipeline works on raw images by removing several instrumental contaminations, implementing photometric calibration and astrometric alignment, and constructing a deep co-added mosaic image complemented by a weight map. We demonstrate the procedure of reducing NGC3923 images from raw data to the final results. We also demonstrate the quality of our data reduction strategy using mag-count and mag-error in mag plots. Emphasis is mainly placed on photometric calibration which is of great interest to us due to our scientific case. Based on the cross-association of the extracted catalogue against a reference catalogue of stellar magnitudes, zero-point calibration is performed. Our data reduction strategy and the method employed for cross-correlating large catalogues is also presented.