Deep blank field catalogue for medium- and large-size telescopes

TL;DR

This paper presents a new catalogue of the deepest blank sky regions identified using Delaunay triangulation, aiding calibration and extragalactic studies for medium and large telescopes.

Contribution

It introduces a comprehensive sky-wide catalogue of deep blank fields with minimum 10 arcmin size, accessible via Virtual Observatory tools, and demonstrates its utility for large telescope calibration.

Findings

Catalogue contains the deepest known blank fields.

Tested regions are effective for telescope calibration.

Galactic extinction estimates provided for each field.

Abstract

The observation of blank fields, defined as regions of the sky that are devoid of stars down to a given threshold magnitude, constitutes one of the most relevant calibration procedures required for the proper reduction of astronomical data obtained following typical observing strategies. In this work, we have used the Delaunay triangulation to search for deep blank fields throughout the whole sky, with a minimum size of 10 arcmin in diameter and an increasing threshold magnitude from 15 to 18 in the R band of the USNO-B Catalog of the United States Naval Observatory. The result is a catalogue with the deepest blank fields known so far. A short sample of these regions has been tested with the 10.4m Gran Telescopio Canarias, and it has been shown to be extremely useful for medium and large size telescopes. Because some of the regions found could also be suitable for new extragalactic studies, we have estimated the galactic extinction in the direction of each deep blank field. This catalogue is accessible through the Virtual Observatory tool TESELA, and the user can retrieve - and visualize using Aladin - the deep blank fields available near a given position in the sky.