[Paper Review] Creating updated, scientifically-calibrated mosaic images for the RC3 catalogue

Jung Lin Lee, Róbert Brunner|arXiv (Cornell University)|Dec 3, 2015

Astronomy and Astrophysical Research4 references3 citations

TL;DR

This paper presents a generalized, automated pipeline to create scientifically-calibrated FITS mosaics and color-composite images for all galaxies in the RC3 catalog using SDSS and POSS-II imaging data. By employing a recursive astrometry update algorithm to correct positional inaccuracies in RC3, the method produces high-fidelity mosaics that enable improved source detection, photometry, and multi-wavelength analysis, with all data and software publicly released for broader use in astronomy research.

ABSTRACT

The Third Reference Catalogue of Bright Galaxies (RC3) is a reasonably complete listing of 23,011 nearby, large, bright galaxies. By using the final imaging data release from the Sloan Digital Sky Survey, we generate scientifically-calibrated FITS mosaics by using the montage program for all SDSS imaging bands for all RC3 galaxies that lie within the survey footprint. We further combine the SDSS g, r, and i band FITS mosaics for these galaxies to create color-composite images by using the STIFF program. We generalized this software framework to make FITS mosaics and color-composite images for an arbitrary catalog and imaging data set. Due to positional inaccuracies inherent in the RC3 catalog, we employ a recursive algorithm in our mosaicking pipeline that first determines the correct location for each galaxy, and subsequently applies the mosaicking procedure. As an additional test of this new software pipeline and to obtain mosaic images of a larger sample of RC3 galaxies, we also applied this pipeline to photographic data taken by the Second Palomar Observatory Sky Survey with $B_J$, $R_F$, and $I_N$ plates. We publicly release all generated data, accessible via a web search form, and the software pipeline to enable others to make galaxy mosaics by using other catalogs or surveys.

Motivation & Objective

• Address the lack of uniformly processed, scientifically-calibrated mosaics for the entire RC3 catalog despite its widespread use in galaxy studies.
• Correct positional inaccuracies in the RC3 catalog that hinder accurate mosaicking of large, extended galaxies.
• Develop a generalized software framework applicable to any user-defined catalog and any scientifically-calibrated imaging survey.
• Generate high-fidelity FITS mosaics and color-composite images for all RC3 galaxies within the SDSS and POSS-II survey footprints.
• Enable broader scientific applications such as spectroscopic target selection, source modeling, and multi-band image combination.

Proposed method

• Use the Montage software to create scientifically-calibrated FITS mosaics from SDSS and POSS-II imaging data across multiple bands (g, r, i, BJ, RF, IN).
• Implement a recursive algorithm to determine the correct central position of each RC3 galaxy by iteratively refining astrometry using mosaic outputs.
• Apply the STIFF program to combine g, r, and i band mosaics into color-composite images for visual and scientific analysis.
• Generalize the pipeline to accept user-defined catalogs with source positions, radii, and unique identifiers for arbitrary source lists.
• Integrate the pipeline with standard astronomical tools like Astrometry.net, SExtractor, ds9, and APLpy for downstream processing and visualization.
• Ensure all generated mosaics and updated coordinates are publicly accessible via a searchable web interface and GitHub repository.

Experimental results

Research questions

• RQ1 Can a robust, automated pipeline correct for astrometric inaccuracies in the RC3 catalog to produce scientifically calibrated mosaics of large, bright galaxies?
• RQ2 How effectively can a recursive mosaicking algorithm identify and center on the true optical center of extended RC3 galaxies despite catalog errors?
• RQ3 To what extent can this pipeline be generalized to work with arbitrary catalogs and diverse imaging surveys, including legacy photographic plates?
• RQ4 What improvements in image fidelity and scientific utility are achieved by using the final SDSS DR10 data release versus earlier data releases?
• RQ5 How can multi-band mosaics from different surveys be combined to enhance morphological and photometric analysis of galaxies?

Key findings

• The pipeline successfully generated scientifically-calibrated FITS mosaics for all RC3 galaxies within the SDSS DR10 footprint, correcting for positional inaccuracies in the original catalog.
• The recursive astrometry update algorithm significantly improved source centering, enabling accurate mosaicking of large, extended galaxies that were previously mislocated in the RC3 catalog.
• Color-composite images were produced using g, r, and i bands from SDSS, providing high dynamic range and photometric accuracy for morphological studies.
• The pipeline was successfully applied to POSS-II photographic plates (BJ, RF, IN bands), extending coverage to galaxies outside the SDSS footprint with improved astrometric solutions.
• All generated mosaics, updated coordinates, and the full software pipeline are publicly released via a searchable web interface and GitHub, enabling reuse across surveys and catalogs.
• The framework is extensible to future surveys such as DES and LSST, and can be adapted for use with 2MASS, GALEX, or other multi-wavelength datasets.