Spectrophotometry: Imaging with custom narrow-band filters and an automated data-reduction pipeline

Kieran P. Forde, Raymond F. Butler, David Peat, Aaron Golden, Seathrun O'Tuairisg

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Abundance variations of carbon and nitrogen in globular star clusters provide astronomers with a means to determine a cluster's evolutionary past. Moreover, these clusters are so ancient (∼13 billion years) and so well preserved that they provide an ideal diagnostic for the overall chemical history of the Milky Way Galaxy. Traditionally, spectroscopy is the preferred method to perform investigations into such theories. However, it is not without its drawbacks: spectroscopy can normally only be obtained star by star, and both large telescopes and a great deal of time is required to carry out research in this manner. As globular clusters are known to contain up to a million stars, studying each star individually would take too much time to return a true representative sample of the cluster stars. So, we opt instead for a spectrophotometric technique and a statistical approach to infer a cluster's composition variations. This has required the design and use of new custom narrow- band filters centered on the CH and CN molecular absorption bands or their adjacent continua. Two Galactic clusters (M71 & M92) with contrasting characteristics have been chosen for this study. In order to process this data a header-driven (i.e. automated) astronomical data-processing pipeline was developed for use with a family of CCD instruments known as the FOSCs. The advent of CCD detectors has allowed astronomers to generate large quantities of raw data on a nightly basis, but processing of this amount of data is extremely time and resource intensive. In our case the majority of our cluster data has been obtained using the BFOSC instrument on the 1.52m Cassini Telescope at Loiano, Italy. However, as there are a number of these FOSC instruments throughout the world, our pipeline can be easily adapted to suit any of them. The pipeline has been tested using various types of data ranging from brown dwarf stars to globular cluster images, with each new dataset providing us with new problems/bugs to solve and overcome. The pipeline performs various tasks such as data reduction including image de-fringing, image registration and photometry, with final products consisting of RGB colour images and colour magnitude diagrams (CMD).

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsF.D. Murtagh
Pages216-224
Number of pages9
Volume5823
DOIs
StatePublished - 2005
Externally publishedYes
EventOpto-Ireland 2005: Imaging and Vision - Dublin, Ireland
Duration: Apr 5 2005Apr 6 2005

Other

OtherOpto-Ireland 2005: Imaging and Vision
CountryIreland
CityDublin
Period4/5/054/6/05

Fingerprint

data reduction
Spectrophotometry
spectrophotometry
Stars
narrowband
Data reduction
Pipelines
Imaging techniques
filters
stars
star clusters
globular clusters
charge coupled devices
brown dwarf stars
telescopes
Milky Way Galaxy
molecular absorption
headers
galactic clusters
color-magnitude diagram

Keywords

  • Abundances
  • Filters
  • Globular Clusters
  • Pipeline

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Forde, K. P., Butler, R. F., Peat, D., Golden, A., & O'Tuairisg, S. (2005). Spectrophotometry: Imaging with custom narrow-band filters and an automated data-reduction pipeline. In F. D. Murtagh (Ed.), Proceedings of SPIE - The International Society for Optical Engineering (Vol. 5823, pp. 216-224). [32] https://doi.org/10.1117/12.605179

Spectrophotometry : Imaging with custom narrow-band filters and an automated data-reduction pipeline. / Forde, Kieran P.; Butler, Raymond F.; Peat, David; Golden, Aaron; O'Tuairisg, Seathrun.

Proceedings of SPIE - The International Society for Optical Engineering. ed. / F.D. Murtagh. Vol. 5823 2005. p. 216-224 32.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Forde, KP, Butler, RF, Peat, D, Golden, A & O'Tuairisg, S 2005, Spectrophotometry: Imaging with custom narrow-band filters and an automated data-reduction pipeline. in FD Murtagh (ed.), Proceedings of SPIE - The International Society for Optical Engineering. vol. 5823, 32, pp. 216-224, Opto-Ireland 2005: Imaging and Vision, Dublin, Ireland, 4/5/05. https://doi.org/10.1117/12.605179
Forde KP, Butler RF, Peat D, Golden A, O'Tuairisg S. Spectrophotometry: Imaging with custom narrow-band filters and an automated data-reduction pipeline. In Murtagh FD, editor, Proceedings of SPIE - The International Society for Optical Engineering. Vol. 5823. 2005. p. 216-224. 32 https://doi.org/10.1117/12.605179
Forde, Kieran P. ; Butler, Raymond F. ; Peat, David ; Golden, Aaron ; O'Tuairisg, Seathrun. / Spectrophotometry : Imaging with custom narrow-band filters and an automated data-reduction pipeline. Proceedings of SPIE - The International Society for Optical Engineering. editor / F.D. Murtagh. Vol. 5823 2005. pp. 216-224
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