Suppressing speckle noise for simultaneous differential extrasolar planet imaging (SDI) at the VLT and MMT

Beth A. Biller, Laird M Close, Rainer Lenzen, Wolfgang Brandner, Donald W Mccarthy, Eric Nielsen, Stephan Kellner, Markus Hartung

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We discuss the instrumental and data reduction techniques used to suppress speckle noise with the Simultaneous Differential Imager (SDI) implemented at the VLT and the MMT. SDI uses a quad filter to take images simultaneously at 3 wavelengths surrounding the 1.62 μm methane bandhead found in the spectrum of cool brown dwarfs and gas giants. By performing a difference of images in these filters, speckle noise from the primary can be significantly attenuated, resulting in photon noise limited data. Non-trivial data reduction tools are necessary to pipeline the simultaneous differential imaging. Here we discuss a custom algorithm implemented in IDL to perform this reduction. The script performs basic data reduction tasks but also precisely aligns images taken in each of the filters using a custom shift and subtract routine. In our survey of nearby young stars at the VLT and MMT (see Biller et al, this conference), we achieved H band contrasts >25000 (5σ ΔF1(1.575 μm) >10.0 mag, ΔH > 11.5 mag for a T6 spectral type object) at a separation of 0.5″ from the primary star. We believe that our SDI images are among the highest contrast astronomical images ever made from ground or space for methane rich companions.

Original languageEnglish (US)
Pages (from-to)571-575
Number of pages5
JournalProceedings of the International Astronomical Union
Volume1
DOIs
StatePublished - 2005

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speckle
extrasolar planets
planet
data reduction
filter
filters
methane
stars
wavelength
shift
photons
gases
gas
wavelengths
customs

Keywords

  • (Stars:) planetary systems
  • Instrumentation: adaptive optics
  • Methods: data analysis
  • Techniques: image processing

ASJC Scopus subject areas

  • Astronomy and Astrophysics

Cite this

Suppressing speckle noise for simultaneous differential extrasolar planet imaging (SDI) at the VLT and MMT. / Biller, Beth A.; Close, Laird M; Lenzen, Rainer; Brandner, Wolfgang; Mccarthy, Donald W; Nielsen, Eric; Kellner, Stephan; Hartung, Markus.

In: Proceedings of the International Astronomical Union, Vol. 1, 2005, p. 571-575.

Research output: Contribution to journalArticle

Biller, Beth A. ; Close, Laird M ; Lenzen, Rainer ; Brandner, Wolfgang ; Mccarthy, Donald W ; Nielsen, Eric ; Kellner, Stephan ; Hartung, Markus. / Suppressing speckle noise for simultaneous differential extrasolar planet imaging (SDI) at the VLT and MMT. In: Proceedings of the International Astronomical Union. 2005 ; Vol. 1. pp. 571-575.
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