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

B. A. Biller, L. Close, R. Lenzen, W. Brandner, D. McCarthy, E. Nielsen, M. Hartung

Research output: Contribution to journalConference articlepeer-review

35 Scopus citations


We discuss data reduction techniques and results from the Simultaneous Differential Imager (SDI) implemented at the VLT (Lenzen et al. 2004a) 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 attenuated by a factor of >10 2. 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 commissioning runs at the VLT and MMT, we achieved contrasts up to a factor of 45000 (ΔH=11.7) at a separation of 0.6" from the primary star. With this degree of attenuation, we should be able to image a 2-4 Jupiter mass planet at 5 AU around a 30 Myr star at 10 pc. We believe that our SDI images are the highest contrast astronomical images ever made from ground or space.

Original languageEnglish (US)
Article number136
Pages (from-to)389-397
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue numberPART 1
StatePublished - 2004
Externally publishedYes
EventAdvancements in Adaptive Optics - Glasgow, United Kingdom
Duration: Jun 21 2004Jun 25 2004


  • Adaptive optics
  • Extrasolar planets
  • High contrast imaging
  • Simultaneous differential imaging

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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