Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy

Details Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy

2010-07-05

arxiv.org/abs/1007.0648v1

Astronomy and Astrophysics

Astrophysics

Instrumentation and Methods for Astrophysics

18 pages, 13 figures, accepted for publication MNRAS July 2010

Scientific paper

We report on the limitations of sky subtraction accuracy for long duration fibre-optic multi-object spectroscopy of faint astronomical sources during long duration exposures. We show that while standard sky subtraction techniques yield accuracies consistent with the Poisson noise limit for exposures of 1 hour duration, there are large scale systematic defects that inhibit the sensitivity gains expected on the summation of longer duration exposures. For the AAOmega system at the Anglo-Australian Telescope we identify a limiting systematic sky subtraction accuracy which is reached after integration times of 4-10 hours. We show that these systematic defects can be avoided through the use of the fibre nod-and-shuffle observing mode, but with potential cost in observing efficiency. Finally we demonstrate that these disadvantages can be overcome through the application of a Principle Components Analysis sky subtraction routine. Such an approach minimise systematic residuals across long duration exposures allowing deep integrations. We apply the PCA approach to over 200 hours of on-sky observations and conclude that for the AAOmega system the residual error in long duration observations falls at a rate proportional to t^-0.32 in contrast to the t^-0.5 rate expected from theoretical considerations. With this modest rate of decline, the PCA approach represents a more efficient mode of observation than the nod-and-shuffle technique for observations in the sky limited regime with durations of 10-100 hours (even before accounting for the additional signal-to-noise and targeting efficiency losses often associated with the N+S technique).[abridged]

Affiliated with

Also associated with

No associations

Rating

Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sky subtraction at the Poisson limit with fibre-optic multi-object spectroscopy will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-594774