Pathfinder Testbed

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Pathfinder Testbed

Post by Borislav on 3rd September 2010, 3:40 am

We installed Pathfinder at HET in March 2010 and conducted two test runs in April and May 2010. While pathfinder has achieved ~7 m/sec on the laboratory tests using a solar integrated light (Ramsey et al3), that was over hours and with a relatively large amplitude signal of ~300 m/sec. With the goal of 1-3 m/sec over months time scales it is critical to conduct telescope observation on real stellar targets. For this initial runs, we chose two relative bright relatively stable radial velocity targets. The first is the giant star HD106714 is known to be stable to ~10m/s. Binned velocities from 3 nights show a scatter of 11.3 m/s. Including the first two nights (where the instrument was still thermally stabilizing) and ~23m/s for all seven nights during the May run. The second target, Sigma Draconis, a know radial velocity stable star, was also observed. The binned velocities show a scatter of ~16.8 m/s including data from all nights and all observations in May. The HD106714 results are in Figure 6. These results are based on a preliminary analysis which we hope to refine in the coming months. We have additional data, including from our April 2010 run under analysis. All observations were taken in the same region in the Y band.

The fiber-fed Pathfinder instrument coupled to the HET is a very stable high resolution NIR spectrograph. Even in this testbed form we have demonstrated the ability to achieve 10-20m/s on stars. The next tests are planned for August 2010 where we will attempt to use a laser frequency comb developed at NIST. After that run we will return Pathfinder to Penn State for a planned upgrade to Pathfinder II incorporating what we have learned. We will substantially increase the efficiency and stability. A planned replacement of the current detector to a H2RG will significantly increase the wavelength coverage as well. Our goal with Pathfinder II is to attempt to achieve < 5m/s precision in the NIR in this next version which will be the final step before the implementation of a facility class instrument.


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