HPF Details
The HPF team is currently maintaining the HPF documentation control of HPF. You can find the details at:
https://psuastro.github.io/HPF/Home/
Additional, the following are excellent technical resources for the instrument and its calibration:
https://arxiv.org/abs/1808.00557
https://arxiv.org/abs/1902.00500
Brief overview:
- HPF is a highly stable fiber fed high precision radial velocity (RV) spectrograph
- Observing range: 810 - 1280 nm
- Science, sky, and calibration fibers are octagonal and 1.7" diameter
- Cross-dispersed echelle spectrograph with 28 orders providing R=lam/dlam~53,000
- RV precision of 1.53 m/s (RMS) has been reached
- Fiber scrambler and agitator contribute to high precision, as does laser frequency comb.
Spectrograph
HPF is a vaccuum-housed cross-dispersed echelle spectrograph with resolving power of R=lam/dlam~53,000. The 28 echelle orders cover 810nm to 1280nm with small gaps between orders. The spectra are recorded on a 2048x2048 Hawaii-2 (H2RG) HgCdTe detector with a 1.7um long wavelength cutoff.
Fiberhead
The HPF fiberhead sits on the focal plane at prime focus and sends light down to the spectrograph room. The image below shows the HPF fiberhead:
We are currently using one of the 1.7" octagonal fibers for science and another for sky observations. The light through the fibers gets scrambled with high-performance ball-lens scramblers and agitated with torsional oscillations to the fiber at a few Hz. The calibration fiber travels along this same path.
See our page on setup methods for more information about choosing the best setup for your target here.
Calibration
The Laser Frequency Comb (LFC) provides high-precision wavelength solutions, and is described in greater detail here. In short, its light can be sent down the calibration fiber and be used for extremely good calibration for relatively bright targets.
Hollow cathode lamps are used for calibrations and there is also a Fabry Perot Etalon calibration system is the back-up wavelength calibrator in case the LFC is unavailable.
HPF Acquisition Camera/CFB
A coherent fiber bundle (CFB) is also used as an acquisition camera for brighter (Imag<11) sources. It is located nearby the science fiber and has a very fine pixel scale for accurate targeting. Sources can be moved from the CFB onto the science fiber using a pre-determined offset.
Last updated: Sat, 30 Dec 2023 03:23:03 +0000 stevenj
|
