A Precise Photometric Ratio via Laser Excitation of the Sodium Layer I: One-photon Excitation Using 342.78 nm Light. (arXiv:2001.10958v2 [astro-ph.IM] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Albert_J/0/1/0/all/0/1">J. Albert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Budker_D/0/1/0/all/0/1">D. Budker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chance_K/0/1/0/all/0/1">K. Chance</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gordon_I/0/1/0/all/0/1">I. E. Gordon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bustos_F/0/1/0/all/0/1">F. Pedreros Bustos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pospelov_M/0/1/0/all/0/1">M. Pospelov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rochester_S/0/1/0/all/0/1">S. M. Rochester</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sadeghpour_H/0/1/0/all/0/1">H. R. Sadeghpour</a>
The largest uncertainty on measurements of dark energy using type Ia
supernovae is presently due to systematics from photometry; specifically to the
relative uncertainty on photometry as a function of wavelength in the optical
spectrum. We show that a precise constraint on relative photometry between the
visible and near-infrared can be achieved at upcoming survey telescopes (such
as at the Vera Rubin Observatory [VRO]) via a mountaintop-located laser source
tuned to the 342.78 nm vacuum excitation wavelength of neutral sodium atoms.
Using a high-power (500 W) laser modified from laser guide star studies, this
excitation will produce an artificial star (which we term a “laser photometric
ratio star,” or LPRS) of de-excitation light in the mesosphere that is
observable from the ground at approximately 20 magnitude (i.e., well within the
expected single-image magnitude limit of VRO) at wavelengths in vacuum of
589.16 nm, 589.76 nm, 818.55 nm, and 819.70 nm, with the sum of the numbers of
589.16 nm and 589.76 nm photons produced by this process equal to the sum of
the numbers of 818.55 nm and 819.70 nm photons, establishing a precise
calibration ratio between, for example, the VRO r and z filters. This technique
can thus provide a novel mechanism for establishing a spectrophotometric
calibration ratio of unprecedented precision, from above most of the Earth’s
atmosphere, for upcoming telescopic observations across astronomy and
atmospheric physics.
This article is the first in a pair of articles on this topic. The second
article of the pair describes an alternative technique to achieve a similar,
but brighter, LPRS than the technique described in this paper, by using two
mountaintop-located lasers, at optical frequencies approximately 4 GHz away
from resonances at wavelengths in vacuum of 589.16 nm and 819.71 nm
respectively.
The largest uncertainty on measurements of dark energy using type Ia
supernovae is presently due to systematics from photometry; specifically to the
relative uncertainty on photometry as a function of wavelength in the optical
spectrum. We show that a precise constraint on relative photometry between the
visible and near-infrared can be achieved at upcoming survey telescopes (such
as at the Vera Rubin Observatory [VRO]) via a mountaintop-located laser source
tuned to the 342.78 nm vacuum excitation wavelength of neutral sodium atoms.
Using a high-power (500 W) laser modified from laser guide star studies, this
excitation will produce an artificial star (which we term a “laser photometric
ratio star,” or LPRS) of de-excitation light in the mesosphere that is
observable from the ground at approximately 20 magnitude (i.e., well within the
expected single-image magnitude limit of VRO) at wavelengths in vacuum of
589.16 nm, 589.76 nm, 818.55 nm, and 819.70 nm, with the sum of the numbers of
589.16 nm and 589.76 nm photons produced by this process equal to the sum of
the numbers of 818.55 nm and 819.70 nm photons, establishing a precise
calibration ratio between, for example, the VRO r and z filters. This technique
can thus provide a novel mechanism for establishing a spectrophotometric
calibration ratio of unprecedented precision, from above most of the Earth’s
atmosphere, for upcoming telescopic observations across astronomy and
atmospheric physics.
This article is the first in a pair of articles on this topic. The second
article of the pair describes an alternative technique to achieve a similar,
but brighter, LPRS than the technique described in this paper, by using two
mountaintop-located lasers, at optical frequencies approximately 4 GHz away
from resonances at wavelengths in vacuum of 589.16 nm and 819.71 nm
respectively.
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