Mark Megahan
Thanks to a new “tunable” filter, the world’s most powerful solar telescope became even more precise. The closest star to Earth, Sol, is the one we know the least about. Just a glimpse of it with the naked eye is enough to fry your optic nerve, so ordinary telescopes are totally useless. The National Science Foundation can now capture “an unprecedented amount of detail.”
Visible Tunable Filter
The Science Foundation recently made public an image “taken during the first-light observation of the new Visible Tunable Filter.”
That’s a brand new instrument attached to the Daniel K. Inouye Solar Telescope, at the summit of Maui’s Mt. Haleakalā. It’s long been described as “the world’s most powerful solar telescope.”
That was before it got the new filter. The “first-light” test image shows the incredibly detailed “intricacies” of a sunspot cluster.
Dark spots on the surface of the Sun are produced by strong magnetic fields. To increase accuracy, the VTF “is designed to isolate specific wavelengths of light.”
Astronomers choose the colors they want exposed and the tunable filter scan’s right through them, “allowing scientists to take hundreds of narrowband images in just seconds.”
Combining that with DKIST’s massive 4-meter mirror, “means its images are also the highest resolution solar images ever acquired.”
Useful to study Doppler shifts
The image going viral in the news was captured at precisely 588.9 nanometers of light wavelength. That’s a particularly useful frequency for the experts because it’s the same part of the spectrum as light created by sodium atoms in the Sun’s atmosphere.
Setting the filter to that notch is “useful to study Doppler shifts due to the surface’s motion, solar flares, and much more.”
To put the accuracy of the image into perspective, the filter allows each individual pixel of the photograph to cover a mere 10 kilometers (6.2 miles) of solar surface.
The team conveniently put a map of the U.S. into the image to show scale.
It’s taken more than ten years to get the VTF from the drawing board to installation. While they’re still getting it warmed up and properly calibrated, scientists are excited about “how compelling future results will be.”
According to KIS VTF Project Scientist Dr. Matthias Schubert, the filter is the greatest thing since the invention of the wheel. “The significance of the technological achievement is such that one could easily argue the VTF is the Inouye Solar Telescope’s heart, and it’s finally at its forever place.“
