Abstract
Over the past five years, 2010-2015, we have observed, in the near infrared
(IR), the maximum magnetic field strengths for 4145 sunspot umbrae. Herein we
distinguish field strengths from field flux. (Most solar magnetographs measure
flux). Maximum field strength in umbrae is co-spatial with the position of
umbral minimum brightness (Norton and Gilman, 2004). We measure field strength
by the Zeeman splitting of the Fe 15648.5 A spectral line. We show that in the
IR no cycle dependence on average maximum field strength (2050 G) has been
found +/- 20 Gauss. A similar analysis of 17,450 spots observed by the
Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory reveal
the same cycle independence +/- 0.18 G., or a variance of 0.01\%. This is found
not to change over the ongoing 2010-2015 minimum to maximum cycle. Conclude the
average maximum umbral fields on the Sun are constant with time.
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