  Intense geomagnetic storms can have a strong impact on the signals (termed
ionospheric scintillations) emitted by any global navigation satellite system
(GNSS). The paper reports the first studies of scintillations at the Indore
region on the NavIC signals due to the impact of the intense geomagnetic storm
event reported on September 8, 2017, at 0151 and 1304 UT. The variation of the
planetary indices as well as the DST index which dropped to a value of -124 nT
on September 8, 2017, indicates the occurrence of an intense geomagnetic storm
on September 8, 2017. The observations presented are carried out at Indore,
which is located at the equatorial anomaly crest. The S4 index measurements of
colocated GNSS receiver showed values of 0.5 or above on the disturbed day
between 15 and 18 UT. The analysis presented clearly signifies the degradation
of the carrier to noise measurements of the NavIC L5 signal during the same
time, which in turn affected the positional accuracy of NavIC, an important
consideration for performance.
