Comet C/2021 A2 (NEOWISE) cyanogen CN radical gas coma diameter 1,7'/50000km and wide fan-shaped cyanogen gas tail length 3,4'/100000km towards PA 10° is visible in this 3870Å narrowband filter image. Comet distance from sun is 1,46au so the sun heat and UV radiation is strong enough to sublimate comet icy surface and photodissociate gases like CN at 3883Å.
Image 1) 30x180s=90min with CN 387nm narrowband filter at 2021-02-16 20:15-21:50UT
Image 2) Processed cropped image 1 with CometCIEF to enhance coma and tail morphology. No significant details visible.