I'm trying to find a short story that I read in some collection of early science fiction. The premise is that scientists detect that the light from a huge star is going to arrive. Everyone is looking forward to it, but when it reaches us it's immensely strong and destroys the earth. I remember a vivid image of a flag, struck by the light of the first new "sunrise," bursting into flames. Not strong on the science, perhaps. But kind of prescient.
I suspect this is Finis by Frank Lillie Pollock, which I have already identified as a possible answer to Bright centre of the Universe. It was published in 1906, which is certainly early in science fiction terms. I read in the anthology This Way to the End Times, which is rather more recent having been published in 2016.
The premise is that the universe is finite and like a massive Solar System having a huge star at the centre with the rest of the stars in the universe revolving around it. At the time of the story the light from this massive central star is about to reach Earth and fry it.
The scene you remember with the flag is:
Mrs. Davis suddenly screamed. An American flag blowing freely from its staff on the roof of the tall building had all at once burst into flame. Low in the east lay a long streak of intense fire which broadened as they squinted with watering eyes. It was as if the edge of the world had been heated to whiteness
It ends as the light from the star is dawning over Earth:
This is the end, Alice,” said Eastwood, and his voice trembled.
She looked at him, her eyes shining with an unearthly softness and brilliancy, and turned her face to the east.
There, in crimson and orange, flamed the last dawn that human eyes would ever see.
The story can be read on the Project Gutenberg web site.