Jeremy Shears

James, it’s difficult to say as it’s so dependent on your specific set-up, plus we have a brightening sky to contend with. If we are going to extract photometry from images, the star and its comparisons should not be saturated. This will result in shorter exposures than you might normally consider to get a “pretty picture” (but a pretty picture would also be nice as this is such a rare event!). Thus it’s best is to bracket with a range of exposures. Also avoid saving as a file type that compresses the image, like jpg, as that will involve loss of data.