The first plate, taken the previous night. It looks more or less the same as the plate in the previous post, without any markings on it.

Notices where this attachment appears

1. Robert McNees (mcnees@mastodon.social)'s status on Friday, 06-Oct-2023 15:41:04 UTC Robert McNees

   in reply to

   You can see three marks "N" on the plate where Hubble identified novae.

   Comparing with a plate taken the night before, he realized that the brightness of one was changing. Recognizing a Cepheid variable star, he crossed out the "N" and wrote ‘VAR!’

   Here are the plates side-by-side. H331H was taken the previous night, a 40-minute exposure with poor seeing conditions. Plate H335H, which revealed the Cepheid, was a slightly longer exposure under better conditions.

   Image: Carnegie Observatories