Sunshine cards serve as a physical measure of the sun’s position and strength for a given time and location on Earth. Sunshine cards from South Pole are created with two Campbell-Stokes recorders. Around most of the world, only one recorder is used at a location. However, south of the Antarctic circle during austral summer, the sun works its way around the entire azimuthal angle of the sky. One recorder cannot then capture the sun’s entire daily traversal. Thus, each day typically has two cards, one from each recorder. Cards are bundled by month, making five bundles for the year 2023.

Notes on missing, damaged, or unlabeled data

January

• No cards dated for the 22nd.

• Four cards dated for the 21st. Given that there are no cards for the 22nd and there should only be two cards per day, it seems likely that one set of the cards from the 21st are dated incorrectly.

• No card labeled for Recorder #1 for the 27th. However, a damaged card with the dated portion ripped off matches the expected burn pattern. Thus, the damaged card is likely the missing card.

February

• No cards labeled for the 8th, 18th, 20th, and 24th.

• Two unlabeled cards. However, by comparing the burn marks with other dated cards, it is likely that they are the missing cards from the 8th.

• Three cards labeled as the 16th, four cards labeled as the 19th, and three cards labeled as 21st. Given that there should only be two cards per day, and these are around the dates of other missing cards, it seems plausible that some of the cards are dated incorrectly.

November

• Four cards that are undated.

• No cards dated for the 10th or 12th.

• No cards for Recorder #2 for the 11th, 13th, and 29th.

December

• For December 1st, the card from Recorder #2 is missing its lower half as it appears the sun burn cut it off.

• Two undated cards. These are assumed to be for the 4th, as that is the only day missing cards in December. Additionally, the burn marks are nearly identical to surrounding cards, indicating they are from that period.