I've been pulling the ETC/USD hourly close price using Coinbase's Candle API (https://api.pro.coinbase.com/products/ETC-USD/candles?start=2020-09-30T19:00:00&end=2020-09-30T20:00:00&granularity=3600). Based on this API the close price for 19:00 was $5.711 and based on my understanding the close price is struck at 19:59:59. Additionally the strike is based off the last trade price prior to that specific time.
Usually I compare the data to another source to verify the integrity of it and I noticed with this particular date the close price was different between the two sources. On further investigation I'm having some trouble understanding what's occurring and hoping someone can clarify.
In order to investigate I ran the same Coinbase API but with a granularity of 60 (1 minute) (https://api.pro.coinbase.com/products/ETC-USD/candles?start=2020-09-30T19:50:00&end=2020-09-30T20:05:00&granularity=60). Based on the returned results the last data point prior to 20:00 was at 19:57 and that close price was $5.723.
Is there a reason why the close price between these two API results are different or is there something that I'm missing or misunderstanding?
Thank you for any help you can provide!