Does anyone know where I can find Arecibo's historical data? After much searching, I can find neither hide nor hair of it. It doesn't help that the search results are completely dominated by the news of the relatively recent collapse of the telescope and I didn't come up with anything through their Science Portal.
Arecibo recently opened the Arecibo Observatory Data Archive, which allows folks to obtain data organized by project. About 1800 proposals are listed, although not all of those have data available because not all of the observatory's data has been transferred to its new home at the Texas Advanced Computing Center. There's also an 18 month period during which each group has exclusive access to its Arecibo data.
You can search the database by project name, a particular discipline (astronomy, atmospheric, or planetary science) or by the instrument used on the telescope (e.g. ALFA, X-band radar, etc.). Each project has a blurb about technical details and then information about which data files are available, although you do need to request access:
The access to the information is controlled, meaning that users need to request access to the desired project. Once Data is requested, Arecibo staff needs to validate that the data is outside the proprietary period and perform other checks to ensure no policies are violated.
It looks like if your access is granted, you'll be sent an email with more information on how to download the relevant files.