The following post is by Martha Haynes.
After a lot of blood and sweat (no tears, but insert here: coffee, sleep deprivation, mild cursing, graying of the hair… and HARD WORK!), we are publishing a catalog containing almost 16,000 HI sources detected in the course of the ALFALFA survey. And we estimate we are only 40% done, so that this is called the α.40 catalog.
So, what does it take to make up a catalog that is of real legacy value? In an era when datasets are made public and used by many people, I wonder if everyone appreciates how much work, meticulous attention, and true cleverness is required of a core group of people to make a survey really useful. In this discussion, I should clarify two important points right away: (1) ALFALFA is not a mega-survey like others (SDSS for example) and (2) The ALFALFA team includes no full-time professional staff. We are teaching faculty and a lot of the heavy ALFALFA lifters are graduate students (especially the fearless Cornell EGGs Amélie, Brian, Sabrina, Ann, Betsey, Shan, Manolis and Greg). But, also, ALFALFA is not the first survey Riccardo and I have been involved in, so we had some idea from the start of what would be required: standardized data and data processing, designed from the outset; careful monitoring of the data at every step along the way; lots of documentation/commenting/verification, including some by individuals where feasible; careful design of data products and access tools which are understandable, documented, simple to use and easily transportable; a philosophy that the success of the survey is measured by how many other people use the survey’s data for their own science. As they say in real estate, it’s all about: quality, quality, quality… and documentation, documentation, documentation.
So, how many hours have gone into making up the 40% catalog? I have no idea, but I know it is a lot, not just for me, but for every single one of the co-authors, who have spent time observing (and learning to observe), flagging, making grids, extracting sources, identifying optical counterparts, testing/verifying, analyzing completeness and worrying about what might have gone wrong. For me, the best part of ALFALFA is working with these amazing, smart and fun folks. And now, with α.40 done, I am reminded of what Wing Comdr. Gibson said to Group Capt. Whitworth in the the classic 1955 film The Dam Busters: “…Have a drink to celebrate. We’ve done the trick! ”
The α.40 catalog will be posted on the main ALFALFA website once its associated data paper (Haynes et al. 2011) is accepted for publication… which should be very soon!