Speech of Dr. Tom Diehl (DES) on January 9, 2019

In Sept. 2012 we celebrated DECam's 1st light.

Wow! That was more than 6 years ago.   At that time, I could see we had a lot of work ahead of us, but I didn't know what a wild adventure and what a great experience DES Operations would be.

These six years have included more than 750 observing nights shared by 300 DES observers. Each of them has their own personal story to tell - the travel, the beautiful mountaintop, the nights staring at walls of computer screens. The tarantulas, allacrans, viscachas (I know they are not really called kangarabbits) and the zorros, but regrettably not one mountain lion (yet).

The 300 observers have had that many carry-all rides here to Tololo and back down to La Serena. They have slept in the dormitories for approximately 1,500 days and they have eaten more than 5000 fantastic meals here in the Casino.  I'd like to thank you for making those rides and dorm rooms comfortable and the chefs for the fantastic breakfasts, lunches, dinners, and night lunches, and for the special lunches such as this one.

758 nights.  That's so many camera and telescope preparation, daily SISPI restarts 4 o'clock meetings, dome flat calibration runs, uncountable SISPI alarms (chicken squawks, please) and night summaries. I want to thank the Telops Team for their superb support of the observers that resulted in making observing a natural, streamlined experience. I also need to thank the Telops Team, the Computer Support Team, and the Engineering and Technical Staff Team for the awesome reliability of both the stately Victor M. Blanco 4m Telescope and the well, sturdy, Dark Energy Camera.  In the past year the combined systems have been operational more than 99% of the scheduled time. That's an outstanding record. It should be a Bragging Right. 

During these six years I've worked with the excellent CTIO Scientific Staff.  including Kathy, Alfredo, Clare, David, Tim and others, who spent many night training new DES observers and filling in when it was difficult to find collaborators to travel. The leadership provided by CTIO Directors Chris Smith, Nicole van der Bliek, and Steve Heathcote has set the tone for the relationship between CTIO and DES, and that is excellent, I think.

I've saved one special thanks for last. That is for Alistair, for his dedication, expertise, and wisdom. We are certainly comrades in science, and I hope even, friends.

Tonight is the final night of DES observations. Six years ago, I couldn't see this day coming nor imagine what it would be like.  It was an honor to be here for First Light, and we have some of the same people here for DES's "last night": Marcelle, Brenna, Alistair, Klaus (remotely), and myself. It is an honor of the same kind to be here for DES's last Night. Still it's not the end of DES. So far, we have accumulated 100,000 observations spanning 1/8th of the night sky. Using the first 1/2 of those observations We have detected dozens of new objects in our solar system, many dwarf Milky Way Galaxies and Stellar streams, and 400 million galaxies. Using the first season of those observations we have produced cosmology results as good or better than every other experiment that exists. We have just started the cosmology, and when we are finished with the results that include those from tonight, our results will be the best. I predict they will be tough to surpass.

It's not the end for DECam or the Blanco Telescope, either. Observers will continue to come here and use it to do their own excellent science for years to come. I hope and am sure that their experience here at CTIO, and using the camera and telescope will be just as good as ours has been. And I expect that you will see many of us from DES here again – maybe soon.

Again, this has been a marvelous six-year adventure in science.

One more time, a heartfelt thank-you from all of DES to all of you. Thank-you.

Tom Diehl

Jan 9, 2019