GOGREEN at Astro Data Lab: A Pilot project to host Gemini-LLP data products at NOIRLab’s CSDC

NOIRLab’s Community Science and Data Center (CSDC) and Gemini Observatory have carried out a pilot project to host reduced and high-level data products generated by the Gemini Large and Long Programs (LLP). As the largest of the first cohort of LLPs, and the first to prepare a data release, the GOGREEN survey team was approached and agreed to collaborate with CSDC’s Astro Data Lab team on this initiative. 


GOGREEN, which is short for “Gemini Observations of Galaxies in Rich Early ENvironments”, is a survey built on multi-object spectroscopy of 26 galaxy clusters in the redshift range 1 < z < 1.5, i.e., representing the Universe when it was only a third of its present age. The First Data Release (DR1), which also includes data assembled by the Gemini Cluster Astrophysics Spectroscopic Survey (GCLASS), coincided with a science workshop on same topic, held on 24-25 August 2020.


In this pilot collaboration, the GOGREEN+GCLASS team released the survey data products simultaneously through the Canadian Astronomy Data Centre (CADC) and NOIRLab’s Astro Data Lab. The data release includes the entire survey file collection, 1-d and 2-d spectra of over 2700 cluster member galaxies, reduced HST images for all GOGREEN clusters, catalogs of cluster and member galaxy properties including individual redshifts and line properties, and extensive collected photometry of these sources comprising over 275,000 measurements. Figure 1 shows all spectra aligned in wavelength in the observed frame.

At Astro Data Lab, the survey catalogs are made available through a Table Access Protocol (TAP) service for easy SQL queries. Through co-location with almost 100 terabytes of other high-value catalogs hosted at Astro Data Lab, users can easily perform cross-matches, opening the potential for powerful analysis and rich scientific return. The survey images have been incorporated into a Simple Image Access (SIA) image cutout service at Astro Data Lab, and the entire survey data collection is exposed through a file service that allows remote access to all files, including through the Astro Data Lab Jupyter notebook server. Figure 2 shows image cutouts of several members of one galaxy cluster, made with the image cutout service at Astro Data Lab.

Finally, the GOGREEN and Astro Data Lab teams have made available Jupyter notebooks that demonstrate various access modes to the data set and which reproduce several results from the Data Release paper.

The successful pilot project informs our process of hosting future LLP data products, and a working group is now under way to define requirements on data formats, metadata fields, and deliverable survey data products for LLPs. Congratulations and thanks to the project team: Michael Balogh and Greg Rudnick for GOGREEN+GCLASS, Oliver Oberdorf for Gemini, Mike Fitzpatrick, Adam Scott, Wendy Huang, and Dara Norman for CSDC / Astro Data Lab.