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We are happy to share with you the latest Astro Data Lab news in this January 2025 newsletter!

In this newsletter

Data Lab at AAS 245 in National Harbor, Maryland

Data Lab team members will be at the AAS 245 winter meeting in National Harbor, Maryland. Come find us at the NOIRLab booth #105D within the larger NSF pavilion, grab some new Data Lab postcards, watch a live demo of some of our Jupyter notebooks and website, and chat with team members Alice Jacques, David Hererra, and Brian Merino about starting up and the science you can do with Astro Data Lab. We are also there to do any troubleshooting with our users.

We have several live demos of Data Lab, SPARCL, DRAGONS, GHOST, and NEID scheduled during the week, at the dedicated demo station in the NOIRLab booth #105D. Drop by during any of the following times:

  • Monday, Jan 13:
    • 10am - 11am = Explore large scale structures of galaxies
    • 1pm - 3pm = Reduce Gemini imaging data with DRAGONS
    • 3pm - 4pm = GHOST spectroscopic data reduction
    • 5:30pm - 6:30pm = Search and retrieve spectroscopy data with SPARCL
  • Tuesday, Jan 14:
    • 10am - 11am = NEID: tips for optimizing your proposal
    • 11am - 12pm = GHOST spectroscopic data reduction
    • 2pm - 3pm = Reduce Gemini imaging data with DRAGONS
    • 3pm - 4pm = Explore large scale structures of galaxies
  • Wednesday, Jan 15:
    • 9am - 10am = Search and retrieve spectroscopy data with SPARCL
    • 11am - 12pm = GHOST spectroscopic data reduction
    • 2pm - 3pm = Reduce Gemini imaging data with DRAGONS
    • 4:30pm - 5:30pm = Explore large scale structures of galaxies
  • Thursday, Jan 16:
    • 9am - 10am = GHOST spectroscopic data reduction

On Thursday Jan 16 at 1-2pm, you are invited to view iPoster 465.04 prepared by student Isabella Olin on "Investigating Galaxy Quenching using SDSS Spectra and Machine Learning Approaches", which features in a new Data Lab Jupyter notebook (details in the New Jupyter Notebooks section below).

New and retired datasets at Data Lab

PGIR DR1

Palomar Gattini-IR (PGIR) is a wide-field, robotic, near-infrared time domain survey covering the entire visible night sky north of declination -28.5 at a median cadence of 2 nights. The survey operates in a single filter (J-band, calibrated to the 2MASS system), with a single exposure field of view of 25 square degrees and a native pixel scale of 8.7 arcsec/pixel. Further details about the instrument and data reduction system can be found in De et al. (2020). Light curves are extracted by performing Point Spread Function (PSF) photometry on the stacked images from each field visit, with the entire observing footprint divided into 1,329 fields. The first data release contains J-band light curves of approximately 286 million sources from the 2MASS catalog, with a total of approximately 50 billion photometric measurements (Murakawa et al. 2024). Read more about PGIR DR1 and how to access the data at Data Lab on our PGIR landing page.

S-PLUS DR4

The data release 4 (DR4) of the Southern Photometric Local Universe Survey (S-PLUS) includes 1,629 fields, covering about 3,000 square degrees. It contains the same regions from the previous DRs (1, 2, and 3) as well as new data from the Magellanic Clouds, the disk of the Galaxy, and some additional high galactic latitude fields. The data reduction is still done the same way but the photometry and the calibration (for all the data in DR4) were done slightly differently, using the most recent version of the pipelines (as described in Herpich et al. 2024). Besides the SExtractor photometry, PSF photometry is also performed - this is very important in the crowded fields of the Magellanic Clouds and the Galactic disk. Astro Data Lab hosts the eight tables released in DR4: the three main tables are psf, dual, and single, and the five Value Added Catalogs (VACs) are calib_flag, qso_z, photoz, splusid, and sqg. Read more about each table on our S-PLUS landing page.

DES Y6 Gold

The Dark Energy Survey is releasing the final catalog of precise measurements of galaxies and stars within the DES 5,000-square-degree footprint in the South Galactic Cap. The Y6 Gold catalog is derived from Data Release 2 and includes all six years of g,r,i,z,Y imaging measurements. Y6 Gold was formulated for the DES final cosmological analyses, but it has very general applicability. Compared to the previous Y3 Gold catalog, the depth, star/galaxy classification, photometric precision, and photometric uniformity are all substantially improved. Y6 Gold contains 669 million objects to i ~ 23.4 (S/N = 10 for extended objects). See more on the DES landing page.

PHAT v3

This is the final legacy version of stellar photometry for the Panchromatic Hubble Andromeda Treasury (PHAT) survey. The team has reprocessed all of the Hubble Space Telescope Wide Field Camera 3 and Advanced Camera for Surveys near-ultraviolet (F275W, F336W), optical (F475W, F814W), and near-infrared (F110W, F160W) imaging from the PHAT survey using an improved method that optimized the survey depth and chip-gap coverage by including all overlapping exposures in all bands in the photometry. An additional improvement was gained through the use of charge transfer efficiency (CTE)–corrected input images, which provide more complete star finding as well as more reliable photometry for the NUV bands, which had no CTE correction in the previous version of the PHAT photometry. The resulting catalog has 138 million stars, 18% more than the previous version, with lower density regions gaining as much as 40% more stars. The new catalog produces nearly seamless population maps that show relatively well-mixed distributions for populations associated with ages older than 1-2 Gyr and highly structured distributions for the younger populations. For more information on the PHAT survey, visit the PHAT data overview page and the PHAT landing page at Data Lab.

DeMCELS DR1

The Dark Energy Camera Magellanic Clouds Emission Line Surveys (DeMCELS) dataset is a compilation of multiple individual programs that used the Dark Energy Camera (DECam) and the narrow-band N662 and N673 filters to map the interstellar component of the Magellanic Clouds to flux limits of a few x 10-18 erg s-1 cm-2 in the Hα and [SII] λλ6716,6731 emission-lines. This first data release only contains LMC data from the Puzia (2018A-0909 and 2018B-0908) and Points (2021B-0060) observations that cover the central 54 deg^2 region of the LMC optical disk. Read more about DeMCELS DR1 and how to access the data on our DeMCELS landing page at Data Lab.

SDSS DR12 galaxy property tables

As part of the large collection of SDSS value-added catalogs (VACs), there are a few distinct catalogs with galaxy properties. Namely, SDSS DR12 contains estimates of stellar masses made by three different groups which are based on different choices of models and assumptions, as described in the respective data models. These stellar mass tables can be useful for comparisons of different estimates so we have added the full set from the Granada, Portsmouth and Wisconsin groups in the following database tables: sdss_dr12.stellarmass_granada, sdss_dr12.stellarmass_portsmouth, and sdss_dr12.stellarmass_wisconsin. You can learn more by reading the section called "Estimated stellar masses in SDSS DR12" on the Data Lab SDSS webpage.

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Data Lab cross-matched tables

The Data Lab team has already crossmatched the PGIR DR1 "sources" table, S-PLUS DR4 "psf" and "dual" tables, and PHAT v3 "phot_mod" table with our reference datasets: Gaia DR3 (for astrometry), AllWISE, NSC DR2, unWISE DR1 (for photometry), and SDSS DR17 (for spectroscopy), and vice versa. We have also added a few other useful columns such as nest4096, ring256, and htm9 for sky tessellation use cases. The pre-crossmatched tables are accessible in the schema browser, and through standard TAP/SQL/ADQL queries, like all other catalogs at Data Lab.

Dataset requests

The Data Lab team evaluates periodically which external survey datasets we should source, ingest, and serve. We appreciate requests and suggestions from our users. Please contact us at datalab@noirlab.edu to send your request and, if possible, mention an example scientific use case.

Retired datasets

The tables in SDSS DR13 (except table galspecline_dr8, which still lives in the SDSS DR13 schema) and SDSS DR14 have been retired from Astro Data Lab, as they are superseded by later data releases.

New Jupyter notebooks

Several new notebooks were recently added to Data Lab’s extensive collection of notebooks for our user community:

Gemini GHOST XX Oph reduction using DRAGONS Python API

Authors: Brian Merino, Vinicius Placco

A data reduction tutorial for one of Gemini Observatory's newest instruments, GHOST, has been added to the Data Lab. This Jupyter Notebook uses the Data Lab's DRAGONS-3.2.2 (DL,Py3.10.14) kernel to reduce IFU data for the star XX Oph taken during GHOST's commissioning run. This tutorial demonstrates how to process the calibration and science data and will generate the final reduced spectra for GHOST's red and blue arms. This notebook was written using the DRAGONS Application Program Interface (API) for Python, based on the example provided in the DRAGONS Documentation.

GHOST

J-band light curves from Palomar Gattini-IR DR1 catalog

Authors: Ryan M. Lau (NSF NOIRLab), Kishalay De (MIT), Shion Murakawa (MIT), Alice Jacques (NSF NOIRLab/CSDC), & the Astro Data Lab Team

This notebook demonstrates how to generate light curves from the Palomar Gattini-IR (PGIR) Data Release 1 (DR1) catalog of infrared J-band light curves and also perform a basic Lomb-Scargle periodogram analysis to identify a period. The science target in this notebook is the enigmatic NaSt1 system (also known as LS IV +005 and WR 122), which is thought to be an early-type wolf-rayet system enshrouded but a dense nebula. We will demonstrate how the PGIR light curves can be used to identify the periodic variability from this system, which was presented by Lau et al. 2021. Below is a plot of the PGIR J-band light curve of our target (NaSt1; pts_key = 673173034).

PGIR lightcurve

SDSS/BOSS Large Scale Structure and the "Cosmic Slime" Catalog

Authors: Isabella Olin (Univ. of Arizona), Stéphanie Juneau (NSF NOIRLab) & the Astro Data Lab Team

This notebook explores the distribution of the matter density in the Coma Cluster using the Cosmic Slime Value Added Catalog (VAC) to investigate the relationship between environment and galaxy quenching. First, we compare the sky coverage between the main SDSS redshift catalog (SpecObj) and the Cosmic Slime VAC as well as their redshift distributions. Noting that the Cosmic Slime data are sparse past redshift z>0.1, the analysis is then focused on the lower redshift range (z<0.1), which is suitable to study the Coma Cluster and reach very dense environments. By creating contours of matter density, we can visualize the distribution of matter in the cluster. Then, the notebook demonstrates how to obtain average stacked SDSS spectra sorted by matter density to look for signs of environment-dependent quenching (figure below).

Cosmic Slime

DESI Legacy Imaging Surveys overview notebook

Authors: David Herrera (NSF NOIRLab), Robert Nikutta (NSF NOIRLab), and the Astro Data Lab Team

This notebook explores the mid-infrared photometry of the DESI Legacy Imaging Surveys: DECaLS, BASS, MzLS, commonly known as "LS". They were conducted at KPNO and CTIO to define targets for the DESI (Dark Energy Spectroscopic Instrument) survey, currently underway on the Kitt Peak National Observatory Mayall 4m telescope. The notebook reproduces several figures from the LS overview paper (Dey et al. 2019), using catalogs currently hosted at Data Lab: sky coverage, comparison of LS and AllWISE W1 photometry, survey depth across LS data releases, and color-color distributions by source classification. The figure below shows the point source 5-sigma depths of the LS data releases 6, 7, and 9 (which was not available at the time the overview paper was published).

DESI LS

Contact Us

You can visit our website, use the helpdesk, reach us via email at datalab@noirlab.edu, and follow us on BlueSky or Twitter/X.

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