The NED Local Volume Sample (NED-LVS) is a subset of NED that contains over 2 million objects with distances out to 1000 Mpc. The distances selected for NED-LVS are based on both redshifts (~99%) and redshift-independent distances integrated from the literature and large surveys. The data in NED are updated regularly, and new versions of NED-LVS are extracted periodically. Consequently, NED-LVS will continue to provide an increasingly complete sample of galaxies for a multitude of astrophysical research areas (star formation, galaxy evolution, large scale structure, galaxy environments, and searches for the electromagnetic counterparts to gravitational wave events) for years to come. For more information and to download the latest version go to https://ned.ipac.caltech.edu/NED::LVS/
NED-LVS is utilized by the NED gravitational wave follow up (NED-GWF) service, which provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert issued by the LIGO-Virgo-KAGRA Gravitational Wave Network, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The galaxy lists produced by NED-GWF also provide several pre-computed prioritization metrics (i.e., stellar mass, star formation rate, and specific star formation rate, etc.), which are available by downloading the entire galaxy list inside an event's probability volume. For more information on NED-GWF go to https://ned.ipac.caltech.edu/NED::GWFoverview/
The January 2025 version of NED-LVS includes new objects ingested by NED and the removal of newly identified non-galaxy contaminants. This updated version contains a total of 2.07M objects, an increase of 203K (10%) over the previous version, where 30K of the newly added objects (after contaminant removal; see below) are from the literature and 173K originate from the Dark Energy Spectroscopic Instrument Early Data Release (DESI-EDR; DESI Collaboration, 2024). Each release of NED-LVS is accompanied by an additional round of vetting of both newly ingested objects and those from the previous version to ensure that this sample will provide a robust and highly complete census of the local Universe. Listed below are details of redshift updates and contaminants identified and removed by our additional vetting for this version of LVS.
- 151K “stars” (0.8% were in the previous version): objects determined to be stars in our Galaxy via one or more of the following reasons:
- stellar spectroscopic classifications and redshifts from DESI-EDR consistent with members of the Milky Way.
- objects with high stellar probabilities from either GAIA astrophysical parameter metrics or the machine learning catalog of Tachibana et al. (2019) based on PanSTARRS1 objects.
- 5K parts of galaxies (“PofGs”; 20.8% were in the previous version): objects that reside in or near large angular-sized galaxies that have been determined via visual inspection and supporting metadata (redshifts, publication classifications, etc.) to be a sub component of a galaxy. These “PofGs” can be many types of physical objects such as HII regions, planetary nebulae, star clusters, etc. During our vetting, we have flagged additional spectroscopic fiber position sources (e.g., SDSS and DESI-EDR) that are located outside of the central part of the galaxy as “PofGs”, unless there is no other object with a redshift for that unique galaxy. Note: PofGs were flagged for future updates to the NED database, but omitted from the LVS galaxy sample
- ~1200 updated redshifts (27.2% were in the previous version): objects with fiducial redshifts that were determined by the NED team to be questionable and were replaced with more reliable measurements. Of the objects with updated redshifts, 859 now have distances beyond the 1000 Mpc limit currently imposed on NED-LVS and have been removed from the sample.
- ~600 “Unmatched data” (74.3% were in the previous version): objects that contain data for existing galaxies in NED that should be merged. Generally these are additional observations of large nearby galaxies whose provided positions or names are discrepant enough from an existing object to result in an ambiguous match. Only obvious matches via visual inspection have been identified and flagged. Note that these flags will help to make these crossmatches in the NED database at a later date, and that the unmatched data have been removed from LVS to avoid duplication of unique galaxies.
- Caveats: In general, any “Unmatched data” and “PofGs” in a galaxy sample would result in over-counting the true number of distinct galaxies in the local volume. Identification of these objects is an on-going process and the next release of NED-LVS will identify and remove additional contaminants.
Comments