NRAO Information

Welcome to the VLBA Calibrator Search Tool (Beta Version)

The VLBA Calibrators List drives a search engine to find calibrators that are close to a specified position. Please fill out the VLBA Calibrators Search Form below. The search will return a table of sources within the search radius and a diagram showing the proximity of each source to the search center. Plots of the source visibility and image distributions are given for many sources.

Users are encouraged to use the NRAO helpdesk to get assistance identifying the optimum calibrator for their observations.


This is the beta version of the new VLBA Calibrator Search Tool. Users are encouraged to report any issues to the helpdesk. Users may also want to try the old Calibrator Search Tool or the RFC VLBI Calibrator Search Tool.


RA Formats: XX:YY:ZZ.ZZZ, XXhYYmZZ.ZZZs, XX YY ZZ.ZZZ, XX YY
DEC Formats: XX:YY:ZZ.ZZZ, XXdYY'ZZ.ZZZ", XX YY ZZ.ZZZ, XX YY
The maximum search radius is 45.0 degrees.
The maximum number of sources allowed is 100.
Select sources with short baseline (<400 km) flux density greater than or equal to the specified value at the selected observing band.

Additional Resources

This catalog contains the same source list that is in the NRAO VLBI SCHED program. More detailed information can be found from:
The Calibrator list and accurate positions as a text file: Calibrator List
The latest IAU standard ICRF3 VLBI Source Position Catalog: ICRF3 source list
The ICRF3 publication: Charlot et al. 2020
The Radio Fundamental Catalog (RFC): RFC
The NRAO SCHED Source list using ICRF3 positions: ICRF3 SCHED calibrator list
Astrogeo VLBI Calibrator Search Tool: RFC Calibrator Search
Astrogeo VLBI image database: Astrogeo image search
The Bordeaux VLBI Image Database: BVID
Each VLBA/GSFC Survey Data: VCS1, VCS2, VCS3, VCS4, VCS5, VCS6,VGaPS,EGaPS,NPCS,LBA