# VLBI ecliptic plane survey: VEPS-1

## TL;DR

This paper reports the first results of the VEPS program, which aims to identify and precisely locate compact radio sources near the ecliptic plane to serve as calibrators for spacecraft observations, achieving high positional accuracy.

## Contribution

The study presents a comprehensive survey of ecliptic plane sources, including detection and position refinement, expanding the catalog of suitable VLBI calibrators with improved accuracy.

## Key findings

- Detected 555 sources out of 3320 observed
- Improved positions of 249 sources
- Achieved positional accuracy at the 1.5 nanorad level

## Abstract

We present here the results of the first part of the VLBI Ecliptic Plane Survey (VEPS) program. The goal of the program is to find all compact sources within $7.5^\circ$ of the ecliptic plane which are suitable as calibrators for anticipated phase referencing observations of spacecraft and determine their positions with accuracy at the 1.5~nrad level. We run the program in two modes: the search mode and the refining mode. In the search mode, a complete sample of all sources brighter than 50 mJy at 5 GHz listed in the Parkes-MIT-NRAO (PMN) and Green Bank 6~cm (GB6) catalogs, except those previously detected with VLBI, is observed. In the refining mode, the positions of all ecliptic plane sources, including those found in the search mode, are improved. By October 2016, thirteen 24-hr sessions that targeted all sources brighter than 100~mJy have been observed and analyzed. Among 3320 observed target sources, 555 objects have been detected. We also conducted a number of follow-up VLBI experiments in the refining mode and improved the positions of 249 ecliptic plane sources.