# The PoGO+ Balloon-Borne Hard X-ray Polarimetry Mission

## TL;DR

The PoGO+ mission is a balloon-borne experiment designed to measure the polarization of hard X-rays from astrophysical sources like the Crab and Cygnus X-1, providing new insights into their emission mechanisms.

## Contribution

This paper reviews the PoGO+ mission, detailing its payload, flight campaigns, and presenting the first independent polarization measurements of the Crab and Cygnus X-1.

## Key findings

- Two independent Crab polarization measurements obtained
- First polarization measurement of Cygnus X-1
- Successful deployment of balloon-borne X-ray polarimetry platform

## Abstract

The PoGO mission, including the PoGOLite Pathfinder and PoGO+, aims to provide polarimetric measurements of the Crab system and Cygnus X-1 in the hard X-ray band. Measurements are conducted from a stabilized balloon-borne platform, launched on a 1 million cubic meter balloon from the Esrange Space Center in Sweden to an altitude of approximately 40 km. Several flights have been conducted, resulting in two independent measurements of the Crab polarization and one of Cygnus X-1. Here, a review of the PoGO mission is presented, including a description of the payload and the flight campaigns, and a discussion of some of the scientific results obtained to date.