The Japan Aerospace Exploration Agency (JAXA) confirmed the completion of a sequence of important operations of the X-ray Astronomy Satellite “Hitomi” (ASTRO-H), including turning the cooling system on, test operation of the Soft X-ray Spectrometer (SXS), and extending the Extensible Optical Bench (EOB). With this confirmation, the critical operation phase (*1) of Hitomi was completed.

Hitomi is now in a stable condition.

We turned on the SXS cooling system for test operations after the launch on February 17, then confirmed that it reached the absolute temperature 50 millidegrees (minus 273.1 degrees Celsius) at around on February 22.

JAXA will perform the initial functional verification of the onboard instruments for about one and half months, then we will conduct calibration observations (*2) for another one and half months.

We would like to express our sincere appreciation to all parties and personnel concerned for their support and cooperation with Hitomi’s launch and tracking control operations.


*1 Critical operation phase
The critical operation phase is a period from the separation from the launch vehicle till the establishment of the stable operation in space including the deployment of the solar array paddles, completing the establishment of the attitude control system, turning on the cooling system, EOB extension, and the functional verification of the ground tracking and control facility.

*2 Calibration observation
By observing a well-known celestial body, we can understand the unique features of the onboard instruments to improve observation precision.