LXeGRIT Balloon Flight Campaign from Fort Sumner, NM, in October 2000

The LXeGRIT Balloon Flight Campaign in October 2000

from Fort Sumner, New Mexico

Right before winter hit Ft. Sumner, NM, the LXeGRIT payload had a great turn-around flight with 24+ hours at float altitude (about 26.5 h including ascent) on October 4-5, 2000. After difficult low-level wind conditions had postponed the flight several times, the NSBF team managed to find a slim launch window, during which the payload was smoothly put afloat. The balloon was released at 19:39:48 UT, which is an unusual early-afternoon launch in Ft. Sumner. The balloon went straight up, heading East initially, but soon changing to a south-western and eventually western course. Due to the western course of the balloon, which is very unusual for a flight here in early October, the science team was flown from Ft. Sumner to a second downlink station in Holbrook, AZ, in the morning of October 5. The gondola landed softly about one hour west of Phoenix, Arizona, near a small town called Buckeye. The payload just tipped over without being dragged, thus producing only minor dammage to the gondola.

The long flight time, the perfect operation of all systems, and the wide field-of-view of the Compton telescope LXeGRIT, which was flown this time without any shields, allowed us to obtain data on all MeV gamma-ray sources within ~45 deg zenith angle. Our main focus is imaging of the Crab nebula, but other strong sources such as 3C273 or Cygnus X-1 have also been in the field-of-view. We collected a total of almost 40 GB of event data, of which about 80% have been stored onboard, and the rest downlinked through two 500 kbps telemetry channels. We are looking forward to our next steps in analysing all the data received.
Many thanks to the NSBF launching team!

The campaign started of course long before the arrival in Ft. Sumner: Acceleration of the data acquisition system and improvements of the trigger system, together with several other improvements since the 1999 flight kept us quite busy. The system was tested and calibrated during runs at Nevis Laboratories and finally at the NSBF site in Ft. Sumner.