The Flight of HBAL608

On 14 May 2021 I captured some photos of a high altitude balloon floating above Anniston, AL which I detailed in this post. Ever since then I have been waiting for another one to float this way and today it happened.

Today’s balloon was a Raven Aerostar Thunderhead, a 64,000 cubic-foot superpressure balloon with an internal balloonet used to control altitude. It was launched from the Raven Aerostar facility north of Sioux Falls, SD on 28 September. It was using the callsign HBAL608 (FAA registration N258TH). The payload it was carrying remains a mystery.

The balloon was transmitting its location over ADS-B making it easy to track. After launch it drifted south-southeast for two days to a point north of Searcy, AR. Then it slowly drifted northeast for two more days with a little excursion south to Jonesboro, AR along the way. On 2 October it started drifting southeast.

Tracking data from FlightAware

By this morning it had reached western Georgia. It was now drifting south-southeast with a forward speed less than 8kts. My calculations showed if it stayed on this course and speed it might be visible from my backyard before sunset. But around 2:00pm it descended 500ft and started drifting southeast along with a forward speed increase to 15kts. By 6pm it was apparent a backyard sighting was not going to happen. However, a sighting from Dowdell’s Knob was still possible so I packed up the camera gear and headed up there.

Tracking data from ADSBExchange

When I arrived at Dowdell’s Knob just before 7pm it took less than a minute to locate the balloon with binoculars. By this time it was located south of Griffin.

Slant ranges to the balloon from Dowdell’s Knob

Using an 8-inch Schmidt-Cassegrain telescope and ZWO ASI294MC Pro camera I was able to capture this video as the balloon passed into sunset.

Over the next several days the balloon drifted southeast and then east. ADS-B tracking was eventually lost northwest of Bermuda.

One comment

Comments are closed.