These two flights we launched during the Great American Solar Eclipse on Aug 21, 2017. It was a busy day for flying High Altitude Balloons.

NSL-58

NSL-58 was flown by Paul L. and his family from a site in Athens, TN. The flight was based off of gear tested on NSL-56. The payload consisted of the NSL-52/56/57 plastic box with:

• GCM-320+ recording Geiger counter

• Mobius Mini Action Camera, looking horizontally

• Mate808 camera, looking down

• 808 #16 camera, looking up

• AP510 APRS tracker

• Spot backup tracker

• Outside Hung Compact Rain-Activated Pull-down

• Directed Arboreal Recovery Node with Integrated Tether

• an Adafruit Feather logger Arduino with TTL camera (looking horizontally) and Bluetooth connection to the AP510.

this, and a 92cm chute, was hauled-up by a 600g cell with an entire HY-80 tank of H₂.

The family set up a command center (air-conditioned minivan) in the parking lot of the Mayfield Corn Maze just northeast of Athens, TN. This site was between the paths of longest totality on the ground and at 25km altitude. The area also provided plenty of nearby fields for recovery on the zigzag flight path.

Paul had a concern that the lack of solar heating during the eclipse may lead to a premature balloon burst, so launch was timed so that eclipse totality would occur when the balloon is just above 18km. So 15 minutes after C1, the balloon was launched.

Launch seen from two perspectives. Note the bite out of the sun in the glare artifact

Directly after launch, the family then switched over to eclipse viewing mode. Cameras were set up and a sheet was laid out to capture 'shadow bands'.

The various cameras struggled through totality as their exposure and focus tried to choose between the illuminated horizon and the dark ground. Only out-of-focus streetlights were visible in the distant town below.

After burst, a large chunk of the 600g cell fouled the parachute. The payload screamed in towards earth. Thankfully it followed its premature-landing track, which was away from population, and it ended up 100m into a forest. A very kind and helpful land owner assisted with the recovery.

There was an interesting external temperature anomaly during ascent. This does not correlate to totality or anything else that we can figure at this time. We will continue to investigate. Perhaps the video can give us clues as to what was going on at this time. The external temperature probe cannot handle temperatures below -49C. This unit has never been this cold before, so it was interesting to see it bottom out.

Totality occurred during the height of the Geiger counter readings. Hmm...

The Arduino on-board was recording the APRS traffic correctly decoded by the AP510. Basically making note of other overheard radios (and balloons) around the region. Over the course of the flight, it recorded 105 individual HAM stations, including 25 coming from balloons! This included the sister flight NSL-59. The longest distance packet seen was from balloon KD9FFX-11 at a distance of 540km (335 miles) !

KD9FFX-11 APBL10,K4UAN-3*,WIDE2*:!3753.96N/08942.81WO088/025/A=035811

NSL-59

NSL-59 had two cameras on-board. Created from a generic lock-and-lock box with black foam padding, Rocketman chute, and all strung under a 600g Hwoyee cell with a 110 tank of helium. Payload weight was 602 grams. Contents:

• Canon SD-780 IS with CHDK load for still picture photography

• 808 camera #9 for video

• APRS tracker

• T-Mobile backup tracker

The launch site was chosen as the grassy median outside a Walmart in Murphy, NC. Murphy's weather conditions seemed best in a game-day call made before 7AM, and they panned out well. The Walmart was a large open area with plenty of horizon, and unlike several other places in extreme southwest NC and northeast GA, they weren't charging $40 per vehicle for parking. We were far from the only ones with this idea.

Due to some question about tank pressurization and flight profile, balloon up was planned for just before 2PM. It would not be near its apogee for burst but would still have a good altitude perspective. Launch team consisted of club members Christopher, Justin, Paul, and Laurel Ann. Due to minor delays was released approximately 2:06 PM.

Notably, shortly after release we saw we were getting packets from both NSL-58 and 59 on the ground: Paul L.'s cell was high enough over Tennessee that we were already in line of sight (though we did not actually see it).

The balloon was visible for quite a few minutes and wasn't apparently drifting far. However, where on an ordinary day we may have tried to see how far we could follow it by eye, we instead returned to "eclipse watching mode" with a few dozen of our new closest friends. The experience itself was somehow beyond words, and we were looking forward to altitude pictures.

As the eclipse drew to its close, the balloon kept ascending, beating our higher end estimates by a bit. In the end, it drifted significantly west of our estimates run the night before: part of this would be the extra few kilofeet of altitude, but we also suspect the air over the mountains behaved differently during the eclipse-driven cooling than it may have otherwise done. As we prepared to go retrieve, we were looking at an area on the map without abundant roads and with more water than we had initially hoped.

Chase team members Christopher and Justin took off westward from town to look for the thing and try to get under it with a radio. Last packet received was 4,905 ft. up over a valley containing the Apalachia and Hiwassee Lakes. Local elevation at Murphy is about 1,600 ft. The team orbited the area around the last known coordinates as best they could, but even given the limited roads visible on the map, a number of them were either private or nonexistent. Team tried to regroup at the top of a large TVA dam with a receiving antenna in the hopes that if it did come down in the valley, they would receive a signal, but there was no such luck.

Search was abandoned when they had approached the area from all available angles and dusk was threatening to set in in the valley, so the team returned to base, and then to their respective home towns.

The box is labeled with a phone number, so perhaps if a Murphy native finds the box, it may still be returned. Due to the rural nature of the area, however, it is not clear that such a find would be likely to occur soon.