- Title Information
- Title
- From Images to Azimuth: A Comprehensive Study of Orientation Calibration Techniques for the EXoplanet Climate Infrared TElescope (EXCITE)
- Type of Resource (primo)
- dissertations
- Name:
Personal
- Name Part
- Deng, Feifan
- Role
- Role Term:
Text
- creator
- Name:
Personal
- Name Part
- Tucker, Greg
- Role
- Role Term:
Text
- Advisor
- Name:
Corporate
- Name Part
- Brown University. Department of Physics
- Role
- Role Term:
Text
- sponsor
- Origin Information
- Copyright Date
- 2025
- Physical Description
- Extent
- , None p.
- digitalOrigin
- born digital
- Note:
thesis
- Thesis (Sc. M.)--Brown University, 2025
- Genre (aat)
- theses
- Abstract
- During the August 2024 test flight of the EXoplanet Climate Infrared TElescope (EXCITE),
a balloon-borne observatory designed to characterize exoplanet atmospheres, absolute azimuth
data from the on-board GPS compass was not available throughout the flight. To supplement the
pointing information, we developed a method to reconstruct the payload’s azimuth using images
from a 360° action camera mounted externally on the gondola. The front-facing lens of the camera
was approximately aligned with the forward (stern-bow) direction of the gondola.
Through a ground-based calibration test, we determined that the camera follows an equidistant
projection model, allowing sun positions in the image to be mapped to azimuth angles with a
resolution of 0.5°. An automated Python pipeline was created to detect and centroid the sun in
each image and to assign an azimuth relative to the camera’s reference frame. These relative angles
were then combined with solar ephemeris data to recover the payload’s absolute azimuth.
The image-derived azimuth was compared with the yaw data calculated from gyroscope in-
tegration. While the two datasets showed similar trends across the flight, a growing offset was
observed in the later hours, likely due to integrated bias in the gyroscope solution. An additional
elevation analysis using both encoder data and image-derived solar elevation helped confirm the
accuracy of the elevation relative to the Sun. The secondary mirror temperature increase near 11:30
AM (GDT-6) is consistent with reconstructed pointing that placed the telescope closely aligned
with the Sun within ±3° elevation and ±5° azimuth relative to the Sun.
This work demonstrates that 360° imaging, combined with basic calibration and supporting
flight data, can provide a robust alternative means of azimuth reconstruction. The approach offers
a valuable tool for future balloon missions where direct azimuth measurements may be limited or
unavailable.
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01063025")
- Topic
- Physics
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/00819797")
- Topic
- Astrophysics
- Subject (fast)
(authorityURI="http://id.worldcat.org/fast", valueURI="http://id.worldcat.org/fast/01146496")
- Topic
- Telescopes
- Language
- Language Term (ISO639-2B)
- English
- Record Information
- Record Content Source (marcorg)
- RPB
- Record Creation Date
(encoding="iso8601")
- 20250707