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The HETE-2 Optical Camera System

The HETE-2 optical camera system essentially replaces the UV cameras on
HETE-1. Instead of four identical near-UV CCD cameras, HETE-2 has two sets of two optical CCD cameras. The optical system determines HETE's attitude using a collection of fast algorithms, one of which is documented here. A Mathematica notebook for the development of this algorith is here.

ACS Cameras

An ACS camera:  click for a larger view! The HETE ACS cameras are essentially copies of the HETE-1 UV cameras: the primary differences are that the CCDs are smaller (.5 sq. cm vs 4 sq. cm), they are not UV sensitive (the filter will be optimized for R band), and they are tilted 45 degrees from the spacecraft z-axis and therefore will not make any scientific contribution to the mission.

The image at left is of an engineering model ACS camera without any of the thermal shielding or struts which mount the camera to the spacecraft.

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Boresight Cameras

A boresight camera:  click for a larger view! The HETE boresight cameras are a new set of optical cameras devoted entirely to supplying good aspect for the SXC system. The boresight cameras are mounted to the SXC baseplate, making thermal variations in pointing negligible.

The boresight cameras use the same CCDs as the ACS cameras, but a lens with a longer focal length: the boresight camera field-of-view measures 5.5 degrees on a side, as opposed to the ACS cameras' 12.5 degrees on a side. The boresight cameras are optimized for the blue region of the spectrum to minimize the effect of scattered moonlight.

The image at left is of an engineering model boresight camera before it is mounted to the SXC baseplate .

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