Calibration Facilities, Test Apparatuses, and Stimuli

Calibration and testing of the Advanced Camera for Surveys takes place at Ball Aerospace and Technologies Corporation (BATC) and at the Goddard Space Flight Center (GSFC) in a number of special facilities. The activities revolve around several major campaigns designed to verify the performance and flight readiness of the instrument by characterizing its detectors and optical and ultraviolet channels, and by verifying the contract-end-item specifications.

Facilities

BATC (Boulder, Colorado) :

• Clean rooms 5 and 6 in the Fisher Testing facility which houses RAS/HOMS, the Optical Bench Assembly Support Structure (OBASS), and other instruments under development.
• MAMA and CCD test labs where our detectors were assembled, selected, and tested.

GSFC (Greenbelt, Maryland) :

• Spacecraft Systems Development and Integration Facility (SSDIF), the largest clean room of its class in the world.
• Diffraction Grating Evaluation Facility (DGEF) where ACS filters and dispersing elements where selected and tested.
• Thermal Vacuum Chamber (see the TB/TV 3 plan, for example)
• EMI/EMC test facility

Additionally, some imaging functional tests were performed in the clean room of Hangar AE at the Kennedy Space Center (KSC) to verify the health of ACS after shipping from BATC in late Nov 2001.

Apparatuses and Light Stimuli

Depending on the location of ACS and the calibration goals there are a number of different apparatuses that can provide the external or internal light stimulus for our testing.

• STUFF : The Stimulus for Ultraviolet Flat Fields (STUFF) provides spatially flat field stimulation of the Solar Blind Channel (SBC) at two far-UV wavelengths: Kr 1236 Ang and Xe 1469 Ang. It can also weakly stimulate the High Resolution Channel (HRC). STUFF was used extensively in the first thermal vacuum campaign (Feb-Mar 1999). A complete description of STUFF is given in "High Throughput Vacuum Ultraviolet Stimulus for Flat Fielding and Spectral Calibration of the HST Advanced Camera for Surveys", Leviton et al. 2000, SPIE Vol. 4139, 110.
• BATC : RAS/HOMS
• GSFC : CDS and RAS/Cal
• Integration sphere
• Internal calibration lamps : Two tungsten lamps, T1 and T2, provide internal illumination for the WFC chip. Similarly, two other lamps, T3 and T4, illuminate the HRC. T2 and T4 give the most uniform illumination and are therefore used for ground-based, and very likely for on-orbit calibrations. The SBC is illuminated by a deuterium lamp, D2, which can also serve as a weak UV source for the HRC. The internal lamps are used for CCD read-noise and gain measurements, timing pattern evaluation, searches for dust motes on the filters, and post-flash evaluation.