ACS STATUS

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Linda Smith

(thanks to David Golimowski for providing the slides)

ACS was repaired in EVA 3: four circuit boards in CEB were replaced and a new LVPS was installed.

Part 1: WFC CEB-R FT

• Criterion: At least one WFC CCD is operational and can be read out through at least one amplifier

Result: Both CCDs and all four amps are operational

• Criterion: At least one WFC CCD amplifier operates with RN~10 e- Result: All amps operate with read noise 3.0–3.6 e- (prescan only) in

DSI mode assuming gain=1

• The WFC TECs can cool focal plane to its max set point (-66.7 C) while operating at < max power, thus operational T < -81 C is achievable (Passed)

• Shutter operates (Passed)

• FW2 can be rotated and FW1 left in open position (Passed)

• WFC commanding and data readout, storage, and dump are possible (Passed)

Part 1: WFC CEB-R FT

Four-amp bias frame (DSI)Bias level: 2260-2600 DNRN: 3.0-3.6 e- (prescan) 3.9-4.4 e- (image area)

Four-amp lamp frame (F814W, DSI)Signal level: 22000-26000 DNNearly identical to Jan 2007 flat!

Part 2: ACS-R System FT

• Initial execution halted due to HRC electrical short

* +35V and +15V did not come up properly & backpower current was higher than expected (~2.2 A vs. ~1.2-1.4 A)

• Reran System FT with all HRC commanding deleted

* WFC DSI images showed same RN as in CEB-R FT* WFC C&S images showed pre-Jan 2007 RN levels* SBC dark exposure improperly truncated but nevertheless

demonstrated that valid science image can be acquired and that SBC functionality has been preserved

• Two baseline O-mode images were obtained to verify oscilloscope functionality (not part of formal pass/fail criteria)

Part 2: ACS-R System FT

• Criterion: At least one WFC CCD is operational and can be read out through at least one amplifier

Result: Both CCDs and all four amps are operational

• Criterion: At least one WFC CCD amplifier operates with RN~10 e- Result: All amps operate with read noise 3.0–3.5 e- (DSI) and 4.0–

4.6 e- (C&S)

• The WFC TECs can cool focal plane to its max set point (-66.7 C) while operating at < max power, thus operational T < -81 C is achievable (Passed)

• Shutter operates (Passed)

• FW1 can be rotated and FW2 left in open position (Passed)

• WFC commanding and data readout, storage, and dump are possible (Passed)

Part 2: ACS-R System FT

Four-amp bias frame (C&S)Bias level: 4750-5000 DNRN: 4.0-4.6 e- (prescan) 4.8-5.5 e- (image area)

SBC, ~35 sec flat, -50 V on MCP Signal level: 0 DNNo interference or noise detected

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