Nicmos post cooldown detector performance
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NICMOS post-cooldown detector performance. 1) SMOV status 2) Dark current 3) Quantum efficiency 4) “First light”, focus and image quality 5) SMOV outlook. Thermal history since NICMOS switch-on (on April 19). Transition to detector control. Transition to Ne control. Setpoint to 72.5 K.

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Nicmos post cooldown detector performance

NICMOS post-cooldown detector performance

1) SMOV status

2) Dark current

3) Quantum efficiency

4) “First light”, focus and image quality

5) SMOV outlook


Thermal history since NICMOS switch-on (on April 19)

Transition to detector control

Transition to Ne control

Setpoint to 72.5 K

Setpoint to 72 K


X

X

X

X


Filter wheel test(G. Schneider, K. Noll, L. Mazzuca, E. Roberts)

  • NICMOS filter wheels have motion sensor only on the motors, not on the wheels themselves

  • Concern about breaking the wheel shaft in case of mechanical contact/blockage

  • careful “two step forward, one step back” approach with analysis of motor currents and flat field images

  • so far, so good: verified normal motion over 9/10 of a full turn

  • side benefit: early measurement of DQE (and more….)


Mean: 0.166 e-/s

Mean: 0.114 e-/s

Mean: 0.148 e-/s

  • NICMOS dark current

  • (C. Xu)

  • preliminary measurements indicate that dark current is nominal, i.e. close to Cycle 7

  • “bump” is NOT observed


The first flat field images

Then…

(1998, T=62 K)

Now…

(2002, T= 77K)

NIC1 NIC2 NIC3



Serendipitous image of a crowded star field

(…taken out from electronic distribution as requested by HST project…)

Camera 2 in H-band (F160W)

FWHM: 2.17 pixels (0.163“) (very close to nominal!)


Mean PSF from 2002 stellar field (NIC1, F095N)

1997 PAM tilt grid (NIC1, F095N)



Summary

- NICMOS has survived its 28 month hiatus without any significant degradation

- performance is nominal so far

- GO science will be enabled within 2 weeks


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