Torsten BökerTorsten Böker TIPS TIPS May 2, May 2, 20022002

NICMOS post-cooldown detector performanceNICMOS 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 K

Setpoint to 72.5 K

X

X

XX

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….)

NICMOS dark current(C. Xu)

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

- “bump” is NOT observed

Mean: 0.166 e-/sMean: 0.114 e-/sMean: 0.148 e-/s

Then…(1998, T=62 K)

Now…(2002, T= 77K)

The first flat field images

NIC1 NIC2 NIC3

DQE – comparison with expectations

Serendipitous image of a crowded star field

Camera 2 in H-band (F160W)

FWHM: 2.17 pixels (0.163“)

(very close to nominal!)

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

First assessment of image quality: (G. Schneider)

-VERY close to nominal focus

- some coma, to be corrected with tilt adjustment of PAM (in time for ERO observations)

1997 PAM tilt grid (NIC1, F095N)

Mean PSF from 2002 stellar field (NIC1, F095N)

4/19 Fri 109 NICMOS restarted, Ne-loop control continues

4/22 Mon 112 Change to mounting cup control

4/23 Tue 113 Return to Ne control, Filter wheel test begins

4/26 Fri 116 Increase control temperature to allow for seasonal margins +2 K

4/29 Mon 119 Begin darks every 3rd orbit

4/30 Tue 120 DQE test visit 1; Control temp +0.5 K

5/02 Thu 122 DQE test visit 2; Control temp –1.0 K

5/03 Fri 123 Filter wheel test complete; Focus sweep, FOM test, Transfer function test

5/04 Sat 124 DQE test visit 3; Control temp +0.5 K (TBD)

5/06 Mon 126 DQE test visit 4; Stop darks

5/08 Thu 129 Final temperature set point (TBD)

5/10 Sat 131 EROs begin, flats, thermal background

5/16 Fri 137 Final focus update, GO science enabled, remaining SMOV begins

NICMOS SMOV: early activities timeline

Torsten BökerTorsten Böker TIPS TIPS May 2, May 2, 20022002

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