Torsten Böker
TIPS
May 2, 2002
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….)
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--/s
Mean:0.114
0.148e-/s
e /s
Mean:
The first flat field images
Then…
(1998, T=62 K)
Now…
(2002, T= 77K)
NIC1
NIC2
NIC3
DQE – comparison with expectations
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!)
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)
Mean PSF from 2002 stellar field
(NIC1, F095N)
1997 PAM tilt grid
(NIC1, F095N)
NICMOS SMOV: early activities timeline
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
Torsten Böker
TIPS
May 2, 2002
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