WFC3 SMOV Science Report
9 July 2009
This presentation contains material that is embargoed until after the SM4
ERO press conference. Images/spectra of external (astronomical) objects
may not be altered, distributed, reproduced, published, displayed, or used in
any other way without the consent of the STScI Director or the HST Project.
WFC3 Focus/Alignment
•
•
IR Focus
– Repeat of Fine Alignment visit 1 (focus sweep) today
– Expect to have IR focus and alignment confirmed
UVIS Focus
– Focus moves showed some settling/non-repeatability
– Focus is established at 2.5micron offset with some uncertainty
– Tip/Tilt ran Wed 5am with data receipt at 7pm last night
– Initial analysis puts us at corner of grid (min achieved??)
– Analysis ongoing
• Need to decide if currently achieved focus is OK or additional
work is required (timescale is 2+ weeks)
• Additional detailed observations of PSF planned for 201SMS
– Will use planned uplink today/tomorrow to center in tip/tilt
Read Noise
Embargoed data - Do not distribute
- Assumes gain 1.5 e-/DN
- Noise from overscans: measured from serial virtual
cols of all full-frame images, 3x3 clipping
- Noise from science pixels: measured from bias pairs
amp nims
A 299
B 299
C 299
D 299
mean stddev median
2.89 0.08
2.87
2.97 0.04
2.95
2.88 0.06
2.86
2.97 0.04
2.97
min
2.74
2.80
2.70
2.80
max
3.17
3.07
3.07
3.11
amp nims
A
12
B
12
C
12
D
12
mean stddev median
2.90 0.03
2.89
2.98 0.02
2.98
2.89 0.02
2.89
3.00 0.03
3.01
min
2.86
2.93
2.85
2.94
max
2.95
3.00
2.92
3.03
Filter shift – early comments
Over the past 24 hours, quicklook has found several frames where
UVIS filter features have shifted, i.e., filter is apparently not
returning to same position
- Frames being examined are all on-orbit.
- To date, occurances are limited to F475X (1*) and F438W (1).
- Both filters reside on wheel 10 (slots 3 & 1, respectively).
- Features shift to the left
~15-20 pix on 3x3 binned frame or 60 unbinned pixels (F475X)
~40 pix shift in F438W unbinned frame
- Estimate that 1 filter wheel step is ~30 pix steps.
- Data for another filter in wheel 10 (F775W) does not show shift;
more data available Thurs/Sat. There are no data yet for fourth
filter in wheel (F395N) and none expected this week.
-SCIENCE Impact expected to be minimal: some cal impact
* Multiple images are affected but likely due to single event (more details in later slide)
F438W intflat, before July 6
Embargoed figure - Do not distribute
F438W intflat, July 6, 05:30
Embargoed figure - Do not distribute