STIS Science SMOV Report
June 5, 2009
Charles Proffitt
for the STIS Science Team
STIS Update For June 5, 2009



Alignment
Lamps
CCD



Housing temperature history
Charge Transfer Efficiency changes
CCD read noise and gain
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
2
Results of STIS-to-FGS Alignment


20 images of astrometric standard with clear CCD
5 point cross pattern, with 4 sub-pixel dithers at each position
for 20 star images total + 3 lamp images of aperture
July 2003
New values
New - old
OV50 V2
-213.999˝
-213.897˝
-0.102˝
OV50 V3
-224.897˝
-224.959˝
+0.062˝
X plate scale
0.050763˝
0.050770˝
+0.000006”
Y plate scale
θ angle
0.050777˝
0.050745˝
-0.000032”
135.056º
135.074º
+0.018º

OV50 reference = pixel (535.384, 516.670) on CCD
Not enough points for definitive plate scale measure, but results
surprisingly close to old results

SMOV requirements 1˝ on alignment; 10’ (0.17º) on angle

SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
3
Preliminary Lamp Test Results

HITM1

No evidence for missing exposures or late turn-on of lamp




HITM1 lamp exposure for each CCD grating (G230LB, G230MB 2697,
G430L, G430M 4451, G750L, G750M 7795),
Compared with exposure from March 2004.
Differential shifts along dispersion direction between -1 and +0.6 pixel





Consistent with MSM uncertainties
Line Intensity ratios are close to unity (+/- few percent).
Line widths very similar
HITM2 - exposures look good, analysis ongoing
Line Lamp



Closer investigation of some 5% effects still needed for some faint expos
Only G230MB 2697 exposures taken so far
Initial analysis shows flux ratio of 0.938+/-0.056 (new/old) to 2004
data
Tungsten

Fluxes within 1-2% of 2004 values (apart from some CTE effects)
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
4
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
5
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
6
STIS CCD


The STIS Side-2 Electronics lack a working sensor or
temperature controller for the CCD chip
Instead we run the TEC at constant current and let the detector
temperature fluctuate


Use CCD housing temperature (OCCDHT) as surrogate for
detector temperature



Cause dark current and hot pixel fluctuations
Old side-2 relation suggests that dark current increases by 7% per
degree increase in OCCDHT
How do current temperatures compare with old side-2?
Current temperatures are high, but not quite unprecedented
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
7
CCDHT Before and After
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
8
STIS CCD CTE - Flat Field
Edge Response




CTI = (1 - CTE)
CTI increases slowed down
after Side-2 switch (colder
detector?)
Serial CTI Consistent with
Side 2 extrapolation
Parallel CTI seems about
50% higher than Side-2
extrapolation.



Is detector warmer now?
Is TEC cooling chip less?
Does rad damage affect a
warm detector more?
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
9
CCD Functional Stats
GAIN xbin ybin Gain (e-)
1
1
1
1
2
4
8


1
1
2
2
1
1
1
1
2
1
2
1
1
1
1.01 +1.00 +1.01 +1.00 +2.00 +3.99 +8.27 +-
0.01
0.01
0.01
0.01
0.01
0.04
0.04
RON (e-)
Flux
5.67 +- 0.07 17516.0
5.75 +- 0.09 11424.0
5.68 +- 0.26 11356.0
5.48 +- 0.15 22688.0
6.62 +- 0.23 53010.0
7.71 +- 0.17 70425.0
11.77 +- 0.14 73008.0
pre-2004.5:
Gain RON
1.00 5.39 +- 0.26
1.01 5.43 +- 0.25
1.00 4.86 +- 0.19
1.00 4.90 +- 0.28
2.01 6.43 +- 0.17
4.02 7.71 +- 0.18
8.32 11.88 +- 0.21
Gain seems unchanged within errors
Read noise slightly higher
SMOV Morning Meeting
Charles R. Proffitt
June 05, 2009
10