Instrument Science Report STIS 2014-02
The Time-Dependent Sensitivity of the
MAMA and CCD Long-Slit Gratings
Stephen T. Holland1 , Alessandra Aloisi 1 , Azalee Bostroem 1 , Cristina Oliveira1 ,
Charles Proffitt1
1
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218
December 3, 2014
ABSTRACT
The sensitivities of the Space Telescope Imaging Spectrograph (STIS) detectors have
varied with time since the instrument was deployed in 1997. These changes must be
corrected for in order to accurately determine the flux from an astrophysical source. In
order to do this we used observations of flux standard stars to determine the trends in
the sensitivities of the five STIS low-resolution, long-slit gratings between 1997 and
2013. We find no significant change in the rate that the sensitivity is decreasing for
each long-slit grating since early 2003, although there is weak evidence for possible
changes of ≈ 0.5%/year for the G140L and G230LB gratings in late 2011 and mid
2012 respectively. The STIS calibration data used in the data processing pipeline, the
exposure time calculators, and pysynphot assumes that the sensitivity trends for the
medium-resolution and echelle gratings are the same as those for the corresponding
low-resolution gratings. We test this assumption and find that it is valid for all mediumresolution and echelle gratings except G430M, which has a sensitivity that is ≈ 1–3%
lower than that of the G430L grating.
Contents
• Introduction (page 2)
• Data (page 2)
Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics
and Space Administration.
• Method (page 5)
• Results (page 6)
• Comparison to Other STIS Gratings (page 18)
• Conclusions (page 26)
• Recommendations (page 27)
• Acknowledgements (page 27)
• Change History (page 28)
• References (page 28)
• Appendix A: Observations (page 28)
1. Introduction
We present an analysis of the sensitivity monitoring observations of the Hubble Space
Telescope’s (HST) Space Telescope Imaging Spectrograph (STIS) first-order low-resolution,
long-slit gratings taken between 1997 and 2013. We determine time-dependent sensitivity (TDS) corrections for these gratings and compare them to those implemented in the
STIS data reduction pipeline, pysynphot, and the Exposure Time Calculators (ETCs).
Previous STIS Instrument Science Reports (ISRs) on this topic were published by Walborn & Bohlin (ISR 1998-27), Bohlin (ISR 1999-07), Smith et al. (ISR 2000-03), Stys
& Walborn (ISR 2001-01), and Stys et al. (ISR 2004-04). The CCD detector suffers
from charge transfer efficiency (CTE) losses. Details of the effects of CTE on STIS
data and mitigation strategies can be found in Bohlin (ISR 2003-03) and Goudfrooij
(ISR 2006-03).
2. Data
2.1 Observations
Long-term changes in the STIS TDS have been monitored by repeated observations of
two flux standard stars since STIS was installed on HST in 1997. These two stars are the
white dwarf GRW+70D5824 and the hot sub-dwarf AGK+81D266. The fundamental
properties of these stars are listed in Table 1. Observations of these stars were taken
with the the low-resolution gratings (the L gratings), the medium-resolution gratings
(the M gratings) and the echelle gratings (the E gratings). As of this writing monitoring
observations are being taken every four months for the L gratings, once a year for the
Instrument Science Report STIS 2014-02 Page 2
Table 1.
Basic parameters of the flux standard stars used in this study
RA (J2000.0)
Dec (J2000.0)
Spectral Type
V (mag)
B −V (mag)
GALEX NUV (AB mag)
GALEX FUV (AB mag)
EB−V (mag)
Table 2.
AGK+81D266
GRW+70D5824
09:21:19.0
+81:43:29
B2 sd0
11.94
−0.34
12.43
···
0.02
13:38:51.8
+70:17:08
DA2.4
12.77
−0.09
12.54
12.58
0.01
STIS CTE Correction Coefficients.
Coefficient
Value
α
β
γ
δ
ζ
η
0.0562
0.82
0.216
3
1.3
0.18
0.060
M gratings, and every three months for the echelles. No observations were taken between August 2004 and May 2009 as the failure of the Side-2 electronics rendered STIS
inoperable during that period.
The datasets used for each of the low-resolution, long-slit gratings (G140L, G230L,
G230LB, G430L, and G750L) are listed in Appendix A.
2.2 Data Reduction
The datasets listed in Appendix A were obtained from MAST and reprocessed using
current calibration data on Mar 7, 2014 with calstis 3.4 to obtain spectra in units of
net count rate. There were two additional processing steps for data obtained using the
CCD detector. First, the net count rate of every pixel that was flagged as saturated by
the processing pipeline was replaced with a value obtained using a linear interpolation
scheme over nearby pixels. Next, the counts on the CCD detector were corrected for
CTE effects using the point source correction described in Goudfrooij (ISR 2006-03).
The CTE parameters for Goudfrooij’s (ISR 2006-03) Eq. (2) are listed in Table 2.
There is an additional correction that needs to be applied to spectra that extend
redder than approximately 8000 Å, i.e., the G750L and G750M gratings. The pointspread function (PSF) of the CCD has broad wings at these wavelengths. Furthermore,
the width of the wings depends on wavelength. The fraction of the source flux in the
Instrument Science Report STIS 2014-02 Page 3
Table 3. The temperature corrections for the STIS detectors as of May 8, 2013. Start
and Stop indicate the date range when the temperature corrections are valid. For times
outside these dates the temperature correction (τ ) is taken to be unity.
Optical Elements
T0
αT
Start
Stop
G140L, G140M, E140M, E140H
G230L, G230M, E230M, E230H
G230LB, G230MB
G430LB, G430MB
G750L, G750M
36.0
None
19.0
19.0
19.0
0.0032
None
0.0032
0.0022
0.0006
1997.38
1997.38
2001.5
2001.5
2001.5
Present
Present
Present
Present
Present
Detector
FUV
NUV
CCD
Table 4.
The wavelength ranges used for the five STIS low-resolution gratings.
Grating
CENWAVE (Å)
λmin (Å)
λmax (Å)
∆λ (Å)
G140L
G230L
G230LB
G430L
G750L
1425
2376
2375
4300
7751
1150
1600
1700
2900
5500
1700
3100
3000
5700
9900
50
100
100
200
400
PSF’s wings needs to be corrected for when determining the CTE correction. This
additional correction was done using the method described in Goudfrooij (ISR 200603).
The sensitivities of the MAMA and CCD detectors depend on temperature, so
the observed count rates are corrected for the detector temperature at the time of each
observation. The temperature correction, τ , is defined as
τ ≡ 1 − αT (T − T0 )
(1)
where T is charge amplifier temperature. The temperature is the value of the OM1CAT
keyword in the header of the SCI extension of the calibrated data files for FUV-MAMA
spectra and the value of the OM2CAT keyword in the SCI extension of the calibrated
data files for NUV-MAMA spectra. For CCD spectra the CCD housing temperature (the
value of the OCCDHTAV keyword in the SCI extension of the calibrated files) is used.
The values used for the reference temperature, T0 , and the temperature sensitivity, αT ,
are listed in Table 3. The count rate is divided by the temperature correction to get the
corrected count rate.
Once the net count rate data for each spectrum has been corrected, the spectrum
is binned in wavelength space to obtain the total count rate in each bin. The widths of
the wavelength bins (∆λ), as well as the minimum and maximum wavelengths (λmin ,
λmax ) that we used for each grating and the central wavelength (CENWAVE) of each
grating, are listed in Table 4. If there is no change in the sensitivity of a detector over
Instrument Science Report STIS 2014-02 Page 4
time then the total count rate from a constant flux source should remain constant, to
within Poisson errors.
3. Method
The TDS correction at a given time, t, is defined to be the ratio of the total corrected
count rate from the flux standard star, C(t), to the total corrected count rate from the
same source at the STIS reference time, C(t0 ) ≡ C0 . We adopt a reference time of May
19, 1997 (t0 = 1997.38 = MJD 50587), which corresponds to the time of the first TDS
calibration observation. This reference time was chosen because it is the reference time
that is currently used in the STIS TDS reference files.
The TDS correction is determined as follows.
First, the piecewise-continuous segmented line model



C0 + m1 t
if t < t1
if ti ≥ t < ti+1 , i = 1 . . . N
C(t) =  C(ti ) + mi (t − ti )

C(tN ) + mN (t − tN ) if t ≥ tN
(2)
is fit to the total corrected count rate data to determine how the count rate changes
with time. This model is described in Eq. 2 (see also § 3 of Holland, STIS TIR 201303). The free parameters in the model are the normalization, C0 , the slope of each line
segment, mi , and the break times between the line segments, ti . The total corrected
count rate at the i’th break time is given by C(ti ) = C(ti−1 ) + mi−1 × (ti − ti−1 ).
The number of line segments is determined iteratively by fitting a model with N line
segments (starting with N = 1), fitting a second model with N + 1 line segments, and
then using an F test to determine if the additional line segment results in a statistically
significant improvement in the model fit to the data. This procedure is described in detail
in Holland (STIS TIR 2013-03). Allowing the breakpoint times to be free parameters
in the fit makes the resulting TDS function objective in the sense that it does not rely
on human input to determine when the rate of change in the sensitivity changes. It
also allows the breakpoint times to adjust in a statistically rigorous way as new data are
obtained.
Next the fitted function is normalized by dividing by C0 to yield the TDS function,
S(t) = C(t)/C0 . At the reference time S(t0 ) ≡ 1. This method is preferable to
normalizing the count rate data by the count rate of the first observation of the flux
standard star because normalizing by the first observation will incorporate any errors
in the first observation into S(t), which will result in an unknown systematic error in
the TDS. It also adds (in quadrature) the statistical errors in the data from the first
observation to the sensitivity values determined at every other observation time, which
results in the uncertainty in the initial observation affecting the weight of the data from
every observation.
Instrument Science Report STIS 2014-02 Page 5
4. Results
4.1 Overall Time-Dependent Sensitivity
The TDS results for the five low-resolution gratings are shown in Figures 1–3 and the
parameters of these fits are listed in Table 5. In all cases the data are qualitatively
and quantitatively well fit by the model. The G140L data show weak evidence for a
change in the rate of sensitivity loss in Nov 2011 while the G230LB data show weak
evidence for a change in Jun 2012. However, for G140L the scatter in the sensitivity
data is larger than the magnitude of the change in the slope, so more data are needed
to determine if the possible break at 2011.83 is real or not. The apparent steepening
seen in the G230LB data is driven by the most recent two sensitivity measurements.
Additional data are needed to determine if this change in the trend is real. Therefore, we
conclude that is no strong evidence that the sensitivity trends of the STIS low-resolution
gratings have changed since STIS was reactivated in 2009. We also note that, aside from
the two uncertain break points for G140L and G230LB, the current rates of change in
sensitivities of all five L gratings appear to be continuations of trends that started before
the STIS failure in 2004.
If the scatter seen in the sensitivity data is due primarily to statistical errors then
the reduced χ2 value (the χ2 /ν column in Table 5) will be approximately unity. In
general this is not the case. The reduced χ2 values for the fits vary from approximately
0.2 to 2. This indicates that the observed scatter is not solely due to statistical uncertainty
in the data, and that the covariance matrix of the fit cannot be used to provide a reliable
estimate of the errors in the fitted parameters. The root mean square deviation (RMS)
of the data around the fit, however, provides a reasonable estimate of the uncertainty
in the relative sensitivity at a given time. RMS values for the fits to each L grating are
listed in Table 5, and are typically 0.2% to 0.5%. We take these values to be reasonable
estimates of the uncertainty in the sensitivity at a given time.
Instrument Science Report STIS 2014-02 Page 6
G140L
1.02
1.00
Relative Sensitivity
0.98
0.96
0.94
0.92
0.90
0.88
1996
1998
2000
2002
2004 2006
Date (year)
2008
2010
2012
2014
Figure 1. The TDS function for the G140L grating. Vertical lines indicate the fitted
break points.
Table 5.
Segment
G140L
1
2
3
4
5
G230L
1
2
3
G230LB
1
2
3
4
G430L
1
G750L
1
Fits to the sensitivity data.
Break Point (year)
Slope (%/year)
···
1998.96
2000.50
2003.04
2011.83
−0.98254
−2.07540
−1.31823
−0.17261
+0.16227
···
1998.93
2002.94
+1.36345
−1.69656
−0.23687
···
1998.96
2002.92
2012.47
+0.77478
−1.53779
−0.41043
−1.02773
···
−0.25621
···
−0.15486
RMS (%)
0.5390
···
···
···
···
···
0.2370
···
···
···
0.2200
···
···
···
···
0.3900
···
0.2200
···
Instrument Science Report STIS 2014-02 Page 7
χ2 /ν
127.9046 / 66
···
···
···
···
···
30.4257 / 74
···
···
···
7.6499 / 42
···
···
···
···
21.6080 / 55
···
43.7933 / 46
···
G230L
1.04
Relative Sensitivity
1.02
1.00
0.98
0.96
0.94
0.92
1996
1998
2000
2002
2004 2006
Date (year)
2008
2010
2012
2014
2008
2010
2012
2014
G230LB
1.02
1.00
Relative Sensitivity
0.98
0.96
0.94
0.92
0.90
0.88
1996
1998
2000
2002
2004 2006
Date (year)
Figure 2. The TDS functions for the G230L (upper) and G230LB (lower) gratings.
Vertical lines indicate the fitted break points.
Instrument Science Report STIS 2014-02 Page 8
G430L
1.02
1.01
Relative Sensitivity
1.00
0.99
0.98
0.97
0.96
0.95
0.94
0.93
1996
1998
2000
2002
2004 2006
Date (year)
2008
2010
2012
2014
2008
2010
2012
2014
G750L
1.005
1.000
Relative Sensitivity
0.995
0.990
0.985
0.980
0.975
0.970
1996
1998
2000
2002
2004 2006
Date (year)
Figure 3. The TDS functions for the G430L (upper) and G750L (lower) gratings.
Instrument Science Report STIS 2014-02 Page 9
4.2 Dependence on Wavelength
The STIS processing pipeline currently assumes that the sensitivity of each STIS grating
varies with wavelength and applies a correction based on the sensitivity computed over
small wavelength bins for each grating. The ∆λ column in Table 4 shows the widths
of these wavelength bins. We investigate the dependence of the TDS on wavelength
for each L grating by binning the count rate data using these wavelength bins. The
sensitivity data in each wavelength bin were fit using the procedure described in § 3
except that the break points were fixed to those listed in Table 5. This was done because
the current TDS corrections in OPUS have the same break points in each wavelength
bin for a given grating. The variation of the TDS with wavelength for each of the L
gratings is shown in Figures 4–6.
The wavelength dependence is strongest for G140L, where the variation can be as
much as 5% about the mean, and essentially non-existent for G430L and G750L. The
change in sensitivity with wavelength suggests that it may be possible to improve the
current sensitivity correction process by fitting a polynomial to the relative sensitivity as
a function of wavelength and using this polynomial to compute a wavelength-dependent
sensitivity correction for each pixel instead of using a single correction within a wavelength bin. A pixel-by-pixel correction would provide a finer resolution of the sensitivity correction than the current method of applying a single correction over a wavelength
range of between 50 Å (G140L) and 400 Å (G750L). Figures 4–6 suggest that a pixelby-pixel polynomial approximation for the TDS could improve the accuracy of the flux
calibration of these gratings by as much as 5%.
Instrument Science Report STIS 2014-02 Page 10
G140L
1.10
1998.96
2000.50
2003.04
2011.83
Relative Sensitivity
1.05
1.00
0.95
0.90
0.85
0.80
1100
1200
1300
1400
1500
Wavelength (Å)
1600
G230L
1.10
1998.93
2002.94
1.05
Relative Sensitivity
1700
1.00
0.95
0.90
0.85
0.80
1600
1800
2000
2200 2400 2600
Wavelength (Å)
2800
3000
3200
Figure 4. The wavelength dependencies of the TDS for the G140L (upper panel) and
G230L (lower panel) gratings. The TDS is evaluated at each of the fitted break points.
The error bars indicate the RMS of the fit in each wavelength bin. The dashed line is a
4th order polynomial fit to the data.
Instrument Science Report STIS 2014-02 Page 11
G230LB
1.10
1998.96
2002.93
2012.47
Relative Sensitivity
1.05
1.00
0.95
0.90
0.85
0.80
1600
1800
2000
2200
2400
Wavelength (Å)
2600
2800
G430L
1.10
3000
2004.46
Relative Sensitivity
1.05
1.00
0.95
0.90
0.85
0.80
2500
3000
3500
4000
4500
Wavelength (Å)
5000
5500
6000
Figure 5. The wavelength dependencies for the G230LB (upper panel) and G430L
(lower panel) gratings. There is no break point for G430L, so the sensitivity is evaluated
at 2004.46, just before the hiatus in STIS operations. This date was choosen because it
is approximately halfway between the initial activation of STIS and the present.
Instrument Science Report STIS 2014-02 Page 12
G750L
1.10
2004.46
Relative Sensitivity
1.05
1.00
0.95
0.90
0.85
0.80
5500
6000
6500
7000
7500 8000 8500
Wavelength (Å)
9000
9500 10000
Figure 6. The wavelength dependence for the G750L grating. There is no break point
for G750L, so the sensitivity is evaluated at 2004.46.
Table 6.
RMS deviation between the sensitivity values derived in this work and those
from previous work. The sensitivities are evaluated at 2012.0.
Grating
RMS
G140L
G230L
G230LB
G430L
G750L
0.0047
0.0086
0.0057
0.0032
0.0073
4.3 Comparison to Previous Results
As a sanity check we compare the results of our analysis with the current TDS calibration. The comparison was done using the predicted sensitivity values at 2012.0. This
comparison is shown in Figures 7–9. The two calibrations agree with each other over
the entire wavelength range of each grating. The RMS differences for each grating are
listed in Table 6.
We find no significant differences between our calibration of the TDS and what is
currently used in the STIS reference files. This agreement between the TDS presented
in this ISR and the previous TDS solution that had break points determined by hand
indicates that the automated method of determining break points described here, and in
Holland (STIS TIR 2013-03), is successful.
Instrument Science Report STIS 2014-02 Page 13
G140L
1.00
This Work
Previous
Relative Sensitivity
0.95
0.90
0.85
0.80
1100
1200
1300
1400
1500
Wavelength (Å)
1600
G230L
1.00
1700
This Work
Previous
Relative Sensitivity
0.95
0.90
0.85
0.80
1600
1800
2000
2200 2400 2600
Wavelength (Å)
2800
3000
3200
Figure 7. A comparison of the TDS values for the G140L (upper panel) and G230L
(lower panel) gratings computed in this ISR to previous values (used by the current
TDS reference file). The sensitivity is evaluated at 2012.00. The error bars indicate the
RMS of the fit.
Instrument Science Report STIS 2014-02 Page 14
G230LB
1.00
This Work
Previous
Relative Sensitivity
0.95
0.90
0.85
0.80
1600
1800
2000
2200
2400
Wavelength (Å)
2600
G430L
1.00
2800
3000
This Work
Previous
Relative Sensitivity
0.95
0.90
0.85
0.80
2500
3000
3500
4000
4500
Wavelength (Å)
5000
5500
6000
Figure 8. A comparison of the TDS values for the G230LB (upper panel) and G430L
(lower panel) gratings computed in this ISR to previous values (used by the current TDS
reference file). The sensitivity is evaluated at 2012.00. The error bars indicate the RMS
of the fit.
Instrument Science Report STIS 2014-02 Page 15
G750L
1.00
This Work
Previous
Relative Sensitivity
0.95
0.90
0.85
0.80
5500
6000
6500
7000
7500 8000 8500
Wavelength (Å)
9000
9500 10000
Figure 9. A comparison of the TDS values for the G750L grating computed in this ISR
to previous values (used by the current TDS reference file). The sensitivity is evaluated
at 2012.00. The error bars indicate the RMS of the fit.
4.4 The Bayesian Information Criterion
The method we use to fit a segmented line model to the sensitivity data uses the F test
to determine the optimal number of break points. However, the F test is only valid if
the test statistic follows the F distribution under the null hypothesis. In our case the test
statistic is the reduced chi-square of the fit and the null hypothesis is that the data were
drawn from the model with the fewer break points. However, for the reduced chi-square
value to be a valid test statistic the observed scatter in the sensitivity values must be due
only to statistical errors in the measurements and not contain any systematic errors or
additional components that could affect the sensitivity measurements. This is not the
case (see § 4.1).
To test if systematic errors are biasing our results, and to investigate the possibility that the underlying statistical model does not represent the data well, we tried an
alternate approach to identifying break points. We computed the Bayesian information
criterion (BIC; Schwarz, 1978) for each model and used this to determine the best number of line segments for each L grating. The value of the BIC depends on the likelihood
function of the model’s free parameters, the number of free parameters, and the number
of data points. It is not a test statistic. Instead it is a numerical measure of the evidence
that the data support a model. The BIC is used to compare two models and the model
with the smaller value is assumed to give a better description of the data.
We found that using the BIC instead of an F test returns identical results for
Instrument Science Report STIS 2014-02 Page 16
G230LB
1.00
1.00
0.98
0.98
0.96
0.94
0.96
0.94
0.92
0.92
0.90
0.90
0.88
1996
1998
2000
2002
2004 2006
Date (year)
G230LB
1.02
Relative Sensitivity
Relative Sensitivity
1.02
2008
2010
2012
2014
0.88
1996
1998
2000
2002
2004 2006
Date (year)
2008
2010
2012
2014
Figure 10. The left panel shows the best-fitting segmented line model to the G230LB
data as determined using an F test. The right panel shows the best-fitting model as
determined using the BIC. The fits are identical until 2012.47, when the F test method
finds a breakpoint but the BIC does not. See § 4.1 for a discussion of the reality of the
2012.47 breakpoint.
G140L, G230L, G430L, and G750L while for G230LB the BIC values suggest that
the break point at 2012.47 is not needed. A visual examination of the G230LB data and
fits (Figure 10) suggests that the break point at 2012.47 may not be real. Additional
data will be needed to determine if the decline in the sensitivity has changed slope at
this point. Given that the BIC and F test methods return the same TDS model for four
L gratings, and a very similar model for the fifth, we find no reason to prefer either
technique at this time.
Instrument Science Report STIS 2014-02 Page 17
5. Comparison to Other STIS Gratings
5.1 The Medium-Resolution Gratings
The STIS TDS reference files used by OPUS, the ETC, and pysynphot currently assume that the time-dependent behavior of the sensitivities of the M gratings behave in
the same way as those of the corresponding L gratings. We tested this assumption by
comparing the relative sensitivities for each M grating to the values obtained from the
corresponding L gratings. The comparison was made to the wavelength bin that most
closely matched the wavelength range of the M grating. The results are show in Figures 11–14.
The observed TDS of the G140M grating approximately follows that of the G140L
grating at both the 1173 Å and 1567 Å settings. The G140M/1173 sensitivity is about
1% lower than the G140L sensitivity after SMOV-4 and approximately 1% higher after.
The G230M TDS approximately follows the G230L TDS, but with a deviation of up
to 1% before 2004. The sensitivities of the G230MB/1995 and G230M/2416 gratings
closely follow that of G230LB. The sharp downturn in the G230LB sensitivity at 1995 Å
after 2012.47 may be an artifact introduced by the two most recent observations. See
§ 4.1 for details. The G750M/7283 TDS closely follows that of the G750L grating.
The TDS data for G430M (at both 3165 and 4149 Å), however, do not agree
with the G430L TDS fit. G430M exhibits a change in the rate of change of the TDS
at about 2000.0 which is not present in the G430L model. However, an examination
of the TDS data and model for G430L (see Figure 3) suggests that there may be a
breakpoint near 2000.0 that our automated breakpoint detection algorithm missed due
to the large uncertainties in the G430L data and the low sensitivity values of the first
three observations (datasets 045a01020, 045a03020, and 045a04020). If these initial
three observations are discarded then the G430L and G430M TDS trends are in closer
agreement. The details of the G430L and G430M TDS fits need to be investigated
further.
Instrument Science Report STIS 2014-02 Page 18
G140M/1173
1.00
0.98
Relative Sensitivity
0.96
0.94
0.92
0.90
0.88
0.86
0.84
0.82
1995
2000
2005
Year
2010
2015
2010
2015
G140M/1567
1.00
Relative Sensitivity
0.95
0.90
0.85
0.80
1995
2000
2005
Year
Figure 11. A comparison of the TDS values between the G140L and G140M/1137
gratings (upper panel). The upturn in the G140L TDS at 2011.83 is likely to be an
artifact of the large scatter in the recent G140L data at at 1567 Å and not a true change
in the TDS trend. The lower panel shows a comparison of the TDS values between the
G140L and G140M/1567 gratings.
Instrument Science Report STIS 2014-02 Page 19
G230MB/1995
1.05
Relative Sensitivity
1.00
0.95
0.90
0.85
1995
2000
2005
Year
2010
2015
2010
2015
G230MB/2416
1.02
Relative Sensitivity
1.00
0.98
0.96
0.94
0.92
0.90
1995
2000
2005
Year
Figure 12. A comparison of the TDS values between the G230LB and G230MB/1995
gratings (upper panel) and between the G230LB and G230MB/2416 gratings (lower
panel).
Instrument Science Report STIS 2014-02 Page 20
G430M/3165
1.00
0.99
Relative Sensitivity
0.98
0.97
0.96
0.95
0.94
0.93
0.92
1995
2000
2005
Year
2010
2015
2010
2015
G430M/4149
1.00
Relative Sensitivity
0.99
0.98
0.97
0.96
0.95
0.94
1995
2000
2005
Year
Figure 13. A comparison of the TDS values between the G430L and G430M/3165
gratings (upper panel) and between the G430L and G430M/4149 gratings (lower panel).
Instrument Science Report STIS 2014-02 Page 21
G230M/2818
1.03
1.02
Relative Sensitivity
1.01
1.00
0.99
0.98
0.97
0.96
0.95
0.94
1995
2000
2005
Year
2010
2015
2010
2015
G750M/7283
1.010
1.005
Relative Sensitivity
1.000
0.995
0.990
0.985
0.980
0.975
0.970
1995
2000
2005
Year
Figure 14. A comparison of the TDS values between the G230L and G230M/2818
gratings (upper panel) and between the G750L and G750M/7283 gratings (lower panel).
Instrument Science Report STIS 2014-02 Page 22
5.2 The Echelle Gratings
As with the medium-resolution gratings the STIS TDS reference files currently assume
that the sensitivities of the echelle gratings behave in the same way as the sensitivities of
the corresponding L gratings. Again, if this is not correct the calibrated flux values for
STIS echelle spectra will be incorrect. In § 5.1 we showed that this assumption is true
for most of the M gratings. Here we test this assumption for the echelles. As above the
comparison was made to the wavelength bin that most closely matched the wavelength
range of the echelle grating. The results are show in Figures 15–17.
The observed TDS of E140H agrees with the G140L TDS with a scatter of ≈0.5%.
The observed TDS of E140M also agrees with that of G140L with a scatter is typically
≈0.5%. However, there are several E140M observations between 2000 and 2005 that
exhibit sensitivities ≈3% lower than the G140L TDS model predicts. The data from
these observations need to be examined to determine the cause of this systematic offset. The TDS for E230M/1978 and E230M/2707 are consistent with the G230L TDS,
although there is scatter of up to ≈5% for E230M/1978. There are no data for E230M
before 2004. The E230H data agree with the G230L TDS model between approximately
1999 and 2004. Before that the E230H sensitivity is significantly higher than the G140L
TDS model predictions. After 2010 the E230H sensitivity is systematically ≈2% below
the G140L values.
The TDS of the echelle gratings are in broad agreement with the G140L and
G230L TDS results, but some of the echelles exhibit systematic differences of up to
≈5%, and the magnitude and sign of these differences change with time. Therefore we
conclude that the flux calibration of the echelle gratings contains an uncertainty of up to
approximately 5% due to the use of the L grating TDS.
Instrument Science Report STIS 2014-02 Page 23
E140H
1.05
Relative Sensitivity
1.00
0.95
0.90
0.85
0.80
0.75
1995
2000
2005
Year
2010
2015
2010
2015
E140M
1.02
1.00
Relative Sensitivity
0.98
0.96
0.94
0.92
0.90
0.88
1995
2000
2005
Year
Figure 15. A comparison of the TDS values between the E140H and G140L gratings
(upper panel) and between the E140M and G140L gratings (lower panel).
Instrument Science Report STIS 2014-02 Page 24
E230M/1978
Relative Sensitivity
1.05
1.00
0.95
0.90
1995
2000
2005
Year
2010
2015
2010
2015
E230M/2707
1.02
Relative Sensitivity
1.00
0.98
0.96
0.94
0.92
1995
2000
2005
Year
Figure 16. A comparison of the TDS values between the G230L and E230M/1978 gratings (upper panel) and between the G230L and E230M/2707 gratings (lower panel).
Instrument Science Report STIS 2014-02 Page 25
E230H
Relative Sensitivity
1.05
1.00
0.95
0.90
1995
2000
2005
Year
2010
2015
Figure 17. A comparison of the TDS values between the G230L and E230H gratings.
6. Conclusions
The behavior of the TDS of the five STIS long-slit, low-resolution gratings is well understood. Since SMOV-4 the sensitivities have dropped slowly, at rates of ≈ 0.2–0.4%
per year. There has, however, been an increase in the scatter in the sensitivity since
SMOV-4 that is not well understood. This is particularly noticeable in the G140L grating.
The TDS depends on wavelength. This is most noticeable for the MAMAs, but
is also seen on the CCD at wavelengths redder than about 8000 Å. G140L shows the
largest wavelength dependence with sensitivities varying by as much as 5%.
We conclude that the TDS calibration that is currently in the STIS reference files
is accurate to better than ≈ 0.5% for the L gratings. The use of the L gratings as proxies
for the M and echelle gratings is valid except possibly for G430M, which needs to be
investigated further.
Instrument Science Report STIS 2014-02 Page 26
7. Recommendations
The following investigations may reduce the scatter, and improve the characterization
of the TDS of each STIS grating.
1. The apparent discrepancy between the G430L TDS and the G430M sensitivity
data needs to be investigated and resolved.
2. The entire sensitivity data set (see Appendix A) should be examined and checked
against observation log files to search for observations that experienced unusual
conditions such as abnormally large jitter, loss of fine guidance sensor lock, unusual detector temperatures, and other oddities. This may reduce the scatter seen
in some of the TDS data, and may resolve the problem with some of the systematic offsets between the M and E grating sensitivity data and the corresponding L
grating TDS model
3. It may be possible to improve the temperature corrections that are applied to the
count rates. At present no temperature correction is applied to data taken before
2001.5 and a single temperature correction (for each grating) is applied to all
data taken since then. The time dependence of the temperature corrections since
2001.5 needs to be investigated. In particular, are the temperature corrections
after SMOV-4 the same as those before SMOV-4? A change in the post-SMOV-4
temperature correction may eliminate some of the increase in scatter seen in the
G140L sensitivities since SMOV-4.
4. The analysis presented here uses the point-source CTE correction method described in Goudfrooij (ISR 2006-03). However, a pixel-based method for performing CTE corrections is under development. Preliminary results suggest that it
results in an improvement over the point-source method. The pixel-based method
should be investigated for use in the TDS analysis when it is available.
5. The CCD detector suffers from fringing at wavelengths redder than ≈8000 Å.
We have not applied fringe flats to the G750L and G750M data, although the
appropriate flat-field data does exist. These flats should be applied and the TDS
analysis repeated to determine if this offers a significant reduction in the scatter.
6. The use of a polynomial function to determine the relative sensitivity as a function
of wavelength should be investigated. This has the potential to improve the flux
calibration by up to 5% for some gratings.
Acknowledgments
The authors would like to thank Ralph Bohlin and Phil Hodge for useful discussions
regarding STIS, the TDS calibration, and the STIS processing pipeline.
Instrument Science Report STIS 2014-02 Page 27
Change History for STIS ISR 2014-02
Version 1.0 December 2014 - Original Document
References
Bohlin, R. C., 1999, STIS Instrument Science Report 1999-07, (Baltimore:STScI)
Bohlin, R., 2003, STIS Instrument Science Report 2003-03, (Baltimore:STScI)
Stys, D. J., & Walborn, N. R., 2001, STIS Instrument Science Report 2001-01, (Baltimore:STScI)
Goudfrooij, P., 2006, STIS Instrument Science Report 2006-03, (Baltimore:STScI)
Holland, S. T., 2013, STIS Technical Instrument Report 2013-03, (Baltimore:STScI)
Schwarz, G. E. 1978, Annals of Statistics 6 (2), 461
Smith, E., Stys, D., Walborn, N., & Bohlin, R., 2000, STIS Instrument Science Report
2000-03, (Baltimore:STScI)
Stys, D. J., & Walborn, N. R., 2001, STIS Instrument Science Report 2001-01, (Baltimore:STScI)
Stys, D. J., Bohlin, R. C., & Goudfrooij, P., 2004, STIS Instrument Science Report
2004-04, (Baltimore:STScI)
Walborn, N. R., & Bohlin, R. C., 1998, STIS Instrument Science Report 1998-27, (Baltimore:STScI)
Appendix A: Observations
Information about the HST/STIS long-slit, low-resolution grating datasets that were
used in this study is listed in Table 7 below.
Instrument Science Report STIS 2014-02 Page 28
Table 7.
Grating
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
STIS TDS monitoring observations used in this study.
Central λ (Å)
Date
Time (UT)
Exposure (s)
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1997-06-21
1997-06-29
1997-07-05
1997-08-12
1997-09-16
1997-10-06
1997-11-17
1997-12-19
1998-01-09
1998-02-12
1998-04-12
1998-05-07
1998-07-04
1998-08-05
1998-09-23
1998-10-14
1998-11-04
1998-12-14
1999-01-03
1999-02-11
1999-03-08
1999-04-11
1999-05-12
1999-06-03
1999-07-03
1999-08-03
1999-09-18
1999-11-09
2000-01-19
2000-02-07
2000-03-10
2000-04-12
2000-05-12
2000-06-06
2000-07-03
2000-08-23
1999-10-01
2000-09-17
2000-10-01
2000-11-09
2000-12-06
2001-01-09
2001-02-07
2001-03-19
2001-04-04
2001-05-05
2001-08-12
2001-09-10
2001-10-07
2001-11-10
2002-01-10
2002-02-16
2002-03-01
2002-04-16
2002-05-18
2002-06-05
11:08:56
06:08:42
06:40:03
09:18:10
21:11:23
13:36:39
17:23:40
23:54:46
15:03:40
14:55:32
17:57:12
02:51:18
18:54:31
07:38:58
08:02:51
22:40:39
06:35:51
14:51:39
08:36:14
12:54:13
16:55:03
05:52:14
18:15:58
02:08:16
08:44:21
00:32:16
00:30:05
14:04:08
08:37:36
02:02:33
02:20:13
12:46:34
19:14:33
10:07:45
02:01:13
16:25:50
18:14:28
04:00:07
07:00:41
05:53:34
12:34:48
04:11:31
13:57:54
14:41:12
06:25:43
08:56:02
18:11:30
03:03:37
05:51:03
13:26:37
14:35:17
17:05:11
14:07:39
10:15:17
21:10:00
13:58:47
240.00
240.00
240.00
180.00
180.00
180.00
180.00
180.00
216.00
189.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
201.00
204.00
201.00
201.00
201.00
201.00
201.00
201.00
201.00
201.00
201.00
204.00
204.00
201.00
204.00
201.00
201.00
201.00
201.00
201.00
201.00
201.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
Target
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
Instrument Science Report STIS 2014-02 Page 29
Proposal ID
7064
7064
7064
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
8424
8424
8424
8424
8424
8424
8424
8424
8424
8424
8424
8424
8424
8857
8857
8857
8857
8857
8857
8857
8857
8857
8857
8919
8919
8919
8919
8919
8919
8919
8919
8919
Dataset
o3yx14040
o3yx15040
o3yx16040
o45901010
o45910010
o45911010
o45912010
o45913010
o45914010
o45915010
o45917010
o45940010
o45942010
o45943010
o45944010
o45945010
o45946010
o45947010
o45948010
o45949010
o45950010
o45951010
o45952010
o45953010
o5jj01010
o5jj02010
o5jj03010
o5jj05010
o5jj07010
o5jj08010
o5jj09010
o5jj10010
o5jj11010
o5jj12010
o5jj13010
o5jj14010
o5jj99010
o69s01010
o69s02010
o69s03010
o69s04010
o69s05010
o69s06010
o69s07010
o69s08010
o69s09010
o69s12010
o6i801010
o6i802010
o6i803010
o6i805010
o6i806010
o6i807010
o6i808010
o6i809010
o6i810010
Table 7. (cont’d)
Central λ (Å)
Date
Time (UT)
Exposure (s)
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
G140L
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
1425
2002-08-03
2002-10-17
2003-01-05
2003-05-06
2003-06-28
2003-09-19
2003-12-01
2004-02-18
2004-06-08
2009-11-27
2010-03-09
2010-06-23
2009-09-28
2010-11-20
2011-03-14
2011-07-09
2011-10-31
2012-07-02
2012-11-03
2013-03-13
2013-07-02
09:57:35
12:44:47
02:37:33
13:27:54
12:52:07
11:02:38
22:17:22
13:22:45
00:09:13
12:31:39
12:33:09
06:59:34
12:39:40
20:07:31
11:11:32
04:48:23
18:46:37
16:22:58
03:41:54
04:53:17
01:23:56
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
331.00
331.00
331.00
331.00
331.00
331.00
331.00
331.00
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
8919
9628
9628
9628
9628
9628
10033
10033
10033
11860
11860
11860
11860
12414
12414
12414
12775
12775
13145
13145
13145
o6i812010
o8ia01010
o8ia02010
o8ia04010
o8ia05010
o8ia06010
o8v501010
o8v502010
o8v503010
ob8703010
ob8704010
ob8705010
ob87n2010
obn6l1010
obn6l2010
obn6l3010
obw3l1010
obw3l3010
oc4kl1010
oc4kl2010
oc4kl3010
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
1997-05-29
1997-06-06
1997-06-13
1997-07-05
1997-08-12
1997-09-16
1997-10-06
1997-11-17
1997-12-20
1998-01-09
1998-02-12
1998-04-12
1998-05-07
1998-07-04
1998-08-05
1998-09-23
1998-10-14
1998-11-04
1998-12-14
1999-01-03
1999-02-11
1999-03-08
1999-04-11
1999-05-12
1999-06-03
1999-07-03
1999-08-03
1999-09-18
1999-11-09
2000-01-19
2000-02-07
2000-03-10
2000-04-12
2000-05-12
22:52:54
00:10:39
21:11:18
06:53:00
10:14:48
21:21:49
13:47:05
17:34:06
00:05:12
15:14:20
15:05:45
18:07:40
03:01:46
19:04:50
07:49:17
08:13:10
22:50:58
06:46:10
15:01:58
08:46:33
13:04:32
17:05:22
06:02:33
18:26:17
02:18:35
08:54:37
00:42:35
00:40:21
14:14:24
08:47:52
02:12:49
02:30:29
12:56:50
19:24:49
636.00
636.00
636.00
636.00
184.00
184.00
184.00
184.00
184.00
216.00
216.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
7064
7064
7064
7064
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
7673
8424
8424
8424
8424
8424
8424
8424
8424
8424
o3yx11030
o3yx12030
o3yx13030
o3yx16030
o45901020
o45910020
o45911020
o45912020
o45913020
o45914020
o45915020
o45917020
o45940020
o45942020
o45943020
o45944020
o45945020
o45946020
o45947020
o45948020
o45949020
o45950020
o45951020
o45952020
o45953020
o5jj01020
o5jj02020
o5jj03020
o5jj05020
o5jj07020
o5jj08020
o5jj09020
o5jj10020
o5jj11020
Grating
Target
Instrument Science Report STIS 2014-02 Page 30
Proposal ID
Dataset
Table 7. (cont’d)
Central λ (Å)
Date
Time (UT)
Exposure (s)
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
G230L
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2376
2000-06-06
2000-07-03
2000-08-23
1999-10-01
2000-09-17
2000-10-01
2000-11-09
2000-12-06
2001-01-09
2001-02-07
2001-03-19
2001-04-04
2001-05-05
2001-08-12
2001-09-10
2001-10-07
2001-11-10
2001-12-01
2002-01-10
2002-02-16
2002-03-01
2002-04-16
2002-05-18
2002-06-05
2002-08-03
2002-10-17
2003-01-05
2003-05-06
2003-06-28
2003-09-19
2003-12-01
2004-02-18
2004-06-08
2009-11-27
2010-03-09
2010-06-23
2009-09-28
2010-11-20
2011-03-14
2011-07-09
2011-10-31
2012-03-14
2012-07-02
2012-11-03
2013-03-13
2013-07-02
10:18:01
02:11:29
16:36:09
18:24:47
04:10:23
07:11:00
06:03:50
12:45:04
04:21:47
14:08:10
14:51:28
06:35:59
09:06:18
18:21:49
03:13:56
06:01:22
13:36:56
11:06:11
14:45:36
17:15:30
14:17:58
10:25:36
21:20:19
14:09:06
10:07:54
12:55:06
02:47:52
13:38:13
13:02:26
11:12:57
22:27:41
13:33:04
00:19:32
12:41:58
12:43:27
07:09:53
12:49:59
20:19:57
11:23:58
05:00:49
18:59:03
01:54:32
16:35:24
03:54:18
05:05:41
01:36:20
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
204.00
368.00
368.00
368.00
368.00
368.00
368.00
368.00
368.00
368.00
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
GRW+70D5824
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
2375
2375
2375
2375
2375
2375
2375
2375
2375
1997-08-03
1997-10-01
1997-12-01
1998-02-04
1998-04-01
1998-05-31
1998-07-31
1998-10-12
1998-12-06
00:31:03
05:49:13
01:43:39
07:59:36
11:00:23
16:13:52
21:27:24
12:29:56
22:46:56
144.00
144.00
144.00
144.00
144.00
172.80
172.80
172.80
172.80
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
Grating
Target
Instrument Science Report STIS 2014-02 Page 31
Proposal ID
Dataset
8424
8424
8424
8424
8857
8857
8857
8857
8857
8857
8857
8857
8857
8857
8919
8919
8919
8919
8919
8919
8919
8919
8919
8919
8919
9628
9628
9628
9628
9628
10033
10033
10033
11860
11860
11860
11860
12414
12414
12414
12775
12775
12775
13145
13145
13145
o5jj12020
o5jj13020
o5jj14020
o5jj99020
o69s01020
o69s02020
o69s03020
o69s04020
o69s05020
o69s06020
o69s07020
o69s08020
o69s09020
o69s12020
o6i801020
o6i802020
o6i803020
o6i804020
o6i805020
o6i806020
o6i807020
o6i808020
o6i809020
o6i810020
o6i812020
o8ia01020
o8ia02020
o8ia04020
o8ia05020
o8ia06020
o8v501020
o8v502020
o8v503020
ob8703020
ob8704020
ob8705020
ob87n2020
obn6l1020
obn6l2020
obn6l3020
obw3l1020
obw3l2020
obw3l3020
oc4kl1020
oc4kl2020
oc4kl3020
7672
7672
7672
7672
7672
7672
7672
7672
7672
o45a01010
o45a03010
o45a04010
o45a05010
o45a06010
o45a12010
o45a13010
o45a14010
o45a15010
Table 7. (cont’d)
Grating
Central λ (Å)
Date
Time (UT)
Exposure (s)
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
G230LB
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
2375
1999-02-07
1999-04-03
1999-06-03
1999-08-01
1999-10-03
2000-01-11
2000-02-01
2000-04-02
2000-06-04
2000-08-01
2000-10-24
2001-01-29
2001-04-01
2001-08-06
2001-10-04
2002-01-01
2002-04-03
2002-06-25
2002-10-06
2003-01-16
2003-03-24
2003-06-24
2003-09-08
2003-11-01
2003-12-21
2004-03-14
2004-05-07
2004-06-15
2004-06-15
2004-08-03
2009-07-01
2009-11-16
2010-04-12
2011-07-04
2011-04-25
2011-11-14
2012-03-14
2012-06-25
2012-11-14
2013-03-14
2013-06-20
00:36:26
15:30:30
13:29:36
01:16:42
02:14:59
22:04:19
15:14:27
04:51:29
17:59:18
15:58:46
21:39:18
01:42:16
00:58:06
07:47:55
18:10:10
20:26:28
23:01:36
17:55:42
12:09:19
06:57:42
01:34:33
20:45:51
12:38:18
03:27:09
02:13:42
14:06:21
02:38:14
12:30:59
14:06:52
12:11:39
20:12:49
22:23:27
08:44:31
14:36:42
06:47:52
01:47:05
03:14:30
02:13:14
02:15:02
12:36:54
13:44:51
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.00
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
7672
7672
7672
8418
8418
8418
8418
8418
8418
8418
8856
8856
8856
8856
8914
8914
8914
8914
9627
9627
9627
9627
10030
10030
10030
10030
10030
10030
10030
10030
11401
11855
11855
12411
12411
12772
12772
12772
13141
13141
13141
o45a16010
o45a17010
o45a18010
o5ig01010
o5ig02010
o5ig03010
o5ig04010
o5ig05010
o5ig06010
o5ig07010
o69l01020
o69l02020
o69l03020
o69l04020
o6i901020
o6i902020
o6i903020
o6i904020
o8jj01020
o8jj02020
o8jj03020
o8jj04020
o8u201020
o8u202020
o8u203020
o8u204020
o8u205020
o8u206020
o8u207020
o8u208020
oa9j01050
obau03020
obau05020
obmzl3020
obmzl4020
obvnl1020
obvnl2020
obvnl3020
oc4il1020
oc4il2020
oc4il3020
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
1997-08-03
1997-10-01
1997-12-01
1998-02-04
1998-04-01
1998-05-31
1998-07-31
1998-10-12
1998-12-06
1999-02-07
1999-04-03
1999-06-03
1999-08-01
1999-10-03
00:39:42
05:57:52
01:52:18
08:08:15
11:09:02
16:23:01
21:36:33
12:39:05
22:56:11
00:45:41
15:39:45
13:38:51
01:25:57
02:24:14
144.00
144.00
144.00
144.00
144.00
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
7672
7672
7672
7672
7672
7672
7672
7672
7672
7672
7672
7672
8418
8418
o45a01020
o45a03020
o45a04020
o45a05020
o45a06020
o45a12020
o45a13020
o45a14020
o45a15020
o45a16020
o45a17020
o45a18020
o5ig01020
o5ig02020
Target
Instrument Science Report STIS 2014-02 Page 32
Proposal ID
Dataset
Table 7. (cont’d)
Central λ (Å)
Date
Time (UT)
Exposure (s)
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
G430L
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
4300
2000-01-11
2000-02-01
2000-04-02
2000-06-04
2000-08-01
2000-10-24
2001-01-29
2001-04-01
2001-08-06
2001-10-04
2002-01-01
2002-04-03
2002-06-25
2002-10-06
2003-01-16
2003-03-24
2003-06-24
2003-09-08
2003-11-01
2003-12-21
2004-03-14
2004-05-07
2004-06-15
2004-06-15
2004-08-03
2009-07-01
2009-08-10
2009-09-28
2009-11-16
2010-01-12
2010-04-12
2010-07-05
2010-11-22
2011-07-04
2011-04-25
2011-11-14
2012-03-14
2012-06-25
2011-11-09
2011-11-09
2011-11-09
2011-11-09
2011-11-09
2011-11-09
2012-11-14
2013-01-18
2013-01-18
2013-01-18
2013-01-18
2013-01-18
2013-01-18
2013-03-14
2013-06-20
22:13:34
15:23:42
05:00:44
18:08:33
16:08:01
21:48:33
01:51:31
01:07:21
07:57:10
18:19:25
20:35:43
23:10:51
18:04:57
12:18:34
07:06:57
01:43:48
20:55:06
12:47:33
03:36:24
02:22:57
14:15:36
02:47:29
12:40:14
14:16:07
12:20:54
21:16:20
06:01:18
23:46:58
22:32:42
12:35:05
08:53:45
11:28:44
17:02:09
14:45:57
06:57:07
01:56:20
03:23:45
02:22:29
02:19:10
02:22:05
02:27:08
02:30:03
02:32:54
02:40:44
02:24:17
16:24:10
16:27:05
16:32:06
16:35:01
16:37:52
16:45:40
12:46:09
13:54:06
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.00
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
172.80
50.00
50.00
50.00
50.00
50.00
50.00
172.80
50.00
50.00
50.00
50.00
50.00
50.00
172.80
172.80
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
8418
8418
8418
8418
8418
8856
8856
8856
8856
8914
8914
8914
8914
9627
9627
9627
9627
10030
10030
10030
10030
10030
10030
10030
10030
11401
11855
11855
11855
11855
11855
11855
12411
12411
12411
12772
12772
12772
12772
12772
12772
12772
12772
12772
13141
13141
13141
13141
13141
13141
13141
13141
13141
o5ig03020
o5ig04020
o5ig05020
o5ig06020
o5ig07020
o69l01030
o69l02030
o69l03030
o69l04030
o6i901030
o6i902030
o6i903030
o6i904030
o8jj01030
o8jj02030
o8jj03030
o8jj04030
o8u201030
o8u202030
o8u203030
o8u204030
o8u205030
o8u206030
o8u207030
o8u208030
oa9j01080
obau01030
obau02030
obau03030
obau04030
obau05030
obau06030
obmzl1030
obmzl3030
obmzl4030
obvnl1030
obvnl2030
obvnl3030
obvnm1090
obvnm10a0
obvnm10b0
obvnm10c0
obvnm10d0
obvnm10f0
oc4il1030
oc4im1090
oc4im10a0
oc4im10b0
oc4im10c0
oc4im10d0
oc4im10f0
oc4il2030
oc4il3030
G750L
G750L
7751
7751
1998-02-04
1998-04-01
08:16:54
11:17:41
360.00
360.00
AGK+81D266
AGK+81D266
7672
7672
o45a05030
o45a06030
Grating
Target
Instrument Science Report STIS 2014-02 Page 33
Proposal ID
Dataset
Table 7. (cont’d)
Grating
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
G750L
Central λ (Å)
Date
Time (UT)
Exposure (s)
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
7751
1998-05-31
1998-07-31
1998-10-12
1998-12-06
1999-02-07
1999-04-03
1999-06-03
1999-08-01
1999-10-03
2000-01-11
2000-02-01
2000-04-02
2000-06-04
2000-08-01
2000-10-24
2001-01-29
2001-04-01
2001-08-06
2001-10-04
2002-01-01
2002-04-03
2002-06-25
2002-10-06
2003-01-16
2003-03-24
2003-06-24
2003-09-08
2003-11-01
2003-12-21
2004-03-14
2004-05-07
2004-06-15
2004-06-15
2004-08-03
2009-07-01
2010-01-12
2010-07-05
2010-11-22
2011-07-04
2011-04-25
2011-11-14
2012-03-14
2012-06-25
2012-11-14
2013-03-14
2013-06-20
16:32:10
21:45:42
12:48:14
23:05:26
00:54:56
15:49:00
13:48:06
01:35:12
02:33:29
22:22:49
15:32:57
05:09:59
18:17:48
16:17:16
21:57:48
02:00:46
01:16:36
08:06:25
18:28:40
20:44:58
23:32:50
18:26:56
12:40:33
07:28:56
02:50:00
21:17:05
13:09:32
03:58:23
02:44:56
14:37:35
03:09:28
13:02:13
14:38:06
12:42:53
21:25:33
12:57:04
11:50:43
17:24:08
15:07:56
07:19:06
02:18:19
03:45:44
02:44:28
02:46:16
13:08:08
14:16:05
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
430.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
432.00
Target
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
AGK+81D266
Instrument Science Report STIS 2014-02 Page 34
Proposal ID
7672
7672
7672
7672
7672
7672
7672
8418
8418
8418
8418
8418
8418
8418
8856
8856
8856
8856
8914
8914
8914
8914
9627
9627
9627
9627
10030
10030
10030
10030
10030
10030
10030
10030
11401
11855
11855
12411
12411
12411
12772
12772
12772
13141
13141
13141
Dataset
o45a12030
o45a13030
o45a14030
o45a15030
o45a16030
o45a17030
o45a18030
o5ig01030
o5ig02030
o5ig03030
o5ig04030
o5ig05030
o5ig06030
o5ig07030
o69l01040
o69l02040
o69l03040
o69l04040
o6i901040
o6i902040
o6i903060
o6i904060
o8jj01060
o8jj02060
o8jj03060
o8jj04060
o8u201060
o8u202060
o8u203060
o8u204060
o8u205060
o8u206060
o8u207060
o8u208060
oa9j01090
obau04060
obau06060
obmzl1060
obmzl3060
obmzl4060
obvnl1060
obvnl2060
obvnl3060
oc4il1060
oc4il2060
oc4il3060