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Instrument Science Report STIS 2013-02(v1)
Full-field sensitivity and its
time-dependence for the STIS CCD
and MAMAs
Julia Roman-Duval1 & Charles Proffitt1,2
2
1
Space Telescope Science Institute, Baltimore, MD
Science Programs, Computer Sciences Corporation, Baltimore, MD
July 01, 2013
ABSTRACT
The three STIS detectors — CCD, NUV-MAMA, FUV-MAMA — are subject to temperatureand time-dependent sensitivity changes. These temporal sensitivity variations are calibrated as part of routine calibration monitoring programs, and corrected for in the
standard CALSTIS pipeline. In order to determine whether the correction algorithms,
developed based on spectroscopic observations prior to the 2004 failure of STIS, are
adequate for pre- and post-SM4 STIS imaging data, we examine the photometry of standard stellar fields (NGC5139 for the CCD, NGC6681 for the MAMAs) obtained between
1997 and 2012 as part of the routine full-field sensitivity calibration programs. For the
CCD, we include a correction for CTE effects. We find statistically significant residual
temporal variations in the full-field sensitivity of 0.5 mmag/year, −0.04 mmag/year, and
0.54 mmag/year for the CCD, NUV-MAMA, and FUV-MAMA respectively. However,
these residual trends are small: they do not incur flux changes exceeding 1% over a 15
year time period.
Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics
and Space Administration.
1. Introduction
The sensitivity of the STIS detectors — the two NUV and FUV MAMAs and the CCD
— is observed to decrease with time, with a rate measured from the STIS sensitivity
monitors. The time-dependent sensitivity (TDS) trends are regularly measured from
spectroscopic observations. In addition, the STIS CCD is subject to temperature fluctuations since the switch to the side 2 electronics, which produces short-term sensitivity
variations.
Both the long term sensitivity decline and the short term sensitivity variations due
to temperature fluctuations are corrected in CALSTIS, using algorithms that were developed prior to the STIS repair in 2009 based on spectroscopic observations. The details
of the derivation of TDS trends from first-order spectroscopic data taken between 1997
and 2004 are described in STIS ISR 2004-04. Both the long-term sensitivity variations
with time and the short-term dependence on temperature are estimated, and corrections
are derived. The coefficients of these corrections are stored in the TDS reference file.
Each STIS exposure has a header keyword pointing to that reference TDS file, so that
CALSTIS can correct for those trends when the exposure is calibrated. Thus, the calibrated exposures we use here have been corrected for TDS effects.
The goal of the full-field sensitivity analysis is to verify that the algorithms implemented in CALSTIS to correct those variations are accurate for imaging observations,
and to verify that there are no residual temporal variations in the imaging sensitivity.
For this purpose, we perform aperture photometry on stars detected in standard calibration fields (NGC5139 for the CCD, NGC6681 for the MAMAs) between 1997 and
2012, and examine the variations of the magnitude of each star with time. We show that
those residual variations (after correction of the TDS by CALSTIS) do not exceed 1%
for the CCD, NUV-MAMA, and FUV-MAMA over a 15 year period. The photometric
analyses are done independently for each STIS detector.
2 Data
2.1
CCD Observations
Observations of NGC5139 are obtained yearly as part of the STIS CCD full-field sensitivity calibration program. We used MAST to identify all STIS CCD observations of
NGC5139. The STIS CCD observations of NGC5139 were taken as part of calibration
programs 7079, 7639, 8056, 8416, 8847, 8912, 9622, 10028, 11854, 12409, 12770,
covering the time period 1997-2012. All exposures use the 50CCD (clear) aperture. We
only include exposures read out through amplifier D (the default for science). Appendix
A summarizes the different parameters of the CCD exposures. Calibrated, cosmic-ray
rejected, and geometrically corrected science files ( sx2.fits) for all STIS CCD full-field
sensitivity programs up to Cycle 19 were retrieved from MAST.
Instrument Science Report STIS 2013-02(v1) Page 2
2.2 MAMA Observations
The globular cluster NGC6681 is the calibration target for the STIS MAMA full-field
sensitivity programs. Yearly observations of this standard stellar field resulted in the
execution of programs 7080, 7132, 7720, 7788, 8422, 8425, 8858, 8918, 9623, 10032,
11856, 12413, 12774, covering the time period 1997-2012. Each program observed
NGC 6681 in both the NUV and FUV. For the NUV, each calibration program consists
of a combination of 300 s exposures with the F25SRF2, F25QTZ, and F25CN182 filters.
For the FUV, each calibration program includes exposures taken with the 25MAMA
(clear), F25QTZ, and F25SRF2 filters. The NUV- and FUV-MAMA exposure parameters are summarized in Appendix A. Calibrated and geometrically corrected science files
(*x2d.fits) for all STIS MAMA full-field sensitivity programs up to C19 were retrieved
from MAST.
3 Reprocessing of the FUV images
No geometric distortion correction is currently implemented for STIS FUV-MAMA observations. As a result, the combined effects of the accuracy of the guide star catalog
GSCII and of the geometric distortion made the registration of FUV exposures difficult.
We are, nonetheless, in the process of developing a new solution for the FUV geometric
distortion. Preliminary results show that the astrometric accuracy of stellar positions
is improved by a factor of 2 when applying the new solution. Therefore, prior to performing the image registration, the star identification, and our photometric analysis of
the FUV exposures, we reprocessed all FUV data with CALSTIS and with a new IDC
reference file based on o8g1508eo idc, but containing the coefficients of our recently
derived geometric distortion solution (ISR in prep.).
4 Image registration
All exposures obtained with different guide stars show astrometric offsets of up to
1”. We first register all calibrated and geometrically corrected exposures with the following method. A reference exposure is chosen for each detector, taken as part of
program 11854 (obat01050 sx2) for the CCD, 11856 for the NUV (obav01v9q x2d)
and FUV (obav01w4q x2d). The cross-correlation function of the reference exposure
and each exposure of the data set (CCD, NUV, or FUV) is calculated using the IDL
routine CORREL IMAGES, and its maximum located using the IDL routine CORRMAT ANALYZE. The location of the maximum of the cross-correlation function corresponds to the shift to be applied to the image to match its astrometry to the reference
exposure. Figure 1 shows an example of alignment (before and after registration) for
the NUV-MAMA.
Instrument Science Report STIS 2013-02(v1) Page 3
Figure 1.: Example of image registration for the NUV-MAMA. The top left panel shows
a zoom in the reference exposure, the top right panel shows the same region in the
exposure to be aligned, and the bottom panel shows the aligned exposure.
4.1 Star catalog
For each detector, once all exposures are astrometrically registered to the reference exposure, a catalog of stars is identified in the reference exposure using Starfinder (Diaolaiti et al. 2000), which uses a PSF-fitting technique. The input parameters of starfinder,
such as minimum correlation between the input PSF and point source shape, and detection threshold, were empirically determined via a trial-and-error method. We chose a
detection threshold of 10σ and a minimum correlation of 0.7. Pairs of stars closer than
0.4” for the MAMAs, and 0.8” for the CCD were excluded from the catalog to avoid
blending and photometric contamination.
The starfinder point source extraction algorithm requires a PSF input to match
the shape of point sources. We derived the PSF directly in each image using a predetermined list of stars identified by eye in each cluster and for each detector. Each star
is centroided and stacked with the IDL routine PSF EXTRACT in order to estimate the
PSF.
The PSF-fitting procedure identified 123 stars in the CCD reference exposure, 359
stars in the NUV-MAMA, and 46 stars in the FUV-MAMA reference exposures respectively. The star catalogs used for this analysis are shown in Figures 2 and 3 for the CCD
and MAMA detectors respectively.
Instrument Science Report STIS 2013-02(v1) Page 4
Figure 2.: STIS CCD reference exposure of NGC 5139 with the 123 stars detected by
Starfinder overlaid as red circles. Some obvious stellar sources are not picked up by
starfinder, either due to saturation, or because they are in a pair closer than the threshold
of 0.8”.
5 Photometry
Our algorithm then performs aperture photometry for each star in the catalog and each
STIS exposure. First, the background and its standard deviation are estimated in predefined regions of the calibration stellar fields (NGC 5139 or NGC 6681) where no stars
or cosmic ray hits are detected in the deepest exposures. We simply compute the mean
and standard deviation of the number of pixel counts within the region, which is a 0.4”
by 0.4” square for the MAMAs, and a 1” by 2” rectangle for the CCD. We also use
the PSF empirically derived in each exposure to compute its FWHM, typically 2 pixels.
CCD pixels are 0.05078”and MAMA pixels are 0.0245”* 0.0247”.
Second, an accurate centroid position for each star in the catalog and in each exposure is determined, and a sub-image centered on the centroid position and width 0.4”
for the MAMAs and 0.8” for the CCD is extracted. This is done in a two step procedure
to ensure that the centroid of the star is in the center of the sub-image before aperture
photometry is performed, and so that no flux is lost due to the star being offset with
respect to the center of the sub-image. This two step procedure thus mitigates residual
astrometric offsets between the considered STIS exposure and the reference exposure.
Such offsets can subsist even after image registration and geometric correction, which
is only accurate to 2 pixels for the MAMAs, and 0.5 pixels for the CCD. In a first
step, a test sub-image centered on the position of a star from the catalog is extracted and
used to compute the centroid position of each star in each exposure. Once the centroid
position is determined, a second sub-image is extracted and centered on the previously
calculated centroid position.
Instrument Science Report STIS 2013-02(v1) Page 5
Figure 3.: STIS NUV (top) and FUV (bottom) reference exposures of NGC 6681 with
the stars detected by Starfinder overlaid as red circles.
Aperture photometry is then performed on this sub-image, using an aperture of 5
times the FWHM of the PSF, and an annulus also of inner radius 5 times the FWHM
of the PSF, and thickness 5 pixels. We use the procedure APER in IDL for this purpose. We also performed the same computation with an aperture of radius 2 times the
FWHM, and observed that the resulting stellar magnitudes were increased by up to 0.1
mag compared to the larger aperture, which corresponds to a decrease in the flux of up
to 100%. Hence, we report photometric results for an aperture of 5 times the FWHM of
the PSF.
The net counts (N C) are converted to magnitudes m using the exposure time Texp
and the ZMAG keyword populated by CALSTIS, which includes the correction for the
Instrument Science Report STIS 2013-02(v1) Page 6
Figure 4.: Example of trend between stellar magnitudes and time for the STIS CCD.
The star is identified at coordinates ra = 201.39975, dec = -47.589165
expected TDS trend:
m = ZM AG − 2.5 ∗ log10 (N C) + 2.5 ∗ log10 (Texp )
(1)
For the STIS CCD, we correct for the flux loss due to charge transfer inefficiency
(CTI) using the algorithm (written in IRAF) CTESTIS presented in STIS ISR 2006-03.
The input parameters of the program are the y position of the star on the detector, the
net counts, and the sky background. The algorithm returns the ∆m to be applied to the
measured stellar magnitude to correct for counts lost in the CTI trails.
6 Results
6.1 Overall time dependence
Our algorithm thus provides a catalog of stars and their magnitudes as a function of
time, covering the time period 1997-2012 for the MAMAs, and 2000-2012 for the STIS
CCD. We only include stars that are detected in at least one exposure of 3 or more
programs. This includes 99 stars for the CCD, all 46 stars identified in the FUV, and
344 stars in the NUV. For each star, we fit a linear function to the trend of the measured
magnitude vs time. We do not average stellar magnitudes between exposures taken in
a single program when fitting the slopes of the full-field sensitivity trend with time.
Figures 4 and 5 show examples of fit for the CCD and MAMAs respectively.
Instrument Science Report STIS 2013-02(v1) Page 7
Figure 5.: Example of trend between stellar magnitudes and time for the STIS NUV
(top) and FUV (bottom) MAMA. The star is identified at coordinates ra = 280.80219,
dec − -32.293045
We calculated the mean, weighted mean, standard deviation, and error on the
mean and weighted mean of the residual slopes of the full-field sensitivity variations
measured in all stars as a function of time for each detector. The weighted mean is
weighted by the squared error on individual slopes. These statistics are summarized in
Table 1. Figures 6 and 7 show the histograms of the slopes for the CCD and MAMAs respectively. The difference between the mean weighted slope and the mean non-weighted
slope can be simply explained by the effect of outliers corresponding to faint stars with
large error bars. Those outliers drive the high non-weighted mean slope, but weighting
by the inverse squared errors reduces the weight of those outliers. Hence, the absolute
mean weighted slope is smaller that the absolute non-weighted slope.
Instrument Science Report STIS 2013-02(v1) Page 8
Figure 6.: Histograms of the slopes of the full-field sensitivity trends with time for the
CCD
Comparing the mean weighted slope and its error for each detector shows that the
calculated mean weighted slopes are statistically significant (thought the mean slope is
not). Hence, our analysis suggests that there is a small residual trend in the full-field
sensitivity as a function of time, even after correcting for time dependent sensitivity effects, calibrated from spectroscopic observations. However, the residual trends do not
exceed the quoted absolute flux calibration accuracy of 1% for STIS: over 15 years,
the fractional change in flux due to the residual time dependent full field sensitivity
corresponds to 0.69% for the CCD, −0.06% for the NUV-MAMA, and 0.74% for the
FUV-MAMA.
Detector Number
of stars
CCD
NUV
FUV
106
344
46
Mean
slope
Weighted
mean slope
mmag/year
−1.28
−1.25
−0.16
mmag/year
0.50
−0.044
0.54
Standard
deviation
Error
Error
on mean
on weighted
slope
mean slope
mmag/year mmag/year mmag/year
15.8
6.39
0.061
4.19
0.47
0.024
3.74
0.27
0.039
Table 1.: Summary of the full-field sensitivity results for the CCD, NUV- and FUVMAMAs.
Instrument Science Report STIS 2013-02(v1) Page 9
% over
15 years
0.69
−0.061
0.74
Figure 7.: Histograms of the slopes of the full-field sensitivity trends with time for the
STIS NUV- (left) and FUV- (right) MAMAs
6.2 Filter dependence for the MAMAs
For the STIS MAMAs, we have examined the residual trend in the full-field sensitivity as a function of time and filter, by selecting the exposures taken in a given filter
for each star. The STIS CCD exposures are all taken in the clear filter, and so this
analysis is not needed for the CCD. For the NUV-MAMA, the filter selection includes
F25SRF2, F25QTZ, and F25CN182, while for the FUV it is comprised of 25MAMA
(clear), F25QTZ, and F25SRF2. The same criteria are used to filter out stars that are
not detected in a sufficient number of exposures and/or programs, i.e., each star has to
be detected in at least 1 exposure in at least 3 programs to be included in the analysis.
The results are summarized in Tables 2 and 3 of the NUV-MAMA and FUV-MAMA
Instrument Science Report STIS 2013-02(v1) Page 10
Filter
F25SRF2
F25QTZ
F25CN182
Number
of stars
Mean
slope
Weighted
mean slope
340
330
290
mmag/year
−0.22
−0.28
−1.67
mmag/year
0.18
0.039
0.88
standard
deviation
Error
on mean
Error
on weighted
mean
mmag/year mmag/year mmag/year
4.49
0.27
0.032
7.29
0.53
0.048
18.9
4.15
0.13
% over
15 years
0.25
0.053
1.22
Table 2.: Summary of the full-field sensitivity results per filter for the NUV-MAMAs.
respectively. The mean weighted slopes appear statistically significant with respect to
their corresponding error. After applying the temperature and time dependent sensitivity corrections measured from the low dispersion grating modes, the residual temporal
changes in the full-field sensitivity for each filter do not exceed 2% over 15 years.
Filter
F25SRF2
F25QTZ
25MAMA
Number
of stars
Mean
slope
Weighted
mean slope
46
46
45
mmag/year
0.18
−1.36
1.07
mmag/year
1.39
−0.36
1.25
standard
deviation
Error
on mean
mmag/year mmag/year
3.70
0.35
3.2
0.47
3.6
1.10
Error
on weighted
mean
mmag/year
0.077
0.12
0.046
Table 3.: Summary of the full-field sensitivity results per filter for the FUV-MAMA
6.3 Dependence on flux/magnitude
Last, we have examined the dependence of the slope of the full-field sensitivity vs time
as a function of stellar magnitude. The results are shown in Figures 8 and 9 respectively
for the CCD and MAMAs respectively. We find no trend for the full-field sensitivity
time dependency with stellar flux. The increase in the scatter of the full-field sensitivity
slope with magnitude is consistent with Poisson noise on the photometric measurements.
7
Conclusions
We have examined the residual time-dependence of the full-field (imaging) sensitivity
of the three STIS detectors (CCD, NUV-MAMA, FUV-MAMA), after applying timedependent sensitivity corrections included as part of the standard CALSTIS pipeline.
Instrument Science Report STIS 2013-02(v1) Page 11
% over
15 years
1.92
−0.50
1.73
Figure 8.: Slope of the full-field sensitivity evolution with time as a function of stellar
magnitude for the STIS CCD
We have identified a catalog of stars for each detector using the PSF fitting algorithm
Starfinder, and performed aperture photometry on each star detected in multiple exposures and calibration programs. With the resulting catalog of stars with associated
magnitudes in each exposure and program, we have computed the slope of the fullfield sensitivity variations with time, between 1997 and 2012. We have done so for
the combined data for each detector, but also on a per filter basis, and as a function of
stellar magnitude. We have found that, over 15 years, the observed residual trends in
the full-field sensitivity, obtained after correcting for TDS effects in CALSTIS, are 0.69
mmag/year for the CCD, −0.06 mmag/year for the NUV-MAMA, and 0.74 mmag/year
for the FUV-MAMA. These represent less than a 1% change in flux for all detectors. In
addition, the residual variations with time for each filter amount to less than 2% over
this time period. We have found no dependence of the full-field sensitivity evolution on
stellar magnitude.
These conclusions indicate that the correction for time- and temperature- dependent sensitivity effects, measured in spectroscopic mode and implemented in CALSTIS
as part of the standard pipeline, accurately corrects fluxes for time-dependent imaging
sensitivity variations as well, to within the quoted absolute flux calibration accuracy of
1%. In addition, for the CCD, the CTI correction presented in STIS ISR 2006-03 seems
to correctly restore fluxes/magnitudes.
8 Recommendations
Considering the small magnitude of the temporal variations of the STIS full-field sensitivity for the three detectors, of order 2% of less, we recommend continuing monitoring
the STIS full-field sensitivity yearly.
Instrument Science Report STIS 2013-02(v1) Page 12
Figure 9.: Slope of the full-field sensitivity evolution with time as a function of stellar
magnitude for the STIS NUV (top) and FUV (bottom) MAMA.
References
Stys, D. J., Bohlin, R., C., & Goodfrooij, P., 2004, STIS Instrument Science Report
2004-04
Goudgrooij, P., & Bohlin, R., 2006, STIS Instrument Science Report 2006-03
Diolaiti, E., Bendinelli, O., Bonaccini, D., et al., 2000, Proc. SPIE, 4007, 879
Instrument Science Report STIS 2013-02(v1) Page 13
9 Appendix
A. Parameters of STIS exposures
Instrument Science Report STIS 2013-02(v1) Page 14
Table 4.
Exposure
o3zf01010
o3zf01020
o3zf01030
o3zf01040
o3zf01090
o3zf010a0
o3zf010b0
o3zf010c0
o3zf010d0
o3zf010e0
o3zf010f0
o3zf010g0
o4go01010
o4go02010
o4go03010
o4go04010
o4go05010
o52301020
o52301030
o5ir01010
o5ir02010
o69901010
o69901020
o69902010
o69902020
o6ib01010
o6ib01020
o6ib02010
o6ib02020
o8h701010
o8h701020
o8h701030
o8h701040
o8h701050
o8uv01010
o8uv01020
o8uv01030
STIS CCD Exposures and their characteristics used in this analysis
Program ID Exposure Time Date of Observation Aperture/filter Orientation
7079
7079
7079
7079
7079
7079
7079
7079
7079
7079
7079
7079
7639
7639
7639
7639
7639
8056
8056
8416
8416
8847
8847
8847
8847
8912
8912
8912
8912
9622
9622
9622
9622
9622
10028
10028
10028
60.0000
60.0000
60.0000
60.0000
64.0000
72.0000
72.0000
72.0000
72.0000
72.0000
72.0000
72.0000
15.0000
15.0000
15.0000
15.0000
15.0000
480.000
90.0000
50.0000
50.0000
3.83849
1.53539
10.0000
60.0000
10.0000
60.0000
10.0000
60.0000
10.0000
10.0000
10.0000
10.0000
60.0000
10.0000
10.0000
10.0000
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1997.48
1999.19
1998.04
1998.24
1998.50
1999.03
1999.51
1999.51
1999.59
2000.32
2000.75
2000.75
2001.17
2001.17
2001.75
2001.75
2002.21
2002.21
2003.18
2003.18
2003.18
2003.18
2003.18
2004.31
2004.31
2004.31
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
Instrument Science Report STIS 2013-02(v1) Page 15
232.720
232.720
232.720
232.720
232.721
232.721
232.719
232.719
232.719
232.719
232.721
232.721
122.250
87.9293
123.651
263.076
79.3240
261.110
261.110
270.068
175.059
314.999
314.999
129.989
129.989
314.823
314.823
129.989
129.989
129.989
129.989
129.989
129.989
129.989
152.101
152.101
152.101
Table 4. (cont’d)
Exposure
o8uv01040
o8uv01050
obat01020
obat01030
obat01040
obat01050
obmj01010
obmj01020
obmj01030
obmj01040
obmj01050
obuo01010
obuo01020
obuo01030
obuo01040
obuo01050
Program ID Exposure Time Date of Observation Aperture/filter Orientation
10028
10028
11854
11854
11854
11854
12409
12409
12409
12409
12409
12770
12770
12770
12770
12770
10.0000
60.0000
10.0000
10.0000
10.0000
60.0000
10.0000
10.0000
10.0000
10.0000
60.0000
10.0000
10.0000
10.0000
10.0000
60.0000
2004.31
2004.31
2010.17
2010.17
2010.17
2010.17
2011.18
2011.18
2011.18
2011.18
2011.18
2012.19
2012.19
2012.19
2012.19
2012.19
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
50CCD
Instrument Science Report STIS 2013-02(v1) Page 16
152.101
152.101
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
129.989
Table 5.
STIS NUV-MAMA Exposures and their characteristics used in this analysis
Exposure
o8vw01duq
o8vw01dvq
o8vw01dxq
o8vw01dzq
o8vw01e1q
o8vw01e3q
o8vw01e5q
o8vw01e8q
o8vw01eaq
obav01v9q
obav01vaq
obav01vcq
obav01veq
obav01vgq
obav01viq
obav01vkq
obav01vmq
obav01w1q
obmi01xlq
obmi01xmq
obmi01xoq
obmi01xqq
obmi01xsq
obmi01xuq
obmi01xwq
obmi01y0q
obmi01y2q
obup01rrq
obup01rsq
obup01ruq
obup01rwq
obup01ryq
obup01s0q
obup01s2q
obup01scq
obup01seq
o40q01a1q
Program ID Exposure Time Date of Observation Aperture/filter Orientation
10032
10032
10032
10032
10032
10032
10032
10032
10032
11856
11856
11856
11856
11856
11856
11856
11856
11856
12413
12413
12413
12413
12413
12413
12413
12413
12413
12774
12774
12774
12774
12774
12774
12774
12774
12774
7080
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
2300.20
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2010.43
2010.43
2010.43
2010.43
2010.43
2010.43
2010.43
2010.43
2010.44
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
1997.49
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25CN182
Instrument Science Report STIS 2013-02(v1) Page 17
81.2556
81.2570
81.2560
81.2545
81.2556
81.2556
81.2556
81.2556
81.2556
85.9580
85.9593
85.9582
85.9568
85.9580
85.9580
85.9580
85.9580
85.9580
85.9580
85.9593
85.9582
85.9568
85.9580
85.9580
85.9580
85.9580
85.9580
83.1942
83.1956
83.1945
83.1931
83.1942
83.1942
83.1942
83.1942
83.1942
89.3722
Table 5. (cont’d)
Exposure
o40q01a3q
o43n02x2q
o43n02x4q
o43n02x6q
o43n02x8q
o43n02xaq
o43n02xcq
o43n02xeq
o43n02xgq
o46h01ccq
o46h01ciq
o46h01ckq
o46h01cmq
o46h01coq
o46h01cqq
o46h02tbq
o46h02tdq
o46h02tfq
o46h02thq
o46h02tjq
o46h03kbs
o46h03kgq
o46h03kiq
o46h03kkq
o46h03kmq
o46h03kpq
o46h04f0q
o46h04f1q
o46h04f3q
o46h04f5q
o46h04f7q
o49y01tiq
o49y01tkq
o49y01tmq
o49y01toq
o49y01tqq
o49y01tuq
Program ID Exposure Time Date of Observation Aperture/filter Orientation
7080
7132
7132
7132
7132
7132
7132
7132
7132
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7788
7788
7788
7788
7788
7788
2565.21
324.000
300.000
360.000
360.000
360.000
432.000
432.000
432.000
300.000
360.000
360.000
318.000
360.000
360.000
314.000
360.000
360.000
360.000
360.000
300.000
300.000
300.000
300.000
276.000
300.000
300.000
300.000
300.000
300.000
300.000
400.000
93.4000
306.600
400.000
400.000
468.000
1997.49
1997.59
1997.59
1997.59
1997.59
1997.59
1997.59
1997.59
1997.59
1997.83
1997.83
1997.83
1997.83
1997.83
1997.83
1998.33
1998.33
1998.33
1998.33
1998.33
1998.79
1998.79
1998.79
1998.79
1998.79
1998.79
1999.32
1999.32
1999.32
1999.32
1999.32
1997.93
1997.93
1997.93
1997.93
1997.93
1997.93
F25CN270
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
F25SRF2
F25SRF2
25MAMA
F25QTZ
F25CN182
F25CN270
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25CN182
F25SRF2
F25SRF2
25MAMA
F25QTZ
F25CN182
F25CN270
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25CN182
F25CN270
F25CN270
F25CN270
F25CN270
F25CN270
F25CN270
Instrument Science Report STIS 2013-02(v1) Page 18
89.3722
185.076
185.075
185.074
185.073
185.073
185.075
185.075
185.074
265.244
265.245
265.244
265.244
265.244
265.244
85.5868
85.5881
85.5870
85.5856
85.5868
262.950
262.952
262.951
262.950
262.950
262.950
84.6969
84.6982
84.6971
84.6957
84.6969
272.064
272.063
272.063
272.063
272.062
272.061
Table 5. (cont’d)
Exposure
o5in01ssq
o5in01sxq
o5in01szq
o5in01t1q
o5in01t3q
o5in01t6q
o5in01t7q
o5in02cgq
o5in02chq
o5in02cjq
o5in02clq
o5in02cnq
o5in02cpq
o5in02crq
o5in02cuq
o5in02cvq
o69g01awq
o69g01b1q
o69g01b3q
o69g01b5q
o69g01b7q
o69g01baq
o69g01bbq
o69g02gxq
o69g02gyq
o69g02h0q
o69g02h2q
o69g02h4q
o69g02h6q
o6i101o6q
o6i101obq
o6i101odq
o6i101ofq
o6i101ohq
o6i101okq
o6i101olq
o6i102g9q
Program ID Exposure Time Date of Observation Aperture/filter Orientation
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8918
8918
8918
8918
8918
8918
8918
8918
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
1999.79
1999.79
1999.79
1999.79
1999.79
1999.79
1999.79
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.80
2000.80
2000.80
2000.80
2000.80
2000.80
2000.80
2001.33
2001.33
2001.33
2001.33
2001.33
2001.33
2001.82
2001.82
2001.82
2001.82
2001.82
2001.82
2001.82
2002.24
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
Instrument Science Report STIS 2013-02(v1) Page 19
263.169
263.170
263.169
263.169
263.169
263.169
263.169
85.3226
85.3239
85.3227
85.3214
85.3226
85.3226
85.3226
85.3226
85.3226
263.501
263.502
263.501
263.501
263.501
263.501
263.501
85.3961
85.3961
85.3961
85.3961
85.3961
85.3961
264.925
264.926
264.925
264.925
264.925
264.925
264.925
79.9857
Table 5. (cont’d)
Exposure
o6i102gaq
o6i102gcq
o6i102geq
o6i102ggq
o6i102giq
o8h901vfq
o8h901vgq
o8h901vmq
o8h901voq
o8h901vqq
o8h901vsq
o8h901vuq
o8h901vwq
o8h901vyq
Program ID Exposure Time Date of Observation Aperture/filter Orientation
8918
8918
8918
8918
8918
9623
9623
9623
9623
9623
9623
9623
9623
9623
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
300.000
2002.24
2002.24
2002.24
2002.24
2002.24
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25SRF2
F25SRF2
F25SRF2
F25QTZ
F25CN182
F25SRF2
F25QTZ
F25CN182
Instrument Science Report STIS 2013-02(v1) Page 20
79.9857
79.9857
79.9857
79.9857
79.9857
85.0970
85.0983
85.0972
85.0958
85.0970
85.0970
85.0970
85.0970
85.0970
Table 6.
STIS FUV-MAMA Exposures and their characteristics used in this analysis
Exposure
o8vw01efq
o8vw01ehq
o8vw01ejq
o8vw01eoq
o8vw01exq
o8vw01f2q
o8vw01f4q
o8vw01f6q
o8vw01fbq
obav01w4q
obav01w6q
obav01w8q
obav01waq
obav01wdq
obav01wpq
obav01wtq
obav01wwq
obav01wzq
obmi01y4q
obmi01y6q
obmi01y8q
obmi01yaq
obmi01yeq
obmi01ygq
obmi01yiq
obmi01ykq
obmi01ymq
obup01sgq
obup01siq
obup01skq
obup01smq
obup01stq
obup01svq
obup01sxq
obup01szq
obup01t1q
o40q01a5q
Program ID Exposure Time Date of Observation Aperture/filter Orientation
10032
10032
10032
10032
10032
10032
10032
10032
10032
11856
11856
11856
11856
11856
11856
11856
11856
11856
12413
12413
12413
12413
12413
12413
12413
12413
12413
12774
12774
12774
12774
12774
12774
12774
12774
12774
7080
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
2500.20
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2004.26
2010.44
2010.44
2010.44
2010.44
2010.44
2010.44
2010.44
2010.44
2010.44
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2011.38
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
2012.29
1997.49
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
F25QTZ
Instrument Science Report STIS 2013-02(v1) Page 21
81.2556
81.2570
81.2560
81.2545
81.2556
81.2556
81.2556
81.2556
81.2556
85.9580
85.9593
85.9582
85.9568
85.9580
85.9580
85.9580
85.9580
85.9580
85.9580
85.9593
85.9582
85.9568
85.9580
85.9580
85.9580
85.9580
85.9580
83.1942
83.1956
83.1945
83.1931
83.1942
83.1942
83.1942
83.1942
83.1942
89.3722
Table 6. (cont’d)
Exposure
o40q01a7q
o40q02nkq
o40q02nmq
o40q02noq
o43n01nqq
o43n01nsq
o43n01nuq
o43n01nwq
o43n01nyq
o43n01o0q
o43n01o2q
o43n01o4q
o46h01csq
o46h01cyq
o46h01d0q
o46h01d2q
o46h02tlq
o46h02tnq
o46h02tpq
o46h02trq
o46h02ttq
o46h03kqq
o46h03kwq
o46h03kyq
o46h03l0q
o46h03l3q
o46h04f9q
o46h04fbq
o46h04feq
o46h04ffq
o46h04fhq
o46h04fjq
o49y01teq
o49y01tgq
o5in01t9q
o5in01tfq
o5in01tiq
Program ID Exposure Time Date of Observation Aperture/filter Orientation
7080
7080
7080
7080
7132
7132
7132
7132
7132
7132
7132
7132
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7720
7788
7788
8425
8425
8425
2600.20
1310.83
429.904
904.339
300.000
333.800
360.000
360.000
360.000
432.000
432.000
432.000
360.000
360.000
360.000
360.000
314.000
300.000
300.000
360.000
360.000
300.000
300.000
300.000
208.000
110.400
300.000
158.200
170.100
360.000
360.000
360.000
300.000
400.000
400.000
400.000
400.000
1997.49
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.60
1997.83
1997.83
1997.83
1997.83
1998.33
1998.33
1998.33
1998.33
1998.33
1998.79
1998.79
1998.79
1998.79
1998.79
1999.32
1999.32
1999.32
1999.32
1999.32
1999.32
1997.93
1997.93
1999.80
1999.80
1999.80
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
25MAMA
25MAMA
F25QTZ
F25SRF2
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
25MAMA
F25SRF2
25MAMA
25MAMA
F25QTZ
Instrument Science Report STIS 2013-02(v1) Page 22
89.3722
204.607
204.607
204.608
205.237
205.236
205.236
205.235
205.234
205.236
205.236
205.235
265.244
265.245
265.244
265.244
85.5868
85.5881
85.5870
85.5856
85.5868
262.951
262.952
262.950
262.950
262.950
84.6968
84.6982
84.6982
84.6971
84.6957
84.6969
272.063
272.063
263.169
263.170
263.169
Table 6. (cont’d)
Exposure
o5in01tjq
o5in01tlq
o5in01tnq
o5in01tpq
o5in02cxq
o5in02czq
o5in02d1q
o5in02d3q
o5in02d6q
o5in02d7q
o5in02d9q
o5in02dbq
o5in02ddq
o69g01bdq
o69g01bjq
o69g01bmq
o69g01bnq
o69g01bpq
o69g01brq
o69g01btq
o69g02h8q
o69g02hbq
o69g02hcq
o69g02heq
o69g02hgq
o69g02hiq
o69g02hkq
o69g02hnq
o6i101onq
o6i101otq
o6i101owq
o6i101oxq
o6i101ozq
o6i101p1q
o6i101p3q
o6i102gkq
o6i102gmq
Program ID Exposure Time Date of Observation Aperture/filter Orientation
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8425
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8858
8918
8918
8918
8918
8918
8918
8918
8918
8918
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
197.000
203.000
400.000
400.000
400.000
400.000
153.000
247.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
198.000
202.000
1999.80
1999.80
1999.80
1999.80
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.32
2000.80
2000.80
2000.80
2000.80
2000.80
2000.80
2000.80
2001.33
2001.33
2001.33
2001.33
2001.33
2001.33
2001.33
2001.33
2001.82
2001.82
2001.82
2001.82
2001.82
2001.82
2001.82
2002.24
2002.24
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
F25SRF2
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
25MAMA
25MAMA
Instrument Science Report STIS 2013-02(v1) Page 23
263.169
263.169
263.169
263.169
85.3225
85.3239
85.3227
85.3214
85.3226
85.3226
85.3225
85.3226
85.3226
263.501
263.502
263.501
263.501
263.501
263.501
263.501
85.3961
85.3961
85.3961
85.3961
85.3961
85.3961
85.3961
85.3961
264.925
264.926
264.925
264.925
264.925
264.925
264.925
79.9857
79.9857
Table 6. (cont’d)
Exposure
o6i102goq
o6i102gqq
o6i102gsq
o6i102guq
o6i102gwq
o6i102gyq
o8h901w0q
o8h901w5q
o8h901w7q
o8h901w9q
o8h901wbq
o8h901wdq
o8h901wfq
o8h901wkq
o8h901wmq
Program ID Exposure Time Date of Observation Aperture/filter Orientation
8918
8918
8918
8918
8918
8918
9623
9623
9623
9623
9623
9623
9623
9623
9623
400.000
400.000
400.000
400.000
155.000
245.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
400.000
2002.24
2002.24
2002.24
2002.24
2002.24
2002.24
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
2003.32
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
F25SRF2
25MAMA
25MAMA
25MAMA
25MAMA
F25QTZ
F25SRF2
25MAMA
F25QTZ
F25SRF2
Instrument Science Report STIS 2013-02(v1) Page 24
79.9857
79.9857
79.9857
79.9857
79.9857
79.9857
85.0969
85.0983
85.0972
85.0958
85.0970
85.0970
85.0969
85.0970
85.0970