Instrument Science Report STIS 97-07
Pre-Launch NUV MAMA Flats
R. C. Bohlin, D. J. Lindler, & M. E. Kaiser
1997 May
ABSTRACT
A full set of flat field calibration files for the NUV MAMA has been generated from preflight laboratory data. An iterative technique with 12 passes through each raw flat data
image is used to separate the illuminating lamp signature from the high frequency structure of the MAMA flat itself. The set of flats consists of one wavelength independent P-flat
that corrects for the high frequency pixel-to-pixel sensitivity variations and 63 L-flats that
correct for the lower frequency, wavelength dependent variations. The S/N of the counting
statistics of the P-flat is over 300 per MAMA resolution element (2x2 lores pixels.) Onorbit tests are required to confirm the validity of the ground based flats for the reduction of
flight data.
1. INTRODUCTION
Bohlin, Lindler, & Baum (1996, hereafter BLB) defined the algorithms for deriving
the STIS MAMA flats. However, one major and a few minor modifications to the BLB
formalism are required. Since the BLB requirement that “...the small scale polish on the
slit jaws must be constant to 1% of the slit width...” is not met for the narrower slits
employed with the internal STIS flat field lamps, a correction for slit defects is necessary.
Fortunately, the narrowest slit used to obtain high S/N P-flat data is the 52x0.1 arcsec slit,
where the narrow slit defects do not exceed 20% transmission loss. The introduction of a
correction, W, for slit width variations can correct all but the largest defects to the required
1% precision. W is an average over wavelength and is a function of pixel position along
the slit. The 1-D function W is the raw flat data image collapsed along the spectral direction and is analogous to the orthogonal correction RL(λ), which is the average lamp
spectrum collapsed along the slit direction and is used to correct the flat field images for
narrow emission lines . The product of the L- and P-flats is the original data image with
the instrumental signature removed; so that the BLB Eq. 4 becomes
RL
LP = ------------------------ ⁄ V
W ⋅ RL ( λ )
1
(Eq. 1.)
where RL is the original calibration lamp image and V is just the correction for large scale
cathode sensitivity changes and any OTA+STIS vignetting, which cannot be distinguished
from illumination variation along the slit direction until a star is observed. V is now
defined as just the denominator of the BLB Eq. 3:
R* ( λ )
V ( p i, λ ) = --------------------R * ( p i, λ )
(Eq. 2.)
where R* is the response to the star after application of the L- and P-flats with the initial
guess of V=1. The smooth 2-D function V defined for every pixel is the smooth fit to
V(pi,λ) at the discrete ~11 pi positions along the slit direction. The average of the 11 stellar
spectra is R* (λ). Figures 1 and 2 show examples of average lamp spectra RL(λ), aka spectral S-flat, and of W, aka slit width W-flat, for a broad 2” wide slit and a narrow 0.1” slit,
respectively.
The BLB Eq. 5 becomes
L = ⟨ LP⟩ = ⟨ R L ⁄ ( W ⋅ R L ( λ ) )⟩ ⁄ V
(Eq. 3.)
Since the image W RL (λ) is normalized to the average of RL, L is just the low frequency
variation of the sensitivity with respect to the average sensitivity.
Eq. 6 is now
RL ⁄ ( W ⋅ RL ( λ ) )
P = LP ⁄ L = LP ⁄ ⟨ LP⟩ = --------------------------------------------⟨ R L ⁄ ( W ⋅ R L ( λ ) )⟩
(Eq. 4.)
where the < > indicates a 9x9 median filter followed by a rebinning to a 128x128 image
followed by a 2x2 box smoothing, instead of the 21x21 median and 256x256 rebinning of
BLB. A 9x9 (lores px) median is sufficient to remove the small MAMA dark spots, while
the heavier binning improves S/N in the short exposure images obtained for the typical Lflat.
A straightforward application of Eq. 3-4 to the lab exposures with V set to unity, consists of the following steps:
1. Geometrically correcting the original co-added image to make the dispersion and
spatial axes parallel to the x and y axes of the rotated image.
2. Collapsing this corrected image along the separate axes to obtain the S-flat and the
W-flat averages.
3. Applying the inverse geometric distortion correction to transform the WS-flat
product image back to the original distorted space to get the denominator of Eq. 3
W RL (λ) for division into the original image RL.
2
4. Filling fiducials in the non-dithered flats and masking other problem regions.
5. Filtering as specified above by the < > operation to get the L-flat from Eq. 3.
6. Applying Eq. 4 to get the P-flat, i.e., removing the lamp signature from the original
co-added RL image and then dividing by the L-flat as rebinned to the original
2048x2048 hires size.
7. The L-flat and the P-flat are both normalized to unity in the central region.
This procedure succeeds in separating the illuminating lamp signature from the detector signature, because the spectral and slit axes are not aligned with the MAMA detector,
which has large sensitivity variations between adjacent rows of the hi-res image of ~4x.
The geometric correction is mostly a rotation of ~0.02 radian for G230M. Thus, the collapsed averages in the geometrically correct space have a residual ripple with a period of
~50 hi-res px that is caused by dropping contributions from one original line, while
including a new independent line that can differ by 4x in signal. The effect of this residual
can be demonstrated by applying the derived LP-flat correction to the original data and
displaying one of the corrected rows, as in Figure 3. Instead of removing the instrumental
signature and producing a smooth spectrum of the continuum lamp, a ~1% ripple with a
half-cycle of ~50px appears. To solve this problem, iterations are necessary to apply the
improved P-flat from one iteration to the original image in order to reduce the error caused
by residual even-odd variation and get improved flats after the next iteration. In other
words, the P-flat from Eq. 4 is applied to RL before solving Eq. 3 again.
Figure 3 demonstrates the effectiveness of the iterative technique on a complete row of
an image corrected by its own flat field. Figure 4 quantifies the improvement for a piece of
the same row after removing the slope with a spline fit. An adequate convergence is found
after an initial pass plus 11 iterations for a total of 12 solutions of Eq. 3-4. Figure 5 shows
the effectiveness of the iterations in reducing the lumpiness of an L-flat, where the periodicity of 50 hires px corresponds to ~3px in the 128x128 rebinned L-flat. Similarly,
Figures 1-2 demonstrate the improvement in the W-flats and S-flats for the standard 11
iterations.
2. P-flats
An extensive set of flat field exposures were obtained during ground testing at Ball
Aerospace and at GSFC. The STIS IDT has stored these images in an on-line database and
has assigned a unique Flight Software (FSW) number to each image. Individual exposures
have up to 3000 counts per resolution element (2x2 lores pixel), so that co-addition is
required to achieve the CEI spec of 10,000 counts or S/N=100 per resolution element.
Masks must be constructed to locate fiducials, so those portions of each image can be
given zero weight in the co-addition. Data of P-flat quality exist at six wavelength settings
in the G230M mode, as summarized in Table 1. The FSW entries in Table 1 are ordered by
3
wavelength and clumped within wavelength for the same lamp+slit setup. Because the
entrance slit is often shifted along its length in the focal plane to move the positions of the
fiducials and fill in the flat field under the fiducials, only clumps of images with the same
lamp illumination along the slit can be co-added. Table column headings are standard IDT
database nomenclature, where eg. a mode_id of 2.2 is G230M, OSWABSP is the slit
wheel step position, and MGLOBAL is the total counts/s in the entire image. The column
“external source” indicates either deuterium (“D2”) for the external lamp or “INTERNAL” for the internal deuterium flat field lamp. As the first step in the production of flats,
each of the 12 clumps of data are co-added to produce 12 raw flat data images with at least
a total of 2500 counts/res-el or a S/N=50.
Eq. 4 with 11 iterations is applied to each of the 12 sets of data in Table 1 to obtain 12
independent P-flats. The narrow slit defect near pixel 1155 in Figure 2 for the 52x0.1” slit
and a similar defect for the two data sets that use the 0.5” wide slit require masks, because
the cumulative effect of the iterative procedure broadens these narrow features in the Wflat that is derived from the geometrically rectified image. More smoothing is caused by
the unrectification procedure; and the use of this broadened correction to remove the
instrumental signature causes an undercorrection, leaving ~2% feature in the P-flat.
Figures 6 and 7 compare P-flat data taken at Ball and a more recent P-flat obtained at
GSFC to the same denominator image obtained at Ball, where both numerator images are
at the same wavelength and utilize the same 52x2” entrance slit. Figure 6 shows only random noise, while a pattern appears in Figure 7, indicating a change between 96Aug-Sep
and 96Nov.
Tables 2-3 and Figure 8 characterize the P-flats and quantify their differences. Table 2
is analogous to Table 5 of BLB and compiles the statistics of the 12 independent P-flats for
the central 20% of the x-range by 10% of the y-range of the images. The columns are in
the same order as the groupings in Table 1 that enumerate the FSW images comprising
each P-flat. The Poisson counting statistics, the actual one sigma rms scatter, and the max
and min are tabulated for each image in three bin sizes: per resolution element of which
there are 512x512 in the whole image, per lores pixel with 1024x1024 px in an image, and
per hires pixel of the 2048x2048 image. The scatter and range is much larger in the hires
case because of the odd-even effect in the MAMA detectors.
Table 3 compares each of the first 11 P-flats to the extreme wavelength 2977Å flat with
the best statistics. Table 3 is similar to Table 2, except the entries are the one sigma values
for ratios of images. Image ratios test the similarity of the flat fields at different wavelengths. The first row for each of the three image sizes is the expected sigma from
counting statistics, the second row is the actual scatter in the ratio images, and the third
row measures the actual difference between the two ratioed images. In other words, these
third rows of each set are the actual scatter with the Poisson uncertainty removed in
quadrature. The results are consistent with no wavelength dependence and little MAMA
4
contribution to the scatter per lores pixel or per resolution element. There is a residual
scatter of a few percent in the hires ratios, which demonstrates the nearly complete
removal of the large ~60% pixel-to-pixel scatter of the hires flats. Since the tabulated Poisson statistics utilize the average counts, the Poisson entries for the hires case are
underestimates of sigma because of the large change in sensitivity between adjacent pixels
due to the odd-even effect in the MAMA electronics. The corresponding hires residuals
are overestimates.
The time change illustrated in Figure 7 for the 96Nov GSFC data appears most
strongly in the hires residual of 9.81% in the last row of Table 3. The other P-flat data
obtained in 96Nov is at 2419Å and also has a high residual of 9.22% per hires pixel at
image center. To better illustrate the time change over the whole NUV MAMA, Figure 8
displays the residual one sigma values for the entire ratio image of Figure 7. This ratio
image is divided into 8x8 blocks and the residual for each of the three types of scatter are
listed in each of the 64 blocks. All blocks show less than 1% change per resolution element; and even most of the lores entries are <1%. However, all regions of the GSFC data
differ from the Ball data by a statistically significant amount.
Even though all 12 independent flats agree within the 1% specification per resolution
element, the GSFC data demonstrate a change from the internally consistent set of Ball
images. Thus, all of the Ball data can be averaged to make a pure NUV MAMA superflat
relevant to the Ball thermal vac time period. Since the 1769 and 1933Å flats have illumination along only the central third of the slit, the superflat is the combination of the Ball
data at the G230M central wavelengths of 2176, 2419, 2659, and 2977Å and is shown in
Figure 9. The Poisson statistic of 0.30% per resolution element for the superflat appears in
the final column of Table 2 and corresponds to a S/N=333 in regions without fiducial or
slit defect masks. On-orbit flats are required to quantify changes, which degrade S/N
achieved when this superflat is applied to flight data.
3. L-flats
There are 63 L-flats required for the prime and intermediate supported modes for the
NUV MAMA, as summarized in Clampin & Baum (1996). Of these 63, measurements for
27 modes exist: the four that also provide the P-flat data and 23 more collated in Table 4 in
the same style as Table 1. The other 36 must be manufactured from measured L-flats,
using assumptions about the continuity of change with wavelength. A variety of complications arise in several combinations for the different modes during the process of making an
L-flat from a long slit spectrum of a continuum calibration lamp. Slit irregularities and the
odd spectral emission line must be removed by geometrically rectifying the co-added
image, extracting the average spectrum (S-flat) and the W-flat, creating the average image,
distorting this average back to the uncorrected geometry, and dividing by the original coadded image by this average. Sometimes an emission line is too strong or the geometric
5
correction coefficients are preliminary, so that a special line mask is required. Emission
lines at the edge of images also require a special mask as do regions of no signal, such as
below the cutoff for the GSFC nitrogen purge data. The 29” long slit is not long enough to
cover the cross-dispersed X-modes, so the L-flats are set to unity beyond the slit ends. For
those L-flats with undithered slit positions, the fiducials must be filled with an average of
the local image beyond the edges of the fiducial.
Another problem is that the iterative procedure fails in regions of the lowest S/N,
which is at the fiducial positions that are dithered and filled by only two of three slit positions. When the average number of counts per pixel in the fiducial positions falls below a
critical value, the fiducial positions are too bright in the L-flat. For 7 hires counts, the fiducial positions are ~1% too high, while the problem is <0.1% but can still be discerned in
the L-flat image at 13 counts. Thus, all future L-flat data should have at least
13 x 16 = 208, or maybe 300 to be safe, counts per resolution element, which is S/N=17.
The lab data for mode G230M at 2739, 2818, 2898, and 3055Å all have less than nine
hires counts at the fiducial positions and do not produce useful L-flats.
The best L-flats are made from the high S/N>50 per resolution element P-flat quality
data at the G230M central wavelengths of 2176, 2419, 2659, and 2977Å. Table 1 lists
three repeat observations at 2419Å, four at 2659Å, and two at 2977Å. The L flats derived
from these observations reproduce to <0.3% at the same wavelength for the external deuterium lamp illumination as illustrated in Figure 10 by the ratio of a 2” to a 0.5” wide slit
observation at 2659Å. Unfortunately, the highest S/N L-flat at 2659Å with the 0.1” wide
slit and the internal deuterium lamp (Figure 5b) does not agree with the L-flat derived
from external lamp illumination, as shown in the ratio image of Figure 11. Differences at
the left and right edges are overplotted in Figure 11 and amount to a total difference from
top to bottom corners at either side of 1.4%. In other words, the lamp energy distributions
at the top and bottom of the slit are different for at least one of the internal or external illuminations. A constant shape for the illumination along the STIS entrance slit is essential
for defining L-flats. The repeat observations of the external lamp can be combined to produce a set of high quality L-flats at 2176, 2419, 2659, and 2977Å. At shorter wavelengths,
the G230M L-flat data from Table 4 at 1769, 1851, 1933, and 2014Å agree within uncertainties, despite the fact that the first three utilize the internal lamp, while 2014Å has
external illumination. These four L-flats are averaged with the counts in each as a weight
to produce a high quality L-flat at the weighted average wavelength of 1915Å.
The core set of five L-flats at 1915, 2176, 2419, 2659, and 2977Å show a consistent
change with wavelength, as illustrated in Figures 12-15. Changes with wavelength
approach 1% only between 2176 and 2419Å, so that interpolation of flats at intermediate
wavelengths may have errors of <1%. For example, the ratio of the G230M measured Lflat at 2257Å to the interpolated L-flat at 2257Å is illustrated in Figure 16. A comparison
of Figure 16 with the ratio images in Figures 12-15 demonstrates that most of the devia-
6
tions from unity and lumpy appearance of the ratio image and of the tracing in Figure 16
are caused by the low statistical significance of the numerator image. Similarly, ratio
images in Figures 17-18 for two cross-dispersed modes show no systematic deviations as
large as 1% from the denominator image, which is extrapolated in the case of Figure 18.
For G230M, only the internal lamp L-flat at 1687Å is discrepant with the extrapolated Lflat; and for the cross-dispersed modes with internal illumination, X230M at 1975Å and
X230H at 2010Å show significant differences with the interpolation.
Because the G230L spectral direction is nearly along the MAMA row direction, the
images are first divided by the super P-flat to speed the convergence of the iterative procedure. The resulting G230L L-flats with internal and external lamps are discrepant by a few
percent. Cuts along a column at nearly constant wavelength do not agree with the corresponding cut that could be interpolated from the set of 5 core L-flats, although the external
lamp L-flat at G230L shows a level of variation more comparable to the core set. Perhaps,
the requirement that the lamp illumination is a constant spectral shape along the entrance
slit cannot be met for the broad wavelength coverage of G230L.
4. Summary
A super P-flat has been constructed and is applicable to all NUV MAMA modes for
data obtained on the ground.
Studies of L-flats revealed these facts:
•
Both external and internal L-flats are repeatable.
•
The internal deuterium lamp produces different L-flats than derived for external illumination, although the internal G230M L-flats at 1769, 1851, and 1933Å are plausible
extensions of the external series to shorter wavelength.
•
External L-flats show less deviation from unity over the detector than L-flats made
with the internal lamp.
•
There is a smooth progression with wavelength for the five core L-flats from 1915 to
2977Å; and most of the measured L-flats are adequately represented to better than 1%
accuracy by interpolation or extrapolation from this set.
•
External cross-dispersed L-flats agree with external G230M L-flats, while internal
cross-dispersed L-flats differ from internal G230M. For example, internal X230M1975Å and X230H-2010Å differ radically from internal G230M data at nearby wavelengths.
•
None of the three possible choices for the G230L L-flat are consistent.
A full set of 63 L-flats can be generated from the core set of five; however, serious discrepancies still exist. Internal and external lamps produce different L-flats, and four of the
27 measured modes have L-flats that do not fit a pattern and cannot be confirmed with
existing data. Hopefully, the on-orbit vignetting measurements using stars at 11 positions
7
along the 52x2” slit will resolve the question of proper L-flats. Because of these problems
and because the L-flats corrections are only of order 1%, we recommend populating the
pipeline with unit L-flat files, initially. An effect of this choice of L=1 is to make the sensitivity for point sources a function of position along the slit direction.
5. References
Bohlin, R. C., Lindler, D. J., & Baum, S. 1996, Instrument Science Report, STIS
96-015, (Baltimore:STScI).
Clampin, M., & Baum, S. 1996, Instrument Science Report, STIS 96-009A,
(Baltimore:STScI).
8
Table 1. STIS prelaunch FWS test data catalog of P flat data
FSW
Entry
mode
_id
cenwave
(Å)
OSWABSP
INTEG
(s)
8438
2.2
1769
3242395
8439
2.2
1769
8440
2.2
1769
8441
2.2
8442
SMS
Name
9
EXPSTART
SLITSIZE
(arcsec)
MGLOBAL
external
source
COMMENTS
2000.0
11-SEP-1996 19:35
52 X 2
163193.0
D2
Band 2 FF Methodology
3245755
2000.0
11-SEP-1996 20:13
52 X 2
156845.0
“
Band 2 FF Methodology
3244076
2000.0
11-SEP-1996 20:53
52 X 2
151363.8
“
Band 2 FF Methodology
1769
3241015
2000.0
11-SEP-1996 21:32
52 X 2
146017.2
“
Band 2 FF Methodology
2.2
1769
3239636
2000.0
11-SEP-1996 22:10
52 X 2
140849.9
“
Band 2 FF Methodology
8431
2.2
1933
3242396
1000.0
11-SEP-1996 17: 9
52 X 2
183579.4
D2
Band 2 FF Methodology
8432
2.2
1933
3241395
1000.0
11-SEP-1996 17:36
52 X 2
177913.5
“
Band 2 FF Methodology
8433
2.2
1933
3240396
1000.0
11-SEP-1996 17:58
52 X 2
173675.7
“
Band 2 FF Methodology
8434
2.2
1933
3242995
1000.0
11-SEP-1996 18:19
52 X 2
169572.9
“
Band 2 FF Methodology
8435
2.2
1933
3243995
1000.0
11-SEP-1996 18:40
52 X 2
165790.1
“
Band 2 FF Methodology
6552
2.2
2176
3240215
3000.0
OFLT2P7B
29-AUG-1996 20:49
52 X 2
144714.6
D2+ND0+DIFFU
B2 Extern Deut FFs
6554
2.2
2176
3240216
3000.0
OFLT2P7B
29-AUG-1996 21:42
52 X 2
144899.1
D2+ND0+DIFFU
B2 Extern Deut FFs
6560
2.2
2176
3240216
3000.0
OFLT2P7B
29-AUG-1996 22:49
52 X 2
145061.7
D2+ND0+DIFFU
B2 Extern Deut FFs
6562
2.2
2176
3240216
3000.0
OFLT2P7B
29-AUG-1996 23:42
52 X 2
145088.2
D2+ND0+DIFFU
B2 Extern Deut FFs
6569
2.2
2176
3240215
3000.0
OFLT2P7B
30-AUG-1996 0:56
52 X 2
145127.9
D2+ND0+DIFFU
B2 Extern Deut FFs
6571
2.2
2176
3240216
3000.0
OFLT2P7B
30-AUG-1996 1:49
52 X 2
145125.0
D2+ND0+DIFFU
B2 Extern Deut FFs
6523
2.2
2419
3406032
3000.0
TST220
29-AUG-1996 8:36
52 X 0.5
113009.4
D2
B2 Extern Deut FFs
6525
2.2
2419
3406032
3000.0
TST220
29-AUG-1996 9:29
52 X 0.5
112833.2
“
B2 Extern Deut FFs
6942
2.2
2419
3243641
2400.0
OFT2P10D
1-SEP-1996 13:28
52 X 2
140261.2
D2+ND0.5
B2 EXT D2 FF
6945
2.2
2419
3241960
2400.0
OFT2P10D
1-SEP-1996 14:14
52 X 2
140166.0
D2+ND0.5
B2 EXT D2 FF
6948
2.2
2419
3240281
2400.0
OFT2P10D
1-SEP-1996 14:59
52 X 2
140114.1
D2+ND0.5
B2 EXT D2 FF
6955
2.2
2419
3238601
2400.0
OFT2P10D
1-SEP-1996 15:59
52 X 2
140249.1
D2+ND0.5
B2 EXT D2 FF
6958
2.2
2419
3236921
2400.0
OFT2P10D
1-SEP-1996 16:44
52 X 2
140417.7
D2+ND0.5
B2 EXT D2 FF
13451
2.2
2419
3240280
3300.0
11-NOV-1996 19: 6
52 X 2
49862.8
D2
Verif. of DMA Timeout Fix
13452
2.2
2419
3240281
3300.0
11-NOV-1996 20: 4
52 X 2
49877.3
“
Verif. of DMA Timeout Fix
13800
2.2
2419
3240281
3000.0
OMIECHK6
12-NOV-1996 11:40
52 X 2
47014.7
“
Verif. of DMA Timeout Fix
13802
2.2
2419
3240281
3000.0
OMIECHK6
12-NOV-1996 12:32
52 X 2
46921.5
“
Verif. of DMA Timeout Fix
13808
2.2
2419
3240281
3000.0
OMIECHK6
12-NOV-1996 13:40
52 X 2
46928.1
“
Verif. of DMA Timeout
5677
2.2
2659
1151367
3000.0
OFLT2STB
23-AUG-1996 5:56
52 X 0.1
256544.0
INTERNAL
Bnd2 Flat Field Stability
5679
2.2
2659
1151366
3000.0
OFLT2STB
23-AUG-1996 6:55
52 X 0.1
256022.8
“
Bnd2 Flat Field Stability
5683
2.2
2659
1151366
3000.0
OFLT2STB
23-AUG-1996 7:57
52 X 0.1
259456.2
“
Bnd2 Flat Field Stability
Table 1. STIS prelaunch FWS test data catalog of P flat data (Continued)
10
FSW
Entry
mode
_id
cenwave
(Å)
OSWABSP
INTEG
(s)
SMS
Name
EXPSTART
SLITSIZE
(arcsec)
MGLOBAL
external
source
COMMENTS
5685
2.2
2659
1151367
3000.0
OFLT2STB
23-AUG-1996 8:57
52 X 0.1
264293.7
INTERNAL
Bnd2 Flat Field Stability
5989
2.2
2659
1151366
3000.0
OFLAT2DF
25-AUG-1996 22:42
52 X 0.1
271570.0
“
Band 2 Flat Field
5991
2.2
2659
1151366
3000.0
OFLAT2DF
25-AUG-1996 23:41
52 X 0.1
277086.8
“
Band 2 Flat Field
5995
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 0:43
52 X 0.1
270530.6
“
Band 2 Flat Field
5997
2.2
2659
1151366
3000.0
OFLAT2DF
26-AUG-1996 1:43
52 X 0.1
264115.7
“
Band 2 Flat Field
6001
2.2
2659
1151366
3000.0
OFLAT2DF
26-AUG-1996 2:45
52 X 0.1
259120.5
“
Band 2 Flat Field
6003
2.2
2659
1151366
3000.0
OFLAT2DF
26-AUG-1996 3:45
52 X 0.1
255270.5
“
Band 2 Flat Field
6007
2.2
2659
1151366
3000.0
OFLAT2DF
26-AUG-1996 4:47
52 X 0.1
251964.6
“
Band 2 Flat Field
6009
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 5:47
52 X 0.1
249449.6
“
Band 2 Flat Field
6013
2.2
2659
1151366
3000.0
OFLAT2DF
26-AUG-1996 6:49
52 X 0.1
247149.9
“
Band 2 Flat Field
6015
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 7:49
52 X 0.1
245441.0
“
Band 2 Flat Field
6019
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 8:51
52 X 0.1
243654.2
“
Band 2 Flat Field
6021
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 9:51
52 X 0.1
242266.3
“
Band 2 Flat Field
6025
2.2
2659
1151367
3000.0
OFLAT2DF
26-AUG-1996 10:53
52 X 0.1
240755.9
“
Band 2 Flat Field
8751
2.2
2659
1151383
3000.0
OFLT2STB
16-SEP-1996 6:58
52 X 0.1
234084.6
“
Flat Field Stability
8753
2.2
2659
1151383
3000.0
OFLT2STB
16-SEP-1996 7:57
52 X 0.1
230312.8
“
Flat Field Stability
8757
2.2
2659
1151383
3000.0
OFLT2STB
16-SEP-1996 8:59
52 X 0.1
227316.9
“
Flat Field Stability
8759
2.2
2659
1151383
3000.0
OFLT2STB
16-SEP-1996 9:59
52 X 0.1
225365.7
“
Flat Field Stability
6500
2.2
2659
3406032
3000.0
OFLT2EX3
29-AUG-1996 1:22
52 X 0.5
84108.9
D2
B2 Extern Deut FFs
6502
2.2
2659
3406031
3000.0
OFLT2EX3
29-AUG-1996 3:10
52 X 0.5
83280.9
“
B2 Extern Deut FFs
6508
2.2
2659
3406032
3000.0
OFLT2EX3
29-AUG-1996 5: 9
52 X 0.5
82878.2
“
B2 Extern Deut FFs
6510
2.2
2659
3406032
3000.0
OFLT2EX3
29-AUG-1996 6: 2
52 X 0.5
82805.9
“
B2 Extern Deut FFs
6516
2.2
2659
3406032
3000.0
OFLT2EX3
29-AUG-1996 7: 5
52 X 0.5
82872.6
“
B2 Extern Deut FFs
8449
2.2
2659
3408174
3000.0
OFLT2EX3
11-SEP-1996 23:51
52 X 0.5
53982.1
“
B2 Flat Field
8451
2.2
2659
3408174
3000.0
OFLT2EX3
12-SEP-1996 0:44
52 X 0.5
47972.1
“
B2 Flat Field
6605
2.2
2659
3240216
1500.0
OFLT2EX3
30-AUG-1996 6:46
52 X 2
99562.9
D2
Band 2 Ext D2 Flat
6607
2.2
2659
3240215
1500.0
OFLT2EX3
30-AUG-1996 7:14
52 X 2
99614.3
“
Band 2 Ext D2 Flat
6609
2.2
2659
3240216
1500.0
OFLT2EX3
30-AUG-1996 7:41
52 X 2
98912.8
“
Band 2 Ext D2 Flat
6611
2.2
2659
3240215
1000.0
OFLT2EX3
30-AUG-1996 8: 8
52 X 2
98639.1
“
Band 2 Ext D2 Flat
6613
2.2
2659
3240216
1000.0
OFLT2EX3
30-AUG-1996 8:27
52 X 2
98747.9
“
Band 2 Ext D2 Flat
Table 1. STIS prelaunch FWS test data catalog of P flat data (Continued)
FSW
Entry
mode
_id
cenwave
(Å)
OSWABSP
INTEG
(s)
SMS
Name
EXPSTART
SLITSIZE
(arcsec)
MGLOBAL
external
source
COMMENTS
14654
2.2
2659
3240281
3300.0
O2P13STBA
22-NOV-1996 13:16
52 X 2
223132.9
D2
Mode2.2p13 FF SN=100
14656
2.2
2659
3241961
3300.0
O2P13STBA
22-NOV-1996 14:13
52 X 2
222746.5
“
Mode2.2p13 FF SN=100
14658
2.2
2659
3238601
3300.0
O2P13STBA
22-NOV-1996 15:11
52 X 2
222743.9
“
Mode2.2p13 FF SN=100
14660
2.2
2659
3236921
3300.0
O2P13STBA
22-NOV-1996 16:10
52 X 2
222763.0
“
Mode2.2p13 FF SN=100
14662
2.2
2659
3243641
3300.0
O2P13STBA
22-NOV-1996 17:10
52 X 2
221392.0
“
Mode2.2p13 FF SN=100
6583
2.2
2977
3240215
3000.0
OFT2P17B
30-AUG-1996 3:30
52 X 2
53921.4
D2+ND0+DIFFU
B2 Extern Deut FFs
6585
2.2
2977
3240215
3000.0
OFT2P17B
30-AUG-1996 4:23
52 X 2
53799.8
D2+ND0+DIFFU
B2 Extern Deut FFs
6594
2.2
2977
3240216
3000.0
OFT2P17B
30-AUG-1996 6:45
52 X 2
53660.5
D2+ND0+DIFFU
B2 Extern Deut FFs
6597
2.2
2977
3240215
3000.0
OFT2P17B
30-AUG-1996 3:44
52 X 2
53727.9
D2+ND0+DIFFU
B2 Extern Deut FFs
6912
2.2
2977
3243640
2400.0
OFT2P17D
1-SEP-1996 6:49
52 X 2
189679.9
D2+ND0
Mode 2.2p17 FF w/Ext D2
6915
2.2
2977
3241961
2400.0
OFT2P17D
1-SEP-1996 7:35
52 X 2
189263.9
D2+ND0
bad: dropped data lines
6918
2.2
2977
3240281
2400.0
OFT2P17D
1-SEP-1996 8:20
52 X 2
189208.2
D2+ND0
Mode 2.2p17 FF w/Ext D2
6925
2.2
2977
3238600
2400.0
OFT2P17D
1-SEP-1996 9:20
52 X 2
189770.4
D2+ND0
Mode 2.2p17 FF w/Ext D2
6928
2.2
2977
3236921
2400.0
OFT2P17D
1-SEP-1996 10: 5
52 X 2
189994.9
D2+ND0
Mode 2.2p17 FF w/Ext D2
11
Table 2. Statistics of the Flat Field Images
1769
52x2
1933
52x2
2176
52x2
2419
52x0.5
2419
52x2
2419
52x2
2659
52x0.1
2659
52x0.5
2659
52x2
2659
52x2
2977
52x2
2977
52x2
SF
Poisson (%)
0.75
0.98
0.91
1.80
1.14
1.73
0.39
1.33
1.85
0.79
1.83
0.97
0.30
Actual sigma (%)
1.48
1.61
1.59
2.15
1.72
2.18
1.37
1.80
2.22
1.55
2.21
1.59
1.33
Minimum
0.83
0.83
0.89
0.88
0.89
0.89
0.88
0.88
0.90
0.87
0.91
0.87
0.89
Maximum
1.07
1.07
1.06
1.09
1.07
1.09
1.07
1.07
1.08
1.07
1.09
1.06
1.07
Poisson (%)
1.49
1.97
1.83
3.60
2.27
3.47
0.78
2.66
3.70
1.57
3.66
1.94
0.60
Actual sigma (%)
2.87
3.13
3.05
4.16
3.34
4.29
2.60
3.45
4.40
3.00
4.38
3.11
2.53
Minimum
0.74
0.75
0.79
0.80
0.79
0.79
0.80
0.79
0.79
0.79
0.80
0.78
0.81
Maximum
1.22
1.22
1.25
1.26
1.22
1.25
1.23
1.22
1.26
1.22
1.25
1.21
1.23
P FLATS (512x512)
P FLATS (1024x1024)
P FLATS (2048x2048)
12
Poisson (%)
2.99
3.94
3.65
7.20
4.55
6.93
1.56
5.31
7.39
3.15
7.31
3.89
1.20
Actual sigma (%)
62.39
62.44
62.18
59.50
62.30
61.27
62.15
59.84
62.55
60.82
62.58
62.31
62.15
Minimum
0.25
0.29
0.25
0.24
0.27
0.24
0.26
0.27
0.24
0.27
0.23
0.24
0.26
Maximum
2.54
2.58
2.62
2.84
2.63
2.66
2.59
2.65
2.78
2.57
2.82
2.65
2.57
Table 3. Statistics for the Ratio of Flat Fields to 2977Å Flat
1769
1933
2176
2419
2419
2419
2659
2659
2659
2659
2977
Poisson (%)
1.23
1.38
1.33
2.05
1.50
1.99
1.05
1.65
2.09
1.25
2.07
Actual sigma (%)
1.24
1.41
1.33
2.04
1.50
2.02
1.07
1.64
2.07
1.33
2.06
Resid. sigma (%)
0.20
0.27
0.00
0.00
0.02
0.38
0.19
0.00
0.00
0.46
0.00
Poisson (%)
2.45
2.77
2.67
4.09
2.99
3.98
2.10
3.29
4.18
2.50
4.14
Actual sigma (%)
2.47
2.80
2.67
4.02
2.99
4.01
2.12
3.31
4.17
2.63
4.13
Resid. sigma (%)
0.29
0.42
0.12
0.00
0.11
0.56
0.34
0.31
0.00
0.80
0.00
Poisson (%)
4.91
5.53
5.33
8.18
5.98
7.95
4.19
6.59
8.35
5.00
8.28
Actual sigma (%)
5.72
6.47
6.15
8.96
6.89
12.18
4.87
7.25
9.63
11.01
9.55
Resid. sigma (%)
2.95
3.34
3.05
3.66
3.42
9.22
2.48
3.04
4.79
9.81
4.75
P FLATS (512x512)
P FLATS (1024x1024)
P FLATS (2048x2048)
13
Table 4. STIS Prelaunch FSW Test Data Catalog of L-flat Data
14
ENTRY
mode
_id
cenwave
(Å)
OSWABSP
INTEG
(s)
SMS Name
EXPSTART
SLITSIZE
(arcsec)
MGLOBAL
external
source
COMMENTS
8545
2.1
2376
4147100
1100.0
OD2LFLAT
13-SEP-1996 5:52
31 X 0.05
145413.0
INTERNAL
Band 2 L-Flats
8547
2.1
2376
4147484
1100.0
OD2LFLAT
13-SEP-1996 6:19
31 X 0.05
144753.7
“
Band 2 L-Flats
8549
2.1
2376
4146870
1100.0
OD2LFLAT
13-SEP-1996 6:47
31 X 0.05
144072.6
“
Band 2 L-Flats
14622
2.1
2376
3240281
800.0
20-NOV-1996 19: 2
52 X 2
59985.0
D2
M2.1 L Flat Fields S/N=10
14623
2.1
2376
3241961
800.0
20-NOV-1996 19:19
52 X 2
60760.9
“
M2.1 L Flat Fields S/N=10
14624
2.1
2376
3238601
800.0
20-NOV-1996 19:39
52 X 2
62287.7
“
M2.1 L Flat Fields S/N=10
8503
2.2
1687
3240281
180.0
OD2LFLAT
13-SEP-1996 0:33
52 X 2
215152.0
INTERNAL
Band 2 L-Flats
8505
2.2
1687
3241814
180.0
OD2LFLAT
13-SEP-1996 0:45
52 X 2
204200.3
“
Band 2 L-Flats
8507
2.2
1687
3238698
180.0
OD2LFLAT
13-SEP-1996 0:58
52 X 2
200738.8
“
Band 2 L-Flats
8509
2.2
1769
3406059
300.0
OD2LFLAT
13-SEP-1996 1:11
52 X 0.5
73991.7
INTERNAL
Band 2 L-Flats
8511
2.2
1769
3407631
300.0
OD2LFLAT
13-SEP-1996 1:25
52 X 0.5
73585.5
“
Band 2 L-Flats
8513
2.2
1769
3404514
300.0
OD2LFLAT
13-SEP-1996 1:40
52 X 0.5
73388.6
“
Band 2 L-Flats
8515
2.2
1851
3406059
180.0
OD2LFLAT
13-SEP-1996 1:55
52 X 0.5
141838.8
INTERNAL
Band 2 L-Flats
8517
2.2
1851
3407631
180.0
OD2LFLAT
13-SEP-1996 2: 7
52 X 0.5
141278.3
“
Band 2 L-Flats
8519
2.2
1851
3404514
180.0
OD2LFLAT
13-SEP-1996 2:20
52 X 0.5
141215.7
“
Band 2 L-Flats
8521
2.2
1933
3406060
180.0
OD2LFLAT
13-SEP-1996 2:33
52 X 0.5
218527.3
INTERNAL
Band 2 L-Flats
8523
2.2
1933
3407631
180.0
OD2LFLAT
13-SEP-1996 2:45
52 X 0.5
217653.7
“
Band 2 L-Flats
8525
2.2
1933
3404514
180.0
OD2LFLAT
13-SEP-1996 2:58
52 X 0.5
217601.4
“
Band 2 L-Flats
13870
2.2
2014
3241960
420.0
O22LFLTR
12-NOV-1996 20:59
52 X 2
86334.5
D2
Mode 2.2 L Flats
13873
2.2
2014
3240281
420.0
O22LFLTR
12-NOV-1996 21: 8
52 X 2
86331.4
“
Mode 2.2 L Flats
13876
2.2
2014
3236920
420.0
O22LFLTR
12-NOV-1996 21:18
52 X 2
86587.0
“
Mode 2.2 L Flats
13280
2.2
2095
3241961
240.0
O22LFLTU
8-NOV-1996 13:42
52 X 2
96165.8
D2
Bnd 2L Flats, short waves
13283
2.2
2095
3240280
240.0
O22LFLTU
8-NOV-1996 13:48
52 X 2
96250.8
“
Bnd 2L Flats, short waves
13286
2.2
2095
3238601
240.0
O22LFLTU
8-NOV-1996 13:55
52 X 2
96369.4
“
Bnd 2L Flats, short waves
13267
2.2
2257
3241960
240.0
O22LFLTU
8-NOV-1996 13:12
52 X 2
102438.2
D2
Bnd 2L Flats, short waves
13270
2.2
2257
3240281
240.0
O22LFLTU
8-NOV-1996 13:19
52 X 2
102547.0
“
Bnd 2L Flats, short waves
13273
2.2
2257
3238601
240.0
O22LFLTU
8-NOV-1996 13:25
52 X 2
102685.0
“
Bnd 2L Flats, short waves
Table 4. STIS Prelaunch FSW Test Data Catalog of L-flat Data (Continued)
15
ENTRY
mode
_id
cenwave
(Å)
OSWABSP
INTEG
(s)
SMS Name
EXPSTART
SLITSIZE
(arcsec)
MGLOBAL
external
source
COMMENTS
13247
2.2
2338
3243641
180.0
O22LFLTB
8-NOV-1996 11:47
52 X 2
78736.4
D2
Band 2L Flats w/ Ext D2
13250
2.2
2338
3241960
180.0
O22LFLTB
8-NOV-1996 11:53
52 X 2
78754.4
“
Band 2L Flats w/ Ext D2
13253
2.2
2338
3240281
180.0
O22LFLTB
8-NOV-1996 11:59
52 X 2
78847.7
“
Band 2L Flats w/ Ext D2
13256
2.2
2338
3238601
180.0
O22LFLTB
8-NOV-1996 12: 5
52 X 2
78947.6
“
Band 2L Flats w/ Ext D2
13259
2.2
2338
3236921
180.0
O22LFLTB
8-NOV-1996 12:11
52 X 2
79115.2
“
Band 2L Flats w/ Ext D2
13349
2.2
2499
3241961
3300.0
OMIECHCK
9-NOV-1996 17:45
52 X 2
38033.3
D2
Verif. of DMA Timeout Fix
13352
2.2
2499
3240281
3300.0
OMIECHCK
9-NOV-1996 18:44
52 X 2
38224.6
“
Verif. of DMA Timeout Fix
13356
2.2
2499
3238600
3300.0
OMIECHCK
14666
2.2
2579
3240281
800.0
14667
2.2
2579
3241961
14668
2.2
2579
3238601
13857
2.2
2739
3241961
420.0
13860
2.2
2739
3240281
13863
2.2
2739
13844
2.2
2818
13847
2.2
13850
9-NOV-1996 19:43
52 X 2
38294.7
“
Verif. of DMA Timeout Fix
22-NOV-1996 18:45
52 X 2
212895.1
D2
Mode 2.2 LFlat S/N=10
800.0
22-NOV-1996 19: 2
52 X 2
212806.2
“
Mode 2.2 LFlat S/N=10
800.0
22-NOV-1996 19:19
52 X 2
212944.2
“
Mode 2.2 LFlat S/N=10
O22LFLTR
12-NOV-1996 20:19
52 X 2
36099.6
D2
Mode 2.2 L Flats
420.0
O22LFLTR
12-NOV-1996 20:29
52 X 2
36059.0
“
Mode 2.2 L Flats
3238601
420.0
O22LFLTR
12-NOV-1996 20:39
52 X 2
36095.1
“
Mode 2.2 L Flats
3241961
420.0
O22LFLTR
12-NOV-1996 19:42
52 X 2
43566.2
D2
Mode 2.2 L Flats
2818
3240281
420.0
O22LFLTR
12-NOV-1996 19:52
52 X 2
43542.0
“
Mode 2.2 L Flats
2.2
2818
3238601
420.0
O22LFLTR
12-NOV-1996 20: 1
52 X 2
43607.9
“
Mode 2.2 L Flats
13831
2.2
2898
3241961
420.0
O22LFLTR
12-NOV-1996 19: 4
52 X 2
42721.8
D2
Mode 2.2 L Flats
13834
2.2
2898
3240281
420.0
O22LFLTR
12-NOV-1996 19:14
52 X 2
42729.0
“
Mode 2.2 L Flats
13837
2.2
2898
3238601
420.0
O22LFLTR
12-NOV-1996 19:24
52 X 2
42766.7
“
Mode 2.2 L Flats
13818
2.2
3055
3241961
600.0
O22LFLTR
12-NOV-1996 18:18
52 X 2
22766.2
D2
Mode 2.2 L Flats
13821
2.2
3055
3240281
600.0
O22LFLTR
12-NOV-1996 18:31
52 X 2
22786.8
“
Mode 2.2 L Flats
13824
2.2
3055
3238601
600.0
O22LFLTR
12-NOV-1996 18:44
52 X 2
22813.4
“
Mode 2.2 L Flats
8539
2.7X3
1975
3989483
1500.0
OD2LFLAT
13-SEP-1996 4:30
0.05 X 31
213131.0
INTERNAL
Band 2 L-Flats
15227
2.7X3
2703
3636422
1000.0
O27XLFLT
24-NOV-1996 14:10
0.2 X 29
130899.2
D2
B2 XDISP FF SN=10 TST496
8541
2.7X4
1760
3636421
1000.0
OD2LFLAT
13-SEP-1996 5: 5
0.2 X 29
177886.9
INTERNAL
Band 2 L-Flats
8543
2.7X4
2010
1015247
400.0
OD2LFLAT
13-SEP-1996 5:32
0.09 X 29
227575.3
INTERNAL
Band 2 L-Flats
15229
2.7X4
2261
3636422
1000.0
O27XLFLT
24-NOV-1996 15:13
0.2 X 29
89144.0
D2
B2 XDISP FF SN=10 TST496
15231
2.7X4
2511
3636422
1000.0
O27XLFLT
24-NOV-1996 15:56
0.2 X 29
110464.2
D2
B2 XDISP FF SN=10 TST496
15233
2.7X4
2760
3636421
1000.0
O27XLFLT
24-NOV-1996 16:40
0.2 X 29
113863.6
D2
B2 XDISP FF SN=10 TST496
15235
2.7X4
3010
3636421
1000.0
O27XLFLT
24-NOV-1996 17:18
0.2 X 29
82944.9
D2
B2 XDISP FF SN=10 TST496
6. Figure Captions
Wflat G230M 2977flat52X2-6912
700
600
500
400
300
0
500
1000
1500
2000
Sflat G230M 2977flat52X2-6912
1.20
1.10
1.00
0.90
0.80
0.70
0.60
0
500
1000
1500
2000
Fig. 1
BOHLIN: pltwsflt 9-May-1997 15:54
Figure 1: Average lamp spectra RL (λ), aka spectral S-flat (below), and W, aka slit width
W-flat (above), as collapsed along the slit direction and along the spectral direction,
respectively. The mode is G230M at 2977Å with a 52x2” slit. The fiducials are filled via a
set of exposures that are dithered by moving the slit along its long dimension. Within each
panel, results are shown for the standard 11 iterations and for zero iterations as offset
lower by a constant. The title of the plot includes the optmode, cenwave, and slitsize,
while 6912 is the FSW number of the first image of the group from Table 1.
16
Wflat G230M 2659flat52X01
4000
3500
3000
2500
0
500
1000
1500
2000
1500
2000
Sflat G230M 2659flat52X01
1.20
1.10
1.00
0.90
0.80
0.70
0.60
0
500
1000
Fig. 2
BOHLIN: pltwsflt 9-May-1997 15:54
Figure 2: Same as Figure 1, except for the 52x0.1” slit and 2659Å. The structure of the
W-flat is caused by irregularities in the narrow slit and by a smooth interpolation across
the two fiducials. The blip on the S-flat trace is anemission line.
17
2977flat52X2-6912/(P*L)
750
Hires Row 1024
700
650
Iterations=11
Iterations=3
600
Iterations=1
Iterations=0
550
500
0
500
1000
x Pixel
1500
2000
Fig. 3
BOHLIN: deflat 21-Apr-1997 14:23
Figure 3: Row 1024 of a 2048x2048 hires image after correction with LP-flats derived
with four different numbers of iterations. Since the LP-flats are applied to the same original data as used to define the flat, noise from counting statistics should cancel, leaving
only the true illumination pattern and the artifacts of the procedure. As the iterations
increase from bottom to top, the results becomes increasingly smooth and better represent
the expected smooth spectrum of the continuum deuterium lamp. The curves are offset by
20 counts for clarity.
18
RESIDUAL NOISE IN 2977flat52X2-6912/(P*L)
1.000
Iterations=11, rms(%)= 0.06
Hires Row 1024
0.990
Iterations=3, rms(%)= 0.08
0.980
Iterations=1, rms(%)= 0.12
0.970
Iterations=0, rms(%)= 0.29
0.960
600
800
1000
x Pixel
1200
1400
Fig. 4
BOHLIN: deflat 21-Apr-1997 14:23
Figure 4: Central portion of the four curves from Figure 3 after division by a smooth
spline fit. The rms scatter of the artifacts of the process drops dramatically with one iteration and more slowly, thereafter. The lower curves are offet progressively by 0.01.
19
MAMA2 L Flat G230M
0.98
1.02
L2659FLAT52X01.ITER0
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-Apr-1997 16:13
20
120
Fig. 5a
MAMA2 L Flat G230M
0.98
1.02
L2659FLAT52X01.FITS
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-Apr-1997 16:13
120
Fig. 5b
Figure 5: L-flat for the 0.1” internal lamp spectrum of G230L at 2659Å for a) zero iterations and b) 11 iterations. The lumpiness before iterating is attributable to imperfect
removal of the lamp signature from the MAMA detector response, which varies by ~4x
between even and odd rows. The line traces overlaying the grey scale images are the intensities in the central column of the 128x128 image and are associated with the abscissa and
ordinate coordinates. Pixel zero is at the bottom.
21
0.98
9pt median, 128x128 bin, Calstis geom
MAMA2 Ratio G230M
P2659flat52X2-6605/P2977flat52X2-6912
1.02
Bohlin: Pfig.pro 22-Apr-1997 08:46
Fig. 6
Figure 6: Ratio of two P-flats obtained at Ball in 96Aug-Sep. Grey scale encoding is from
0.98 to 1.02, as indicated on the reference scale at the top.
22
0.98
9pt median, 128x128 bin, Calstis geom
MAMA2 Ratio G230M
P2659flat52X2-14654/P2977flat52X2-6912
1.02
Bohlin: Pfig.pro 22-Apr-1997 09:24
Fig. 7
Figure 7: Same as Figure 6, except that the numerator image was obtained at GSFC in
96Nov. The pattern superposed on the statistical noise is the difference between the two
flats.
23
Figure 8: Quantification of the difference between the two flats ratioed in Figure 7. The
ratio image is divided into 8x8 blocks and the one sigma rms residual scatter is computed
for three different NUV MAMA picture element sizes in each block. Each set of three
numbers is this rms for resolution elements (2x2 lores px), for lores (2x2 hires px), and for
hires readout mode from top to bottom, respectively. The rms residual scatter has the
counting statistical uncertainty removed and is the net change attributable to the MAMA
detector. The orientation of Figure 7 & 8 are the same, so that both figures show the most
change in the top left portion. No block exceeds a 1% change per resolution element (2x2
lores pixels).
24
0.95
1.05
MAMA2 P Flat G230M
PG230Msuperflat.fits
Bohlin: Pfig.pro 22-Apr-1997 09:53
Fig. 9
Figure 9: Binned 1024x1024 super P-flat, which is the combination of all P-flat quality
data obtained in the 96Aug-Sep timeframe. Features visible are fringing due to the nonintegral relation between the microchannel plate pores and the MAMA pixels, a few blemishes, the hexagonal pattern of the bundles of microchannel plate pores, and fine structure
in the orthogonal x-y directions.
25
MAMA2 L Flat G230M
0.98
1.02
L2659FLAT52X2-6605.FITS / L2659flat52x05.FITS
Central Column Intensity
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 9-May-1997 16:15
120
Fig. 10
Figure 10: Ratio image of two L-flats at the same wavelength with external illumination
but with different slit sizes. Maximum differences are ~0.3%. The line plots from bottom
to top and x,y axis labels show the intensity of column 10 (offset by -.01), the central column, and column 118 (offset by +.01) of the 128x128 pixel L-flat. The slit for the image
with 52x05 in the name is 52x0.5”.
26
MAMA2 L Flat G230M
0.98
1.02
L2659FLAT52X01.FITS / L2659flat52x05.FITS
Central Column Intensity
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 9-May-1997 16:15
120
Fig. 11
Figure 11: As for Figure 10, except for the ratio of an internal L-flat to the same external
flat used in the denominator of Figure 10. The plots for columns 10 and 118 demonstrate a
smooth and systematic difference between the internal and external L-flat of -.8% in the
top left corner to +.8% in the top right corner.
27
MAMA L Flat G230M
0.98
1.02
G230M_1915_AVG.FITS / G230M_2977_LFL.FITS
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 16:37
120
Fig. 12
Figures 12-15: Ratio of core L-flat at 1915, 2176, 2419, and 2659Å to core flat at 2977Å,
respectively. Grey scale and line plots are as in Figure 10. This series of four figures demonstrates continuity of change with respect to wavelength.
28
MAMA L Flat G230M
0.98
1.02
G230M_2176_LFL.FITS / G230M_2977_LFL.FITS
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 16:37
120
Fig. 13
Figures 12-15: Ratio of core L-flat at 1915, 2176, 2419, and 2659Å to core flat at 2977Å,
respectively. Grey scale and line plots are as in Figure 10. This series of four figures demonstrates continuity of change with respect to wavelength.
29
MAMA L Flat G230M
0.98
1.02
G230M_2419_LFL.FITS / G230M_2977_LFL.FITS
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 16:37
120
Fig. 14
Figures 12-15: Ratio of core L-flat at 1915, 2176, 2419, and 2659Å to core flat at 2977Å,
respectively. Grey scale and line plots are as in Figure 10. This series of four figures demonstrates continuity of change with respect to wavelength.
30
MAMA L Flat G230M
0.98
1.02
G230M_2659_LFL.FITS / G230M_2977_LFL.FITS
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 16:37
120
Fig. 15
Figures 12-15: Ratio of core L-flat at 1915, 2176, 2419, and 2659Å to core flat at 2977Å,
respectively. Grey scale and line plots are as in Figure 10. This series of four figures demonstrates continuity of change with respect to wavelength.
31
0.98
MAMA L Flat G230M
1.02
L2257flat52X2.fits / G230M_2257_LFL.fits
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 17:00
120
Fig. 16
Figure 16: Ratio of measured L-flat for G230M at 2257Å to the higher S/N interpolated
L-flat for the same wavelength.
32
0.98
MAMA L Flat X230M
1.02
L2703FLAT02X29.FITS / X230M_2703_LFL.fits
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 17:00
120
Fig. 17
Figure 17: Ratio of measured L-flat for X230M at 2703Å to the higher S/N interpolated
L-flat for the same wavelength.
33
0.98
MAMA L Flat X230H
1.02
L3010FLAT02X29.FITS / X230H_3010_LFL.fits
Central Column Intensity & cols 10 & 118
1.01
1.00
0.99
0
20
40
60
80
Pixel in 128x128 binned image
100
Bohlin: biglfig.pro 21-May-1997 17:00
120
Fig. 18
Figure 18: Ratio of measured L-flat for X230H at 3010Å to the higher S/N extrapolated
L-flat for the same wavelength.
34