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Technical Instrument Report WFPC2-97-05

Results of the WFPC2 SM-2 Lyman- Throughput Check (prop-ID 7018 and 7029)
C. O'Dea, S. Baggett, S. Gonzaga June 19, 1997

ABSTRACT The WFPC2 throughput at wavelengths near 1200 Angstroms was monitored over the period 27-Feb-97 to 05-May-97. The far UV throughput was not significantly affected by the February 1997 servicing mission. Any change is less than the roughly 20% measurement uncertainty.

1. Introduction
Although WFPC2 was not serviced during the second servicing mission, the SM-2 activities and/or the new instruments could have released significant contaminants into the HST environment. Thus, it was important to check that the throughput of WPFC2 was maintained. Several programs were designed to test various aspects of WFPC2 throughput. A suite of filters covering a broad range of wavelengths showed no significant change (Whitmore et al. 1997). Examination of the throughput at F170W showed that the contamination rates after SM-2 were initially higher than normal, but declined with time (Stiavelli et al. 1997). A third check was performed to measure the throughput at the shortest wavelengths at which WFPC2 is sensitive -- i.e., around 1200 Angstroms (close to Lyman-). A similar program was carried out during the first year of WFPC2 operation to monitor the far-UV throughput (Mackenty & Baggett 1996). In this TIR we describe the results of the SM-2 Lyman alpha throughput check (proposal 7018 and its extension 7029). Observations were made of the UV-bright star WD0310-688 at several epochs in order to measure any far-UV throughput decrease due to contamination of the WFPC2 pick-off mirror. The properties of the star are summarized in Table 1. The post-SMOV data was compared with pre-SMOV data taken on 18-Nov-96. Observations are made in far-UV filters F122M and F160BW. However, both of these filters have a significant red leak. Thus, images are also taken with these filters crossed with F130LP, so as to isolate counts con-

1


tributed by the red leak in F122M and F160BW. The observations were taken in both the PC1 and WF3 chips. Two observations were taken in each filter/chip combination. In addition, a F555W image was taken in PC1 as an overall sanity check. The observations in 7018 consisted of three epochs of observation, each within 1-2 days after a DECON. Because of a delay in the comissioning of the STIS MAMAs, and the need to continue monitoring far-UV throughput, the program was extended (ID 7029) for another six epochs at roughly weekly intervals up to 05-May-97.

2. Procedure
A rapid turnaround was not required for these results, so the data were calibrated via the normal pipeline procedures. Because a flat field reference file is not available for the filters crossed with F130LP, a crude flat field was applied in three ways and the results compared, (1) these data were flatfielded with a dummy file of unity value, (2) they were corrected by hand using a local median filtered flat field value from the uncrossed filter flatfield, and (3) recalibrated using the flat field from the uncrossed filter. The data were reduced by Gonzaga using scripts initially created by Christine Ritchie and modified by Gonzaga. Selected data sets were analysed independently by O'Dea and Baggett, obtaining consistent results. The two observations in each filter/chip combination were reduced separately and the results compared afterwards. Cosmic rays were removed by hand and the centers of the stars were determined by eye due to asymmetries in the PSF. O'Dea also reduced selected data implementing CR removal with crrej and obtained similar results. The stars were checked for saturation with none found. Aperture photometry was obtained with the task "phot" using an aperture radius of 0.5 arcsec (5 pixels in WF3 and 11 pixels in PC1) and a sky subtraction annulus between 1.5 and 2.0 arcsec. The count rates in the F130LP crossed filters (the red counts) were subtracted from the uncrossed filters (the total counts) to produce the "approximate" red leak corrected (blue) count rates. Notes and Caveats In this section we note various features of the data, some of which may affect the uncertainties of the results. Note that some of the filter/chip combinations were not observed on the pre-SM-2 visit, thus for them, a pre/post SM-2 comparison is not possible. The flat fields for the F122M and F160BW filters are somewhat uncertain since they are based on ground TV data and no on-orbit calibrations are available. Hot pixels appear to be present in the flatfields. There are no flat fields available for the filters crossed with F130LP and we instead used flat field values for the uncrossed filters. There is a significant red leak (over 70% of the light from our white dwarf calibration star WD0310-688

2


through the F122M and F160BW filters is due to red leak). Thus, the flat field response in the F122M and F160BW filters is dominated by the red component, yet we are trying to measure the blue component of the light through the filter. The uncertainty in the flat fields is relevant because of a large shift in position on the chip between the pre-SM-2 and postSM-2 observations of the standard star, i.e., in the PC the star is located near 455, 560 in the the pre-SM2 observation and near 530, 326 in the post-SM-2 observations. There is a ghost in the WF3 F122MxF130LP image to the upper right of the star. There is a bad column (a trap - see Whitmore & Wiggs 1995) at x=529 in the PC which is at the location of the star in the post-SM-2 data. No attempt was made to mask out the bad column. Table 2 gives the x, y pixel locations of the star in the different filter/chip combinations. On the PC the star position in the UV filters differs by 2-3 pixels from the position in the F555W filter. Crossing the UV filters with the F130LP results in an additional position shift of the star of about 4.5 pixels in x and 1.4 pixels in y, i.e., a total angular shift of about 0.2 arcsec. Since the bad column in the PC was at x=528, the star's motion on the chip from one filter to the next introduced errors in the red leak correction.

3. Results
Plots of the normalized ratios of the count rates are given in Figures 1-5. The countrates are normalized to the 26-Apr-97 values which were obtained less than 4 hrs after a decontamination. The statistics of the normalized count rates are given in Table 3 and the individual measurements of the count rates are given in Table 4. Figure 1 shows the normalized count rates for the F555W filter on the PC. These observations are consistent with the typical 2% repeatibility and show that the instrument was well behaved during these observations. There may also be a long term trend for a small increase in normalized countrate with time. This effect is under investigation. Figure 2 shows the count rates in the F122M and F160BW filters for both PC and WF3. These observations show no significant trend with time, but show a scatter of ~7%. The normalized count rates for the F122M and F160BW crossed with the F130LP are shown in Figures 3 (PC) and 4 (WF3) with and without a flat field correction applied. These data are also consistent with no general trend in the data, but show a scatter of 5-10% in the PC and WF3. The WF3 data in Figure 4 hint at a decrease in normalized countrate with time, but this is not confirmed by the other data and is probably due to the large scatter. A comparison of the uncrossed and crossed filter countrates shows that the red leak contribution is high for this star, roughly 70% (see Table 1). Thus in Figure 5 we show the count rates with an approximate correction for the red leak. These results are again consistent with no general trend in the throughput, but with a large scatter of ~15-25%. While it is clear that the data have much scatter, it is clear that the pre-SM-2 (MJD ~ 50404) and post-SM-2 (MJD 50500-50600) results show good agreement on the PC in Figure 5. Thus, we conclude that the far-UV throughput of

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WFPC2 was not significantly affected by contamination due to the second servicing mission. Any change is less than the ~20% uncertainty.

Table 1: Properties of WD0310-688 (LB3303) in March 1997
Property RA (J2000.0) DEC (J2000.0) Type F555W (STMAG) in 0.5" aperture B-V U-B Avg count rate F555W Avg count rate F122M Redleak Fraction in F122M Avg count rate F160BW Redleak Fraction in F160BW Value 3:10:30.970 -68:36:03.05 DA3 12.3 0.02 -0.62 13140 DN/s 39 DN/s 72% 142 DN/s 78%

Table 2: Location of Star on Chip and Integration Time
Chip PC1 Filter1 F122M F122M F160BM F160BM F555W WF3 F122M F122M F160BM F160BM F130LP F130LP F130LP F130LP Filter2 x 532.19 527.73 533.22 528.68 531.92 384.00 380.95 385.10 382.20 y 326.98 325.66 328.28 326.84 328.87 469.00 464.66 470.11 465.81 Integration Time (s) 100.0 100.0 40.0 40.0 0.5 100.0 100.0 40.0 40.0

4


Table 3 contains the count rates normalized to the value on 26-Apr-97 which was taken less than 4 hrs after a decontamination. Table 3. Normalized Count rates
chip PC filter1 F555W filter2 none ff y npts 10 mean 0.985 rms 0.014 median 0.991 min 0.959 max 1.000

PC PC PC PC

F122M F122M F122M F122M

none F130LP F130LP none(r)

y y n y

18 16* 18 18

0.940 0.960 0.964 0.893

0.064 0.030 0.030 0.142

0.933 0.967 0.963 0.873

0.843 0.895 0.893 0.715

1.128 1.004 1.007 1.372

PC PC PC PC

F160BW F160BW F160BW F160BW

none F130LP F130LP none(r)

y y n y

18 16* 18 18

0.958 0.889 0.978 1.311

0.068 0.056 0.041 0.385

0.956 0.880 0.982 1.415

0.825 0.820 0.886 0.850

1.070 1.000 1.028 2.099

WF3 WF3 WF3 WF3

F160BW F160BW F160BW F160BW

none F130LP F130LP none(r)

y y n y

16 16 16 16

0.938 0.974 1.005 0.850

0.074 0.067 0.126 0.109

0.938 0.973 0.987 0.861

0.791 0.865 0.855 0.615

1.042 1.075 1.223 1.009

WF3 WF3 WF3 WF3

F122M F122M F122M F122M

none F130LP F130LP none(r)

y y n y

17** 16 16 17**

0.911 0.914 0.923 0.851

0.074 0.071 0.068 0.245

0.927 0.928 0.934 0.876

0.791 0.796 0.813 0.000

1.003 1.012 1.020 1.101

Notes to Table 3. Flat fielded for crossed filters means flat for uncrossed filter was applied. * Two fewer flat fielded observations: November 1996 data not reprocessed with flat. ** No other WF3 observations done in November, just one image of WF3,F122M. (r) in filter2 column indicates stats for red leak corrected values.

5


In Table 4, the flags "t, r, or m" mean that pipeline calibration was applied, i.e., with no flatfield correction applied to the crossed filter data.The flag "f" means that the flat field for the uncrossed filter was applied to the data. Table 4: Count rates
Chip 1 1 1 1 1 1 1 1 1 1 1 1 3 Filter1 F555W F555W F160BW F160BW F160BW F160BW F170W F170W F122M F122M F122M F122M F122M Filter2 none none none none F130LP F130LP none none none none F130LP F130LP none countrate per sec 12918. 13122. 130.14 130.02 106.27 108.74 331.44 335.43 40.14 38.23 26.77 26.72 36.07 error 48.77 48.66 0.56 0.55 0.52 0.52 1.20 1.21 0.20 0.19 0.17 0.17 0.17 Date dd/mm/yy 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 17/11/96 MJD 50404.8884 50404.8898 50404.8919 50404.8932 50404.896 50404.8974 50404.8995 50404.9009 50404.903 50404.9051 50404.9085 50404.9106 50404.9148 Flag t t t t t t t t t t t t t Aper pixels 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 5.

1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

39.44 39.74 27.53 27.49 25.66 25.64

0.20 0.20 0.18 0.18 0.18 0.18

27/02/97 27/02/97 27/02/97 27/02/97 27/02/97 27/02/97

50506.8904 50506.8925 50506.896 50506.8981 50506.896 50506.8981

r r r r f f

11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

144.28 146.15 111.54 111.61 107.59 107.57

0.57 0.57 0.52 0.52 0.52 0.52

27/02/97 27/02/97 27/02/97 27/02/97 27/02/97 27/02/97

50506.9009 50506.9023 50506.905 50506.9064 50506.905 50506.9064

r r m r f f

11. 11. 11. 11. 11. 11.

6


Table 4: Count rates
Chip Filter1 Filter2 countrate per sec error Date dd/mm/yy MJD Flag Aper pixels

1

F555W

none

13231.

47.98

27/02/97

50506.9613

r

11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

39.15 39.34 25.87 25.45 25.83 25.41

0.17 0.17 0.14 0.14 0.14 0.14

27/02/97 27/02/97 27/02/97 27/02/97 27/02/97 27/02/97

50506.9099 50506.912 50506.9154 50506.9495 50506.9154 50506.9495

r r r r

5. 5. 5. 5. 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

123.25 126.24 97.13 100.28 91.63 94.64

0.48 0.49 0.43 0.44 0.43 0.45

27/02/97 27/02/97 27/02/97 27/02/97 27/02/97 27/02/97

50506.9523 50506.9536 50506.9564 50506.9578 50506.9564 50506.9578

5. 5. 5. 5. 5. 5.

1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

46.56 39.19 28.21 27.75 26.13 25.72

0.21 0.19 0.18 0.18 0.18 0.18

4/03/97 4/03/97 4/03/97 4/03/97 4/03/97 4/03/97

50511.5661 50511.5682 50511.5717 50511.5738 50511.5717 50511.5738

11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

137.28 139.19 110.55 111.79 103.83 104.79

0.56 0.56 0.52 0.53 0.52 0.53

4/03/97 4/03/97 4/03/97 4/03/97 4/03/97 4/03/97

50511.5766 50511.5779 50511.5807 50511.5821 50511.5807 50511.5821

11. 11. 11. 11. 11. 11.

7


Table 4: Count rates
Chip 1 Filter1 F555W Filter2 none countrate per sec 13025. error 48.53 Date dd/mm/yy 4/03/97 MJD 50511.6328 Flag Aper pixels 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

37.60 38.80 26.59 27.21 26.57 27.19

0.17 0.17 0.15 0.15 0.15 0.15

4/03/97 4/03/97 4/03/97 4/03/97 4/03/97 4/03/97

50511.5856 50511.5877 50511.5911 50511.6085 50511.5911 50511.6085

5. 5. 5. 5. 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

128.47 130.02 97.12 98.61 93.37 94.65

0.49 0.49 0.43 0.43 0.43 0.43

4/03/97 4/03/97 4/03/97 4/03/97 4/03/97 4/03/97

50511.6113 50511.6127 50511.6154 50511.6168 50511.6154 50511.6168

r r r r f f

5. 5. 5. 5. 5. 5.

1 1 1 1 1 1 1 1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M F160BW F160BW F160BW F160BW F160BW F160BW F555W

none none F130LP F130LP F130LP F130LP none none F130LP F130LP F130LP F130LP none

37.26 37.29 26.96 26.77 25.05 24.84 153.18 154.60 106.56 106.66 105.49 105.29 13341.

0.19 0.19 0.18 0.18 0.17 0.17 0.59 0.59 0.52 0.51 0.50 0.50 48.85

28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97

50535.005 50535.0071 50535.0106 50535.0127 50535.0106 50535.0127 50535.0154 50535.0168 50535.0196 50535.021 50535.0196 50535.021 50535.1384

r r r r f f r r r r f f r

11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11.

3

F122M

none

32.15

0.16

28/03/97

50535.0717

r

5.

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Table 4: Count rates
Chip 3 3 3 3 3 3 3 3 3 3 3 Filter1 F122M F122M F122M F122M F122M F160BW F160BW F160BW F160BW F160BW F160BW Filter2 none F130LP F130LP F130LP F130LP none none F130LP F130LP F130LP F130LP countrate per sec 32.75 23.49 23.51 23.18 23.21 113.14 114.71 80.46 81.88 81.58 83.02 error 0.16 0.14 0.14 0.14 0.14 0.47 0.46 0.40 0.40 0.40 0.40 Date dd/mm/yy 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 28/03/97 MJD 50535.0738 50535.0773 50535.0821 50535.0773 50535.0821 50535.0849 50535.0863 50535.0891 50535.0904 50535.0891 50535.0904 Flag r r r f f r r r r f f Aper pixels 5. 5. 5. 5. 5. 5. 5. 5. 5. 5 5.

1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

37.39 37.53 25.49 26.99 25.37 26.86

0.19 0.19 0.17 0.18 0.17 0.18

11/04/97 11/04/97 11/04/97 11/04/97 11/04/97 11/04/97

50549.8543 50549.8564 50549.8599 50549.8599 50549.862 50549.862

r r f r f r

11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

134.52 134.40 99.45 103.66 101.39 105.78

0.56 0.55 0.50 0.51 0.50 0.52

11/04/97 11/04/97 11/04/97 11/04/97 11/04/97 11/04/97

50549.8648 50549.8661 50549.8689 50549.8689 50549.8703 50549.8703

r r f r f r

11. 11. 11. 11. 11. 11.

1

F555W

none

13341.36

48.23

11/04/97

50549.9411

r

11.

3 3

F122M F122M

none none

36.64. 37.22

0.17 0.17

11/04/97 11/04/97

50549.9189 50549.921

r r

5 5.

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Table 4: Count rates
Chip 3 3 3 3 Filter1 F122M F122M F122M F122M Filter2 F130LP F130LP F130LP F130LP countrate per sec 24.28 24.2 24.48 24.39 error 0.14 0.14 0.14 0.14 Date dd/mm/yy 11/04/97 11/04/97 11/04/97 11/04/97 MJD 50549.9245 50549.9245 50549.9293 50549.9293 Flag f r f r Aper pixels 5. 5. 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

114.50 115.98 81.96 79.14 84.33 81.36

0.47 0.47 0.40 0.39 0.41 0.40

11/04/97 11/04/97 11/04/97 11/04/97 11/04/97 11/04/97

50549.9321 50549.9335 50549.9363 50549.9363 50549.9377 50549.9377

r r f r f r

5. 5. 5. 5. 5. 5.

1 1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M F555W

none none F130LP F130LP F130LP F130LP none

34.77 35.18 24.12 25.56 23.62 25.00 13353.

0.19 0.19 0.17 0.17 0.17 0.18 48.33

19/04/97 19/04/97 19/04/97 19/04/97 19/04/97 19/04/97 19/04/97

50557.9182 50557.9203 50557.9238 50557.9238 50557.9259 50557.9259 50557.9898

m m f m f m m

11. 11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

119.23 120.45 99.26 96.29 100.09 97.01

0.54 0.54 0.50 0.50 0.50 0.50

19/04/97 19/04/97 19/04/97 19/04/97 19/04/97 19/04/97

50557.9286 50557.93 50557.9328 50557.9328 50557.9342 50557.9342

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3

F122M F122M F122M F122M

none none F130LP F130LP

31.27 31.74 21.48 21.80

0.16 0.16 0.14 0.13

19/04/97 19/04/97 19/04/97 19/04/97

50557.9377 50557.9398 50557.9432 50557.9432

m m f m

5. 5. 5. 5.

10


Table 4: Count rates
Chip 3 3 Filter1 F122M F122M Filter2 F130LP F130LP countrate per sec 21.38 21.68 error 0.13 0.13 Date dd/mm/yy 19/04/97 19/04/97 MJD 50557.9779 50557.9779 Flag f m Aper pixels 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

98.72 101.58 76.14 71.19 77.20 72.11

0.44 0.44 0.39 0.37 0.39 0.37

19/04/97 19/04/97 19/04/97 19/04/97 19/04/97 19/04/97

50557.9807 50557.9821 50557.9849 50557.9849 50557.9863 50557.9863

m m f m f m

5. 5. 5. 5. 5. 5.

1 1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M F555W

none none F130LP F130LP F130LP F130LP none

41.08 41.46 26.28 27.87 26.47 28.13 13464.8

0.20 0.20 0.17 0.17 0.17 0.18 48.31

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.1078 50564.1099 50564.1134 50564.1134 50564.1154 50564.1154 50564.2411

m m f m f m m

11. 11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

144.11 144.94 121.00 108.84 121.12 108.64

0.57 0.57 0.53 0.51 0.53 0.52

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.1182 50564.1196 50564.1224 50564.1224 50564.1238 50564.1238

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

44.71 45.46 30.28 30.12 30.79 30.59

0.21 0.21 0.18 0.18 0.18 0.18

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.171 50564.1731 50564.1766 50564.1766 50564.1814 50564.1814

m m f m f m

11. 11. 11. 11. 11. 11.

11


Table 4: Count rates
Chip Filter1 Filter2 countrate per sec error Date dd/mm/yy MJD Flag Aper pixels

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

139.32 141.12 97.36 90.53 98.63 91.79

0.59 0.59 0.51 0.48 0.52 0.49

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.1842 50564.1856 50564.1884 50564.1884 50564.1898 50564.1898

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

39.41 39.63 26.67 26.47 27.06 26.87

0.18 0.18 0.15 0.15 0.15 0.15

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.171 50564.1731 50564.1766 50564.1766 50564.1814 50564.1814

m m f m f m

5. 5. 5. 5. 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

123.71 125.78 87.34 81.36 88.72 82.64

0.49 0.49 0.42 0.40 0.42 0.40

26/04/97 26/04/97 26/04/97 26/04/97 26/04/97 26/04/97

50564.1842 50564.1856 50564.1884 50564.1884 50564.1898 50564.1898

m m f m f m

5. 5. 5. 5. 5. 5.

1 1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M F555W

none none F130LP F130LP F130LP F130LP none

39.12 38.76 25.99 27.57 25.52 27.06 13440.

0.19 0.19 0.17 0.17 0.17 0.18 48.44

28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97

50566.9016 50566.9036 50566.9071 50566.9071 50566.9092 50566.9092 50566.9432

m m f m f m m

11. 11. 11. 11. 11. 11. 11.

1

F160BW

none

145.21

0.58

28/04/97

50566.912

m

11.

12


Table 4: Count rates
Chip 1 1 1 1 1 Filter1 F160BW F160BW F160BW F160BW F160BW Filter2 none F130LP F130LP F130LP F130LP countrate per sec 145.34 110.87 106.95 111.48 107.94 error 0.58 0.52 0.52 0.52 0.52 Date dd/mm/yy 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 MJD 50566.9134 50566.9161 50566.9161 50566.9175 50566.9175 Flag m f m f m Aper pixels 11. 11. 11. 11. 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

42.07 42.07 29.19 29.21 28.92 28.95

0.21 0.21 0.18 0.18 0.18 0.18

28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97

50566.921 50566.9231 50566.9266 50566.9266 50566.9314 50566.9314

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

133.29 134.15 97.18 85.74 98.54 87.01

0.58 0.58 0.52 0.48 0.52 0.48

28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97

50566.9342 50566.9356 50566.9384 50566.9384 50566.9398 50566.9398

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

36.47 36.95 25.40 25.42 25.40 25.42

0.17 0.17 0.14 0.14 0.14 0.14

28/04/97 28/04/97 28/04/97 28/04/97 28/04/97 28/04/97

50566.921 50566.9231 50566.9266 50566.9266 50566.9314 50566.9314

m m f m f m

5. 5. 5. 5. 5. 5.

3 3 3 3

F160BW F160BW F160BW F160BW

none none F130LP F130LP

118.03 119.01 86.94 76.49

0.48 0.48 0.42 0.39

28/04/97 28/04/97 28/04/97 28/04/97

50566.9342 50566.9356 50566.9384 50566.9384

m m f m

5. 5. 5. 5.

13


Table 4: Count rates
Chip 3 3 Filter1 F160BW F160BW Filter2 F130LP F130LP countrate per sec 87.90 77.41 error 0.42 0.39 Date dd/mm/yy 28/04/97 28/04/97 MJD 50566.9398 50566.9398 Flag f m Aper pixels 5. 5.

1 1 1 1 1 1 1

F122M F122M F122M F122M F122M F122M F555W

none none F130LP F130LP F130LP F130LP none

37.60 37.50 24.73 26.37 24.66 26.25 13365.

0.20 0.20 0.17 0.18 0.17 0.18 48.11

5/05/97 5/05/97 5/05/97 5/05/97 5/05/97 5/05/97 5/05/97

50573.2807 50573.2828 50573.2863 50573.2863 50573.2884 50573.2884 50573.3606

m m f m f m m

11. 11. 11. 11. 11. 11. 11.

1 1 1 1 1 1

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

134.03 134.77 110.97 102.05 112.51 103.94

0.56 0.56 0.52 0.51 0.51 0.50

5/05/97 5/05/97 5/05/97 5/05/97 5/05/97 5/05/97

50573.2911 50573.2925 50573.2953 50573.2953 50573.2967 50573.2967

m m f m f m

11. 11. 11. 11. 11. 11.

3 3 3 3 3 3

F122M F122M F122M F122M F122M F122M

none none F130LP F130LP F130LP F130LP

33.33 33.60 22.59 22.54 22.97 22.97

0.16 0.16 0.14 0.14 0.14 0.14

5/05/97 5/05/97 5/05/97 5/05/97 5/05/97 5/05/97

50573.3384 50573.3404 50573.3439 50573.3439 50573.3488 50573.3488

m m f m f m

5. 5. 5. 5. 5. 5.

3 3 3 3 3 3

F160BW F160BW F160BW F160BW F160BW F160BW

none none F130LP F130LP F130LP F130LP

108.34 109.95 80.98 70.14 81.43 70.66

0.47 0.47 0.40 0.37 0.40 0.37

5/05/97 5/05/97 5/05/97 5/05/97 5/05/97 5/05/97

50573.3516 50573.3529 50573.3557 50573.3557 50573.3571 50573.3571

m m f m f m

5. 5. 5. 5. 5. 5.

14


Figure 1: Normalized countrates for the PC F555W observations. Dotted lines represent DECON dates.

PC, F555W 1.4

1.2
normalized countrate

1

.8

.6 50400 50450 50500 MJD 50550 50600

15


Figure 2: Normalized count rates for F122M and F160BW in PC (left) and WF3 (right). Dotted lines represent DECON dates.
PC, F160BW 1.4 1.4 WF3, F160BW

1.2
normalized countrate normalized countrate

1.2

1

1

.8

.8

.6 50400 50450 50500 MJD PC, F122M 1.4 50550 50600

.6 50400 50450 50500 MJD WF3, F122M 1.4 50550 50600

1.2
normalized countrate normalized countrate

1.2

1

1

.8

.8

.6 50400 50450 50500 MJD 50550 50600

.6 50400 50450 50500 MJD 50550 50600

16


Figure 3: Normalized Count rates in F122M and B160BW crossed with the F130LP in the PC with flat field (of uncrossed filter) applied (left) and not applied (right). Dotted lines represent DECON dates.
PC, F160BW+F130LP 1.4 1.4 PC, F160BW+F130LP, no flat

1.2

1.2

normalized countrate

1

normalized countrate

1

.8

.8

.6 50400 50450 50500 MJD 50550 50600

.6 50400 50450 50500 MJD 50550 50600

PC, F122M+F130LP 1.4 1.4

PC, F122M+F130LP, no flat

1.2

1.2

normalized countrate

1

normalized countrate

1

.8

.8

.6 50400 50450 50500 MJD 50550 50600

.6 50400 50450 50500 MJD 50550 50600

17


Figure 4: Normalized Count rates through F122M and F160BW crossed with F130LP in WF3 with flat field (of uncrossed filter) applied (left) and not applied (right). Dotted lines represent DECON dates.
WF3, F160BW+F130LP 1.4 1.4 WF3, F160BW+F130LP, no flat

1.2

1.2

normalized countrate

1

normalized countrate

1

.8

.8

.6 50400 50450 50500 MJD 50550 50600

.6 50400 50450 50500 MJD 50550 50600

WF3, F122M+F130LP 1.4 1.4

WF3, F122M+F130LP, no flat

1.2

1.2

normalized countrate

1

normalized countrate

1

.8

.8

.6 50400 50450 50500 MJD 50550 50600

.6 50400 50450 50500 MJD 50550 50600

18


Table 5. Redleak corrected normalized count rates through F160BW and F122M in the PC (left) and WF3 (right). Dotted lines represent DECON dates.
PC, F160BW, redleak corrected 2 2 WF3, F160BW, redleak corrected

1.5
normalized countrate normalized countrate

1.5

1

1

.5

.5

0 50400 50450 50500 MJD 50550 50600

0 50400 50450 50500 MJD 50550 50600

PC, F122M, redleak corrected 2 2

WF3, F122M, redleak corrected

1.5
normalized countrate normalized countrate

1.5

1

1

.5

.5

0 50400 50450 50500 MJD 50550 50600

0 50400 50450 50500 MJD 50550 50600

Acknowledgements We are grateful to John Biretta for writing this SMOV proposal, for his diligent efforts to coordinate WFPC2 SMOV, and for comments on the TIR. We thank Brad Whitmore and Inge Heyer for comments on the TIR.

19


References Mackenty, J. W., Baggett, S., WFPC2 ISR 96-07 Stiavelli, M., Biretta, J., Baggett, S., Gonzaga, S., Mutchler, M., WFPC2 TIR 97-02 Whitmore, B., Gonzaga, S., Heyer, I., WFPC2 TIR 97-01 Whitmore, B., Wiggs, M., WFPC2 ISR 95-03

20