XRT Stray Light Study 2022 -- phase 5 (after 8-Jun-2022).

Link to the 2014 summary page.
Link to the 2015 phase 1 summary. (after 9-May-2012 ← 1st pre-filter failure event)
Link to the 2015 phase 2 summary. (after 14-Jun-2015 ← 2nd failure event)
Link to the 2016 page and 2017 phase 2 page.
Link to the 2017 phase 3 page (after 27-May-2017 ← 3rd event).
Link to the 2018 phase 4 page (after 29-May-2018 ← 4th event).
Link to the 2019 phase 4 page.
Link to the 2020 phase 4 page.
Link to the 2021 phase 4 page.
Link to the 2022 phase 4 page.
Link to the 2023 phase 6 page (after 5-May-2023 ← 6th event).

(24 August 2022 by Aki Takeda, with light curve anlysis by R. Fleming)
(26 August 2022 by Aki Takeda, added pointing info)

1. Purposes of the stray light measurement in 2022.

We had a new increase of stray light level on 6/8 at around 12:40 UT (cf. XRT DV report by L. Guliano for 6/13 [xrt_co:47011]). This means that we have entered the 5th stray light phase. This page reports the results of the measurements performed in July 2022 (phase 5).

2. Summary of Results.

3. Measurements 2022 (phase 5) at a glance.

ID No. date & time (UT) XOB purposes (link: obtained plots & images) memo
18 9-Jul-2022, 18:04:00 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) at DC. previous bakeout + 3 day.
19 10-Jul-2022, 17:01:30 1CDD light crv., thin-Be (11.3s) at DC. prev. b.o. + 4 day.
20 11-Jul-2022, 19:15:00 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) on N-pole prev. b.o. + 5 day.
frequent telemetry loss
21 12-Jul-2022, 16:34:00 1CE3 light crv., Al-poly/Ti_poly (4.0s) and Al-poly (2.0s) at DC prev. b.o. + 6 days.
22 13-Jul-2022, 18:48:00 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) on S-pole. prev. b.o. + 7 days.
23 14-Jul-2022, 17:45:00 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) on W-limb prev. b.o. + 8 days.
24 15-Jul-2022, 18:20:30 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) on E-limb prev. b.o. + 9 days.
monitor Xray images saturated.
25 19-Jul-2022, 19:04:00 1CDC light crv., Al-mesh (1.4s) and Al-poly (2.0s) at NE-quad. prev. b.o. + 13 days.

4. Stray light images 2022 (phase 5), at a glance.

The stray light component included in the Al_mesh filter was increased by the factor of 1.1 compared with the corresponding 2018 July data (the beginning of the phase 4).

- DC pointings
[NOTE] pnt. indicates the satellite pointing at the time of data acquisition, i.e., (index.xcen, index.ycen) corrected by the the coalignment DB.

Al-mesh, 20220709(1.4s)
[pbo+3d]
pnt.(-20.5,28.2) 		Al-mesh, 20180712(1.4s)
[pbo+2d]
pnt.(-22.1,19.8) 		After PREP comparison
with 2018

- limb pointings

Al-mesh, 20220711(1.4s)
[pbo+5d]
pnt.(-47.6, 889.2) 		Al-mesh, 20220713(1.4s)
[pbo+7d]
pnt.(-7.6,-920.6) 		Al-mesh, 20220714(1.4s)
[pbo+8d]
pnt.( 893.4, 41.0) 		Al-mesh, 20220715(1.4s)
[pbo+9d]
pnt.(-959.5, 15.2)

- Other pointings

Al-mesh, 20220719(1.4s)
[pbo+13d]
pnt.(-555.9, 549.1)
The stray light component included in the Al_poly filter was increased. The the same factor as Al_mesh, 1.1 (compared with 2018) is aplicable to the Al_poly filter. The West pointing anomaly (significant amount of stray light intensity near West-limb pointing) is now the level of ~44 DN/sec/half-res pix).

- DC pointings

Al-poly, 20220709(2.0s)
[pbo+3d]
pnt.(-20.5, 28.2) 		Al-poly, 20220712(2.0s)
[pbo+6d]
pnt.(-20.0, 29.0) 		Al-poly, 20180712(2.0s)
[pbo+2d],
pnt.(-22.2,19.8) 		After PREP comparison
comparison with 2018

- limb pointings

Al-poly, 20220711(1.4s)
[pbo+5d]
pnt.(-47.6, 889.2) 		Al-poly, 20220713(1.4s)
[pbo+7d]
pnt.(-7.6,-920.6) 		Al-poly, 20220714(1.4s)
[pbo+8d]
pnt.( 893.5, 41.0) 		Al-poly, 20220715(1.4s)
[pbo+9d]
pnt.(-959.5, 15.2)

- Other pointings

Al-poly, 20220719(2.0s)
[pbo+13d]
pnt.(-555.9, 549.1)
Stray light level in the thin_Be and Al_poly/Ti_poly images are in negligible level.

- DC pointings

thin_Be,20220710
(11.3s), pnt.(-19.9,29.9)		 Apol/Tpol,20220712
(4.0s), pnt.(-20.0, 29.0)