XRT Stray Light Study 2025 -- phase 7 (after 11-May-2024).

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 2022 phase 5 page (after 8-Jun-2022 ← 5th event).
Link to the 2023 phase 6 page (after 5-May-2023 ← 6th event).
Link to the 2023 phase 6 & 7 page (after 11-May-2024 ← 7th event).

(11 May 2025, initial version by Aki Takeda)
(28 May 2025, added thin_Be limb data and pointing info.)

1. Purposes of the stray light measurement in 2025.

Initial purpose was to confirm the stray light level of the phase 7 (since 11-May-2024) after one year.

2. Summary of Results.

3. Measurements 2025 (phase 7) at a glance.

ID No. date & time (UT) XOB purposes (link: obtained plots ) memo
1 3-May-2025, 17:19:30 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at DC. previous bakeout + 3 day.
2 4-May-2025, 17:51:30 1D32 light crv., thin-Be (11.3s) at DC. prev. b.o. + 4 day.
3 5-May-2025, 18:24:00 1D33 light crv., med-Be (22.6s) at DC. prev. b.o. + 5 day.
4 6-May-2025, 14:01:30 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at N-limb at HOP130 prev. b.o. + 6 day.
5 6-May-2025, 15:39:30 1D33 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at S-limb at HOP130 prev. b.o. + 6 days.
6 6-May-2025, 17:18:00 1D34 light crv., med-Al (32.0s) at DC prev. b.o. + 6 days.
7 6-May-2025, 22:12:30 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at E-limb at E-coal. prev. b.o. + 6 days.
8 7-May-2025, 17:50:00 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at W-limb prev. b.o. + 7 days.
9 8-May-2025, 15:06:00 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at (-21,-492) at HOP412 prev. b.o. + 8 days.
10 8-May-2025, 18:22:30 1D36 light crv., Al-poly/Ti-poly (4.0s) and Al-poly (2.0s) at DC prev. b.o. + 8 days.
11 8-May-2025, 21:38:30 1D31 light crv., Al-mesh (1.4s) and Al-poly (2.0s) at (-21,398) at HOP412 prev. b.o. + 8 days.
12 9-May-2025, 17:16:30 1D32 light crv., thin-Be (11.3s) at W-limb prev. b.o. + 9 days.
13 10-May-2025, 17:48:30 1D32 light crv., thin-Be (11.3s) at E-limb prev. b.o. + 10 days.
14 11-May-2025, 18:21:00 1D32 light crv., thin-Be (11.3s) at N-limb prev. b.o. + 11 days.
15 12-May-2025, 17:15:00 1D32 light crv., thin-Be (11.3s) at S-limb prev. b.o. + 12 days.

4. Stray light images 2025 (phase 7), at a glance.

The stray light component included in the Al_mesh filter was at the same level as that of 2024. The new stray light pattern started to appear since 2023 on the E-limb images was reproduced.

- 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, 20250503(1.4s)
phase 7 [pbo+3d]
pnt.(-15.0, 9.8)
Al-mesh, 20240523(1.4s)
phase 7 [pbo+8d]
pnt.(-17.6, 28.5)
Al-mesh, 20230506(1.4s)
phase 6 [pbo+10d]
pnt.(-15.9, 17.3)
After PREP comparison
with phase 7 & 6

- limb pointings

Al-mesh, 20250506(1.4s)
[pbo+6d]
pnt.(-33.1,955.5)
Al-mesh, 20250506(1.4s)
[pbo+6d]
pnt.(3.7,-926.0)
Al-mesh, 20250506(1.4s)
[pbo+6d]
pnt.(-983.9,-3.5)
Al-mesh, 20250507(1.4s)
[pbo+7d]
pnt.(933.2,34.1)

- Other pointings

Al-mesh, 20250508(1.4s)
[pbo+8d]
pnt.(-23.1,-477.1)
Al-mesh, 20250508(1.4s)
[pbo+8d]
pnt.(-40.7,413.8)
The stray light component included in the Al_poly filter was the same level as that taken in 2024 (phase 7). The West pointing anomaly (significant amount of stray light intensity near West-limb pointing) was also reproduced.

- DC pointings

Al-poly, 20250503(2.0s)
phase 7 [pbo+3d]
pnt.(-15.2, 9.8)
Al-poly, 20250508(2.0s)
phase 7 [pbo+8d]
pnt.(-32.8, 12.9)
Al-poly, 20240523(2.0s)
phase 7 [pbo+8d]
pnt.(-17.6, 28.5)
Al-poly, 20230506(2.0s)
phase 6 [pbo+10d]
pnt.(-15.9, 17.3)
After PREP comparison
with phase 7 & 6

- limb pointings

Al-poly, 20250506(2.0s)
[pbo+6d]
pnt.(-33.1,955.5)
Al-poly, 20250506(2.0s)
[pbo+6d]
pnt.(3.6,-926.0)
Al-poly, 20250506(2.0s)
[pbo+6d]
pnt.(-983.9,-3.5)
Al-poly, 20250507(2.0s)
[pbo+7d]
pnt.(933.2, 34.1)

- Other pointings

Al-poly, 20250508(2.0s)
[pbo+8d]
pnt.(-32.8, 12.9)
Al-poly, 20250508(2.0s)
[pbo+8d]
pnt.(-40.7, 413.8)
The stray light component included in the thin_Be filter was the same level as that of phase 6 (2024) and is still negligible.

- DC pointings

thin_Be,20250504(11.3s)
phase 7,
pnt.(-15.5,12.8)
thin_Be,20240505(11.3s)
phase 6,
pnt.(-16.5, 14.4)
After PREP comparison
with phase 7 & 6

- limb pointings

thin_Be, 20250509(2.0s)
[pbo+9d]
pnt.(933.1,38.2)
thin_Be, 20250510(2.0s)
[pbo+10d]
pnt.(-959.6,-0.4)
thin_Be, 20250511(2.0s)
[pbo+11d]
pnt.(-37.0,964.3)
thin_Be, 20250512(2.0s)
[pbo+12d]
pnt.(2.7,-923.7)
The stray light component included in the med_Be filter was the same level as that of phase 6 (2024) and is still negligible.

med_Be,20250505
(22.6s), pnt.(-16.4,14.0)
med_Be,20240506
(22.6s), pnt.(-15.3, 15.5)
After PREP comparison
with phase 7 & 6
The stray light component included in the med_Al filter was measured for the first time after 2021. The stray light level turned out ~4 times larger than that in 2021 (phase 4), it is still at a negligible level.

med_Al,20250506
(32.7s), pnt.(-14.4, 14.8)
med_Al,20210512
(32.7s), pnt.(-17.0, 14.4)
After PREP comparison
with phase 7 & 6
The stray light component included in the Al_poly/Ti_poly filter was measured for the first time after 2022. The stray light level turned out to be the same level as that in 2022 and still negligible.

Apol+Tpol,20250508
(4.0s), pnt.(-32.8,12.9)
Apol+Tpol,20220712
(4.0s), pnt.(-20.0, 29.0)