Hinode/XRT stray light correction 2022

XRT Stray Light Study 2022 -- phase 4 (after 29-May-2018).

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 5 page (after 8-Jun-2022 ← 5th event).

(27 Jun, 2022 by Aki Takeda)
(15 July, 2022 : light curves, Al_mesh images & plots made by R. Fleming)

1. Purposes of the stray light measurement in 2022.

This year's hard eclipse (with night transition) season started on 3-May. I started the stray light measurements on 5/7 in my first timeline in my duty week (5/7 to 5/20).

Judging from the intensity level of G-band images and FLD images, 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 entered the 5th stray light phase. This page reports the results of the measurements before that event, while we were in the phase 4.

The purpose of 2022 measurements (in the phase 4) is to take Open/Al_mesh and Al_poly/Open stray light images at various pointings so that the whole AR belt is covered (see the right figure). This is suggested by S. Saar at the XRT calibration meeting held on 3/29, 2022. The stray light images with the filters thicker than thin_Be were forgone due to the limited number of observations during my duty weeks.

2. Summary of Results.

It was confirmed that there was no chanage in the stray light level of the measured filters compared with those at the start of the phase 4.
[Al_mesh] No change in the stray light component (pattern & intensity level) since the beginning of the phase 4 (Aug-2018).
[Al_poly] No change in the stray light component either, since Aug-2018. The West-pointing anomaly (significant amount of visible light component, ~40 DN/sec/half-res-pix, noticed near West-limb pointing) was reproduced.
[thin_Be] Stray light component is still in a negligible level.

3. Measurements 2022 at a glance.

ID No.	date & time (UT)	XOB	purposes (filter, exposure & location [in the above figure])	memo
1	07-May-2022, 12:03:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at DC (loc.[a])	previous bakeout + 3 day.
2	07-May-2022, 16:58:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at W-limb(loc.[e])	prev. b.o. + 3 day.
3	08-May-2022, 14:16:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at S-pole(loc.[c])	prev. b.o. + 4 day.
4	09-May-2022, 18:08:30	1CDD	light crv., thin-Be (11.3s) at DC	prev. b.o. + 5 days.
5	10-May-2022, 17:05:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at E-limb(loc.[d])	prev. b.o. + 6 days.
6	11-May-2022, 17:41:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [f]	prev. b.o. + 7 days.
7	12-May-2022, 18:16:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [g]	prev. b.o. + 8 days.
8	13-May-2022, 17:13:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [h]	prev. b.o. + 9 days.
9	14-May-2022, 17:48:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [i]	prev. b.o. + 10 days.
10	15-May-2022, 18:24:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [j]	prev. b.o. + 11 days.
11	16-May-2022, 17:21:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [k]	prev. b.o. + 12 days.
12	17-May-2022, 01:32:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [m]	prev. b.o. + 13 days.
13	17-May-2022, 14:39:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at N-pole(loc.[b])	prev. b.o. + 13 days.
14	17-May-2022, 17:56:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [l]	prev. b.o. + 13 days.
15	18-May-2022, 18:31:30	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [n]	prev. b.o. + 14 days.
16	19-May-2022, 19:07:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at location [o]	prev. b.o. + 15 days.
17	20-May-2022, 17:55:00	1CDC	light crv., Al-mesh (1.4s) and Al-poly (2.0s) at DC(loc.[a])	prev. b.o. + 16 days.

4. Stray light images 2021, at a glance.

Al_mesh filter

No change in the stray light component included in the Al_mesh filter (no new pattern found). Observed no increase of the stray light level since the 2018 July data.

- 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, 20220507(1.4s) [pbo+3d] pnt.(-16.8, 13.4)	Al-mesh, 20220520(1.4s) [pbo+16d] pnt.(-18.4, 23.0)	Al-mesh, 20180712(1.4s) [pbo+2d] pnt.(-22.1,19.8)	After PREP comparison 1 comparison with 2018

- Limb pointings

Al-mesh, 20220507(1.4s) [pbo+3d] pnt.(797.9, 22.6)	Al-mesh, 20220508(1.4s) [pbo+4d] pnt.(-5.9, -921.3)	Al-mesh, 20220510(1.4s) [pbo+6d] pnt.(-961.8, 4.7)	Al-mesh, 20220517(1.4s) [pbo+13d] pnt.(-45.5, 865.2)

- Other pointings (locations, f,g,h,i & g)

Al-mesh, 20220511(1.4s) [pbo+7d] pnt.(-674.0, 410.1)	Al-mesh, 20220512(1.4s) [pbo+8d] pnt.(-338.2, 315.6)	Al-mesh, 20220513(1.4s) [pbo+9d] pnt.(-26.1, 655.8)	Al-mesh, 20220514(1.4s) [pbo+10d] pnt.(293.3, 326.3)	Al-mesh, 20220515(1.4s) [pbo+11d] pnt.(627.4, 432.0)

- Other pointings (locations, k,l,m,n & o)

Al-mesh, 20220516(1.4s) [pbo+12d] pnt.(-659.2, -387.2)	Al-mesh, 20220517(1.4s) [pbo+13d] pnt.(-328.4, -281.7)	Al-mesh, 20220517(1.4s) [pbo+13d] pnt.(-29.8, -614.9)	Al-mesh, 20220518(1.4s) [pbo+14d] pnt.(302.3, -272.7)	Al-mesh, 20220519(1.4s) [pbo+15d] pnt.(639.7, -367.7)

Al_poly filter

No change in the stray light component included in the Al_poly filter. No change in the stray light intensity since 2018. The West pointing anomaly (significant amount of stray light intensity near West-limb pointing, ~40 (DN/sec/half-res-pix) 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-poly, 20220507(2.0s) [pbo+3d] pnt.(-16.8, 13.4)	Al-poly, 20220520(2.0s) [pbo+16d] pnt.(-18.4, 23.0)	Al-poly, 20180712(2.0s) [pbo+2d] pnt.(-22.1,19.8)	After PREP comparison 1 comparison with 2018

- Limb pointings

Al-poly, 20220507(2.0s) [pbo+3d] pnt.(797.9, 22.6)	Al-poly, 20220508(2.0s) [pbo+4d] pnt.(-5.9, -921.3)	Al-poly, 20220510(2.0s) [pbo+6d] pnt.(-961.8, 4.7)	Al-poly, 20220517(2.0s) [pbo+13d] pnt.(-45.5, 865.1)

- Other pointings (locations, f,g,h,i & g)

Al-poly, 20220511(2.0s) [pbo+7d] pnt.(-674.0, 410.1)	Al-poly, 20220512(2.0s) [pbo+8d] pnt.(-338.0, 315.5)	Al-poly, 20220513(2.0s) [pbo+9d] pnt.(-26.1, 655.8)	Al-poly, 20220514(2.0s) [pbo+10d] pnt.(293.3, 326.3)	Al-poly, 20220515(2.0s) [pbo+11d] pnt.(627.4, 432.0)

- Other pointings (locations, k,l,m,n & o)

Al-poly, 20220516(2.0s) [pbo+12d] pnt.(-659.7, -387.3)	Al-poly, 20220517(2.0s) [pbo+13d] pnt.(-328.4, -281.7)	Al-poly, 20220517(2.0s) [pbo+13d] pnt.(-29.8, -614.9)	Al-poly, 20220518(2.0s) [pbo+14d] pnt.(302.4, -272.7)	Al-poly, 20220519(2.0s) [pbo+15d] pnt.(639.8, -367.7)

Thin_Be filters

Stray light included in thin_Be is the same level as the previous measurements and still in negligible level.

- DC pointings

thin-Be,20220509(11s)
pnt.(-16.9, 16.3)

Quick Look of the Phase 5 data analysis

- DC pointings

Al-mesh,20220709(1.4s) pnt.(xx, xx)	Al-mesh after PREP comparison with phase 4	Al-poly,20220709(2.0s) pnt.(xx, xx)	Al-poly after PREP comparison with phase 4