Hinode/XRT New FLare Detection Images

XRT new flare detection (FLD) images monitoring.

(9-Jun-2017, initial version by Aki Takeda)
(20-Oct-2017, records for Sep-2017 updated based on Chunming Zhu's list.)
(31-Oct-2017, added the conclusion section.

Background

Because of XRT's pre-filter failure (ruptures) first occurred in May-2012, the Ti-poly filter started to suffer with visible light contamination. Since the second rupture of pre-filter (in Jun-2015), we do not take scientific images with Open/Ti-poly filter pair, because the correction of stray light turned out not effective. However, our flare detection images has remained to be taken with Open/Ti-poly, because flare detection algorithm is not affected by the steady increase of the stray light pattern (detection was made by using intensity variation). Rather, the change of filter requires the adjustment of the parameters used by the algorithm (different filter should have different values). This is the reason we have kept using the Ti-poly filter in spite of the stray light contamination.

On 27-May-2017, the third rupture event occurred and the CO of the week changed the FLD filter from Ti-poly to Al-poly as a response. (it was a week of Hinode/IRIS meeting and we did not have enough time for discussion.) Since the flare-detection parameters have not yet been optimized for the Al-poly filter, we need to monitor the performance of flare detection carefully in coming months (or years).

Goal of XRT's Flare Detection

"Observe M5 flares in flare mode from the time of 10% of its peak flux." (requirement from Hinode/SWG)

This is interpreted as the flare mode should be triggered at C5.

Performance Check of the Al-poly FLD filter (30-May-2017 through 31-Oct-2017)

Jump to Conclusion.

1. XRT flare mode triggered.

ID	date	time (UT)	GOES event (start--peak--end)	memo
1	2017/06/01	01:40:40 -- 01:48:22	C6.6 (01:12 -- 01:43 -- 01:53)
2	2017/06/03	19:28:40 -- 19:35:08	C2.5 (19:21 -- 19:34 -- 19:41)
3	2017/07/07	15:11:44 -- 15:12:22	B8.1 (15:07 -- 15:11 -- 15:15)	Compact spiky saturation on FLD.
4	2017/07/08	23:52:48 -- 23:57:41	C3.4 (23:50 -- 23:53 -- 23:57)
5	2017/07/09	03:15:48 -- 03:19:28	M1.3 (03:09 -- 03:18 -- 03:37)	SAA/NGT entry at 03:19:30.
6	2017/07/11	20:23:20 -- 20:32:14	C1.2 (20:18 -- 20:31 -- 20:35)	Drastic change in FLD.
7	2017/07/13	20:04:07 -- 20:10:50	C8.4 (20:01 -- 20:05 -- 20:11)
8	2017/07/13	21:54:53 -- 21:58:44	C5.9 (21:46 -- 21:55 -- 21:58)
9	2017/07/13	23:34:56 -- 23:43:33	C3.0 (23:30 -- 23:40 -- 23:44)
10	2017/07/14	01:55:03 -- 02:02:35	M2.4 (01:07 -- 02:09 -- 03:24)	SAA/NGT 01:25 -- 01:54
11	2017/07/14	02:02:47 -- 02:10:19	M2.4 (01:07 -- 02:09 -- 03:24)	flare mode ended at the peak.
12	2017/07/14	07:08:03 -- 07:15:44	SF (06:55 -- 07:02 -- 07:09)	Start of a new XOB.
13	2017/07/14	07:16:12 -- 07:18:48	no GOES report.	a spike during long M2.4 decay phase.
14	2017/07/14	07:21:27 -- 07:21:47	no GOES report.	a spike during long M2.4 decay phase.
15	2017/07/14	07:25:05 -- 07:39:11	SF (07:31 -- 07:33 -- 07:35)	Start of a new XOB.
16	2017/07/14	09:02:33 -- 09:09:17	SF (09:04 -- 09:07 -- 09:08)	Start of a new XOB.
17	2017/07/14	19:24:57 -- 19:26:17	C1.4 (19:18 -- 19:25 -- 19:44)	SAA/NGT 19:27 -- 20:08
18	2017/07/15	19:33:32 -- 19:43:09	C5.8 (19:26 -- 19:36 -- 19:44)
19	2017/07/16	02:02:34 -- 02:06:21	C3.1 (01:58 -- 02:35 -- 02:57)	SAA/NGT 02:34 -- 03:04
20	2017/08/03	00:00:47 -- 00:03:58	B9.4 (8/2 23:53 -- 23:59 -- 00:04)
21	2017/08/19	21:44:05 -- 21:58:13	C7.0 (8/20 20:54 -- 21:55 -- 22:55)	(*1)
22	2017/08/20	01:44:28 -- 01:57:12	M1.1 (8/20 01:36 -- 01:52 -- 02:03)	(*1)
23	2017/08/20	04:28:10 -- 04:40:51	C1.8 (8/20 04:22 -- 04:40 -- 04:53)	(*1)
24	2017/08/20	07:48:39 -- 07:56:24	C2.9 (8/20 07:45 -- 07:50 -- 07:54)	(*1)
25	2017/08/20	19:28:18 -- 19:38:40	C9.4 (8/20 19:20 -- 19:39 -- 19:49)	(*1)
26	2017/08/21	03:13:16 -- 03:21:34	C5.6 (8/21 03:05 -- 03:16 -- 03:30)	(*1)
27	2017/08/23	13:31:50 -- 13:41:50	C2.2 (8/23 13:24 -- 13:43 -- 13:55)
28	2017/08/24	00:13:23 -- 00:17:29	B8.1 (8/24 00:06 -- 00:14 -- 00:18)
29	2017/08/25	07:28:57 -- 07:38:11	C5.5 (8/25 07:15 -- 07:27 -- 07:46)
30	2017/09/01	15:39:28 -- 15:42:43	C2.0 (9/1 15:31 -- 15:37 -- 15:41)
				FLD filter in Ti-poly (9/4 -- 9/7).
31	2017/09/07	14:33:07 -- 14:39:58	X1.3 (9/7 14:20 -- 14:36 -- 14:55)
32	2017/09/07	16:38:34 -- 16:47:55	no GOES report.	No significant change in FLD. SAA (16:14 -- 16:37).
33	2017/09/07	18:27:08 -- 18:36:02	C5.2 (9/7 18:04 -- 18:28 -- 18:36)	No FLD (17:50 -- 18:27) due to SAA and Synoptic.
34	2017/09/07	19:51:36 -- 19:59:45	no GOES report.	No significant change in FLD. SAA (19:27 -- 19:50).
35	2017/09/07	21:29:07 -- 21:35:42	C5.4 (9/7 21:24 -- 21:37 -- 21:47)
36	2017/09/07	23:04:04 -- 23:07:20	C2.7 (9/7 22:57 -- 23:00 -- 23:02)	SAA (22:42 -- 23:03). FLD shows flaring feature.
37	2017/09/07	23:56:41 -- 00:05:35	M3.9 (9/7 23:50 -- 23:59 -- 00:14)
38	2017/09/08	00:29:04 -- 00:35:07	no GOES report.	SAA (00:19 -- 00:28). FLD flare region significant decay.
39	2017/09/08	02:03:28 -- 02:06:45	no GOES report.	SAA (01:43 -- 02:02). FLD flare region significant decay.
40	2017/09/08	03:39:37 -- 03:45:35	M1.2 (9/8 03:39 -- 03:43 -- 03:45)
41	2017/09/08	06:13:08 -- 06:20:26	no GOES report.	SAA (06:00 -- 06:13). FLD flare region significant decay.
42	2017/09/08	06:54:37 -- 06:58:27	no GOES report.	SAA (06:28 -- 06:53). FLD flare region significant decay.
43	2017/09/08	08:31:39 -- 08:42:09	no GOES report.	No data (07:27 -- 08:08, memory filled-up?). SAA (08:08 -- 08:30).
44	2017/09/08	10:06:08 -- 10:13:40	no GOES report.	SAA (09:48 -- 10:05). No significant change in FLD.
45	2017/09/08	15:26:36 -- 15:39:55	M2.9 (9/8 15:09 -- 15:47 -- 16:04)	SAA (15:13 -- 15:25).
46	2017/09/08	17:13:05 -- 17:23:31	no GOES report.	SAA (16:48 -- 17:12). No significant change in FLD.
47	2017/09/08	18:13:08 -- 18:24:13	no GOES report.	No FLD (17:59 -- 18:12, Synop.). C1.7 flare happened in this flare mode (18:15 -- 18:18 -- 18:20).
48	2017/09/08	18:50:06 -- 19:02:04	no GOES report.	SAA (18:25 -- 18:49). FLD flare region expanded.
49	2017/09/08	20:26:34 -- 20:36:47	C1.7 (9/8 20:10 -- 20:14 -- 20:16)	SAA (20:02 -- 20:25). FLD flare region expanded.
50	2017/09/08	22:03:37 -- 22:15:51	no GOES report.	SAA (21:39 -- 22:02). FLD flare region expanded.
51	2017/09/08	23:37:37 -- 23:51:22	M2.1 (9/8 23:33 -- 23:45 -- 23:56)	SAA (23:17 -- 23:36).
52	2017/09/09	01:02:05 -- 01:07:37	no GOES report.	SAA (00:54 -- 01:01). No significant change in FLD.
53	2017/09/09	02:37:35 -- 02:40:58	no GOES report.	SAA (02:17 -- 02:36). No significant change in FLD.
54	2017/09/09	04:14:38 -- 04:25:02	M1.1 (9/9 04:14 -- 04:28 -- 04:43)	SAA (03:49 -- 04:13).
55	2017/09/09	05:52:06 -- 05:55:11	no GOES report.	SAA (05:23 -- 05:51). FLD flare region shows decay.
56	2017/09/09	07:29:33 -- 07:35:09	C1.5 (09/09 07:17 -- 07:27 -- 07:40)	SAA (07:04 -- 07:28).
57	2017/09/09	09:06:07 -- 09:12:40	no GOES report.	SAA (08:43 -- 09:05).
58	2017/09/09	11:01:06 -- 11:14:20	M3.7 (09/09 10:50 -- 11:04 -- 11:42)	No FLD (10:25 -- 11:01, timeline switching period).
59	2017/09/09	17:48:09 -- 17:54:27	no GOES report.	SAA (17:23 -- 17:47). FLD flare cusp expanded.
60	2017/09/09	18:15:39 -- 18:20:56	no GOES report.	No FLD (18:02 -- 18:15, Synop.). Start of a new XOB.
61	2017/09/09	19:24:38 -- 19:29:19	C1.8 (09/09 19:09 -- 19:15 -- 19:20)	SAA (19:00 -- 19:23). FLD flare region brightened.
62	2017/09/09	21:02:08 -- 21:12:49	C4.7 (09/09 21:00 -- 21:11 -- 21:25)	SAA (20:37 -- 21:01). FLD flare region brightened.
63	2017/09/09	22:38:10 -- 22:45:59	M1.1 (09/09 22:04 -- 23:53 -- 00:41)	SAA (22:14:-- 22:37).
64	2017/09/10	01:18:43 -- 01:18:43	no GOES report.	SAA (01:19 -- 01:35). No significant change in FLD.
65	2017/09/10	01:36:12 -- 01:41:57	no GOES report.	SAA (01:19 -- 01:35). FLD flare region significant decay.
66	2017/09/10	03:12:44 -- 03:21:00	C9.0 (09/10 02:40 -- 03:09 -- 03:25)	SAA (02:51 -- 03:11). FLD flare region brightened.
67	2017/09/10	04:49:39 -- 04:54:52	no GOES report.	SAA (04:19 -- 04:48). FLD flare region significant decay.
68	2017/09/10	15:40:47 -- 16:17:29	X8.2 (09/10 15:35 -- 16:06 -- 16:31)	FLD performed perfectly! (GOES level C2.5 at the start of flare mode at 15:40:47.) Site detection failed.
69	2017/09/10	18:39:01 -- 18:42:42	no GOES report.	Decay phase of X8.2 flare. No significant change in FLD.
70	2017/09/10	19:59:36 -- 20:04:52	no GOES report.	SAA (19:35 -- 19:58). Decay phase of X8.2 flare.
71	2017/09/11	02:52:18 -- 02:52:53	no GOES report.	Decay phase of X8.2 flare. No significant change in FLD.
72	2017/09/25	15:04:33 -- 15:20:33	B5.9 (09/25 14:35 -- 15:14 -- 15:32)	Weak flare, but significant change in FLD.
73	2017/09/27	00:55:28 -- 01:05:33	C1.7 (09/27 00:50 -- 01:01 -- 01:07)	Weak flare, but significant change in FLD.
74	2017/10/20	23:21:39 -- 23:29:25	M1.1 (10/20 23:10 -- 23:28 -- 23:37)

[Note] *1: Special setting for eclipse obs. FLD_ENA, but FLD_CTL_DIS. This means that flares can be detected, but not going to the flare-mode.

2. C5 and larger flares missed by XRT flare detection.

ID	date	GOES class (start--peak--end)	memo
1	2017/06/02	C8.0 (17:50 -- 17:57 -- 18:01)	during SAA/NGT period
2	2017/07/03	M1.3 (15:37 -- 16:15 -- 16:18)	(*)Limb. FLD flare kernel changed slow.
3	2017/07/09	C5.3 (11:44 -- 12:12 -- 12:28)	Started in SAA, FLD before/after changed not much.
4	2017/08/30	C5.2 (18:38 -- 18:45 -- 18:50)	Flare region outside FLD FOV.
5	2017/09/07	M1.4 (09:49 -- 09:54 -- 09:58)	No observation (timeline switching period).
6	2017/09/07	M7.3 (10:11 -- 10:15 -- 10:18)	No observation (timeline switching period).
7	2017/09/08	C5.3 (01:36 -- 01:40 -- 01:42)	(*) missed! Compact saturation?
8	2017/09/08	M1.3 (02:19 -- 02:24 -- 02:29)	(*) missed!
9	2017/09/08	C8.3 (05:31 -- 05:48 -- 05:53)	(*) missed!
10	2017/09/08	C6.0 (07:04 -- 07:08 -- 07:10)	(*) missed!
11	2017/09/08	M8.1 (07:40 -- 07:49 -- 07:58)	No data where they should be (memory filled up?).
12	2017/09/08	C5.9 (12:09 -- 12:13 -- 12:15)	(*) missed!
13	2017/09/09	C6.3 (03:02 -- 03:09 -- 03:25)	(*) missed!

[Note] *: means the events the flare-mode is expected, no excuse (during SAA, out of FOV, etc) found.

3. Comparison with Ti_poly FLD performance.

The FLD filter was back to Ti_poly in the timelines that covered the period from 2-Sep to 7-Sep-2017. It was due to the XRT_CO's miss-operation, but this provided us with a good opportunity to make comparison of Al_poly FLD performance with that of Ti_poly.

Flare mode observations.

ID	date	time (UT)	GOES event (start--peak--end)	memo
T1	2017/09/04	05:43:17 -- 05:43:22	M1.2 (05:36 -- 05:49 -- 06:05)	SAA passage (05:43 -- 06:10).
T2	2017/09/04	06:37:28 -- 06:45:19	no GOES report.	No significant change in FLD. Start of a new XOB.
T3	2017/09/04	15:33:07 -- 15:35:49	no GOES report.	Start of a new XOB. FOV changed.
T4	2017/09/04	21:21:08 -- 21:27:56	no GOES report.	No significant change in FLD. SAA (20:56 -- 21:20).
T5	2017/09/05	03:03:06 -- 03:09:54	no GOES report.	Start of a new XOB. FOV changed.
T6	2017/09/05	03:32:10 -- 03:41:39	no GOES report.	No significant change in FLD. SAA (03:10 -- 03:31).
T7	2017/09/05	04:03:06 -- 04:12:32	no GOES report.	No significant change in FLD. Start of a new XOB.
T8	2017/09/05	06:05:07 -- 06:14:36	no GOES report.	No significant change in FLD. Start of a new XOB.
T9	2017/09/05	08:23:39 -- 08:28:47	no GOES report.	No significant change in FLD. SAA (08:00 -- 08:22).
T10	2017/09/05	17:41:18 -- 17:52:11	M2.3 (17:37 -- 17:43 -- 17:51)
T11	2017/09/05	18:07:27 -- 18:12:20	no GOES report.	No FLD, 17:53 -- 18:03 (Synoptics). Start of a new XOB.
T12	2017/09/06	09:03:27 -- 09:14:46	X2.2 (08:57 -- 09:10 -- 09:17)
T13	2017/09/06	11:56:43 -- 12:07:59	X9.3 (11:53 -- 12:02 -- 12:10)
T14	2017/09/06	12:56:24 -- 13:04:30	no GOES report.	Additional peak in the decay phase of X9.3.
T15	2017/09/06	17:40:16 -- 17:48:40	no GOES report.	No significant change in FLD. SAA (17:15 -- 17:39).
T16	2017/09/06	18:09:10 -- 18:16:04	no GOES report.	No significant change in FLD. Start of a new XOB.
T17	2017/09/06	19:17:09 -- 19:25:50	no GOES report.	No significant change in FLD. SAA (18:52 -- 19:16). M1.4 flare (19:21 -- 19:30 -- 19:35) just happened during this flare mode.
T18	2017/09/06	20:54:10 -- 21:01:37	no GOES report.	No significant change in FLD. SAA (20:29 -- 20:53).
T19	2017/09/06	22:30:10 -- 22:36:33	no GOES report.	No significant change in FLD. SAA (22:07 -- 22:29).
T20	2017/09/06	23:58:10 -- 00:03:31	no GOES report.	No significant change in FLD. SAA (23:44 -- 23:57).
T21	2017/09/07	05:02:06 -- 05:07:35	M2.4 (04:59 -- 05:02 -- 05:08).

Missed flares larger than C5.

ID	date	GOES class (start--peak--end)	memo
T1	2017/09/02	C7.7 (15:26 -- 15:41 -- 15:56)	Flare region outside FLD FOV.
T2	2017/09/04	C8.3 (12:12 -- 12:25 -- 12:33)	Flare region outside FLD FOV.
T3	2017/09/04	M1.5 (15:11 -- 15:30 -- 15:33)	Flare region outside FLD FOV.
T4	2017/09/04	C6.0 (17:20 -- 17:39 -- 17:48)	Flare region outside FLD FOV.
T5	2017/09/04	M1.0 (18:05 -- 18:22 -- 18:31)	No FLD until 18:19 (Synoptics). Flare region on FLD FOV boundary.
T6	2017/09/04	M1.7 (18:46 -- 19:37 -- 19:52)	Flare region on the FLD FOV boundary.
T7	2017/09/04	M5.5 (20:28 -- 20:33 -- 20:37)	Flare region on the FLD FOV boundary.
T8	2017/09/04	M2.1 (22:10 -- 22:14 -- 22:19)	Flare region on the FLD FOV boundary.
T9	2017/09/05	C9.8 (00:30 -- 00:35 -- 00:41)	Flare region on the FLD FOV boundary.
T10	2017/09/05	M4.2 (01:03 -- 01:08 -- 01:11)	Flare region on the FLD FOV boundary.
T11	2017/09/05	M1.0 (03:42 -- 03:51 -- 04:04)	(*) Missed! Flare kernel changed slow.
T12	2017/09/05	M3.2 (04:33 -- 04:53 -- 05:07)	during SAA (04:40 -- 05:08).
T13	2017/09/05	M3.8 (06:33 -- 06:40 -- 06:43)	during SAA (06:19 -- 06:45).
T14	2017/09/05	C5.4 (10:13 -- 10:19 -- 10:25)	No observation (SAA + timeilne switching period).
T15	2017/09/05	C6.9 (13:26 -- 13:34 -- 13:51)	(*) Missed!
T16	2017/09/06	M2.5 (15:51 -- 15:56 -- 16:03)	SAA (15:39 -- 15:53, 15:55 -- 16:02).
T17	2017/09/06	M1.2 (23:33 -- 23:39 -- 23:44)	(*) Missed! Less flare kernel expansion.
T18	2017/09/07	C8.2 (06:19 -- 06:28 -- 06:42)	(*) Missed! Synoptics (06:28--06:38).

Conclusion

We found no urgent reason to alter the FLD parameters for Al_poly from the current settings (which were determined for Ti_poly).
During this checking period, there were a lot of failing cases of flare detection, but they are not likely due to the change of the FLD filter.

Several flares were missed without reasons (such as SAA, out of FOV), but the flare detection with Ti_poly were not perfect, either. (according to the comparison with the Ti_poly cases of 2-7 Sep.).
The flare-mode was sometimes triggered for the flares weaker than C5 class, but it is also true for Ti_poly FLD (according to the XRT flare catalog).
When the Sun is highly active (e.g., 7/14, 9/7-10), we found the flare-mode was often triggered right after exiting from SAAs, or at the very beginning of a new XOB, rather than by an actual increase of the solar activity. We observed the same phenomena when the Ti_poly was the FLD filter during 9/4-7. It is weird because the MDP_XRT_FLD_RESET command is included in the BAD_PHOTO_ENTRY sequence and in most sequences for starting XOB. This might indicate a flaw of the current flare trigger algorithm, but NOT indicate the change of the FLD filter is the matter.
When the Sun is not so active (when the flares are well isolated), the FLD is working no problem.