Sky transparency — night of 21–22 October 2026

Cloud arrived at 20:51 — detected by the all-sky camera, independent of N.I.N.A. Before it the sky ran at index 0 (IQR 0–0); after it 18 (IQR 0–86). 0 of 44 light frames landed before the cloud. 110 of 114 failures are attributed to cloud, 2 to post-slew guide-star acquisition; 2 remain unexplained and deserve a look. Guiding held at 1.39″ RMS (RA 0.97″, Dec 0.99″) over 3.9 h; the worst minute was 13.35″ at 20:59.

Index before 20:51

0 · IQR 0–0

Index after 20:51

18 · IQR 0–86

Cloud onset (all-sky)

20:51 · independent

Errors after onset

112 of 114 · solve + PHD2

Guide RMS

1.39″ · RA 0.97 · Dec 0.99

Normalised transparency index, by filter

100 = that target and filter's own clear‑sky median (rolling median over recent clear nights). Shaded columns are autofocus runs; the first target is named at the top left and dashed vertical rules mark each target change; ticks along the base are errors.

H α O III S II ▲ Plate solve failed ◆ PHD2 error

All‑sky background brightness

Mean luminance of the upper sky per all‑sky still — independent of anything N.I.N.A. recorded. The camera auto‑exposes, so this is an instrumental number, not photometry.

PHD2 guiding

RMS tracking error per minute from the PHD2 guide log, taken about zero rather than about each minute's mean, so slow drift counts as error. 1550 guide frames over 3.9 h of guiding in 23 sessions; the gaps are slews, dither settles and autofocus runs, when PHD2 was not guiding. PHD2 discarded 827 further frames — usually a lost star. The worst minute (13.35″ at 20:59) is clamped at the top of the plot.

RA RMS Dec RMS ◆ PHD2 error

All‑sky frames at the key moments

Times come from the still filenames, so they line up with the charts exactly.

All-sky at 20:47 — **20:47** · start of night

All-sky at 20:51 — **20:51** · cloud onset

All-sky at 20:49 — **20:49** · peak brightness 89.8

All-sky at 04:57 — **04:57** · end of night

Clear‑sky reference medians

The divisors behind the index — median detected stars per light sub before 20:51.

Target	Filter	Median stars	Frames	Source
IC 434 Panel 3	H	305	8	earlier clear nights
IC 434 Panel 3	O	215	7	earlier clear nights
IC 434 Panel 3	S	467	4	earlier clear nights
NGC 7293	O	183	49	earlier clear nights
NGC 7293	S	231	45	earlier clear nights

Event timeline

All observatory events with their attributed causes.

20:50:37AF failedautofocus run started 20:47:19 did not completeunexplained

20:51:04solve failedASTAP plate solve failedunexplained

20:51:05solve failedASTAP plate solve failedunexplained

20:53:10solve failedASTAP plate solve failedcloud

20:53:11solve failedASTAP plate solve failedcloud

20:55:18solve failedASTAP plate solve failedcloud

20:55:33solve failedASTAP plate solve failedcloud

20:58:04PHD2timed-out waiting for guider to settlecloud

21:03:55PHD2timed-out waiting for guider to settlecloud

21:09:37PHD2failed to find a suitable guide starcloud

21:17:36PHD2timed-out waiting for guider to settlecloud

21:22:39solve failedASTAP plate solve failedcloud

21:22:48solve failedASTAP plate solve failedcloud

21:29:48solve failedASTAP plate solve failedcloud

21:30:03solve failedASTAP plate solve failedcloud

00:00:05PHD2failed to find a suitable guide starcloud

00:00:32PHD2failed to find a suitable guide starcloud

00:01:11PHD2failed to find a suitable guide starcloud

00:06:41PHD2failed to find a suitable guide starcloud

00:07:58PHD2failed to find a suitable guide starcloud

00:13:33PHD2failed to find a suitable guide starcloud

00:22:25solve failedASTAP plate solve failedcloud

00:22:31PHD2failed to find a suitable guide starcloud

00:22:38solve failedASTAP plate solve failedcloud

00:23:10PHD2failed to find a suitable guide starcloud

00:23:43PHD2failed to find a suitable guide starcloud

00:29:08solve failedASTAP plate solve failedcloud

00:29:17solve failedASTAP plate solve failedcloud

00:29:56PHD2failed to find a suitable guide starcloud

00:34:42PHD2failed to find a suitable guide starcloud

00:42:16PHD2timed-out waiting for guider to settlecloud

00:47:20solve failedASTAP plate solve failedcloud

00:47:28solve failedASTAP plate solve failedcloud

00:51:52PHD2timed-out waiting for guider to settlecloud

00:56:55solve failedASTAP plate solve failedcloud

00:57:03solve failedASTAP plate solve failedcloud

00:57:36PHD2failed to find a suitable guide starcloud

01:02:21PHD2failed to find a suitable guide starcloud

01:03:22PHD2failed to find a suitable guide starcloud

01:12:58solve failedASTAP plate solve failedcloud

01:13:07solve failedASTAP plate solve failedcloud

01:13:37PHD2failed to find a suitable guide starcloud

01:19:13PHD2failed to find a suitable guide starcloud

01:23:58PHD2failed to find a suitable guide starcloud

01:33:17AF failedautofocus run started 01:30:08 did not completecloud

01:34:07solve failedASTAP plate solve failedcloud

01:34:08solve failedASTAP plate solve failedcloud

01:36:13solve failedASTAP plate solve failedcloud

01:36:14solve failedASTAP plate solve failedcloud

01:38:19solve failedASTAP plate solve failedcloud

01:38:20solve failedASTAP plate solve failedcloud

01:39:04PHD2failed to find a suitable guide starpost_slew

01:44:12PHD2failed to find a suitable guide starcloud

01:51:52PHD2timed-out waiting for guider to settlecloud

01:54:23PHD2timed-out waiting for guider to settlecloud

02:02:00PHD2timed-out waiting for guider to settlecloud

02:07:04solve failedASTAP plate solve failedcloud

02:07:14solve failedASTAP plate solve failedcloud

02:07:44PHD2failed to find a suitable guide starcloud

02:13:52PHD2failed to find a suitable guide starcloud

02:18:38PHD2failed to find a suitable guide starcloud

02:27:26solve failedASTAP plate solve failedcloud

02:27:30PHD2failed to find a suitable guide starcloud

02:27:38solve failedASTAP plate solve failedcloud

02:30:15PHD2timed-out waiting for guider to settlecloud

02:35:18solve failedASTAP plate solve failedcloud

02:35:28solve failedASTAP plate solve failedcloud

02:36:11PHD2failed to find a suitable guide starcloud

02:43:01PHD2timed-out waiting for guider to settlecloud

02:48:05solve failedASTAP plate solve failedcloud

02:48:15solve failedASTAP plate solve failedcloud

02:49:05PHD2failed to find a suitable guide starcloud

02:58:25PHD2timed-out waiting for guider to settlecloud

03:03:29solve failedASTAP plate solve failedcloud

03:03:40solve failedASTAP plate solve failedcloud

03:03:47PHD2failed to find a suitable guide starcloud

03:04:15PHD2failed to find a suitable guide starcloud

03:04:53PHD2failed to find a suitable guide starcloud

03:10:16solve failedASTAP plate solve failedcloud

03:10:23PHD2failed to find a suitable guide starcloud

03:10:28solve failedASTAP plate solve failedcloud

03:13:38PHD2timed-out waiting for guider to settlecloud

03:18:42solve failedASTAP plate solve failedcloud

03:18:52solve failedASTAP plate solve failedcloud

03:20:56PHD2timed-out waiting for guider to settlecloud

03:21:19PHD2failed to find a suitable guide starcloud

03:22:08PHD2failed to find a suitable guide starcloud

03:28:00PHD2failed to find a suitable guide starcloud

03:36:53solve failedASTAP plate solve failedcloud

03:36:58PHD2failed to find a suitable guide starcloud

03:37:04solve failedASTAP plate solve failedcloud

03:37:59PHD2failed to find a suitable guide starcloud

03:45:02PHD2timed-out waiting for guider to settlecloud

03:53:05solve failedASTAP plate solve failedcloud

03:53:16solve failedASTAP plate solve failedcloud

03:53:46PHD2failed to find a suitable guide starcloud

03:59:21PHD2failed to find a suitable guide starcloud

04:06:57PHD2timed-out waiting for guider to settlecloud

04:12:01solve failedASTAP plate solve failedcloud

04:12:12solve failedASTAP plate solve failedcloud

04:14:48PHD2timed-out waiting for guider to settlecloud

04:19:19PHD2timed-out waiting for guider to settlecloud

04:27:52AF failedautofocus run started 04:24:47 did not completecloud

04:28:42solve failedASTAP plate solve failedcloud

04:30:48solve failedASTAP plate solve failedcloud

04:32:54solve failedASTAP plate solve failedcloud

04:33:46PHD2failed to find a suitable guide starpost_slew

04:40:49PHD2timed-out waiting for guider to settlecloud

04:42:51PHD2failed to find a suitable guide starcloud

04:47:09PHD2failed to find a suitable guide starcloud

04:52:00PHD2failed to find a suitable guide starcloud

04:58:35PHD2failed to find a suitable guide starcloud

05:00:20PHD2failed to find a suitable guide starcloud

05:05:50PHD2failed to find a suitable guide starcloud

All 118 frames

Time	Class	Target	Filter	Exp	Stars	HFR	Index
20:47:25	centering	NGC 7293	L	5s	0	0.00	—
20:47:43	centering	NGC 7293	L	5s	4	1.99	—
20:47:58	centering	NGC 7293	L	5s	4	2.47	—
20:48:13	centering	NGC 7293	L	5s	3	2.97	—
20:48:28	centering	NGC 7293	L	5s	4	3.92	—
20:48:43	centering	NGC 7293	L	5s	3	5.36	—
20:49:03	centering	NGC 7293	L	5s	44	2.11	—
20:49:23	centering	NGC 7293	L	5s	25	2.62	—
20:49:38	centering	NGC 7293	L	5s	22	3.29	—
20:49:53	centering	NGC 7293	L	5s	13	4.06	—
20:50:13	centering	NGC 7293	L	5s	7	1.90	—
21:08:58	light	NGC 7293	S	300s	9	11.56	4%
21:22:39	light	NGC 7293	S	300s	4	9.76	2%
21:29:47	light	NGC 7293	S	300s	37	8.84	16%
21:35:24	light	NGC 7293	S	300s	46	7.73	20%
21:43:26	light	NGC 7293	S	300s	57	6.74	25%
21:48:56	light	NGC 7293	S	300s	58	6.20	25%
21:54:25	light	NGC 7293	S	300s	71	5.71	31%
21:56:18	autofocus	NGC 7293	L	5s	113	2.00	—
21:56:33	autofocus	NGC 7293	L	5s	48	4.00	—
21:56:48	autofocus	NGC 7293	L	5s	86	2.28	—
21:57:03	autofocus	NGC 7293	L	5s	140	1.55	—
21:57:18	autofocus	NGC 7293	L	5s	125	1.56	—
21:57:38	autofocus	NGC 7293	L	5s	117	1.95	—
21:57:58	autofocus	NGC 7293	L	5s	67	3.17	—
21:58:18	autofocus	NGC 7293	L	5s	50	3.99	—
21:58:38	autofocus	NGC 7293	L	5s	30	5.25	—
21:58:58	autofocus	NGC 7293	L	5s	30	5.70	—
21:59:13	autofocus	NGC 7293	L	5s	30	6.40	—
21:59:33	autofocus	NGC 7293	L	5s	123	1.81	—
22:06:34	light	NGC 7293	S	300s	190	2.52	82%
22:12:25	light	NGC 7293	S	300s	202	2.33	87%
22:17:57	light	NGC 7293	S	300s	199	2.27	86%
22:23:26	light	NGC 7293	S	300s	171	2.70	74%
22:24:43	autofocus	NGC 7293	L	5s	120	1.63	—
22:24:58	autofocus	NGC 7293	L	5s	26	5.36	—
22:25:13	autofocus	NGC 7293	L	5s	42	4.27	—
22:25:28	autofocus	NGC 7293	L	5s	54	3.27	—
22:25:43	autofocus	NGC 7293	L	5s	86	2.26	—
22:26:03	autofocus	NGC 7293	L	5s	121	1.66	—
22:26:23	autofocus	NGC 7293	L	5s	109	1.92	—
22:26:43	autofocus	NGC 7293	L	5s	93	2.29	—
22:26:58	autofocus	NGC 7293	L	5s	49	3.56	—
22:27:13	autofocus	NGC 7293	L	5s	36	4.59	—
22:27:33	autofocus	NGC 7293	L	5s	119	1.73	—
22:33:24	light	NGC 7293	S	300s	183	2.45	79%
22:38:56	light	NGC 7293	S	300s	210	2.16	91%
22:44:31	light	NGC 7293	S	300s	213	2.17	92%
22:49:59	light	NGC 7293	S	300s	212	2.11	92%
22:55:52	light	NGC 7293	S	300s	199	2.24	86%
23:01:47	light	NGC 7293	O	300s	191	2.18	104%
23:07:20	light	NGC 7293	O	300s	200	2.00	109%
23:12:50	light	NGC 7293	O	300s	186	2.18	102%
23:18:20	light	NGC 7293	O	300s	180	2.19	98%
23:19:13	autofocus	NGC 7293	L	5s	109	1.38	—
23:19:28	autofocus	NGC 7293	L	5s	23	5.73	—
23:19:43	autofocus	NGC 7293	L	5s	35	4.61	—
23:19:58	autofocus	NGC 7293	L	5s	50	3.09	—
23:20:13	autofocus	NGC 7293	L	5s	69	2.16	—
23:20:33	autofocus	NGC 7293	L	5s	107	1.40	—
23:20:53	autofocus	NGC 7293	L	5s	105	1.48	—
23:21:13	autofocus	NGC 7293	L	5s	79	2.15	—
23:21:33	autofocus	NGC 7293	L	5s	47	3.14	—
23:21:48	autofocus	NGC 7293	L	5s	27	4.29	—
23:22:08	autofocus	NGC 7293	L	5s	104	1.40	—
23:27:58	light	NGC 7293	O	300s	171	2.11	93%
23:33:27	light	NGC 7293	O	300s	133	2.37	73%
23:39:03	light	NGC 7293	O	300s	154	2.33	84%
23:39:58	autofocus	NGC 7293	L	5s	88	1.44	—
23:40:13	autofocus	NGC 7293	L	5s	21	5.48	—
23:40:28	autofocus	NGC 7293	L	5s	31	4.31	—
23:40:43	autofocus	NGC 7293	L	5s	51	3.06	—
23:40:58	autofocus	NGC 7293	L	5s	64	2.19	—
23:41:18	autofocus	NGC 7293	L	5s	95	1.34	—
23:41:38	autofocus	NGC 7293	L	5s	95	1.42	—
23:41:58	autofocus	NGC 7293	L	5s	65	2.31	—
23:42:18	autofocus	NGC 7293	L	5s	35	3.16	—
23:42:33	autofocus	NGC 7293	L	5s	24	4.27	—
23:42:53	autofocus	NGC 7293	L	5s	82	1.33	—
23:48:43	light	NGC 7293	O	300s	142	2.11	78%
23:54:16	light	NGC 7293	O	300s	76	2.12	42%
23:59:45	light	NGC 7293	O	300s	23	2.08	13%
00:06:32	light	NGC 7293	O	300s	1	0.00	1%
00:22:24	light	NGC 7293	O	300s	0	0.00	0%
00:29:07	light	NGC 7293	O	300s	0	0.00	0%
00:47:19	light	NGC 7293	O	300s	0	0.00	0%
00:56:54	light	NGC 7293	O	300s	0	0.00	0%
01:12:57	light	NGC 7293	O	300s	0	0.00	0%
01:30:28	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:30:43	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:30:58	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:31:13	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:31:28	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:31:58	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:32:18	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:32:38	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:32:53	centering	IC 434 Panel 3	L	5s	0	0.00	—
01:59:26	light	IC 434 Panel 3	H	300s	0	0.00	0%
02:07:03	light	IC 434 Panel 3	H	300s	0	0.00	0%
02:27:25	light	IC 434 Panel 3	H	300s	0	0.00	0%
02:35:17	light	IC 434 Panel 3	H	300s	0	0.00	0%
02:48:04	light	IC 434 Panel 3	O	300s	0	0.00	0%
03:03:28	light	IC 434 Panel 3	O	300s	0	0.00	0%
03:10:15	light	IC 434 Panel 3	O	300s	0	0.00	0%
03:18:41	light	IC 434 Panel 3	O	300s	0	0.00	0%
03:36:51	light	IC 434 Panel 3	S	300s	0	0.00	0%
03:53:04	light	IC 434 Panel 3	S	300s	0	0.00	0%
04:11:59	light	IC 434 Panel 3	S	300s	0	0.00	0%
04:24:22	light	IC 434 Panel 3	S	300s	0	0.00	0%
04:25:03	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:25:18	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:25:33	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:25:48	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:26:03	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:26:28	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:26:48	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:27:08	centering	IC 434 Panel 1	L	5s	0	0.00	—
04:27:28	centering	IC 434 Panel 1	L	5s	0	0.00	—

Star counts come from Hocus Focus detection on each saved sub, tagged with the filter in place at exposure start and the target then being imaged. Frames inside completed autofocus runs are excluded. Still capture times come from the AllSky filenames. All times are local.