Sky transparency — night of 3–4 September 2026

Cloud arrived at 21:20 — detected by the all-sky camera, independent of N.I.N.A. Before it the sky ran at index 100 (IQR 87–101); after it 72 (IQR 49–104). 20 of 97 light frames landed before the cloud. 18 of 18 failures are attributed to cloud. Guiding ran at 0.73″ RMS before the cloud and 1.36″ after; the worst minute was 10.83″ at 05:34. Morning sky flats: 60 frames (H 20, O 20, S 20), 06:36–06:42, auto-exposure 2.9–6.0 s.

Index before 21:20
100 · IQR 87–101
Index after 21:20
72 · IQR 49–104
Cloud onset (all-sky)
21:20 · independent
Errors after onset
18 of 18 · solve + PHD2
Guide RMS
1.19″ · RA 0.87 · Dec 0.82

Normalised transparency index, by filter

100 = that target and filter's own clear‑sky median (this night's own pre-cloud median). 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
05010015020019:0020:0021:0022:0023:0000:0001:0002:0003:0004:0005:0006:00% of clear-sky medianclear-sky baselineIC 4628→ NGC 2070HSO

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.

030609012019:0020:0021:0022:0023:0000:0001:0002:0003:0004:0005:0006:00Mean sky luminance (0–255)all-sky

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. 3508 guide frames over 9.8 h of guiding in 21 sessions; the gaps are slews, dither settles and autofocus runs, when PHD2 was not guiding. PHD2 discarded 2262 further frames — usually a lost star. The worst minute (10.83″ at 05:34) is clamped at the top of the plot.

RA RMS Dec RMS ◆ PHD2 error
0.00.30.60.91.219:0020:0021:0022:0023:0000:0001:0002:0003:0004:0005:0006:00RMS guide error (arcsec)night RMS 1.19″DecRA

All‑sky frames at the key moments

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

All-sky at 18:59
18:59 · start of night
All-sky at 21:20
21:20 · cloud onset
All-sky at 22:19
22:19 · peak brightness 111.1
All-sky at 06:11
06:11 · end of night

Clear‑sky reference medians

The divisors behind the index — median detected stars per light sub before 21:20.

TargetFilterMedian starsFramesSource
IC 4628H3578tonight, clear frames
IC 4628O8688tonight, clear frames
IC 4628S12284tonight, clear frames
NGC 2070H31035earlier clear nights
NGC 2070O22836earlier clear nights
NGC 2070S87930earlier clear nights

Event timeline

All observatory events with their attributed causes.

PHD2timed-out waiting for guider to settlecloud
PHD2timed-out waiting for guider to settlecloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
solve failedASTAP plate solve failedcloud
PHD2timed-out waiting for guider to settlecloud
PHD2timed-out waiting for guider to settlecloud
PHD2timed-out waiting for guider to settlecloud
PHD2timed-out waiting for guider to settlecloud
PHD2failed to find a suitable guide starcloud
PHD2timed-out waiting for guider to settlecloud
All 300 frames (excludes the 60 sky flats — no stars to detect)
TimeClassTargetFilterExpStarsHFRIndex
18:59:12autofocusIC 4628L5s4174.52—
18:59:30autofocusIC 4628L5s8292.03—
18:59:50autofocusIC 4628L5s8861.99—
19:00:05autofocusIC 4628L5s7232.49—
19:00:20autofocusIC 4628L5s5173.55—
19:00:40autofocusIC 4628L5s3874.62—
19:01:00autofocusIC 4628L5s2745.58—
19:01:20autofocusIC 4628L5s4763.08—
19:01:40autofocusIC 4628L5s3354.06—
19:01:55autofocusIC 4628L5s2664.96—
19:02:15autofocusIC 4628L5s7972.14—
19:09:09lightIC 4628H300s3803.26106%
19:14:57lightIC 4628H300s3693.31103%
19:15:30autofocusIC 4628L5s7772.03—
19:15:50autofocusIC 4628L5s2635.67—
19:16:05autofocusIC 4628L5s3253.99—
19:16:20autofocusIC 4628L5s4033.16—
19:16:35autofocusIC 4628L5s6352.37—
19:16:55autofocusIC 4628L5s8851.84—
19:17:15autofocusIC 4628L5s8142.03—
19:17:35autofocusIC 4628L5s6502.71—
19:17:50autofocusIC 4628L5s5043.53—
19:18:05autofocusIC 4628L5s3964.46—
19:18:25autofocusIC 4628L5s8091.97—
19:24:19lightIC 4628H300s3593.37101%
19:29:41lightIC 4628H300s3553.4699%
19:30:50autofocusIC 4628L5s8371.91—
19:31:10autofocusIC 4628L5s2425.59—
19:31:25autofocusIC 4628L5s3494.32—
19:31:40autofocusIC 4628L5s4173.39—
19:31:55autofocusIC 4628L5s5912.49—
19:32:15autofocusIC 4628L5s8141.93—
19:32:35autofocusIC 4628L5s8072.04—
19:32:55autofocusIC 4628L5s5882.91—
19:33:10autofocusIC 4628L5s4573.79—
19:33:25autofocusIC 4628L5s3224.74—
19:33:45autofocusIC 4628L5s8581.88—
19:39:34lightIC 4628O300s8693.60100%
19:44:55lightIC 4628O300s9403.39108%
19:50:12lightIC 4628O300s8803.55101%
19:55:28lightIC 4628O300s8683.53100%
19:56:10autofocusIC 4628L5s7492.08—
19:56:30autofocusIC 4628L5s2685.64—
19:56:45autofocusIC 4628L5s3614.19—
19:57:00autofocusIC 4628L5s4203.37—
19:57:15autofocusIC 4628L5s6232.39—
19:57:35autofocusIC 4628L5s8531.84—
19:57:55autofocusIC 4628L5s8022.04—
19:58:15autofocusIC 4628L5s6272.70—
19:58:30autofocusIC 4628L5s4303.93—
19:58:45autofocusIC 4628L5s3364.72—
19:59:05autofocusIC 4628L5s8721.81—
20:04:56lightIC 4628S300s12283.08100%
20:10:15lightIC 4628S300s12063.1398%
20:15:32lightIC 4628S300s12623.03103%
20:16:05autofocusIC 4628L5s8521.82—
20:16:25autofocusIC 4628L5s2855.31—
20:16:40autofocusIC 4628L5s3434.20—
20:16:55autofocusIC 4628L5s4153.17—
20:17:10autofocusIC 4628L5s7032.06—
20:17:30autofocusIC 4628L5s8751.73—
20:17:50autofocusIC 4628L5s7662.04—
20:18:10autofocusIC 4628L5s6312.63—
20:18:30autofocusIC 4628L5s4753.52—
20:18:50autofocusIC 4628L5s3214.59—
20:19:10autofocusIC 4628L5s8681.74—
20:25:02lightIC 4628S300s9993.4881%
20:30:12lightIC 4628H300s3573.43100%
20:35:35lightIC 4628H300s3083.6686%
20:36:50autofocusIC 4628L5s7042.06—
20:37:10autofocusIC 4628L5s2125.86—
20:37:25autofocusIC 4628L5s3194.37—
20:37:40autofocusIC 4628L5s3983.34—
20:38:00autofocusIC 4628L5s5082.63—
20:38:20autofocusIC 4628L5s6772.12—
20:38:40autofocusIC 4628L5s6872.19—
20:39:00autofocusIC 4628L5s5392.75—
20:39:20autofocusIC 4628L5s4363.55—
20:39:35autofocusIC 4628L5s3364.34—
20:39:55autofocusIC 4628L5s5862.35—
20:45:46lightIC 4628H300s2653.9874%
20:51:31lightIC 4628H300s2953.7483%
20:57:07lightIC 4628O300s6573.9476%
20:57:40autofocusIC 4628L5s6252.17—
20:57:54autofocusIC 4628L5s2315.51—
20:58:09autofocusIC 4628L5s3004.38—
20:58:24autofocusIC 4628L5s3933.45—
20:58:39autofocusIC 4628L5s4952.60—
20:58:59autofocusIC 4628L5s6312.14—
20:59:19autofocusIC 4628L5s6362.20—
20:59:39autofocusIC 4628L5s5302.84—
20:59:59autofocusIC 4628L5s4263.72—
21:00:14autofocusIC 4628L5s3644.47—
21:00:34autofocusIC 4628L5s6672.03—
21:06:22lightIC 4628O300s7823.6190%
21:11:41lightIC 4628O300s8203.5194%
21:16:57lightIC 4628O300s8653.28100%
21:22:26lightIC 4628S300s6843.5156%
21:27:27lightIC 4628S300s5423.5444%
21:32:28lightIC 4628S300s7803.5764%
21:38:02lightIC 4628S300s5563.7745%
21:43:17lightIC 4628H300s3163.5789%
21:43:50autofocusIC 4628L5s5552.13—
21:44:04autofocusIC 4628L5s2045.81—
21:44:19autofocusIC 4628L5s2434.46—
21:44:34autofocusIC 4628L5s3513.20—
21:44:49autofocusIC 4628L5s1602.32—
21:45:09autofocusIC 4628L5s2942.03—
21:45:29autofocusIC 4628L5s2032.08—
21:45:49autofocusIC 4628L5s5042.67—
21:46:10autofocusIC 4628L5s4053.67—
21:46:24autofocusIC 4628L5s2704.29—
21:46:44autofocusIC 4628L5s2402.02—
21:52:37lightIC 4628H300s3483.4097%
21:58:01lightIC 4628H300s3033.3285%
22:04:07lightIC 4628H300s3393.3795%
22:09:21lightIC 4628O300s5023.5958%
22:15:24lightIC 4628O300s3293.7138%
22:20:25lightIC 4628O300s643.447%
22:25:26lightIC 4628O300s00.000%
22:31:40lightIC 4628S300s874.177%
22:36:41lightIC 4628S300s804.977%
22:41:42lightIC 4628S300s187.091%
22:46:43lightIC 4628S300s10.000%
23:03:11lightIC 4628H300s1764.8649%
23:08:12autofocusIC 4628H300s1834.84—
23:08:30autofocusIC 4628L5s4242.44—
23:08:50autofocusIC 4628L5s876.86—
23:09:05autofocusIC 4628L5s1725.40—
23:09:20autofocusIC 4628L5s2324.23—
23:09:35autofocusIC 4628L5s3063.21—
23:09:55autofocusIC 4628L5s4462.34—
23:10:15autofocusIC 4628L5s2331.96—
23:10:35autofocusIC 4628L5s2052.15—
23:10:55autofocusIC 4628L5s2152.80—
23:11:10autofocusIC 4628L5s2393.48—
23:11:25autofocusIC 4628L5s554.73—
23:11:45autofocusIC 4628L5s371.92—
23:17:36lightIC 4628H300s2613.6073%
23:22:37lightIC 4628H300s1363.8038%
23:27:51lightIC 4628O300s4213.9749%
23:33:40lightIC 4628O300s4753.7455%
23:38:56lightIC 4628O300s4763.7055%
23:44:16lightIC 4628O300s3963.7946%
23:44:55autofocusIC 4628L5s1532.01—
23:45:15autofocusIC 4628L5s455.85—
23:45:30autofocusIC 4628L5s584.56—
23:45:45autofocusIC 4628L5s643.22—
23:46:05autofocusIC 4628L5s1102.61—
23:46:25autofocusIC 4628L5s2062.11—
23:46:45autofocusIC 4628L5s4272.12—
23:47:05autofocusIC 4628L5s3212.88—
23:47:25autofocusIC 4628L5s2753.59—
23:47:40autofocusIC 4628L5s1914.44—
23:48:00autofocusIC 4628L5s4401.95—
00:07:40autofocusNGC 2070L5s3202.21—
00:08:00autofocusNGC 2070L5s1094.58—
00:08:15autofocusNGC 2070L5s1723.33—
00:08:30autofocusNGC 2070L5s2612.41—
00:08:45autofocusNGC 2070L5s3482.06—
00:09:05autofocusNGC 2070L5s3222.17—
00:09:25autofocusNGC 2070L5s2712.51—
00:09:45autofocusNGC 2070L5s1823.51—
00:10:05autofocusNGC 2070L5s1024.52—
00:10:25autofocusNGC 2070L5s805.77—
00:10:45autofocusNGC 2070L5s3541.98—
00:17:57lightNGC 2070H300s1904.1561%
00:23:20lightNGC 2070H300s2233.9672%
00:28:49lightNGC 2070H300s2993.6096%
00:34:08lightNGC 2070H300s3303.47106%
00:39:21autofocusNGC 2070O300s1714.59—
00:39:40autofocusNGC 2070L5s4341.85—
00:40:00autofocusNGC 2070L5s925.66—
00:40:20autofocusNGC 2070L5s1444.31—
00:40:35autofocusNGC 2070L5s1963.34—
00:40:50autofocusNGC 2070L5s3022.36—
00:41:10autofocusNGC 2070L5s4071.87—
00:41:30autofocusNGC 2070L5s4271.94—
00:41:50autofocusNGC 2070L5s2952.62—
00:42:10autofocusNGC 2070L5s2053.53—
00:42:25autofocusNGC 2070L5s1524.43—
00:42:45autofocusNGC 2070L5s4371.77—
00:48:33lightNGC 2070O300s3833.21168%
00:54:18lightNGC 2070O300s2543.46111%
00:59:19lightNGC 2070O300s2883.58126%
01:05:07lightNGC 2070S300s6273.3471%
01:10:33lightNGC 2070S300s6603.2375%
01:16:03lightNGC 2070S300s6983.1479%
01:16:40autofocusNGC 2070L5s4821.78—
01:17:00autofocusNGC 2070L5s1075.59—
01:17:15autofocusNGC 2070L5s1534.15—
01:17:30autofocusNGC 2070L5s2452.86—
01:17:45autofocusNGC 2070L5s3642.14—
01:18:05autofocusNGC 2070L5s4541.85—
01:18:25autofocusNGC 2070L5s4072.04—
01:18:45autofocusNGC 2070L5s2792.76—
01:19:00autofocusNGC 2070L5s2203.61—
01:19:20autofocusNGC 2070L5s1534.63—
01:19:40autofocusNGC 2070L5s4441.80—
01:25:28lightNGC 2070S300s6733.1977%
01:30:58lightNGC 2070H300s3643.38117%
01:36:23lightNGC 2070H300s3243.58105%
01:41:40lightNGC 2070H300s3823.26123%
01:46:57lightNGC 2070H300s3993.23129%
01:47:25autofocusNGC 2070L5s4701.97—
01:47:40autofocusNGC 2070L5s1065.92—
01:47:55autofocusNGC 2070L5s1544.52—
01:48:10autofocusNGC 2070L5s2063.49—
01:48:30autofocusNGC 2070L5s3562.35—
01:48:50autofocusNGC 2070L5s4491.93—
01:49:10autofocusNGC 2070L5s4641.91—
01:49:30autofocusNGC 2070L5s3342.49—
01:49:50autofocusNGC 2070L5s2383.47—
01:50:05autofocusNGC 2070L5s1814.40—
01:50:20autofocusNGC 2070L5s1345.30—
01:50:40autofocusNGC 2070L5s4801.85—
01:56:27lightNGC 2070O300s3523.39154%
02:01:44lightNGC 2070O300s3903.34171%
02:07:07lightNGC 2070O300s3803.42167%
02:12:23lightNGC 2070O300s3133.35137%
02:17:36lightNGC 2070S300s2933.3533%
02:23:39lightNGC 2070S300s4443.4351%
02:28:58lightNGC 2070S300s5553.4763%
02:34:23lightNGC 2070S300s6483.3174%
02:39:36lightNGC 2070H300s4033.16130%
02:44:52lightNGC 2070H300s3623.37117%
02:50:11lightNGC 2070H300s3683.36119%
02:50:45autofocusNGC 2070L5s4661.90—
02:51:05autofocusNGC 2070L5s996.00—
02:51:20autofocusNGC 2070L5s1444.55—
02:51:35autofocusNGC 2070L5s2173.44—
02:51:50autofocusNGC 2070L5s2952.70—
02:52:10autofocusNGC 2070L5s5231.83—
02:52:30autofocusNGC 2070L5s4791.97—
02:52:50autofocusNGC 2070L5s3302.65—
02:53:10autofocusNGC 2070L5s2253.53—
02:53:25autofocusNGC 2070L5s1864.57—
02:53:45autofocusNGC 2070L5s5161.82—
02:59:38lightNGC 2070H300s3213.55104%
03:04:52lightNGC 2070O300s2094.1192%
03:09:53lightNGC 2070O300s1524.4167%
03:14:54lightNGC 2070O300s1704.2875%
03:19:55lightNGC 2070O300s1624.3671%
03:25:06lightNGC 2070S300s4164.2047%
03:30:08lightNGC 2070S300s5913.5867%
03:35:09lightNGC 2070S300s4953.9156%
03:41:48lightNGC 2070S300s6433.3073%
03:42:45autofocusNGC 2070L5s4741.84—
03:43:05autofocusNGC 2070L5s1205.39—
03:43:20autofocusNGC 2070L5s1454.41—
03:43:35autofocusNGC 2070L5s2023.20—
03:43:50autofocusNGC 2070L5s3692.18—
03:44:10autofocusNGC 2070L5s5131.81—
03:44:30autofocusNGC 2070L5s4312.01—
03:44:50autofocusNGC 2070L5s2882.83—
03:45:05autofocusNGC 2070L5s2163.64—
03:45:20autofocusNGC 2070L5s1494.67—
03:45:40autofocusNGC 2070L5s4721.83—
03:51:30lightNGC 2070H300s3863.16125%
03:56:49lightNGC 2070H300s3713.22120%
04:02:06lightNGC 2070H300s3603.24116%
04:07:33lightNGC 2070H300s3823.12123%
04:12:46lightNGC 2070O300s1643.9172%
04:17:48lightNGC 2070O300s1693.8774%
04:22:49lightNGC 2070O300s1734.0576%
04:27:50lightNGC 2070O300s1824.0880%
04:33:01autofocusNGC 2070S300s4563.96—
04:33:25autofocusNGC 2070L5s4201.88—
04:33:45autofocusNGC 2070L5s1025.57—
04:34:00autofocusNGC 2070L5s1384.14—
04:34:15autofocusNGC 2070L5s2033.04—
04:34:35autofocusNGC 2070L5s3582.10—
04:34:55autofocusNGC 2070L5s4561.83—
04:35:15autofocusNGC 2070L5s4032.03—
04:35:35autofocusNGC 2070L5s2512.88—
04:35:50autofocusNGC 2070L5s1923.76—
04:36:05autofocusNGC 2070L5s1444.61—
04:36:25autofocusNGC 2070L5s4501.89—
04:42:13lightNGC 2070S300s5653.3864%
04:47:33lightNGC 2070S300s1614.1818%
04:52:34lightNGC 2070S300s3713.8042%
04:57:46lightNGC 2070H300s2853.4092%
05:03:49lightNGC 2070H300s2833.4391%
05:09:30lightNGC 2070H300s1893.8961%
05:14:31lightNGC 2070H300s1764.1357%
05:19:42lightNGC 2070O300s785.1734%
05:24:43lightNGC 2070O300s1193.7952%
05:29:44lightNGC 2070O300s196.608%
05:34:45lightNGC 2070O300s383.9517%
05:35:15autofocusNGC 2070L5s1671.75—
05:35:35autofocusNGC 2070L5s415.51—
05:35:55autofocusNGC 2070L5s544.22—
05:36:10autofocusNGC 2070L5s863.22—
05:36:30autofocusNGC 2070L5s1402.18—
05:36:50autofocusNGC 2070L5s1861.76—
05:37:10autofocusNGC 2070L5s841.95—
05:37:30autofocusNGC 2070L5s1042.66—
05:37:45autofocusNGC 2070L5s593.64—
05:38:00autofocusNGC 2070L5s604.54—
05:38:20autofocusNGC 2070L5s841.77—

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.