Bitung, Sulawesi Utara

Period: 01 Jan 2026 — 01 Agu 2026212 days
Datum: Nol sensor stasiun (bukan MSL)
gaps: 27707 jam
Source: IOC Sea Level Station Monitoring Facility (UNESCO/IOC & VLIZ)

Source, licence and datum notes

Licence: Akses terbuka dengan kewajiban sitasi (VLIZ/IOC, DOI 10.14284/482)

Flanders Marine Institute (VLIZ); Intergovernmental Oceanographic Commission (IOC) (2026): Sea level station monitoring facility. https://www.ioc-sealevelmonitoring.org — DOI 10.14284/482

Not for navigationThe official Indonesian tide tables are published by Pushidrosal.

The limit

Resolution

Two constituents can only be separated if the record is long enough for them to drift a full cycle apart. Shorten the window and watch constituents drop out and the condition number rise.

Window length (days)

30 days

The full record is 212.0 days. The window is taken from its start.

Condition number

1.48

good

Still separable

M2 · S2 · N2 · K1 · O1 · Q1 · M4 · MS4

Not separable on this window

K2 · P1

Result

Request refused

The standard set was requested on a window of 30 days. These pairs cannot be separated:

S2 and K2 differ by only 0.0821°/h: separating them needs a record of 182.6 days, and 30.0 are available.
K1 and P1 differ by only 0.0821°/h: separating them needs a record of 182.6 days, and 30.0 are available.

Harmonic constants per constituent
Constituent	Amplitude H (m)	Phase g (°)	Lag (h)	Speed (°/h)	Period (h)	Nodal factor f	Nodal correction u (°)
M2255.555	0.3447±0.0026	276.7±0.4	9.55	28.984104	12.421	0.9652	0.68
K1165.555	0.2459±0.0023	317.1±0.5	21.08	15.041069	23.934	1.1083	2.48
S2273.555	0.2177±0.0025	336.1±0.7	11.20	30.000000	12.000	1.0000	0.00
O1145.555	0.1116±0.0022	288.7±1.1	20.71	13.943036	25.819	1.1753	-2.80
N2245.655	0.0353±0.0027	249.9±4.3	8.79	28.439730	12.658	0.9652	0.68
Q1135.655	0.0227±0.0022	277.4±5.5	20.70	13.398661	26.868	1.1753	-2.80
M4455.555	0.0124±0.0027	165.7±12.7	2.86	57.968208	6.210	0.9316	1.37
MS4473.555	0.0048±0.0026	238.7±31.8	4.05	58.984104	6.103	0.9652	0.68
K2	UnresolvedK2/S2 · 183 days
P1	UnresolvedP1/K1 · 183 days

The second axis: not how long, but how complete

The Rayleigh criterion sees only span — first sample to last. The hours in between do not enter it at all, so by that measure a record missing half its readings is exactly as good as a complete one. The table below refits this record under two kinds of loss of the same size and of identical span, and they come out nothing alike.

Condition number by shape of data loss
Shape of the loss	Removed	Samples	Span (days)	Condition number κ	Most parallel pair
The record as it stands	—	4381	212.0	1.65	K1/P1 0.26
One long outage in the middle	25%	3286	212.0	2.21	K1/P1 0.59
Scattered losses	25%	3287	212.0	1.66	S2/K2 0.27
One long outage in the middle	50%	2190	212.0	3.88	S2/K2 0.86
Scattered losses	50%	2192	212.0	1.67	K1/P1 0.27
One long outage in the middle	70%	1314	212.0	7.55	K1/P1 0.96
Scattered losses	70%	1315	211.8	1.68	S2/K2 0.26

Look at the span column: it is the same on every row. The outage is taken from the middle, so the first and last samples never move — and span is the only thing the Rayleigh criterion reads. By that measure every row above is the same record. They are not: a single long outage leaves two clusters of samples with nothing joining them, so the phase difference across the hole becomes ambiguous and close pairs collapse back together. The same hours removed at scattered times leave the record joined up and cost almost nothing. The masks are constructed by a fixed rule rather than sampled, so this table is the same on every build.

The pairs that set the record length

Two constituents can only be separated once the record is long enough for them to drift a full cycle apart: T = 360° / |σᵢ − σⱼ|. The closer two speeds are, the longer the record has to be.

Pair	Minimum length (days)
K1 / P1	183
K2 / S2	183
M2 / N2	27.6
O1 / Q1	27.6
M4 / MS4	14.8
M2 / S2	14.8

How long you have to watch