Observation 14745990
Sofia SAT Club - Hadji Boby VHFUND ROADS 1NORAD 64535FSK AX.100 Mode 5label: without-signalqueue rank 5
The black and white points open at a fixed pair, not one fitted to this image. Across the 25 committed waterfalls the noise floor runs from 0.20 to 0.38, so on most observations the ramp starts well below the first real sample and a weak pass reads flat until the black point is raised toward the floor.
Reviewer note
The observation disagrees with the NORAD catalogue, suggesting a frequency of 145.9 MHz instead of the reported 145.900 MHz. Focus on the center of the waterfall image around 145.9 MHz. A definitive observation would be the clear detection of a signal at the exact frequency of 145.900 MHz, which would resolve this discrepancy.
Check a claim about this observation
The grounding checker from the pipeline, ported to TypeScript and running here. Edit the sentence, or start from one of the drafts below, and the verdict changes as you type. Nothing is sent anywhere: the whole rule set is in the page.
328 of 700 characters
GROUNDED
Every number in this sentence is a token of the packet below, every code and label in it is this observation’s, and no permission rule fired. That is all the checker claims: the sentence is consistent with what was measured, not that the measurement is right.
The evidence packet this is checked against, exactly as the model was shown it
observation_id : 14745990 ground_station_id : 4272 ground_station_name : Sofia SAT Club - Hadji Boby VHF norad_catalogue_id : 64535 transmitter_mode : FSK AX.100 Mode 5 receiver_frequency_hz : 145900000 network_label : without-signal pass_duration_s : 439 max_elevation_deg : 88.0 closest_approach_fraction : 0.50 fitted_offset_hz : 4628 fitted_offset_ppm : 31.7 corridor_half_width_hz : 2000 sigma_curved : 0.3 sigma_vertical : 0.3 hz_per_pixel : 1157.0 seconds_per_pixel : 0.29 axis_derivation : axis_ticks_ocr axis_derivation_confidence : 0.70 model_probability : 0.650 ensemble_uncertainty : 0.0271 flat_row_fraction : 0.00 queue_rank : 5 queue_score : 0.596 queue_reason_codes : STALE_CATALOGUE_FREQ offset_at_bound : false
The closed world. A number that is not a token of this text is not grounded, which is why 6490 is refused although those digits appear inside 436490000: containment is not membership, and a transposed offset passed the old check for exactly that reason.
The pass
The same propagation that produced the corridor above, drawn from the station's point of view and from orbit. Elevation is measured from the WGS-84 geodetic normal, which is the reference the corridor was scored against.
Sky track
Azimuth clockwise from true north, elevation from the horizon at the rim to the zenith at the centre. The open circle is the rise, the square is the set, and the filled mark is closest approach at 88.0°.
Ground track
The subsatellite point, the station as a cross, and the satellite’s horizon circle at closest approach from 500 km. There is no basemap: this console ships no coastline data and will not draw one it cannot cite.
Elevation and Doppler against time
The same pass on a time axis. Two stacked panels rather than one panel with two vertical scales, because a twin-axis chart lets the author choose where two curves appear to cross. This window spans closest approach, and the Doppler zero crossing lands on the sample where elevation peaks, because both happen at the same instant.
| Quantity | Value | Where it comes from |
|---|---|---|
| Maximum elevation | 87.957° | Highest sample of the propagated pass, from the geodetic normal |
| Azimuth at closest approach | 262.59° | Clockwise from true north |
| Slant range at closest approach | 499.5 km | Station to satellite, the minimum over the pass |
| Closest approach, as a fraction of the pass | 0.4990 | 0 is the start of the recording window, 1 the end |
| Samples propagated | 512 | An error count above zero means the orbit model refused part of the window, and the track is drawn only where it did not |
The fit
The fitted curve is the predicted Doppler curve shifted by the fitted frequency offset, which is the path the matched filter scored.
The predicted curve is the same shape at zero offset, so the gap between them is the measurement.
Time runs bottom to top: the first row is the end of the pass.
The frequency axis runs against the Doppler sign.
Why it is in the queue
The composite score and the criteria it met, from the queue receipt.
| Field | Value | What it is |
|---|---|---|
| Rank | 5 | inside the review budget of 50 |
| Composite score | 0.596098 | rank-normalised blend of model disagreement, uncertainty and physics |
| Model p(signal) | 0.650000 | calibrated probability from the shipped image and corridor arm |
| Ensemble spread | 0.027128 | disagreement between seeds; a proxy for how sure the arm is |
| Flat rows | 0.0000 | fraction of the waterfall with no luminance variation |
| Episode | 4272:64535:6 | station, satellite and orbital revolution: the unit the interval is grouped on |
| Conflict | true | Stale catalogue frequency |
Precedent
The five nearest passes in the snapshot under the Granite embedding of a text card built from this pass's numbers.
Two conditions: any station, and then a condition that excludes this station and this satellite so a neighbour cannot be a near-duplicate of the query.
The measured agreement is on the precedent page, and under the second condition it does not beat chance.
| Condition | Neighbour | Station | Satellite (NORAD) | Start | Network label |
|---|---|---|---|---|---|
| Any station | 14746055 | 4272 | 41187 | 2026-08-09T23:42:07Z | with-signal |
| 14745653 | 4272 | 98272 | 2026-08-09T22:10:09Z | without-signal | |
| 14743986 | 4272 | 41183 | 2026-08-09T15:22:36Z | with-signal | |
| 14745455 | 4272 | 40086 | 2026-08-09T21:00:50Z | without-signal | |
| 14745989 | 4272 | 41188 | 2026-08-09T22:51:21Z | with-signal | |
| Other station, other satellite | 14737461 | 4460 | 69015 | 2026-08-09T20:37:32Z | with-signal |
| 14742225 | 3677 | 62713 | 2026-08-09T20:24:17Z | without-signal | |
| 14742228 | 3677 | 62713 | 2026-08-09T21:59:13Z | without-signal | |
| 14742226 | 3677 | 98671 | 2026-08-09T20:31:29Z | with-signal | |
| 14742224 | 3677 | 98526 | 2026-08-09T18:49:25Z | without-signal |
Provenance
Enough to fetch the original and check it.
| Field | Value |
|---|---|
| Source | network.satnogs.org/observations/14745990 |
| Original waterfall SHA-256 | af3db9b4c972f688911af1dd7731c2e44c70a37299f8dd461851f5bc24f90e18 |
| Window | 2026-08-09T23:03:36Z to 2026-08-09T23:10:55Z |
| Receive frequency | 145,900,000 Hz |
| Axis derivation | read off the spectrogram's own tick labels (confidence 0.70) |
| Displayed image | unweighted mean of the R, G and B channels, 8-bit |