Other Questions

My camera caught a meteor but it isn't in the Matches

Only about 20% of detections match with another station, so don't be too surprised if you find an event that isn't in the matches report. There are lots of reasons for this.

Genuine single-station detection

The commonest by far is that the event really was seen by only one camera. Variations in local weather, cloud and sky conditions are the commonet reason but local obstructions to the field of view or temporary glitches such as car headlights shining into a camera, or a bird perching on it (seriously!) can also mean that what one camera sees, another misses.

Different meteors

Another reason why events might not match is that they might be different meteors at the same time. This is more common than you might think and we often see a single 10s clip containing two or even three meteors, especially during showers. Plus of course with 100+ cameras in the UK, its inevitable that we will have two unrelated meteors seen from say Cornwall and Glasgow at the same time.

Calibration Problems

Another possibility is that RMS wasn't able to recalibrate the detection. Every morning, RMS reviews and recalibrates the astrometry and photometry of each individual detection from the previous night. If the recalibration fails - normally because not enough stars were visible - then that detection will be marked uncalibrated and excluded from the solver.
There's more information about calibration and what to look for here

Timing or other Discrepancies

Even if an image is calibrated and visually matches other images, it still might not be possible to correlate it all. Sometimes, images are rejected because they would introduce too large an error in the result, or would prevent a solution being found altogether. Indeed, the data might not be solvable as some data issue excludes too many cameras. For more information on this see here

Whats going on here is that after grouping detections with similar timestamps the solver reviews all possible combinations to find the best solution that matches all the cameras, within a decent margin of error. Sometimes, due to the viewing angle, local obstructions, cloud passing through the image, distance, elevation etc, the data from a camera can't be made to fit with the others without creating too large an uncertainty in the result.

In such a case, the troublesome camera is excluded from the solution. This typically happens with distant detections which tend to be picked up close to the horizon where there is more distortion due to the atmosphere, but it can also happen with nearby events because they're brighter and often saturate the sensor so that the estimation of trajectory has larger error bars, or because the detection was right on the edge of the field of view, and either distorted or partly lost offscreen, or the viewing angle makes it hard to determine trajectory accurately.

And bear in mind when considering these possibilities, that it need not be your detection that was the problem. You might have had a great view, but if the other cameras only caught a glimpse, or were under cloudy skies, then no match will be made.

Nothing has gone wrong here, its working as it should. The system is designed to capture as much data as possible, then exclude the data that generates low quality, high uncertainty results. But we have kept ALL the data - and so if later on we recieve a new dataset, or a better way of matching, we can rerun the whole thing.

Interpreting the Uncalibrated Report

The uncalibrated report on the Archive website helps camera operators identify and fix issues with their camera.

Each morning, RMS reviews every potential detection to calculate its brightness and location. To do this, it must calibrate the visible stars against the theoretical star map. If this process fails, then RMS can't calculate the meteor's apparent trajectory or brightness, and its marked "not recalibrated". The calibration status is included in the data uploaded to our website.

Two sorts of issue are shown in the report, lets take them in turn:

Skipping, not recalibrated

This message tells you that an individual detection could not be recalibrated by RMS.

Its completely normal to see this message for some detections each night - possibly even most detections. RMS requires at least 20 stars for this process, and so if the sky was part cloudy, or moonlit, or it was near dawn or dusk, there might not be enough stars. However, if you know the sky was clear, you should do a few checks as noted below.

Skipping due to missing data files

This message tells you that RMS didn't calibrate any data at all.

Again, this is absolutely normal if it was a cloudy night so its not a 'hard fail'. However, again if you know the sky was clear, you should do a few checks.

What to Check

The all-night timelapse is really useful here. Firstly you can see if there were any clear patches or meteors that should have been detected but were missed. Secondly, focus issues should be apparent. Focus does not need to be perfect but if its too far off the faint stars will be invisible.

If there were clear patches and meteors, and focus looks good, then you need to check the platepar. Start by looking at the jpg that ends in calib_report_astrometry.jpg.

Normally, on a clear night this will show red stars with yellow circles over them indicating the fitted stars. Each yellow circle will have a short stick on it, indicating the size and direction of any error in the fit. Some sticks may be too short to see, indicating a really good fit. An example of this report is shown below.

If its a clear night, and this report says "NO MATCHED STARS" in big letters, the platepar must be refitted. Probably the camera has been knocked and has moved too far for RMS to automatically correct. A common cause is birds sitting on the camera....

If the sticks show a distinct pattern - all pointing in one direction or forming a 'swirl' or anything like that, then the camera is moving on its mount and must be secured. The platepar may then also need to be refitted, but usually RMS will automatically recover.

If you need to redo the platepar, there's a separate wiki entry on that.

/images/calib_report.jpg