Common errors before and after a meteor observation with MetRec 4.1

If you observed no meteor so far, just delete the logfile and the data directory and restart the observation.
If you observed already some meteors, restart the observation immediately. At the end of the night, you edit the logfile in your data directory, which contains both observations. Delete everything from the end of the first observation starting at

19:19:00 End of recognition request
19:19:00 Saving flatfield ... ok!
19:19:00 Saving sensitivity image ... ok!
Freeing resources and finishing ... ok!

and the start of your second observation until

Initializing PosDat files '1118data.dbf' and '1118head.dbf'... ok!
Creating recognition threshold history file 'metrec.thr' ... ok!
Creating auto-subdirectory '20061118' ... ok!
19:20:19 Initialize flatfield
19:20:30 Start recognition

and add two new lines

19:19:00 Suspend recognition
19:20:30 Restart recognition

instead. You end up with a file that looks as if you did not interrupt the observation, but just suspended it. You copy the modified logfile into your data directory and post-process with the additional parameters -summary and -posdat. The first parameter will correct the observation summary and the second the PosDat files.

If you restarted the camera several times, you can repeat this procedure, i.e. you replace the begin of all following observations by the two suspend and restart lines.

Starting from MetRec v.5, the limiting magnitude is calculated each minute. That gives you precise information about the sky coverage. However, if the lm calculation fails (e.g. because of poor reference stars), you need a fallback. If you have false detections, it is usually quite easy to find out when it was clouded. But sometimes it is just foggy or the limiting magnitude goes down dramatically. All you find is that there are large gaps without any meteor. If no lm information is available, PostProc will check for gaps without meteors, and if the gap is longer as a certain threshold, PostProc will offer to add a break. You should accept the offered breaks unless you are perfectly sure that it was clear all the time.

The maximum length of gap that is still accepted varies with time. At local midnight, the default is 60 min. At 6 p.m. it is 4/3 of that value, and at 6 a.m. 2/3 of that value. You can modify the default value with the -maxbrk parameter. For highly sensitive image-intensified cameras in time with high sporadic rates, a value of 30 will be appropriate, whereas for less sensitive non-intensified cameras in times with low sporadic activity, a value of 75 may be more appropriate.

Run PostProc with the -summary parameter.

Sometimes MetRec detects two meteors at the same time. Since it cannot save images for both meteors, PostProc will report "No image available" or it will display the image of the previous meteor again. That does not mean, however, that you have to delete the meteor without image. Just check the x/y-position of the meteor

21:36:05 Meteor #20 at (0.343,0.758)->(0.385,0.688) frames=19 dur=0.74s pixel=7 dir=301° vel=5.0°/s s=2.3
shower=SPO bright=1.8mag (1.894h,47.96°) -> (1.765h,51.36°) acc=2.4'

which is roughly 0.3 / 0.7 is this case, look at the image of the other meteor, and check, whether there is indeed a second meteor at the given position (whereas 0.0 / 0.0 is the lower left, and 1.0 / 1.0 the upper right corner). If that's the case, you can keep the meteor without image. If not, delete it.

In the case, that the previous meteor was much earlier, you need to delete the meteor without image as well. In this case there was a slow moving target (like a satellite) in the background, which prevented from saving the image, but was discarted later on because of its velocity.

That happens sometimes, especially with bright meteors. Please, keep only the record that consists of more video frames, and delete the other one. I don't care if you keep a copy of the image for your own records, but the meteor should appear only once in the archive.

When you plot the line of the detected meteor position in PostProc you sometimes see, that the begin or end of the meteor was misidentified (i.e. the line deviates significantly from the true meteor position). That happens frequently with bright meteors which burn our the image completely. Please, correct the individual shutter breaks with the frame measurement function of PostProc version 5.2 or later, or delete this meteors! Even if you think it might be pity for the bright meteor, you should remember that the position you measured is simply wrong, and from a PosDat entry you do not see anymore that this was a measurement error.

Look at the meteor frame by frame by pressing "M" in PostProc. When the meteor seems to fly around the corner, or when it is moving irregularly - delete it. If you are not sure - delete it. Remember the archive size given above, and that quality comes before quantity.

Yes. But, please, do not send these flash images to me at the end of the month, because they will not be archived (e.g. with the -noflash parameter)!

Yes. But, please, do not send the MISC directory to me at the end of the month, because it will not be archived!

Yes. But, please, delete them before you send in your observation at the end of the month (e.g. with the -nosingle or -upload parameter)!

Yes. But please reduce their resolution with the redres tool or with the -upload parameter in PostProc before upload them to the central database.

Yes. Remember, that each data directory should contain the following files when you send it to me:

If you run your camera automatically, you may need to rename your generic configuration file metrec.cfg and logfile metrec.log before copying them into the data directory. Typically, PostProc will do that for your when you quit the program.

Yes, since otherwise the meteor files will not be deleted, nor the PosDat entries. To save time, however, you can delete more than one meteor at a time with PostProc by pressing "D". In addition, you can delete a number of meteors in advance with the command line options of PostProc.

No. You should create a new reference star file at the next possible occasion, and re-run PostProc with the -ref option. This will recompute the meteor position from the new reference star file. You can verify that by comparing the position given in the meteor data window at left (that's the corrected one) with the position given in the logfile window below (that's the original position). Beware the the reference star file created that night, as well as the limiting magnitude and the flux density files typically need to be deleted, because they are invalid if the stars could not be identified in the field of view.

Don't correct anything - just tell me when you send me the data. I have some little scripts that can easily correct all the incorrect values (config file, logfile, PosDat data file, meteor data files, meteor file names).; last change: July 20, 2014