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Coping With Very High Meteor Activity

Contents

 

Introduction

Very high meteor activity is an exciting thing to be privileged to witness, and is extremely rare. The most vital thing, should you be fortunate, is not to panic! Recording what happens as accurately as possible is an important aspect of the event for many people, but never forget to take time out to enjoy the spectacle too.

Visual Observing

Normal visual meteor watch details should be recorded, as outlined in the Section's booklet Observing Meteors, for as long as possible. As activity increases, this will become impossible; you must decide for yourself when that point is reached. After that, the most important features to record are the magnitudes of the individual storm meteors only. Try to ensure that you note the time at least every five to ten minutes, so your counts can be correlated, and an approximate rate worked out later. Timings for individual meteors, except particularly brilliant fireballs, are not necessary. There may come a point when recording all the meteor magnitudes you see is no longer feasible either. In this case, only maintain details on the brighter events - magnitude +4 or +3 and brighter - reducing the magnitude level further if necessary, even to magnitude 0. As activity decreases, you can then reverse this procedure.

Alternatively, you can reduce the area of sky you are counting meteors in. Pick a well-known, and easily recognisable constellation of reasonable size, such as The Plough, the Square of Pegasus, or Orion, for instance. Any meteor that crosses through your chosen asterism should be counted, and the magnitude recorded.

The reliable paper-and-pencil approach is just as suitable for coping with very high meteor activity as normal rates, particularly if you can write legibly without having to look at what you are doing. However, a voice-recorder, either tape or digital, that can be carried and used safely and easily outdoors while meteor observing, is very helpful for reporting such details instead. Make sure the device has fresh batteries, and that you have spare batteries with you before setting-out to observe. Remember to check before and during the high activity that it is working properly, so as not to lose your unique verbal record!

Imaging Observing

A better variant than visual recording, is to have a camera available. Suitable equipment and techniques for meteor imaging are discussed in Observing Meteors, and in more detail on the Imaging Meteors – Advanced Notes webpage. Once you reach the point where you must reduce to counting only magnitude +4 or +3 meteors visually, providing the sky limiting magnitude is at least +5.0, stop visual observations, and continue to observe just with your camera. Make this change when you need to count only magnitude +1 or 0 meteors if the limiting magnitude is worse than +5.0. Aim the camera opposite the shower radiant in the sky (unless this will mean a bright light source like the Moon will be in the frame), at around 60°-80° elevation above the horizon. The higher the radiant, the lower the camera field centre should be. Ensure the horizon or other obstructions do not block any part of the field. A shot or two directly at the radiant would also be interesting for your photo album, again assuming the Moon is not too near.

Apart from normal considerations, the imaging exposure durations should be varied depending on how high the meteor activity is, so as not to swamp the image with many meteor trails. If activity is not too high, normal exposure lengths should be fine, but reduced exposure times may be necessary if an extraordinary storm happens, particularly if there are numerous bright meteors in it (the kind you would ordinarily expect to record easily using your system). If possible, ensure you have fresh batteries in your camera shortly before any meteor storm peak is expected, and always ensure you have plenty of spare batteries on-hand, as well as spare memory capacity in your camera! If using a film camera, try to avoid changing the film in mid-storm if at all possible. This may necessitate some rapid mental arithmetic to maximise your options, of course!

Even if you do not have a dedicated CCD video-meteor system, a video camera can be useful in recording very high meteor rates, including a normal colour camcorder, although they are not especially sensitive for night-sky work. For non-specialized video systems, use the widest possible aperture, manually focus the lens at infinity (autofocus mechanisms frequently will not operate when aimed at the dark sky), and set the time display to its finest possible increment. If you have no timer, deliberately cover the field several times at specific instants (and note the exact times of these), or add an accurate verbal time-base using the video's microphone. Use the highest-quality settings for your recordings (and best-quality recording media). Aim the field as for a still camera, but ensure at least three recognisable stars can be seen.

All cameras used for meteor work, whether still-imaging or video, must be mounted on a tripod, either firmly fixed, or if a clock-driven mount is available (such as for a telescope), on that.

Records should be kept of the timing for every exposure's start and end, to at least the nearest second, and provided in your report to the Meteor Section, as well as all the usual camera and exposure notes. Details on every meteor recorded (time, direction and estimated magnitude) should be submitted after you have reviewed images or recordings for those systems not using automated meteor-recognition software. Also give all other normal watch details as appropriate (such as your name and site location).

However you observe, and whether you are fortunate in seeing exceptionally high meteor activity or not, good luck, and clear skies!

By Alastair McBeath