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Observing Meteors and Variable Stars. Martin Crow Crayford Manor House Astronomical Society. Beginners Astronomy . Last time. A bit about the Solar System and other things. About observation. Types of observation – visual and imaging.

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martin crow crayford manor house astronomical society

Observing Meteors and

Variable Stars

Martin Crow Crayford Manor House Astronomical Society

Beginners Astronomy

last time
Last time

A bit about the Solar System and other things

About observation

Types of observation – visual and imaging

Martin Crow Crayford Manor House Astronomical Society

this week practical visual observing
This week: Practical visual observing

Visually observing variable stars

Meteor watch:

What are meteors

Visual observation

Imaging meteors

A look at setting up and using telescopes

Martin Crow Crayford Manor House Astronomical Society

practical observing
Practical observing

Visual observations of variable stars

Naked eye is perfectly adequate for observing variable stars brighter than mag 4.

Martin Crow Crayford Manor House Astronomical Society

practical observing1
Practical observing

The sight of ‘Shooting Stars’ is quite spectacular and ‘Fire Balls’ even more so.

Shooting stars are meteors.

The word Meteor comes from the Greek ‘meteōros’ meaning ‘high in the air’.

Meteoroid:

The current official definition of a meteoroid from the

International Astronomical Union is "a solid object moving in interplanetary

space, of a size considerably smaller than an asteroid and considerably larger

than an atom".

Meteorite:

A meteorite is a portion of a meteoroid or asteroid that survives its passage

through the atmosphere and impact with the ground without being destroyed

Martin Crow Crayford Manor House Astronomical Society

practical observing2
Practical observing

So what are meteors?

Grain sized particle entering the top of the atmosphere at high speed. Most

Observed meteors are in the magnitude range of 1 to 4.

They can also be larger objects also entering at high speed. These are much

brighter and are called ‘fire balls’ or ‘Bolides’ if above magnitude -5.

Re-entering rocket parts are also sometimes seen.

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Meteor groups:

Sporadics

Showers

Meteor showers are generally associated with periodic comets and are linked to

known passes in the past.

The showers form as the Earth passes through the streams of particles left by

the comet and so happen at certain times of the year.

The Perseid shower is associated with comet 109P Swift - Tuttle

The Leonids with 55P Tempel-Tuttle

The Geminids with the asteroid 3200 Phaethon

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

The shower meteors all appear to radiate from a single point in the sky.

This is a perspective effect.

The constellation that contains these point give rise to the shower name

i.e. the Perseid radiant is in the constellation Perseus

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Meteor watch: Things to consider.

Ideally a dark site is needed away from interfering lights.

Haze and the Moon will also interfere.

It is better when the radiant is high.

Comfort is essential. A recliner and warm clothes, woolly hat and warm shoes.

Do it as part of a team if you can – it’s much more fun.

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Where to look

Observe the sky at about 50 deg in altitude and about 40 deg in azimuth

away from the radiant.

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Stuff you’ll need

An accurate time piece

A dim red torch

Note pad / observing sheet and pens

Martin Crow Crayford Manor House Astronomical Society

slide15

Magnitude Object(s)-4 Venus-2 Jupiter-1 Sirius0 Capella, Rigel, Arcturus+1 Regulus, Spica, Pollux+2 Belt stars of Orion, Beta Aurigae, Gamma Geminorum, Pointers of Plough, Polaris, Denebola, Alphard+3 Delta UrsaeMajoris, Gamma and Delta Leonis, Epsilon Geminorum+4 EtaPersei, Delta Aurigae, RhoLeonis+5 Faintest meteors generally visible to naked eye

Martin Crow Crayford Manor House Astronomical Society

practical observing8
Practical observing

What to record

Time of the appearance (UT)

Magnitude estimate

Type: shower or sporadic

Constellation seen in

Presence and duration of any train if seen.

Any additional notes – colour, break up

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Next

Send your observations off to the Meteor section of the BAA.

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Imaging meteors

A DSLR camera is generally a better option although some ‘point and shoot’

cameras are up to the job.

Generally use a wide field setting.

Focus is very important for sensitivity. Once focused disable the auto focus function.

Set the ISO 800 or 1600 and low f number.

Exposure times 30 seconds to 120 seconds depending on light pollution.

Use a programmable timer to take the exposures.

Spare batteries or external power source very useful.

Martin Crow Crayford Manor House Astronomical Society

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Practical observing

Imaging meteors continued

Make sure that the camera date and clock is correct (UT)?

Also keep a visual watch

As a general rule of thumb only meteors brighter than zero magnitude will show up.

This apparent short coming can be put to good use.

It is very difficult to capture images of meteors

Observing as part of an organised team effort

Martin Crow Crayford Manor House Astronomical Society