Total Lunar Eclipse – Jan 20, 2019

Posted by as Observing Highlights

Total Lunar Eclipse on Sep 27, 2015 from Victoria
Total Lunar Eclipse on Sep 27, 2015 from Victoria – photo by Joe Carr

On Sunday, January 20th, 2019, we will be able to view a total eclipse of the Moon (weather permitting). The Moon will be in partial phase after rising from the eastern horizon, and move into full eclipse in evening hours as it climbs in altitude and moves to the southeast. The Total Lunar Eclipse will develop over the course of about 3 hours, will be in Totality for about an hour, and will end just before midnight.

This is a perfect opportunity to visually observe this beautiful celestial event, and possibly capture some photographs from a location with an unobstructed view to the east and south.

ECLIPSE TIMELINE
Eclipse beginsMoon’s eastern limb enters the penumbra6:36 pm PST
Partial eclipse begins – 1st ContactMoon’s eastern limb enters the umbra7:33 pm PST
Total eclipse starts – 2nd ContactMoon entirely in the umbra;
deep orange red
8:41 pm PST
Totality9:12 pm PST
Total eclipse ends – 3rd Contact9:43 pm PST
Partial eclipse ends – 4th ContactMoon’s western limb leaves the umbra10:51pm PST
Eclipse endsMoon leaves the penumbra11:48 pm PST
Above Eclipse times are for Pacific Standard Time (PST) for the west coast of North America, and are calculated from UT as presented in the Observers Handbook 2019, pages 127-29.

What’s Happening

A total lunar eclipse occurs when the Earth comes between the Sun and the Moon. During a lunar eclipse the Moon’s position traverses the Earth’s shadow. The Moon’s first contact with the Earth’s shadow is at the outer band of the shadow called the penumbra. The light falling on the Moon is progressively blocked until at the moment of total eclipse the Moon is completely in the darkest central area of the Earth’s shadow called the umbra. At the point of total eclipse the process starts to reverse itself until the Moon is totally out of the Earth’s shadow.


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Glossary

  • limb – the outer edge of the Moon
  • penumbra – the outer band of the Earth’s shadow
  • umbra – the darker central area of the Earth’s shadow
  • partial eclipse – the Moon is positioned within the penumbra
  • total eclipse – the Moon is positioned totally within the umbra

Observing Tips

What do you need?

Everything from your eyes, binoculars and telescope are suitable. Bear in mind this is a long process and at this time of year dress warmly and bring a chair if you want to be comfortable.

Find yourself a location that has a clear horizon view to the east and south especially if you wish to view during the late stages.

Keep a log of what you see and note the time. Pay attention to how much of the light on the moon is obscured and if there are any colouration changes. During the total eclipse the Moon will take on a deep orange-red colour. The colour of the Moon is a function of contaminants in the atmosphere and varies from year to year.

A good observing project for this long-lasting eclipse will be to observe the craters on the Moon as the eclipse progresses. Craters will be immersed and emerge from the Earth’s shadow on the Moon at times specified in the Observers Handbook 2019, page 129.

Totally eclipsed Moon over the Salish Sea from Cattle Point – Sep 27, 2015

Photographic Tips

Equipment

Any camera with the capability of setting shutter speeds and aperture settings manually will do fine. The ability to use interchangeable lenses will be an advantage for more detailed images of the Moon. For the darker parts of the eclipse, eg. totality you should use a tripod support for best results. If you have access to a telescope you can try capturing the event using prime focus techniques through the telescope optics.

Settings

Today’s digital cameras are very sensitive to light reflected by the Moon. Use ISO 400 to ISO 800 and a long telephoto lens or zoom setting. Smartphones and point-and-shoot digital cameras will not produce rewarding photos of the eclipsed Moon, but can be useful for taking panoramic shots of your surroundings which include the eclipsed Moon.

Technique for smartphone cameras

Smartphone cameras typically do not support manual settings, so using them to capture a lunar eclipse will be less rewarding than using more capable cameras. That said, smartphone cameras can be held up to a telescope eyepiece to capture an image of the Moon. Aligning the tiny lens to the eyepiece can be tricky, however there are platforms made to clamp onto an eyepiece barrel which will hold smartphones steady enough to take acceptable photos of the Moon, including the eclipsed Moon.

Technique for interchangeable lens cameras

The simplest eclipse pictures can be taken with manual settings on your camera and a normal lens, preferably supported by a tripod. For best results use a cable release to minimize vibration. Images taken in this fashion result in a small lunar image. This is why it is preferable to use a telephoto lens to photograph the Moon.

For a full frame camera try a 200mm lens or something close to this, even better a 500mm lens or higher. You may also use teleconverters to increase magnification, these typically come in 1.4x and 2x strengths. Their downside is they reduce the effective aperture of your optical system. A 1.4x teleconverter will decrease your effective exposure by 1 stop, a 2x teleconverter will decrease your effective exposure by 2 stops. Work out your effective aperture of your optical system ahead of time so you don’t have to think about it on the night of the eclipse.

Note for the smaller sub-full frame sensors of some digital cameras you gain an extra advantage as the focal length of the lens is effectively magnified by a factor. For example a Nikon DX body your 200mm lens would be effectively 300mm.

  • APS-C Nikon DX, Pentax : 1.5x
  • APS-C Canon EF-S : 1.6x
  • Four Thirds : 2x

Example:

 Focal Length ApertureEffective Focal Length
with 2x teleconvertor
Effective Aperture
with 2x teleconvertor
 180mm 2.8 360mm 5.6
 480mm 6.8 960mm 13.6

To achieve any higher magnification than what is stated above you will have to use a telescope at prime focus. For this your manual camera does need to have the capability of using interchangeable lenses. For prime focus you will use the telescope optics as your interchangeable lens. To attach your camera to your telescope you will need two things a T-adapter that fits your camera and a telescope camera adapter that fits your telescope.

The telescope camera adapter is designed to fit in the focusing tube of your telescope and is threaded to accept the T-adapter of your camera. With the magnification involved with telescopic optics it is likely that you will need to use a tracking mount. Preferably the mount should be able to track at lunar speed as opposed to sidereal but if the shutter speeds chosen are shorter than 1 or 2 minutes this is not critical.

Exposure times are the next consideration. The following exposure times are based on a medium ISO setting and an effective aperture that would be common with a long telephoto and teleconverter combination. Exposures may vary with your equipment based on ISO speed and effective aperture. The Danjon Lunar Eclipse Luminosity Scale has been included to provide better guesstimates for totality.

Exposure Times: based on ISO 400
Full Moon1/500 second at f/16
1st Contact1/250 second at f/16 see note 1.
2nd Contact1 second at f/16 see note 2.
Totality
*see table below
L = 4 : 4 seconds at f16  L = 3: 15 seconds at f16  L = 2: 1 minute at f16  L = 1: 4 minutes at f16
3rd Contact1 second at f/16 see note 2.
4th Contact1/250 second at f/16 see note 1.
* Danjon Lunar Eclipse Luminosity Scale
 L = 1dark eclipse; lunar surface details distinguishable only with difficultly
 L = 2deep red or rust coloured eclipse; central part of the umbra dark but outer rim relatively bright
 L = 3brick-red eclipse; usually with a brighter (frequently yellow) rim to the umbra
 L = 4very bright copper-red or orange eclipse, with a bluish, very bright umbral rim

Note 1. 1st and 4th contact times given for the partial phases are biased for the light part of the Moon. Remember you are dealing with vastly different exposures between the light and dark parts of the Moon during eclipse. The bias of about 1 stop minus avoids overexposure of the dominant bright area of the Moon.

Note 2. 2nd and 3rd contact times given for the partial phases are biased for the dark part of the Moon. The bias of about 1 stop plus is a good strategy for negative film not quite so good for slides and digital capture given they don’t tolerate overexposure well.

The exposure times are only recommendations. Remember the cardinal rule about photography … bracket. Always try exposures plus and minus your chosen exposure. This gives you a better chance at getting usable results. Let’s all hope for clear weather. If you have any questions please send email to David Lee at davidflee7331@gmail.com.


David Lee – original text
Joe Carr – updated for 2019
Brenda Stuart – illustrations


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