{"id":57826,"date":"2024-04-25T06:21:15","date_gmt":"2024-04-25T06:21:15","guid":{"rendered":"http:\/\/0955637b-8322-4113-ae14-dbdd401a064a"},"modified":"2024-04-25T07:09:36","modified_gmt":"2024-04-25T07:09:36","slug":"see-the-lunar-occultation-of-globular-cluster-m4-23-24-may","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/see-the-lunar-occultation-of-globular-cluster-m4-23-24-may\/","title":{"rendered":"See the lunar occultation of globular cluster M4, 23\/24 May"},"content":{"rendered":"

See this star cluster disappear behind the Moon. <\/p>

By Pete Lawrence\n <\/p>

Published: Thursday, 25 April 2024 at 06:21 AM<\/p>

\n\n

On the night of 23\/24 May, the Moon will appear to pass in front of globular cluster M4, in an event known as a lunar occultation.<\/p>

A lunar occultation<\/a> occurs when the Moon appears to move in front of something more distant, such as a star or a planet.<\/p>

Lunar occultations of brighter objects aren\u2019t as common as you might think, but on the night of 23\/24 May, the bright full Moon will occult the globular cluster<\/a> Messier 4 in the constellation of Scorpius.<\/p>

However, the M4 cluster’s magnitude of 5.9 and low altitude from the UK mean this lunar occultation won\u2019t be straightforward to observe<\/p>

For more stargazing dates and advice, sign up to receive the weekly BBC Sky at Night Magazine e-newsletter<\/a> and listen to our Star Diary podcast<\/a>.<\/em><\/strong><\/p>

Globular cluster M4 will be hidden by the Moon in an event known as a lunar occultation on 23\/24 May 2024. Credit: CEDIC Team, Herbert Walter \/ CCDGuide.com<\/figcaption><\/figure>

Lunar occultation of M4 timings<\/strong><\/h2>

On the evening of 23 May, the Moon rises above the southeast horizon at 22:00 BST (21:00 UT), as the sky is darkening.<\/p>

As it gains altitude, look out for the red supergiant star Antares<\/a> (Alpha (\u03b1) Scorpii) making an appearance to the lower left of the Moon, with Alniyat (Sigma (\u03c3) Scorpii) above and to the left of the Moon\u2019s disc.\u00a0<\/p>

As the sky continues to darken, fainter stars will become visible.<\/p>

The brilliance of the Moon\u2019s full phase will make these difficult to see with the naked eye.<\/p>

But for those with a small telescope pointed at the Moon, you may be able to see the faint glow of the globular cluster M4 just east of the Moon\u2019s position before the lunar occultation commences.<\/p>

\"Lunar
Lunar occultation of Venus captured by Shreya Roy, Kolkata, India, 24 March 2023. Equipment: Nikon D5600 DSLR, Nikkor 70\u2013300mm lens, Digitek tripod<\/figcaption><\/figure>

With an integrated magnitude of 5.9 and at low altitude, M4 won\u2019t be easy to see, but it is there.<\/p>

As time progresses, the northwest edge of the Moon will get closer to the globular, passing in front of the object from around 00:45 BST on 24 May (23:45 UT on 23 May) until 02:20 BST (01:20 UT) on 24 May.<\/p>

This unusual lunar occultation of M4 may be seen visually, but should also be a viable target for photography.<\/p>

It will be interesting to see what results can be obtained and whether a clearer view of the occultation can be had.\u00a0<\/p>

As the Moon approaches setting in the early hours of 24 May, it\u2019ll be tracking east to pass approximately half a degree south of Antares at moonset.<\/p>

\"Chart
Chart showing the lunar occultation of globular cluster M4 on 23\/24 May 2024. Credit: Pete Lawrence<\/figcaption><\/figure>

Observing the lunar occultation of M4<\/strong><\/h2>

If you try to follow the lunar occultation of M4 using binoculars, the Moon\u2019s glare will make the globular hard to see.<\/p>

Use a telescope with a low- to mid-power eyepiece and you stand a better chance, but M4 will still struggle against the bright Moon.<\/p>

Another way to observe the occultation is to photograph it, as the camera should be able to record the globular stars up to the point of occultation.<\/p>

An image scale that will let you record a large portion of the Moon\u2019s limb should give you a good chance of recording something.<\/p>

Photographing the lunar occultation of M4<\/strong><\/h2>

If you want to photograph the lunar occultation of M4, the weather and state of your optics will have a big effect.<\/p>

Any mist or fogging of lenses will cause the Moon\u2019s glare to spread and you\u2019ll lose M4.<\/p>

The best strategy is to grab M4 as soon as you can, ahead of the event, and experiment to get the best camera settings. <\/p>

Then, during the event, apply those settings and take images at frequent, regular intervals.<\/p>

Set-up<\/strong><\/h3>

Many different camera types can capture the occulation, but it\u2019s worth bearing in mind that DSLRs and other one-shot-colour cameras will be at a disadvantage due to a prismatic effect called atmospheric dispersion.<\/p>

The atmosphere disperses light, with different wavelengths dispersing differing amounts.<\/p>

The lower the altitude, the more this effect increases, due to the fact that you\u2019re looking through a thicker layer of atmosphere.<\/p>

Colour cameras capture all the dispersed light. Mono cameras aren\u2019t immune, but you can at least limit the effect by fitting a single-colour pass filter.<\/p>

An atmospheric dispersion corrector<\/a> (ADC) will allow colour cameras to be used with the dispersion effects minimised too.<\/p>

\"lunar
Lunar occultation of Mars. Credit: Pete Lawrence<\/figcaption><\/figure>

Capture<\/strong><\/h3>

The relative faintness of M4 compared to the fully lit lunar surface means the Moon will be over-exposed if the cluster stars are to record well.<\/p>

The way around this is to pre-image M4 and the Moon at the correct exposures.<\/p>

During the lunar occultation, take sequence shots showing where M4 is located relative to the Moon, and then construct a composite using the pre-shot images.<\/p>

If you do this, it\u2019s important to make it clear that the result is a composite, preferably showing the component images in the result too.<\/p>

You should also keep relative brightnesses as close to realistic as you can, so your image doesn\u2019t give a false impression of the actual view.<\/p>

It might be used as a guide for a future event \u2013 therefore it\u2019s vital to have as much information as possible on it to detail what settings and processes were used.<\/p>

Equipment<\/strong><\/h3>