#astronomy Autumn Comets, Mira’s Eye & The Orionid Meteor Bathe

October 19, 2019 - Comment

4 comets, a well-known variable star, and sprinkles of mud from Halley’s Comet (which create the Orionid meteor bathe) are highlights of the October sky. Comet C/2018 W2 (Africano) glows inexperienced and displayed a brief tail to the northeast across the time of its peak brightness on October 6, 2019. Try this time-lapse video of

4 comets, a well-known variable star, and sprinkles of mud from Halley’s Comet (which create the Orionid meteor bathe) are highlights of the October sky.

C/2018 W2 in full glory

Comet C/2018 W2 (Africano) glows inexperienced and displayed a brief tail to the northeast across the time of its peak brightness on October 6, 2019. Try this time-lapse video of the comet.
Rolando Ligustri

I hope you had the chance to watch C/2018 W2 (Africano), the brightest comet of the summer time and fall. It peaked round ninth magnitude earlier this month whereas rushing by Pisces after making its closest strategy to Earth on September 27th. I noticed it final on October third earlier than the Moon interfered. In my 15-inch at 64× magnification, the comet’s reasonably condensed coma measured about three′ throughout with a stubby tail pointing to the northeast. Images reveal inexperienced carbon emission, a brilliant pseudo-nucleus and smear of a tail.

Comet Africano continues to clip southward. This week and subsequent it slices throughout Piscis Austrinus earlier than dropping out of view for observers at mid-northern latitudes. The comet can even fade from its present magnitude of 9.5 to the mid-10s by late October, so catch it the following clear night time. Moonless skies return as quickly as tonight, with finest viewing occasions between Eight and 11 p.m. native time.

Faint Fall Comets

Matchstick comet

Comet C/2018 N2 (ASASSN) appears like a matchstick with its brilliant, compact head and slender south-pointing tail on this photograph taken on September 21st.
Alfons Diepvens

Three further comets ply the autumn skies, and all are seen in 10-inch and bigger telescopes: C/2018 N2 (ASASSN), 260P/McNaught, and C/2017 T2 (PanSTARRS).

C/2018 N2 proved a nice shock at 142× on October seventh with a strongly condensed (DC=6) coma 1.5′ throughout. With averted imaginative and prescient and 245× I teased out a faint, 14th-magnitude stellar nucleus and suspected a ~1.5′ tail to the south. Given its excessive DC and total magnitude of 11.5, an Eight-inch scope beneath darkish skies ought to nail this one.

Closest strategy to Earth happens on October 20th adopted by perihelion on November 10th, so this celestial Q-tip will probably be simple to comply with all through the autumn because it brightens a smidge by late October. For those who’re on the lookout for the right time to seek out it, C/2018 N2 will cross inside 1° of 2nd-magnitude Beta (β) Andromedae on October 19-20 and three° southwest of the Andromeda Galaxy on November 2nd.

Tiny-tailed wonder

Small however with a pleasant tail. That is what 260P/McNaught regarded like in my 15-inch with a magnification of 142×. This photograph reveals the comet on October Eight, 2019.
Martin Mobberley

260P/McNaught, one other minnow of a comet, spends October wriggling northeastward throughout Perseus. On October seventh, it glowed at magnitude 12 however was  simple to see even at low magnification due to its small measurement — simply 1′ throughout — and compact (DC=5) coma. You’d assume a 12th-magnitude comet would not present a tail, however it was surprisingly simple to spy with averted imaginative and prescient as a 1.5′ lengthy streak pointing southwest. I estimated the false stellar nucleus at magnitude 13.5. At the same time as 260P slowly fades this month it stays well-placed for viewing from mid-northern latitudes all through the autumn.

C/2017 T2 (PanSTARRS) is anticipated to be the principle act for comets in 2020, because it’s anticipated to brighten to magnitude Eight by subsequent Might. For now, it slumbers round magnitude 12.5 whereas inching northwestward by the open cluster-rich area of central Auriga. On the nights of October 27th and 28th, the comet ambled up alongside the intense open cluster M36, some 20′ east of its core. Whereas the earlier three comets are seen at dusk, C/2017 T2 does not climb excessive sufficient for look till after 11 o’clock native time (10 p.m. by finish of month). Remember that the Moon will intrude till Oct. 20.

Cometary ups and downs

The anticipated mild curve for C/2017 T2 reveals a peak round eighth magnitude subsequent spring. A magnitude scale is proven at left; time is plotted alongside the axis. The black dots are magnitude estimates to this point. For extra on present comets go to Weekly Details about Vivid Comets.
Seiichi Yoshida

On October seventh, PanSTARRS sported a small, dense 45″ coma with a DC=6 at 142×. Upping to 245× I famous an almost opaque internal coma with a 15th-magnitude flicker of a nucleus. I utilized a Swan Band filter on this and the opposite three comets, however none confirmed an enchancment in distinction or brightness — a sign that the whole thing are comparatively wealthy in mud in comparison with fluorescing diatomic carbon fuel, one of many substances that causes comas to glow inexperienced.

Orientation map

Basic map exhibiting the situation of 4 at the moment seen comets. Use this for orientation after which seek the advice of the detailed maps (beneath) to seek out your technique to every comet.

Beneath you may discover detailed maps created with SkyMap to trace every of our 4 guests over the following few weeks. The wide-field map above offers you an concept of when and the place to start out wanting. North is up in all charts and positions are proven day by day at zero hours UT. Subtract four hours for EDT, 5 for CDT, 6 for MDT and seven for PDT. For instance: October 20, 0h UT = October 19, Eight p.m. EST.

C/2018 W2 (Africano)
C/2018 N2 (ASASSN)
C/2017 T2 (PanSTARRS)

You is likely to be questioning what’s up with interstellar comet 2I/Borisov. It stays very faint at round magnitude 16. I’ve heard of no novice visible sightings, although it is more and more exhibiting up in astrophotos. We’ll test in with this alien customer once more in December when it is nearer to perihelion. I’ve nonetheless bought my fingers crossed amateurs will spot it in larger devices across the time of its December perihelion.

Borisov's Travels

Interstellar comet 2I/Borisov (above heart) is a blip with a tiny tail crossing by the constellation Leo this month. Animation was made on Oct. 11, 2019. 
Michael Jäger

Underneath Mira’s Eye

I wish to image all these comets wending their methods beneath the watchful eye of Mira the Fantastic, top-of-the-line identified and beloved variable stars. The brightness of the pink big star varies over a interval of about 333 days and is simply now coming into good view, whereas concurrently experiencing certainly one of its brighter maxima. With a present magnitude of about 2.9, you may’t miss it! Particularly when this weekend’s full moon departs the scene. Will you be capable of detect the star’s ruddy hue with the bare eye? I do know it is seen in my binoculars.

Tracking Down Mira

There are a lot of methods to seek out Mira! You may shoot a line diagonally throughout the Nice Sq. and lengthen it 5 ½ fists to the decrease left. Or you may drop down from Triangulum to seek out the constellation Aries, then look somewhat greater than two fists beneath Aries. You additionally triangulate to Menkar (a Dipper-bright star) and from there to Mira utilizing the Pleiades star cluster and Aldebaran.

Mira comparison-star magnitude chart

Mira is a simple naked-eye object this month. Comparability-star magnitudes, courtesy the American Affiliation of Variable Star Observers, are given to the closest tenth, with decimal factors omitted to keep away from confusion with faint stars.

Mira’s peak brightness varies from cycle to cycle, however proper now it is at or close to most. Regulate it and you’ll watch it slowly return to minimal brightness over the approaching months. The chart above will show you how to estimate the Mira’s altering brightness.

Orionid Meteor Bathe

Radiant of Orionid meteor shower, near Betelgeuse

Orionid meteors, created by bits of particles from Halley’s Comet, seem to radiate from some extent close to the upraised membership or Orion. Bathe most happens within the early morning hours of Oct. 22.
Sky & Telescope illustration

Hmm … what else would boost late October skygazing? How a couple of good little meteor bathe? The annual Orionids peak on the night time of October 21-22 (that’s, Monday night time by Tuesday morning), with 15-20 swift meteors seen per hour from a darkish, moonless sky. Every crumble of rock or mote of mud flashing earlier than your eyes is a memento from Halley’s Comet. Though the waning last-quarter Moon (42% illuminated) will intrude, it isn’t so brilliant as to name off spending a soothing hour earlier than daybreak watching meteors fly. You would possibly even strive your luck from 11:30 to 12:30 earlier than moonrise when Orion first seems within the east.

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