Comet Alert: 46P/Wirtanen

There is a comet in our skies.  Well, there are 6,339 comets in our Solar System that we have discovered.  The question is, why is everyone getting excited about 46P?

It was discovered on January 17, 1948 by an American astronomer named Carl Wirtanen at Lick Observatory just outside of San Jose.  It was exposed photographically and found through observing its proper motion relative to the background.

Comet 46P's coma extends more than 45 arcminutes in this picture taken on November 26, 2018.
Gerald Rhemann (Namibia)

Comet 46P/Wirtanen is a short period comet that orbits the Sun every 5.4 years.  Compare this to Halley's Comet which has a period of 75.3 years.  Hale-Bopp of 1990s fame orbits the Sun in a little over 2500 years.  Some comets may even come for a close approach and then leave the Solar System completely.

46P will be within 11.5 million kilometers of Earth at its closest approach making it the 20th closest comet since the 9th century. 

The reason there is excitement over 46P is that it may be bright enough to see with the naked eye in mid-December.  As of November 29, 2018 in the Comet Observers Database: https://cobs.si/ the average magnitude for observers is 5.8.  In dark sites within 30 minutes of Calgary I tend to be able to see to magnitude 5.0.  Each increase in the magnitude number is approximately 2.5 times dimmer.

As you can see from the chart below the magnitude has been steadily becoming brighter.  Magnitude 14 is in the range of Pluto which is on my bucket list for backyard astronomy in my largest (14") telescope.  It will be very difficult.  I can see magnitude 10-12 faintly through a moderately large telescope.  6-10 objects are generally accessible through binoculars and less than 5 can reach the naked eye.  Some people can reach 6.5 with their naked eye at a very dark site with no Moon.  At my location is suburban Calgary my limit is about 4.3 with my eyes.

Light Curve of Comet 46P/Wirtanen - as of November 29

This curve is approaching magnitude 4-5 which may make it possible to see the comet with just your eyes.  A telescope or binoculars on this object will certainly reel it in at this moment in time.

As the comet gets closer to us it will become brighter reaching its peak on December 16.  It will also be with the Pleiades (M45) in a wide field binocular view on this evening.

Where can you find the comet?

I have created a PowerPoint presentation that maps the comet between November 29-December 21.  If you can make your way around the late Autumn sky you should have no trouble finding it.  The stars are mapped to magnitude 6.5 in the charts found below.

Comet 46P/Wirtanen Finder Charts

I hope you have success in finding this comet!

2018 Week 48: (November 25-December 1)

We are now in the 48th week of the year and December is soon approaching.  Comet 46P/Wirtanen is currently averaging at 5.6 magnitude and still making its way through the Lacaille constellation of Fornax.  The table below shows everything happening in our sky this week.

Date	Event
November 25	Neptune Stationary
November 26	Jupiter in Conjunction with Sun
November 27	Mercury at Inferior Conjunction
November 27	Moon 0.7°S of Beehive (M44)
November 29	Last Quarter
December 1	Venus Greatest Illuminated

Neptune will be stationary as it begins its prograde transit East through the sky.  Our furthest planet still sits in the middle of Aquarius less than 2° from Lambda Aquarii.  This is a worthy target for any beginning or intermediate visual astronomers.

Neptune (Cell Phone Through Telescope Capture)

The following two days we will have two planets in conjunction with the Sun.  Jupiter will be aligned behind the Sun and Mercury in front.  These planets will not be visible until they move further away from the large star in the middle of our Solar System.  Perhaps you will catch a glimpse of Jupiter in the early morning close to the New Year.

The moon is continuing its progression through its waning gibbous phase and approaches the Beehive Cluster on November 27th.  This may be a good target for skilled astrophotographers.  Two days later the Moon will be at its previous month's Halloween phase of Last Quarter.

Beehive Cluster (M44)

Something you should not miss is Venus at its greatest illumination.  In the southeastern sky during morning twilight you will see Venus shining brightly near Virgo's shining star Spica.  It will be -4.7 magnitude -- the brightest object in the sky besides the Sun and Moon.  This is nearly 20 times brighter than the brightest star -- Sirius.  In dark sites, Venus is known to cast shadows in the absence of the Moon.

There will be a couple rocket launches occurring this week.  The Falcon 9 with the multi-satellite payload has been rescheduled to November 28.  The next day India will be launching an imaging satellite with a few smaller payloads.  The time for this launch is yet to be determined but you can watch all flights at: https://spaceflightnow.com/

Date	Event
November 28	Falcon 9 - Spaceflight SSO-A (11:31)
November 29	PSLV - HySIS

I promise to write a full article on Comet 46P/Wirtanen as I am running out of time before it reaches perihelion during the middle of December.  Stay tuned for how you may be able to see it with your naked eye in our northern skies!

2018 Week 47: (November 18-November 24)

This week we will have a Full Moon brightening the cool late Autumn sky.  The next day the Full Moon will be in conjunction with the bright red star in Taurus called Aldebaran.  The chart below highlights these events.

Date	Event
November 22	Full Moon
November 23	Aldebaran 1.7°S of Moon

The other morning I was walking around the house at around 7 in the morning.  I looked in the southeastern sky and noticed Venus was very bright.  Our closest planetary neighbour was in close proximity to the brightest star in Virgo--Spica.  They are less than 2° apart in the sky and would fit quite nicely in binoculars or a wide field telescope.

Venus

It is amazing that Venus is so bright.  Only 14% of the planet is currently illuminated in its waxing crescent phase.  The above image shows Venus as a waning crescent from 2016.  The planet is quite close to the Earth right now at approximately 50 million kilometers.  The closest Venus can get to us in around 38 million kilometers.

When you are up in the morning look to the southeast to see this great sight!

The great constellation Orion is now peaking above the eastern horizon early in the evening.  By 9pm you should be able to see its bright belt stars above the houses in the suburbs.

Southern Sky This Week (Left is East) 22:30

The Pleiades is in a perfect position to view with your eyes or any optical instrument.  In four weeks Comet 46P/Wirtanen will be less than 5° from this famous cluster of stars.  The comet may even reach naked eye visibility as it makes its closest approach to Earth on the 18th of December.  I am sure you will see this in news reports over the next few weeks when the media catches a hold of this fish.

As of today the comet is current at -30° declination in the constellation of Fornax with a current average estimate of 6.5 magnitude.  We will have a full write-up about this comet very soon.

There are two scheduled rocket launches happening this week.  A Falcon 9 will be taking off from Vandenburg Air Force Base in California just before Noon on Monday.  It is carrying several satellites to a polar orbit for a variety of different countries.

The next day a Vega rocket wll be taking off from French Guiana with an Earth observation satellite for Morocco.  If you would like to check out either of these launches live the information is provided in the table below.

Date	Event
November 19	Falcon 9 - Spaceflight SSO-A (11:31)
November 20	Vega - Mohammed VI-B (20:42)

These launches can be viewed from the website below.

https://spaceflightnow.com/

Stay tuned for the latest Calgary astronomy information on our Facebook Page below.

www.facebook.com/simonjastronomy

2018 Week 46: (November 11-November 17)

This week in the sky we have two Meteor Showers reaching their peaks!  The Moon should not even play a role in polluting the light sky with its unnecessary light.  The highlights of the week are shown in the chart below.

Date	Event
November 11	Saturn 1.5°S of Moon
November 12	Northern Taurid Meteors Peak
November 15	First Quarter
November 15	Mars 1.0°N of Moon
November 17	Leonid Meteors Peak

The Moon has begun a new cycle and we may have started to see it creep into the evening sky as a waxing crescent.  It will be in conjunction with the great ringed planet, Saturn, during Sunday evening. You do not want to miss Saturn, it is currently singing its 2018 swan song and will be below the horizon.  The ringed planet is speedily heading towards its solar conjunction on January 2, 2019.

Saturn

The next evening the Northern Taurid Meteor Shower will peak.  We talked about these a little bit last week.  They are not very prolific but with good eyes and dark skies you may catch a few.  The radiant point for the Northern Taurids is shown below.

The peak is in a very convenient position as it sits right next to the Pleiades Star Cluster.  By the time Taurus is high in the sky the Moon will be long gone down below the horizon.

Northern Taurid Radiant

The First Quarter Moon follows a few days later with the terminator running right through the middle.  This is a great time to see some of the best features on our lunar neighbour.  During the same evening you will be able to catch brilliantly red Mars in conjunction with the Moon.  They will be only 1° apart.  Provided below is a map of the sky at 19:30 on November 15, 2018.

Grab your binoculars, telescope or just your eyes and take in this sight.  If you would like to get creative take your camera out and see if you can grab this pairing.

Mars/Moon Conjunction - November 15, 2018

If you think the wonders of the week are over you will be surprised.  We have another meteor shower coming up at the end of the week.  The Leonid Meteors will peak.  This, unfortunately is a morning shower with the radiant coming above the horizon after midnight.  However, if you get up early, Leo will be high in the sky and you may be able to catch several Leonids.  The radiant point is shown in the map below.

Leonid Radiant

If you would like to sketch some of the observed meteors, please find a fillable map linked below.

Leonid Observation Sheet

A full description of this shower can be found on my post from last year below.

https://simonjastronomy.blogspot.com/2017/11/the-leonid-meteor-shower.html

The estimated hour rate as stated by the American Meteor Society can be found below.  As a person who lives in the suburbs I should hopefully be able to catch 5 per hour.  It is more likely I will be catching Zzz's instead.

City	Suburbs	Rural	Optimal
3	5	10	20

I hope to spend some time this week organizing some more personal and public observing.  Orion is now heading up into the sky and we hope to showcase this wonderful constellation at a community star night.  Also, stay tuned, I may have the opportunity to write new blog posts on things I observed last Summer in Sagittarius.

2018 Week 45: (November 4-November 10)

This week in the sky there will be a meteor shower and some tricks with the planet Mercury.  The chart below highlights everything that is going on!

Date	Event
November 4	Daylight Saving Time Ends
November 5	Southern Taurid Meteors Peak
November 6	Mercury Greatest Elongation East
November 7	New Moon
November 8	Mercury 1.8°N of Antares

As we all know Daylight Saving Time ends at 2am on Sunday, November 4.  We push the clocks back an hour and hopefully enjoy an extra hour in bed.

The Southern Taurid Meteors will peak during the evening of November 5.  The constellation Taurus will be in the eastern sky and certainly visible by 9pm.  The Pleiades Star Cluster is a famous sight in the great bull constellation.  If you look in the general direction of the Pleiades you may catch a meteor.  It is a particularly sparse shower and may only peak at 2-3 per hour from suburban conditions.  You may be able to catch a few more in darker skies.  The image below provides the location of the shower radiant (M45 - Pleiades).

Southern Taurid Radiant

Mercury is playful this week.  It will reach its greatest elongation East on Thursday evening.  This means it is as far East of the Sun as it gets this orbit.  However, the geometry for Northern Hemisphere observers is not that great.  If you are out for a walk with a clear view of the western horizon just after sunset you may have a shot at seeing this diminutive planet.  A map to its location can be found below.

Mercury

It is tucked in nice and close to Jupiter and the bright red star Antares.  As you can see it also sets right after the Sun.  The bright twilight may wash out both the largest and smallest planet of our Solar System.  After the Sun goes down try seeking them out with binoculars.  Please, wait for the Sun to go down before you try!

Map to Mercury - Thursday, November 8, 2018

There are three rocket launches scheduled at the time of writing.  Launch dates and times can change quickly without notice.  The chart below indicates when they will occur.  As always, you can catch live launches from the following webpage:

https://spaceflightnow.com/

Date	Event
November 6	Soyuz - MetOp C (17:47)
November 7	Pegasus XL - ICON (01:00)
November 10	Electron - It's Business Time (20:00)

A Soyuz rocket will launch from South America and carry a polar-orbiting weather satellite for the ESA.  The next day (or 6 hours later) a Pegasus XL rocket will be taking the delayed ionosphere monitoring satellite into orbit.  Finally on the 10th of November a Electron rocket will be launching from New Zealand.  This launch has been scrubbed since late June.

There are no public events occurring this week but the next RAO open house will be happening the following weekend.  Stay tuned for more information soon!  If you are reading this and haven't subscribed to our Facebook Page, now is the time.  We have an action packed Winter with many free events!  Join us below!

www.facebook.com/simonjastronomy