March 2013 Highlights * Comet C/2011 L4 (PANSTARRS) will be visible in the evening sky for northern observers at magnitude 1-2 though it will be very low on the horizon * Comet C/2012 F6 (Lemmon) will be 4th-5th magnitude for SH observers * Saturn rises before midnight * Jupiter continues to dominate the evening sky * Mercury starts a great morning apparition for southern observers (not so good for northerners) Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.
Planets
Evening Planets
Jupiter – The King of the Planets dominates the evening sky being visible nearly overhead at the end of evening twilight. Jupiter is now three months past opposition. It spends the month just north of the stars of the Hyades cluster in Taurus as it fades from magnitude -2.3 to -2.1. The Moon pays Jupiter a visit on the evening of the 17th.
Saturn – Saturn is an early morning object rising around 11:00 am at the start of the month and 9pm by the end of the month. All month Saturn glows at magnitude +0.2 between Virgo and Libra. The Moon passes close to Saturn on the morning of the 2nd.
Morning Planets
Mercury – Mercury starts the month too close to the Sun to be seen. By the last third of the month, the innermost planet is rapidly rising out of the morning twilight glow for southern observers. Up north, the view will be much poorer.
Venus and Mars – Both planets are too close to the Sun for easy observation this month. They will be back this summer, Venus in the evening sky and Mars in the morning sky.
Meteors
The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. Meteor activity is near its annual minimum this month.
Sporadic Meteors
Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During March mornings, 5 or so Sporadic meteors can be observed per hour from a dark moonless sky. The rate is near an annual minimum this month.
Major Meteor Showers
None this month.
Minor Meteor Showers
Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.
Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.
Comets
Naked Eye Comets (V < 6.0)
C/2011 L4 (PANSTARRS)
Last month Comet PANSTARRS looked on pace to peak around magnitude -1 near its March 10th perihelion. But over the past few weeks the comet has not been brightening as quickly as hoped. As a result it is likely that the comet will be much fainter than -1 at its peak brightness and more along the lines of 2nd to 4th magnitude. The comet will still be a nice sight especially in binoculars and telescopes.
The comet was first seen by the Hawaiian based PanSTARRS asteroid survey on June 6, 2011 at a large distance of 7.9 AU from the Sun. At perihelion it will approach within 0.30 AU of the Sun. The comet is a new Oort cloud comet meaning it is making its first passage through the inner Solar System. The fact that it is a new Oort cloud comet explains its failure to brighten as quickly as first predicted. These sort of comet often appear relatively bright when far from the Sun because they still contain a large amount of very volatile ices. As the comet approaches the Sun, these ices sublimate and the comet brightens at a slower rate.
Even though we are only 10 days from perihelion, the comet’s peak brightness is still uncertain. The comet should be a 1st or 2nd magnitude object as it rounds the Sun near mid-month. The comet also becomes visible again from the Northern Hemisphere around that time though it will never stray far from the western horizon during evening twilight. Its low elevation and the bright evening sky will make the comet a difficult sight.
Finder charts can be found at Chasing Comets.
Ephemeris for C/2011 L4 (PANSTARRS) Date RA DEC Delta r Elong V 2013 Mar 01 23h 25m -27d 18' 1.111 0.411 21 2.5 2013 Mar 11 00h 25m -02d 52' 1.115 0.303 15 1.4 2013 Mar 21 00h 35m +19d 43' 1.186 0.444 21 2.9 2013 Mar 31 00h 31m +35d 14' 1.267 0.662 31 4.5 RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU r = distance from the Sun in AU, Elong = elongation from Sun in degrees V = Visual magnitude
C/2012 F6 (Lemmon)
Everyone was expecting C/2011 L4 (PANSTARRS) and C/2012 S1 (ISON) to be the two naked eye comets of 2013. No one was expecting C/2012 F6 (Lemmon) to be vying for the status of naked eye comet when it was discovered by Alex Gibbs of the Mount Lemmon survey back on March 23, 2012. At that time the comet was a faint 20th-21st magnitude and 5.0 AU from the Sun. It also appeared to be an intrinsically faint comet. So faint in fact that I though it had a good chance of disintegrating near perihelion. Instead the comet brightened at a rapid rate. Perihelion will occur on March 24, 2013 at a distance of 0.73 AU from the Sun.
Over the past few days visual observers have estimated the comet at magnitude 6.2 to 6.5.
The comet is too far south for most northern observers and the comet will continue to travel the southern sky this month. As a result, this comet will only be visible to southern observers till May.
Though the comet rapidly brightened for months after discovery, its rate of brightening has slowed down markedly. Observations at the end of February place it between magnitude 5.0 and 5.5. This month the comet should brighten some more up to magnitude ~4.7.
Finder charts can be found at Chasing Comets.
Ephemeris for C/2012 F6 (Lemmon) Date RA DEC Delta r Elong V 2013 Mar 01 00h 04m -51d 22' 1.167 0.867 46 4.9 2013 Mar 11 00h 08m -39d 10' 1.301 0.780 36 4.7 2013 Mar 21 00h 09m -29d 31' 1.430 0.735 28 4.7 2013 Mar 31 00h 10m -18d 46' 1.538 0.743 23 4.9 RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU r = distance from the Sun in AU, Elong = elongation from Sun in degrees V = Visual magnitude
Binocular Comets (V = 6.0 – 8.0)
None
Small Telescope Comets (V = 8.0 – 10.0)
C/2011 F1 (LINEAR)
No one has seen this comet for a few months because it has been too close to the Sun. Still it should have been seen by now yet it is still AWOL. Perhaps as it moves further from the glare of the Sun, it will be more easily spotted.
The LINEAR near-Earth asteroid survey picked up this comet back on March 17, 2011 at 18th magnitude. It passed perihelion on January 8 of this year at 1.82 AU from the Sun.
It is yet another comet that can only be seen from the Southern Hemisphere this month as it moves from Sagittarius to Microscopium.
Finder charts can be found at Chasing Comets.
Ephemeris for C/2011 F1 (LINEAR) Date RA DEC Delta r Elong V 2013 Mar 01 21h 18m -40d 51' 2.607 1.935 38 10? 2013 Mar 11 21h 54m -41d 55' 2.585 1.981 43 10? 2013 Mar 21 22h 29m -42d 39' 2.570 2.034 47 10? 2013 Mar 31 23h 05m -43d 03' 2.561 2.092 51 10? RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU r = distance from the Sun in AU, Elong = elongation from Sun in degrees V = Visual magnitude
The Transient Sky - Comets, Asteroids, Meteors 