APOD: Sweeping Through Southern Skies (2013 Feb 16)

[APOD Robot]

Sweeping Through Southern Skies

Explanation: For now, Comet Lemmon (C/2012 F6a), and Comet PanSTARRS (C/2011 L4) are sweeping through southern skies. Lemmon's lime green coma and thin tail are near the left edge of this telephoto scene, a single frame from a timelapse video (vimeo here) recorded on February 12, tracking its motion against the background stars. Comet Lemmon's path brought it close to the line-of-sight to prominent southern sky treasures the Small Magellanic Cloud and globular cluster 47 Tucanae (right). Sporting a broader, whitish tail, Comet PanSTARRS appears in later video frames moving through the faint constellation Microscopium. Visible in binoculars and small telescopes, both comets are getting brighter and headed toward northern skies in coming months.

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[Boomer12k]

Wondering through the sky. Like a dream...

Wonderful photo.

:---[===] *

[Ann]

I like the colors and "textures" of this image!

The Small Magellanic Cloud is blue and loose. 47 Tuc is like a heap of salt, white in color, densest in the middle and with grains of salt spread around the main concentration. Note the smaller globular, NGC 362, to the (slightly lower) right of the Small Magellanic Cloud. This globular looks even more concentrated than 47 Tuc, yet still slightly grainy.

The comet looks like a drop of clear green liquid, leaving a trail of blue-gray smoke behind.

Beautiful!

Ann

[LocalColor]

Looking forward to when the comets travel north.

[Boomer12k]

"Run, Run, Comet...." dunt ta dunta dunta dunnn, "Run, Run, Comet....Run until the break of DAAAAaaayyy!!! YEEEEAAAHHHHH!!!"

I am still working on it...

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[C.Garrison.White]

I suggest that ALL photos to be displayed on NASA sites [Astronomy Picture of the Day]
have a number/letter grid. Ex: 1-10 across, A-K [no I] up-down.

Then pinpointing items for the viewer would be clearer than "near the left side";
especially if the item has no outstanding features. Ex: Comet @ B2.

Thank-you, Garrison

[FloridaMike]

This year is turning out to be the most interesting year in Astronomy, ever!

[DavidLeodis]

Does anyone know over what time spans the timelapse video sections were recorded, as this does not seem to be given with the video in 'vimeo'. If they are in real time then that would surprise me that there would be such noticeable movements in so few seconds.

Edit added a little while after my initial post. In information with the video that I have now found in Alex Cherney's 'Terrastro' website it states "The video shows about 5 hours of comet Lemmon and an hour of comet PanSTARRS before the astronomical twilight", so I now have the answer. I probably should have checked that website before!

[Jacob]

I suggest that ALL photos to be displayed on NASA sites [Astronomy Picture of the Day]
have a number/letter grid. Ex: 1-10 across, A-K [no I] up-down.

Then pinpointing items for the viewer would be clearer than "near the left side";
especially if the item has no outstanding features. Ex: Comet @ B2.

Thank-you, Garrison

I like the format APoD sometimes uses of overlaying labels when the reader hovers their cursor over the image.

[StarCuriousAero]

Interesting comet-brightness graph I found today while looking for predicted brightness graphs of these two, looking forward to seeing something similar with Lemmon and PanSTARRS added, and maybe a comparison of predicted to actual magnitudes.
http://www.lesia.obspm.fr/perso/nicolas ... 2012s1.jpg

Found the brightness tracking so far through the "For now" link: http://www.aerith.net/comet/catalog/2012F6/2012F6.html

[Anthony Barreiro]

I'm catching up on a few days of apod's after being out in the boonies away from the internet leading a skywatching holiday weekend. This is a beautiful image! I love thinking about the relative distances and sizes of this comet, globular cluster, and dwarf galaxy, in relation to how they appear in the image. If Charles Messier were alive, he might say, "one out of three ain't bad." Or however you say that in French!

[Anthony Barreiro]

I like the colors and "textures" of this image!

The Small Magellanic Cloud is blue and loose. 47 Tuc is like a heap of salt, white in color, densest in the middle and with grains of salt spread around the main concentration. Note the smaller globular, NGC 362, to the (slightly lower) right of the Small Magellanic Cloud. This globular looks even more concentrated than 47 Tuc, yet still slightly grainy.

The comet looks like a drop of clear green liquid, leaving a trail of blue-gray smoke behind.

Beautiful!

Ann

47 Tuc looks too yellow to be salt. I would worry about what made the salt yellow! Are there mice in the pantry?

Thanks for pointing out NGC 362, I would have missed it otherwise. And what is the bright, slightly extended object that would make the upper left corner of a parallelogram with Comet Lemmon, NGC 362, and 47 Tuc? Is it just a bright foreground star?

[bystander]

The Year of the Comets: Three Reasons Why 2013 Could be the Best Ever
Universe Today | Bob King | 2013 Feb 19

2013 could turn out to be a comet bonanza. No fewer than three of these long-tailed beauties are expected to brighten to naked eye visibility.

• C/2011 L4 PanSTARRS
• C/2012 F6 Lemmon
• C/2012 S1 ISON

[neufer]

And what is the bright, slightly extended object that would make the upper left corner of a parallelogram with Comet Lemmon, NGC 362, and 47 Tuc? Is it just a bright foreground star?

<<Beta Hydri (β Hyi, β Hydri) is a star in the southern circumpolar constellation of Hydrus. (Note that Hydrus is not the same as Hydra.) With an apparent visual magnitude of 2.8, this is the brightest star the constellation. Based upon parallax measurements the distance to this star is about 24.33 light-years.

This star has about 108% of the mass of the Sun and 181% of the Sun's radius, with more than three times the Sun's luminosity. The spectrum of this star matches a stellar classification of G2 IV, with the luminosity class of 'IV' indicating this is a subgiant star. As such, it is a slightly more evolved star than the Sun, with the supply at its core becoming exhausted. It is the nearest subgiant star to the Sun and one of the oldest stars in the solar neighborhood. This star bears some resemblance to what the Sun may look like in the far distant future, making it an object of interest to astronomers.

At around 150 BC, this star was two degrees away from the southern celestial pole. It is currently the nearest relatively bright star to the southern pole.

In 2002 Endl et al. inferred the possible presence of an unseen companion orbiting Beta Hydri as hinted by radial velocity linear trend with a periodicity exceeding 20 years. A substellar object with minimum mass of 4 Jupiter masses and orbital separation of roughly 8 AUs could explain the observed trend. If confirmed, it would be a true Jupiter-analogue, though 4 times more massive. So far no planetary/substellar object has been certainly detected. These results were not confirmed in CES and HARPS measurements published on the arXiv in 2012. Instead the long-term radial velocity variations may be caused by the star's magnetic cycle.>>