Saturday, November 04, 2017
Comet 96P/Machholz zooms past the sun
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| Single image of comet 96P Machholz from the SOHO LASCO C3 instrument on 27 October 2017. Click on any image to embiggen | Composte series of images as the comet swung around the sun fro 26-28 October. The gap is where some images were not taken | Animation of the same series. |
Comet 96P/Machholz came to perihelion on October 27, unfortunately, it was too close to the sun for us Earth-bound observers, but fortunately a bevy of sun-observing spacecraft watched intently as it passed by. It was picked up by the Solar and Heliospheric Observatory (SOHO) and the Solar TErrestrial RElations Observatory Ahead (STEREO-A) spacecraft.
Two of these fragments had been seen in the 2012 passage of the comet, the third was new.
You can read about the background to the comet, other observations and its fragmentation in far more detail at the excellent skyhunt blog (go now, you won't be disappointed, I'll wait).
I won't try and duplicate Trygve Prestgard's excellent work,I will just presnt my images from the STEREO spacecraft where I hunted for the fragments. Despite high resolution COR2A images, I found no fragments.
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| Comet 99P Macholz in the STEREO COR2 Imager on 26 October | Animation of 26 October images, note tail movement |
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| Single image of STEREO COR2A from 28 October, 2017 | Animation of 28 October images |
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| Comet 96P Machholz in the STEREO H1A imager on 23 October (right down the bottom left) click to emggen | Animation of the comets brief sojourn in the H1A imager field of view |
Labels: comet, comet 96P Machholz stereo astronomy, Soho, Stereo astronomy
Thursday, April 04, 2013
A Sundiving Comet Meets its End (27-03-13)
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| Sundiving Kreutz comet captured in the STEREO COR2A instrument at 04:54 UT (click to embiggen) | Same comet captured in the SOHO Lasco C2 instrument at 05:00 UT |
While all eyes are on the spectacle of comet C/2011 L4 PanSTARRS (and rightly so), there is a lot of other cometary action out there. The STEREO and SOHO spacecraft recently caught a bright Kreutz comet on its final plunge into the Sun.
The comet evaporates before it reaches the occulting disks of the respective spacecraft imagers. The comet approaches from diffent quadrants of the imagers because of the spacecraft's different orbits. In the SOHO images the bright object bottom right is Venus, the long bright horizontal spike is an imaging artefact. Venus is not Visible from STEREO COR2A.
Animation of the comet in STEREO COR2A. Images stacked, cropped and animated using ImageJ.
Animation of the comet in SOHO Lasco C2. Images processed as above.
Labels: comet, Soho, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Saturday, March 23, 2013
Comet PanSTARRS Does Not Dodge a Coronal Mass Ejection
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| Comet C/2011 L4 PanSTARRS on 15 March, 2013 as seen from the STEREO H1B imager showing the comet and a billowing Coronal Mass Ejection. It looks like the CME just misses the comet, but this is an illusion due to the spacecraft's perspective, the comet and CME are nowhere near each other. Click to Embiggen. | Location of the comet in respect to the Earth and the STEREO B spacecraft simulated in Celestia (click to embiggen). My STEREO orbit files are a little old, so it's position is not exact, but it's not very different from the real position. The CME of 15 March was Earth directed and I've indicated it on the chart. You can see it goes nowhere near the comet. |
There is a stunning video from the Sungrazer Comets group that shows comet C/2011 L4 PanSTARRS for the 9th to the 16th as it passes through the field of view of the SETREO B spacecraft's H1 imager. On the 15th, there was a large coronal mass ejection which produced lots of aurora here on Earth on the 17th and 18th. You can see the comet glide past the CME in stunning detail in the video (my less awesome effort is below).
Some commentators on the video around the web are saying the comet "dodged the CME" (in the sense that it just missed the comet). But that,s an illusion of perspective. The spacecraft is is almost behind the Sun from the Spacecrafts perspective looking back at Earth. The CME was Earth directed. fanning out to be sure but faning AWAY from the spacecraft. And the comet, which is above the plane of the Sun (not shown in the Celestia perspective) and over 90 degrees away from the CME Earth axis.
Occasionally someone will claim that comets cause CME's so it's useful to try and think about the geometry and timing of these events. In this case, the CME occurred 5 days after the closest approach to the Sun, and was directed away from the comet.
Labels: animation, celestia, comet, comets, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Sunday, March 17, 2013
Comet C/2011 PanSTARRS in STEREO, 13-14 March 2013
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Comet C/2011 L4 PanSTARRS from 18:29 UT on 13 March. A Coronal Mass Ejection is billowing out tworads the comet. The bright object to the upper right is Earth, the vertical spikes image artefacts. Click to embiggen. Image credit NASA/STEREO | An image from earlier in the sequences from the H1B imager I've used the difference method in ImageJ to enhance the dust features in the tail, the CME and the ion spikes. Thanks CometAl for the suggestion Click to embiggen |
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| C/2011 L4 PanSTARRS on the 14th. Click to embiggen. Getting the dust stream brightness balance is not easy. | A blast from the past, this is comet C/2006 P1 McNaught, the most impressive comet we've had in a long time, as seen in the H1B imager. It also had impressive dust steamers. |
Previous images are here and here.
Here's a YouTube Animation for the 13th.
And another for the 14th.
Labels: comet, Comet Al, comets, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Thursday, March 14, 2013
Comet C/2011 PanSTARRS in STEREO, 11 March 2013
Comet C/2011 L4 PanSTARRS from 23:29 UT on 11 March, high resolution images from the STEREO Behind H1 imager. The image has been inverted to make the faint tails clearer. Image stretched in ImageJ after background subtraction. Contrast enhanced to make details in the dust tail clear at the expense of the intensity of the ion tail. The long straight lines (and apparent holes in the comets tail) are imaging artefacts. Click to embiggen.
In this image you can see the detail in the main dust tail (Compare to yesterdays image here), as well there is the ion tail to the right, and what may be a large particle tail to the left. In order to bring out the detail in the main dust tail I've had to make the ion and other tail dimmer.
The broad conical fan of dust looks quite beautiful, If I get figure out a more clever way of bringing out the detail in the main dust tail while keeping the side tails, this will look really good.
Here's a YouTube Animation (the animated GIF was just too big). The colours have also been inverted.
Labels: comet, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Wednesday, March 13, 2013
Comet C/2011 PanSTARRS in STEREO, 9-10 March 2013
Comet C/2011 L4 PanSTARRS from 20:49 UT on 10 March, high resolution images from the STEREO Behind H1 imager. The image has been inverted to make the faint tails clearer. Image stretched in FITS liberator after background subtraction in ImageJ. Click to embiggen.
Finally downloaded the high resolution images. (Yes Daniel, I know Karl Battams did it better earlier). In this image you can see the complex tails of the comet. (Compare to the beacon images here and here, although Messier hunter did a good job cleaning them up here).
There are at least thee tails visible (see here for a more detailed processed image from the STEREO group that shows the tails more clearly).
There has been a lot of discussion on the STEREOHUNTERS group of what the tails consist of, the thin far right-hand tail that is pointing directly at the Sun might be something like iron (Fe) ions blasted off the surface of the comet, something similar was seen with comet McNaught. It may also be CO+ or H2O+ (or perhaps a combination). It's unlikely to be sodium ions due to the wavelength sensitivity of the H1 behind imager.
The dark, broad conical fan is the dust tail, and the shorter tail on the left with the fainter fan connecting to the broad fan may be large dust particles.
Here's a YouTube Animation (the animated GIF was just too big). The colours have also been inverted.
Labels: comet, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Tuesday, March 12, 2013
Update on Comet PanSTARRS in STEREO
Comet C/2011 L4 PanSTARRS captured in the low resolution beacon images for the STEREO Behind H1 imager.
Still waiting to download the high resolution images, but this expanded set of beacon images you can distinguish between the image artefact spike and the dust tail (the spike is the straightish line, the broad fan of the dust tail sweeps off to the right, compare to yesterdays set).
Also in the image is Mercury (up close to the Sun) and Earth (the bright dot centre right).
Here's another animated GIF. There is a better one at the STEREO site.
Labels: comet, Stereo astronomy, Stereo comet astronomy, Stereo Satellite
Friday, March 01, 2013
Further Updates on the Potential Impact of C/2013 A1 (Siding Spring), it gets closer and watching it in STEREO
Events are moving rapidly in the story of C/2013 A1 Siding Spring and its close approach to Mars in 2014.
Leonid Elenin and the ISON team have made new measurements of the comets position, the refined orbit brings it to within 41,000 Km from Mars (we still can't exclude an impact yet though).
Talk about luck, Astroswanny notes that the Mars atmospheric analysis orbiter MAVEN arrives a few days before the comets closest approach.
While the close approach can be seen with telescopes, if you don't have a telescope then you can watch the event in the STEREO H2A instrument.
Hopefully I can get some images of the comet over the next few days and contribute to the effort of making its orbit more accurate.
Leonid Elenin and the ISON team have made new measurements of the comets position, the refined orbit brings it to within 41,000 Km from Mars (we still can't exclude an impact yet though).
Talk about luck, Astroswanny notes that the Mars atmospheric analysis orbiter MAVEN arrives a few days before the comets closest approach.
While the close approach can be seen with telescopes, if you don't have a telescope then you can watch the event in the STEREO H2A instrument.
Hopefully I can get some images of the comet over the next few days and contribute to the effort of making its orbit more accurate.
Labels: comet, impact, Mars, NEO, public outreach, Stereo astronomy, Stereo Satellite
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