APOD: Comet ISON from STEREO (2013 Nov 23)

[alter-ego]

What is the object, almost directly above the last digit (the # 1) in the time - moving slower than the background stars but moving in the same direction as the Comets, in the direction of the Sun?

Comet Lovejoy : http://asterisk.apod.com/viewtopic.php? ... 97#p214454

Lovejoy is a logical guess, but it is not in the Stereo A APOD Field of View at all. Even in the earlier top-view diagrams Lovejoy is the leftmost object relative to ISON, Mercury, Encke and Earth.
The object in question is fairly bright amongst the stars (limiting magnitude ≈ +11), and assuming it was real, I thought I'd look for just what object it was. Interestingly, I found no asteroid or comet candidate from a total minor planet database collection of about 12,000 objects (234 comets, 10,265 NEAs, and 1426 PHAs).

Click to view full size image 1 or image 2

In the first image, I show the position of the object in question, asteroid 2007 TC66 which is the closest possibility (but has an apparent magnitude of ~+21), and 6063 Jason (1984KB) which is the brightest asteroid candidate in the field (~+17.7). The position differences from the unknown object are significant as well as their apparent brightnesses.
In the overlay image an arrow points to the unknown object which can be seen moving wrt the stars in the APOD video.

What is this object?
It is bright enough that, if it's real, I'd expect it to be in the data base(s) - unless it is a new object Could it be an optical artifact originating from one of the excessively bright subjects, Earth or Mercury? Maybe, but it's position wrt these bright objects is not constant. I'd expect it would be because the planets are at a fixed position wrt the image. Lastly, the objects drift wrt the stars is directly in line with hundreds of other further away asteroids. My conclusion? I don't think this object is an artifact. I'll bet it's a new object or a known one that's not in the minor planet data base yet.

[geckzilla]

It's not the other STEREO craft or any other artificial object, is it?

[neufer]

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It's not the other STEREO craft
or any other artificial object, is it?

• Not the other [BEHIND] STEREO craft.

<<This figure plots the December 1, 2013 positions of the STEREO Ahead (red) and Behind (blue) spacecraft relative to the Sun (yellow) and Earth (green). The dotted lines show the angular displacement from the Sun. Units are in A.U.>>

[neufer]

Click to view full size image 1 or image 2

What is the [November 21] object, almost directly above the last digit (the # 1) in the time - moving slower than the background stars but moving in the same direction as the Comets, in the direction of the Sun?

Comet Lovejoy : http://asterisk.apod.com/viewtopic.php? ... 97#p214454

Lovejoy is a logical guess, but it is not in the Stereo A APOD Field of View at all. Even in the earlier top-view diagrams Lovejoy is the leftmost object relative to ISON, Mercury, Encke and Earth.

The object in question is fairly bright amongst the stars (limiting magnitude ≈ +11), and assuming it was real, I thought I'd look for just what object it was. Interestingly, I found no asteroid or comet candidate from a total minor planet database collection of about 12,000 objects (234 comets, 10,265 NEAs, and 1426 PHAs).

ARTifact left over from running caption

7 meg gif file.
Nov. 10-14, 2013 processed images from STEREO-A's HI2 imager.
Running difference imaging in which each image is subtracted
from the one following it. This makes it easier to see faint changes.

<<Four comets are now visible in STEREO-A's Heliospheric Imager 2, although you'll have to look very closely to see them all! If you look carefully enough you can see comets ISON, Lovejoy, Encke, and now Nevski. These movies were supplied by Alan Watson, one of a group of amateur comet watchers accessing data from STEREO and SOHO.

Processed images from STEREO-A's HI2 imager, with labels showing the approximate locations of comets ISON, Lovjoy, Encke, and Nevsky from Nov. 10-14, 2013. The comets are faint and can be seen moving against the stationary field of stars. The frames are run forwards and then backwards in time to make the comets easier to spot. Also in the movie is M45 (the Pleiades star cluster). The bright features with the vertical lines through them are planets. The Sun is out of the field of view to the right and a coronal mass ejection (CME) can be seen moving through the images.>>

[neufer]

MESSENGER Mission News
November 14, 2013

<<On November 18, just a few days shy of its perihelion on November 21, Encke will travel within 3.7 million kilometers of Mercury. According to the Minor Planet Center, if Encke came this close to Earth, it would rank as the third closest known approach of a comet to our planet. On November 19, ISON will pass within 36.2 million kilometers of Mercury while at a distance of 71 million kilometers from the Sun.

"By next week, we expect Encke to brighten by approximately a factor of 200 as seen from Mercury, and ISON by a factor of 15 or more," Vervack said. "So we have high hopes for better images and data." Three of MESSENGER's instruments -- MDIS, the Mercury Atmospheric and Surface Composition Spectrometer, and the X-Ray Spectrometer -- will be trained on the two comets and will collect as many observations as payload operational constraints will allow.>>

[b][color=#0000FF]On November 18, NASA's Mercury-orbiting MESSENGER spacecraft pointed its Mercury Dual Imaging System (MDIS) at 2P/Encke and captured this image of the comet as it sped within 3.7 million kilometers of Mercury's surface.[/color][/b]

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[b][color=#0000FF] The next day, the probe captured this companion image of C/2012 S1 (ISON), as it cruised by Mercury at a distance of 36.2 million kilometers on its way to its late-November closest approach to the Sun.[/color][/b]

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<<MESSENGER's cameras have been acquiring targeted observations of Encke since October 28 and ISON since October 26, although the first faint detections didn't come until early November. During the closest approach of each comet to Mercury, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) and X-Ray Spectrometer (XRS) instruments also targeted the comets. Observations of ISON conclude on November 26, when the comet passes too close to the Sun, but MESSENGER will continue to monitor Encke with both the imagers and spectrometers through early December.

The spacecraft has a view of the comets very different from that of Earth-based observers. "MESSENGER imaged Encke only a few days before its perihelion when it was at its brightest," explains Ron Vervack, of the Johns Hopkins University Applied Physics Laboratory, who is leading MESSENGER's comet-observation campaign. "That we are so close to the comet at this time offers a chance to make important observations that could shed light on its asymmetric behavior about perihelion."

In contrast, ISON did not pass as close to Mercury, but the comet was between the Earth and Mercury when it passed closest to MESSENGER. "We saw the side opposite to that visible from Earth," says Vervack, "so our images and spectra are complementary to observations from Earth made at the same time and could aid in understanding the variable activity of the comet as it approached the Sun."

On the day that Encke was closest to Mercury, the MDIS wide-angle camera scanned the comet with all of its 12 filters while the instrument's narrow-angle camera (NAC) snapped images of the rotating comet every 10 minutes to capture a full 360-degree view. The imaging campaign for ISON was similar, with the NAC capturing a series of stills every 30 minutes.

Several ground- and space-based NASA observatories, as well as many other observatories around the world, are collecting data on the comets. However, none will be able to collect simultaneous images and spectra from X-ray through near-infrared wavelengths when the comets are so close to the Sun, as will MESSENGER. Vervack expects MESSENGER to gather 15 hours worth of data on Encke and another 25 hours on ISON. "These observations of Encke and ISON fill a gap in heliocentric coverage to which most other observatories don’t have access," Vervack says.

Scientists are still combing through the data collected by MASCS, but there are already confirmed detections of several molecules and atoms, including OH, NH, CS, oxygen, carbon, sulfur, and hydrogen. "Far-ultraviolet observations can't be made from ground-based observatories, and only a few instruments in space have been able to look at the comets in the ultraviolet," says Vervack. "The MASCS observations are therefore of great interest." Scientists were also hoping to obtain the first definitive detections of cometary X-ray emission from silicon, magnesium, and aluminum. "NASA's Chandra X-ray space telescope has observed ISON and Encke and seen X-ray emission from them both," Vervack says. "We are able to make these observations when both comets are closer to the Sun, so the X-ray emissions have the potential to be much more intense." However, a series of large solar flares during the observations increased the contaminating background in the X-ray spectra and have complicated the analysis. "We can't help what the Sun does," says Vervack, "but we're going to analyze the data carefully to see if there are any detections to be had."

Taken together, the MESSENGER observations offer a varied science investigation of the comets. "Whereas the MDIS images will provide a global picture of the comet coma morphology, MASCS observations will inform us about the composition of the cometary ices and XRS may be able to tell us what the dust is made of," Vervack says. "Comet encounters were not considered when the MESSENGER mission was designed," adds MESSENGER Principal Investigator Sean Solomon of Columbia University. "If Encke and ISON share a few of their secrets on the formation and evolution of the Solar System, the MESSENGER team will be delighted with the scientific bonus.">>

[Nitpicker]

I'm sorry, but I don't follow. Has the object first mentioned by astrocrazythings been convincingly identified?

[neufer]

I'm sorry, but I don't follow. Has the object first mentioned by astrocrazythings been convincingly identified?

Nope.

[Nitpicker]

I'm sorry, but I don't follow. Has the object first mentioned by astrocrazythings been convincingly identified?

Nope.

How interesting! Whatever it is, I'm hoping it gets the name "astrocrazything".

[alter-ego]

I'm sorry, but I don't follow. Has the object first mentioned by astrocrazythings been convincingly identified?

Nope.

How interesting! Whatever it is, I'm hoping it gets the name "astrocrazything".

I have a asteroid candidate for that object.
Earlier, I reviewed a combination of small-body data bases amounting to ~15,000 objects without luck Today on a whim, I looked at a data base of "numbered" small bodies. This was an astounding 92,186 objects. The region of interest was so populated with so many objects, I could hardly make out stars. HOWEVER, as I drew closer to the target position, I was surprised to FINALLY see one object hit the mark: It is Asteroid 216 (Kleopatra). This asteroid does exist in another data base, but it didn't show up then - I don't know why.

Click to view full size image 1 or image 2

Horizons lists Kleopatra as having an apparent magnitude of ~11.8 from Stereo A, and Horizon's apparent RA/Dec is within 0.1° of my coordinate estimate from the APOD. Also, the limiting magnitude of 11⁺ magnitudes is pretty close to the estimated apparent magnitude of Kleopatra. Although I was expecting a brighter object (~10 to 11), I believe the uncertainties of magnitude estimates are large enough to have Kleopatra show up in STEREO A's picture.

I think Kleopatra is the Unidentified Space Object (USO) in the APOD.

[Ann]

Thanks for identifying it for us, alter-ego! That's so well done!

Ann

[alter-ego]

Thanks for identifying it for us, alter-ego! That's so well done!

Ann

Thank you, Ann.
Sometimes I think it's a curse that I do kind of thing. But I love the challenge of understanding what I experience. APOD puzzles are high on my list and there are many that I do that I don't post about because the discussion does not lend itself to do so.

I happen to love egg-nog lattes. I make my own. You should see my spreadsheet with weekly calorie intake estimates as well as a predictor to tell me how long my remaining egg nog will last

That's the curse again...

[Nitpicker]

I think Kleopatra is the Unidentified Space Object (USO) in the APOD.

Excellent work!