2014 AA has impacted Earth on Jan. 02

UPDATE JAN. 04: http://neo.jpl.nasa.gov/news/news182a.html

Peter Brown (University of Western Ontario) and Petrus Jenniskens (SETI Institute) searched the data from low frequency infrasound observation sites of the Comprehensive Nuclear-Test-Ban Treaty Organization. They found weak signals from stations in Bolivia, Brazil and Bermuda that indicated that the likely impact location was indeed positioned within the predicted impact area. The location of impact, marked with a red dot in the image below, is still somewhat uncertain due to observational factors, including atmospheric effects upon the propagation of infrasound signals (low frequency sound waves due to atmospheric explosions).
This impact information is preliminary and has uncertainties of perhaps a few hundred kilometers in impact location and tens of minutes in impact time.

2014aa_imploc

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2014 has began in a particular way: the first asteroid that received a designation this year, 2014 AA, has impacted Earth on 2014, Jan. 02.2.
On Jan. 01.26 Richard Kowalski, from Catalina Sky Survey, discovered a possible NEO with the 1.5-m f/2 telescope located on Mount Lemmon. It received the temporary designation VA9A092 and the Minor Planet Center posted it on the NEO Confirmation Page.
Below we can see the discovery animation (courtesy of CSS/NASA):

2014AA-Catalina
It received no other confirmations, though, and the following day (Jan. 02 @ 13.08 UT) MPEC 2014-A02 was issued, with the discovery observations, the preliminary orbit (70 minutes arc), the ephemerides and a note in the bottom of the circular:

“It is virtually certain that 2014 AA hit the Earth’s atmosphere on 2014 Jan. 2.2 +/- 0.4, as demonstrated by independent calculations by Bill Gray, the MPC and Steve Chesley (JPL). According to Chesley, the impact locations are widely distributed, most likely falling on an arc extending from Central America to East Africa, with a best-fit location just off the coast of West Africa on Jan. 2.10. 2014 AA was unlikely to have survived atmospheric entry intact, as it was comparable in size to 2008 TC3, the only other example of an impacting object observed prior to atmospheric entry.”

Bill Gray provided through MPML two maps of the possible impact region:

impact2impact3
Then Pasquale Tricarico, Senior Scientist at the Planetary Science Institute in Tucson, published an animation showing the Earth as observed from the asteroid using the nominal orbit solution. The asteroid approaches the Earth from the night side, and enters Earth’s shadow cone at approximately 01:45 UT of January 2, approximately 40 minutes before entering the Earth’s atmosphere:

2014AA

It is worthy to note that Richard Kowalski, with the same telescope, already discovered the 3-4 meter asteroid 2008 TC3, which impacted the Earth on 2008, Oct. 7 in a desertic region in Sudan.

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Discovery of cometary nature of 2013 EW90

2013 EW90 was discovered by the Tenagra survey (located near Nogales, AZ, U.S.A.) on images taken by M. Schwartz and P. R. Holvorcem with a 0.41-m f/3.75 reflector on 2013, Mar. 3. Its Tj parameter is 2.75, so it was a good T3 candidate.
Hidetaka Sato remotely observed it on 2013 Apr. 30.15 using a 0.51-m f/4.5 reflector from iTelescope, Mayhill (MPC H06), finding a softer aspect respect to stars (FWHM 4.3″ vs 3.3″) and a coma up to 18″ wide on a stack of 10 x 60 seconds images. He observed it again on May 02.17 with the same telescope/site, finding a 12″ coma on a stack of 6 x 120 seconds images, and FWHM of 5.1″ respect to 3.4″ of stars.
Following his alert to the T3 mailing-list, I asked for some confirmations, which came as following.
L. Buzzi, on behalf of the IASC team (P. Miller, P. Roche, A. Tripp, R. Miles, R. Holmes, S. Foglia, L. Buzzi, T. Vorobjov, T. Lister) obtained 6 x 180 seconds images on May. 03.42-43 in good seeing with the 2.0-m f/10 Faulkes Telescope North from Haleakala. All the images were stacked and measured by himself and S. Foglia, finding a clear cometary aspect, with a diffuse coma at least 5″ wide.
L. Buzzi obtained two night of observations from Schiaparelli Observatory (MPC 204) with a 0.60-m f/4.64 reflector. On the first night (May. 04.90-92) a stack of images totalling 43 minutes of exposure time, 2013 EW90 appears clearly softer respect to stars, with a FWHM about 25% larger and a round 11-12″ coma. On the second night (May. 06.85-89) a stack of images totalling 48 minutes of exposure time in slightly better seeing, the object appears again softer respect to stars, with a FWHM 15-20% larger than stars nearby and a 9″ coma with no tail.
T. Lister, Las Cumbres Observatory Global Telescope Network, obtained 9 x 300 seconds images with the 1.0-m f/8 Ritchey-Chretien from LCOGT Node at McDonald Observatory. All the images were stacked and measured by L. Buzzi, S. Foglia and himself, finding a FWHM more than double respect to stars (3.2″ vs 1.4″) and a 5″ coma.
CBAT released CBET 3522 (subscription required) on May 13; all the observations can be found on MPEC 2013-J52.

Below is the first detection made by H. Sato on Apr. 30:

2013EW90_20130430_H06Then another image taken on May 02, with the profiles:

2013EW90-image_20130502_H062013EW90_20130502_H06This is my confirmation obtained with the 2.0-m FTN, in which it’s clear its diffuse aspect respect to stars:

2013EW90_20130503_F65Below are my own FWHM profiles from May. 04 and 06:

2013EW90_20130504_2042013EW90_20130506_204And here is the aspect of the comet with the LCOGT 1.0-m f/8 from McDonald Observatory:

2013EW90_20130507_711

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Discovery of cometary nature of 2013 EV9

2013 EV9 was discovered by the Spacewatch survey on images taken by T. H. Bressi with the Spacewatch 0.90-m f/3 reflector (+ CCD mosaic) on 2013, Mar. 2. Its Tj parameter is 2.77, so it was a good T3 candidate.
Hidetaka Sato remotely observed it on 2013 Apr. 28.42 using a 0.51-m f/4.5 reflector from iTelescope, Siding Spring (MPC Q62), finding a softer aspect respect to stars (FWHM 4.8″ vs 3.6″-3.8″) and a small coma on a stack of 10 x 60 seconds images. On the following night (Apr. 29.16) he observed it again remotely with the same instrumentation but located near Mayhill (MPC H06), finding the FWHM to be 4.0″ respect to 3.3″ for the stars, with a compact coma 6-8″ wide in a stack of 10 x 60 seconds. Following his alert to the T3 mailing-list, I asked for some confirmations, which came as following.
Tomas Vorobjov observed it on two nights (Apr. 29.17-21 and Apr. 30.17-27) using the 1.3-m f/13 Western Kentucky University reflector at Kitt Peak. On the first night, stacking 18 x 120 seconds images, he found a coma 5″ across and a hint of tail in PA 120 degrees. On the second night, a stack of 54 x 120 seconds reveals a coma 5″ x 5″ and a tail 15″ long in PA 120 degrees.
Bill Ryan, Magdalena Ridge Observatory, obtained a set of images with the 2.4-m f/8.9 reflector on May 01.21. A stack of 4 x 60 seconds images measured by L. Buzzi, S. Foglia and himself shows a FWHM 50% larger than stars nearby (2.8″ vs 1.8″) with a coma 10″ wide, clearly extended to the south-east.
A stack of 31 x 75 seconds images obtained on May 01.12-14 by R. Holmes, Astronomical Research Institute, with a 0.76-m f/4 astrograph, and measured by L. Buzzi, S. Foglia and T. Vorobjov shows clearly a softer aspect respect to stars, with a 15″ coma elongated to the south-east.
Americo Watkins obtained remotely a set of images with the Mt.Lemmon 0.81-m f/7 reflector as part of the Sierra Stars Observatory Network, on Apr. 30.13-14. A stack of 8 x 60 seconds images measured by himself and L. Buzzi shows a 6″ x 5″ coma extended to the east.
CBAT released CBET 3503 (subscription required) on May 2; all the observations can be found on MPEC 2013-J10.
This is the first image of the discovery, made by Hidetaka Sato using iTelescope:

2013EV9_20130428_Q62
T. Vorobjov’s image from Kitt Peak:

2013EV9_20130430_695
W.H. Ryan image and FWHM profiles from MRO:

2013EV9_20130501_H01H01-profilesR. Holmes profiles from his 0.76-m f/4 – ARI:

H21-profilesA. Watkins’s image and profiles from Mt.Lemmon SkyCenter – SSON:

2013EV9_20130430_G84G84-profiles

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Discovery of cometary nature of 2012 OP

2012 OP was originally discovered as a minor planet by R.H. McNaught using the Uppsala 0.5-m Schmidt from Siding Spring Survey on 2012 Jul. 16.62, when it was at mag. 20V. It was also a T3 candidate because of is Tj parameter (-0.98).
It was observed by other southern observatories for 2 months, then it was “lost” in the solar conjunction (2012 Dec. 4).
It was recovered by Hidetaka Sato on 2013, Mar. 20 using remotely a 0.51-m f/6.8 reflector from iTelescope Observatory, Siding Spring (MPC Q62), then it was observed again by himself on Apr. 9 and 11 remotely from iTelescope Observatory, Mayhill (MPC H06) with the same instrumentation.
Hidetaka sent an alert to the T3 mailing-list noting its apparent cometary feature (FWHM larger than stars nearby). After his alert, I successfully observed it from Schiaparelli Observatory on Apr. 15 with a 0.60-m f/4.64 reflector, and I could confirm what Hidetaka found. In a stack of images totalling 30 minutes of exposure time in good conditions, it had a FWHM profile about 20% larger than stars nearby (4.1″ vs 3.4″), but I knew I had to request the attention of a larger telescope…
In the meantime, Minor Planet Center issued 2012 OP recovery with MPEC 2013-H12 on Apr. 17.
On behalf of a larger collaboration I have with IASC team (composed of P. Miller, P. Roche, A. Tripp, R. Miles, R. Holmes, S. Foglia, T. Vorobjov, T. Lister, E. Gomez and myself) I managed to observe it on Apr. 19.48-49 with the 2.0-m f/10 Faulkes Telescope North: a stack of 14×60 seconds images reveals a softer aspect respect to stars, with a coma at least 4″ wide possibly elongated toward the west.
I then alerted both Tim Lister from LCOGT and Bill Ryan from Magdalena Ridge Observatory.
A stack of images taken by Tim with one of their 1.0-m f/8 telescopes from Cerro Tololo (MPC W85) revelaed a clear larger profile respect to stars (2.1″ vs 1.5″), but the definitive evidence came from the terrific images taken by Bill with the MRO 2.4-m f/8.9 reflector. Even in single images a coma and a tail was visible, and a stack of 10×60 seconds images shows a strong central condensation with a 10″ coma and a broad tail 20″ long centered in PA about 250°.
CBAT then issued CBET 3486 (subscription required), though not including all the people involved, on Apr. 23 with the discovery of the cometary nature of this unusual minor planet, again a proof of how fruitful a pro-am collaboration can be. All the astrometry from the discovery until now can be seen on MPEC 2013-H36.
Below the various images/profiles:

2012OP_20130409_H06(FWHM profiles from H. Sato from Q62, 2013 Apr. 9, larger profile but low SNR)

2012OP_20130415_204(my own profiles on Apr. 15, evidence of a larger FWHM)

2012OP_20130418_W85(T. Lister images from W85, 1.0-m f/8 reflector, here the evidence is much clear)

2012OP_20130419_F65(FTN image, 14x60seconds, softer aspect and evidence of a coma toward the south-west)

2012OP_20130422_H01(the definitve confirmation images from Magdalena Ridge Observatory 2.4-m telescope, each frame is a 5×60 seconds, 0.48″/px resolution. Many thanks to the kindness of Bill Ryan).

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2012 DA14 close approach

2012 DA14 was discovered on 2012, Feb. 23 by La Sagra Sky Survey in Spain using a 0.45-m f/2.8 telescope, and the discovery was issued on MPEC 2012-D51. Soon it was clear that it would have passed very close to Earth almost exactly one year after the discovery, and so it was.
On 2013, Feb. 15 around 19.30 UT it reached perigee at a distance of about 27.700 km from the surface of the Earth (0.09 LD), well inside the belt of geosyncronous satellites but with no risk of collisions given its orbit.
The asteroid has an estimated diameter of about 40 meters, and it is currently the biggest asteroid passed so close to the Earth: other objects passed closer, but they were smaller.

2012DA14_orbit

Despite some clouds interfered with the observations, we were able to catch it at 21.21 UT, when it was in constellation Ursa Major (the Big Dipper) at a distance of 59,000 km and moving at 1084″/min in PA around 6.0°.
The 60-sec image, visible below, was taken with a Pentax 75mm refractor f/6.7 and a CCD SBIG ST8-XME (FOV approx 90′ x 60′). The beginning of the trail (bottom) has the following coordinates: RA 12h 31m 25s – DEC +52° 16′ 50″.

2012DA14_1
After one hour I also imaged it with a 0.38-m f/6.8 reflector and the same CCD, giving a FOV of (only) 18′ x 12′. The asteroid had half the speed of the previous image (576″/min).
Here the beginning of the trail (bottom) has the following coordinates: RA 12h 44m 31s – DEC +67° 11′ 26″.

2012DA14_2

During the close approach 2012 DA14 was observed with the 70-m DSN antenna at Goldstone; the result was this interesting movie:

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Parallax experiment on (Y5705) 2006 VB14

For a work with a student here at Schiaparelli Observatory I decided to determine the distance of an asteroid by parallax, a good educational experiment.
Even with NEOs, it will be good to have the longest possible baseline, so I’ve asked the help of Robert Holmes from ARI Observatory, Illinois, USA (H21).
I chose NEO (Y5705) 2006 VB14, bright and of course visible at the same time from both observatories.
On 2012, Dec. 11 the sky was clear from both locations so we exposed the field for nearly half an hour with different exposure times to maximize the number of frames with the same exposure time. In the end I found several images taken at the exact second and I started to do the calculation of parallax.
Using Astrometrica I precisely determined the RA & DEC position of the asteroid on both images. Just an example from an image taken at 23.46.50 UT:

From 204: 02h 40m 18.83s – +26° 43′ 45.3″
From H21: 02h 40m 25.54s – +26° 43′ 52.5″

The parallax measured is 89” (+/- 1”).
To determine the effective distance between the two locations I’ve used the following formula:

cos (d) = sen (lat1) * sen (lat2) + cos (lat1) * cos (lat2) * cos (dlong)

where d is the angle between the observatories, lat1 is the latitude of 204, lat2 the latitude of H21 and dlong is the difference in longitude. Coordinates are the following:

204 – Schiaparelli
LAT1: 45° 52′ 04” N (45.86778° N)  -  LONG1: 08° 46′ 15” E (8.77083° E)
H21 – ARI
LAT2: 39° 27′ 20” N (39.45556° N)  -  LONG2: 87° 59′ 49” W (87.99694° W)

so d is 66.87440°

To have the distance D in km:

D = 2 * r * sin (d/2)

where r is the radius of the Earth and d the angle in degrees.

The result is 7,029 km.

Then, the distance of the asteroid (assuming the angle between the baseline and the bisector is 90°):

ASTD = D/tang (p)

where p is the parallax in degrees.

The final result was 16.290.000 km, in very good agreement (difference of only 0.77%) with the orbital distance (16.165.000 km).

Below you can find the image:

Parallax_Y5705

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New comet C/2012 X1 (LINEAR)

C/2012 X1 (LINEAR) was discovered by the LINEAR survey using a 1.0-m f/2.15 reflector from Socorro, NM, USA, on Dec. 08.38. Their automatic routines do not require human intervention, so it was reported as asteroidal and posted in the NEO Confirmation Pageunder the temporary designation CE63887.
I was able to image it the following night with a 0.38-m f/6.8 reflector. Visually (i.e. on the screen) it appeared slightly diffuse respect to stars, and the analysis with the “FWHM method” clearly revealed its nature: profile 30% larger than stars nearby, and a coma 8″ wide.
This is again a demonstration of how good is the FWHM method (used largely in our T3 project) in discerning comets among asteroids.
Many other observatories detected it, and results were published in CBET 3340 (subscription required) and astrometry, together with preliminary parabolic orbital elements, in MPEC 2012-X70.
204 image (and FWHM boxes):

C2012X1_20121209_buzzi204

C2012X1_20121209_boxes

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