Friday 27 February 2015

OT: another update on NEA 2015 CA40

Our Near Earth Asteroid discovery (see earlier post) 2015 CA40 is now past it's point of closest approach. It reached that point, at 6.3 lunar distances, on Feb 23 near 21:49 UT.

The animated GIF above shows the asteroid early on Feb 24, about 12 hours after closest approach, imaged with the 0.61-m F/10 Cassegrain of MPC G68 Sierra Stars Observatory in California, USA. The animation is made from 6 images taken over a 10-minute timespan. Each image was 30 second exposure, and the images were separated by 2 minutes.

The observed orbital arc of the asteroid now extends from Feb 15.93 to  Feb 24.58, or 8.5 days. Updated orbital elements from the MPC (MPEC 2015-D86, 26 Feb 2015):

Epoch 2014 Dec. 9.0 TT = JDT 2457000.5
M 298.05944              (2000.0)
n   0.84818796     Peri.  176.19408    T = 2457073.52693 JDT
a   1.1052859      Node   334.93169    q =     1.0044127
e   0.0912644      Incl.   15.06659    Earth MOID = 0.01553 AU
P   1.16           H   24.6
From 147 observations 2015 Feb. 15-24, mean residual 0".74.

13 observatories have now contributed to the observations, including our own MPC 461 Piszkéstetö where we discovered the object, and two observatories I used myself for 'remote' observations: MPC G68 Sierra Stars Observatory in the US and Q65 Warrumbungle observatory in Australia. The full list of contributing observatories (up to 24 Feb 2015) is:

461   Piszkéstetö Stn. (Konkoly), Hungary
J95   Great Shefford, UK
246   Klet obs. KLENOT, Czechia
J69   North observatory, Clanfield, UK
703   Catalina Sky Survey, USA
F65   Haleakala-Faulkes Telescope North, Hawaii, USA
C47   Nonndorf, Austria
G68   Sierra Stars Observatory, Markleeville, USA
474   Mount John Observatory, New Zealand
A48   Povegliano Veronese, Italy
B18   Terskol, Russia
Q65   Warrumbungle, Australia
W87  Cerro Tololo-LCOGT C, Chile

The asteroid is currently only observable from the southern hemisphere.

Sunday 22 February 2015

OT: An update on Near Earth Asteroid 2015 CA40

2015 CA40, the Amor Near Earth Asteroid discovered by Krisztián Sárneczky and me with the 0.60-m Schmidt telescope of MPC 461 Piszkéstetö (Konkoly) in Hungary on Feb 15, 2015 (see previous post) has now been observed for a week.

The animated GIF above shows the asteroid zipping through the FOV of the 0.61-m Cassegrain telescope of MPC G68 Sierra Stars Observatory in Markleeville, USA, in the morning of Feb 21. It was made from 5 images of 30 seconds exposure each, separated by 5 minutes each. A single frame from this sequence (taken 21 Feb 2015 at 09:45 UT) is below. Even at a relatively short exposure of 30 seconds, the asteroid has trailed:

With an observational arc of over 6 days, the orbital solution already is much better than it was when the discovery MPEC was issued. A number of observatories have now contributed to the observations. As of 22 February, these included, apart from our observatory MPC 461 Piszkéstetö (Konkoly):

246 Klet obs. KLENOT
703 Catalina Sky Survey
C47 Nonndorf
F65 Haleakala-Faulkes Telescope North
G68 Sierra Stars Observatory, Markleeville
J69 North observatory, Clanfield

J95 Great Shefford

The G68 observations are 'remote' observations by myself (see images above) on Feb 21.

Current orbital elements (source MPC, MPEC 2015-D57 of Feb 22):

Epoch 2014 Dec. 9.0      TT = JDT 2457000.5 
M 298.04783 (2000.0) 
n 0.84852056     Peri. 176.17901      T = 2457073.51198 JDT 
a 1.1049971      Node 334.93125       q = 1.0043903 
e 0.0910471      Incl. 15.04633  
P 1.16           H 24.5             Earth MOID = 0.01551 AU

From 104 observations 2015 Feb. 15-21, mean residual 0".54.

When we discovered 2015 CA40 on Feb 15 it was at 15.6 lunar distances. Tomorrow near 21:48 UT (Feb 23, 2015) it will have its closest approach, to 6.3 lunar distances. In the days following this it will move out of view of the Northern hemisphere, but I hope to be able to follow it a few days using the 50-cm telescope of MPC Q65 Warrumbungle Observatory in Australia.

NASA has placed 2015 CA40 on the NHATS page. This page lists objects in orbits suitable for potential future crewed space missions. NHATS stands for Near-Earth Object Human Space Flight Accessible Targets Study.

Last but not least, a picture of the 0.60-m Schmidt telescope at MPC 461 Piszkéstetö (Konkoly) in Hungary with which we discovered the asteroid (image Krisztián Sárneczky/Miclós Rácz):

For those able to read Hungarian (or use Google Translate), a nice story about the discovery in Hungarian is here. Stories in Dutch are here, here and here (and of course my previous blogpost).

Tuesday 17 February 2015

OT: the discovery of Near Earth Asteroid 2015 CA40 (updated)

Satellites is not the only thing I dabble with: as some long-time readers of this blog know, I am also involved in asteroid searches.

Since 2012 I am part of a small team that searches for asteroids with the 60-cm Schmidt telescope of Piszkéstető (MPC 461, Konkoly obs, Szeged university) in Hungary. The project is run by Dr Krisztián Sárneczky from the Szeged university.

My task in this project is to visually inspect the images for objects that have been missed by the automated (computerized) moving object detection routines. Typically, Krisztián sends the images to me via Dropbox within hours of the observing session. I then inspect them on my pc at home here in the Netherlands and measure any unidentified objects I encounter on the images. Over the years I have fished out a number of new main belt asteroids from our imagery.

This weekend, I found a Near Earth Asteroid in the imagery, my first NEA find in this project and my second in total (10 years ago I found NEA 2005 GG81 when I was a plate reviewer with the Spacewatch FMO project).

Part of one of the discovery images from Feb 15. Note the faint trail.

We had a run of several nights with the Piszkéstető Schmidt telescope last week. On Monday around lunchtime I was inspecting images taken Sunday-on-Monday night by Krisztián at high declination (+56 degrees) in Ursa Major. Usually, images at this high a declination are devoid of asteroids. But this time I noted a small moving streak in the images near RA 14h 22m 32.6s, dec. +56 16' 37". See above for (a part of) one of the images, and the animation below. Each frame in the animation below is a 5-minute exposure.

Animation of the discovery images.

Initially I was a bit cautious. As can be seen in the animation above, the object was very faint in the first two frames and brighter in the last two. This is a bit unusual (it can be due to rapid rotation of the object, or -most likely in this case- to changing sky conditions). My first thought therefore was a high altitude slowly flaring satellite: but checking the image times it was clear that this object moved much too slow for a satellite. So: a Near Earth Asteroid?!

I mailed Krisztián the positions noting that it looked like an FMO, a fast moving NEA. Krisztián remeasured the images (measuring is difficult with trailing objects, and certainly faint trails) and sent the observations to the Minor Planet Center (MPC) of the IAU in Harvard, under our temporary object designation "SaLa122".

It was then posted on the MPC's "NEOCP" page, a webpage that lists potential Near Earth Asteroid discoveries with a request to other observatories for confirmation. Due to a mistake it initially appeared as "SaLa123" there (see below) with only 50% of our data: this was however quickly corrected and soon it was on under the correct designation "SaLa122".

SaLa122 (under the erroneous designation SaLa123) on the NEOCP

At that moment we had a 30-minute observational arc, which is very short. It was vital that the object should be recovered over the next day, otherwise the object would be regarded as "lost" and would not count as a discovery.

Luckily, that recovery happened! The next night (16-17 Feb) Krisztián managed to relocate the object with the 60-cm Schmidt (see image below) and could follow it for several hours. In addition, astronomers at the Czech Klét observatory and British amateur astronomer Peter Birtwhistle at his private Great Shefford Observatory in the UK looked for the object too and could confirm it. This expanded the observational arc to 29 hours, enough for a preliminary orbit determination.

Stacked follow-up images from MPC 461 in the night of Feb 16-17

In the late afternoon of Feb 17 the MPC made the official discovery announcement in MPEC 2015-D10: the object now has the official designation 2015 CA40.

2015 CA40 is a borderline Amor/Apollo asteroid with [updated 22 Feb 2015] a semi-major axis of 1.1049538 AU, an eccentricity of 0.0910145 and an orbital inclination of 15.04 degrees. The perihelion is just outside the orbit of the earth at 1.004 AU. The aphelion is at 1.20 AU, well within the orbit of Mars. The orbital period of the asteroid is 1.16 years. With H=24.5 the asteroid is estimated to be about 45 meters in diameter.

Orbit of 2015 CA40

[Updated] 2015 CA40 orbital elements (MPC, from MPEC 2015-D47)

Epoch 2014 Dec. 9.0   TT = JDT 2457000.5 
M 298.04901 (2000.0) 
n 0.84857047     Peri. 176.17310     T = 2457073.50630 JDT 
a 1.1049538      Node 334.93131      q = 1.0043870 
e 0.0910145      Incl. 15.04278      Earth MOID = 0.01551 AU
P 1.16           H 24.5 

From 98 observations 2015 Feb. 15-21, mean residual 0".51. 

The theoretical minimum distance (MOID) of the asteroid's orbit  to the orbit of the Earth is 0.0155 AU or about 6 times the Earth-Moon distance. Closest actual approach of the asteroid to Earth this year, to about 6.3 times the lunar distance, is in the night of Feb 23-24 when it might reach mag. +16.6 and will be moving at a speed of 42" per minute.

Objects in this kind of orbit with a semi-major axis of ~1.0 AU (similar to the orbit of the Earth) are objects that already must have had one or more close encounters with the Earth and/or Mars.

We plan to follow the object over the coming nights, to expand the observational arc as much as possible, in order to increase the chances of it being found back during the next similarly close approach, which will be on 23 February 2066. There are some earlier dates at which the asteroid comes near Earth too (indicated in the diagram below: e.g. 2022, 2029, 2037, 2044, 2051 and 2058), but at a clearly larger distance than in 2015 and 2066. It will be much fainter and hence harder (but not impossible, given a big enough telescope) to detect during those years.

click diagram to enlarge: distance (in AU) of 2015 CA40 to earth over the coming century

Earlier close approaches to less than 0.1 AU over the past 200 years were in 1813 (0.0161 AU);  1849 (0.0429 AU); 1863 (0.0245 AU); 1899 (0.0773 AU); 1928 (0.0469 AU); 1950 (0.0503 AU); and 1979 (0.0665 AU).

2015 CA40 is  the 7th Near Earth Asteroid discovered by the Konkoly survey and my second NEA discovery (and my first in the Konkoly project).

More on my other asteroid discoveries here.

Update (21 Feb 2015): we are still following this object and the arc now includes observations from early Feb 21.

Acknowledgement: we thank Peter Birtwhistle and the people of Klet observatory for their follow-up observations.

Saturday 14 February 2015

ATV-5 'Georges Lemaitre' and the ISS chasing each other in a partly cloudy sky

ESA's ATV-5 'Georges Lemaitre' cargoship undocked from the ISS in the afternoon of February 14, 2015. A few hours later they made a fine zenith pass over Leiden, stille relatively close together, chasing each other in the sky.

Unfortunately, an untimely fields of clouds passed through the sky as the pass commenced. Still, the duo was well visible amidst the clouds. ATV-5 was an easy naked eye object at mag. +1. It was some 25 degrees (25-30 seconds) in front of the ISS.

ATV-5 near Capella

The image above shows ATV-5 amidst clouds near Capella. The image below shows both the ISS (top) and ATV-5 (bottom) descending to the east in a partly clouded sky. Both images were made with an EF2.0/35 mm lens.

ISS (top) and ATV-5 (bottom)

Frustatingly enough, the clouds disappeared and it was completely clear just 5 minutes after the pass....