ALERT! Asteroid 2014 JO25 comes close to Earth, 19 April
Saturday, April 15, 2017 at 11:16PM
Ian Musgrave in Alerts, Asteroid, Asteroids, alert

Asteroid 2014 JO25 as seen from Mayhill New Mexico 4:40 am, (10:40 UT) 16 April - 21 April. The crosses mark the position of the asteroid every 3 Hours, click to embiggen.

Asteroid 2014 JO25 will  come close to Earth on 12:24 UT 19 April at distance of 0.012 AU (around 4.6 Earth-Moon distances). At an estimated diameter of around 650m it is abot the size of the Chelyabinsk impactor.

The asteroid is currently magnitude 20.0, and will be a moderately bright magnitude 10.8 at closest approach. Unoftunately, for the iTelescopes the sun will have risen before then'

It is visible from the Northern Hemisphere scopes with the best views from the US, where it will be magnitude 11.3 before astonomical twilight. From SPain it will get to magnitude 12.6.

At magnitude 11, 60 second exposures may be reasonable, shorter exposures may be too dim, it will be moving too fast for the scopes to track accurately.

Asteroid 2014 JO25 as seen from Mayhill New Mexico from 00:40 am.  The crosses mark the position of the asteroid every 15 minutes. The large rectangle is the field of view of T14/T20, the small that of T5. Click to embiggen.

Asteroid 2014 JO25 moves through Draco on the morning of the 19th.

It is moving fast (239 arc seconds/minute at its brightest), and at the limit of  the tracking capability of the iTelescopes at its brightest. It may be best  to use a topocentric ephemeris and camp out on the asteroid track in this case (you will have to do this for T14 and T20, they do not track minor bodies).

The asteroid will cross the FOV of T14 in 30 minutes and T5 in less than 15 minutes.

There is a  modest  parallax effect (~ 5 arc minutes at maxi,um brightness fro Mayhill), so unless your planetarium program is able to cope with close parallax (most can't), you will need to work from topocentric coordinates.

For topocentric ephemerides go to http://www.minorplanetcenter.net/iau/MPEph/MPEph.html

or JPL and choose the ephemeris link https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2014%20JO25

Use the oobservatory code for your observatory eg  MPC Mayhill Code H06.

Always use the latest possible orbital elements and ephemeris.

The planning guides to viewing YU55 here and here will help organising topocentric ephemerides for close approaching NEO's.

You will need to use unguided exposures.

Choose a point where the asteroid will pass and aim at that. Remember that it takes time for the iTelescopes scopes to get to tracking position. T12 and T14 can take up to 5 minutes (depending on there being reliable stars in the field for tracking, check your logs to see what the average slew time is), so offset you initial position by around 4 minutes or so (this will be a significant distance) so the asteroid will be in field. The asteroid will cross the T14 FOV in about 15 minutes at its brightest approach (due to the orientation of the CCD).

Ephemeris for Mayhill, starting at 6:00 UT 19th(midnight local time). It is still best to get your own ephemeris closer to the day, but you can us ethis for planning.

======================================================================

     K14J25O       [H=18.1]
Date       UT      R.A. (J2000) Decl.    Delta     r     El.    Ph.   V      Sky Motion        Object    Sun   Moon                Uncertainty info
            h m s                                                            "/min    P.A.    Azi. Alt.  Alt.  Phase Dist. Alt.    3-sig/" P.A.
... Suppressed ...
2017 04 19 013000 21 46 23.1 +63 12 38   0.015   0.999   67.0 112.2  13.2  149.42    316.6    170  +08   +00   0.54   085  -74        19 349.8 / Map / Offsets
2017 04 19 060000 19 55 21.0 +70 41 44   0.013   1.002   78.9 100.4  12.3  198.21    291.3    201  +25   -44   0.52   089  -23        23 321.0 / Map / Offsets
2017 04 19 061500 19 45 50.2 +70 58 56   0.013   1.002   79.7  99.6  12.2  200.91    289.0    201  +27   -45   0.52   089  -20        24 318.6 / Map / Offsets
2017 04 19 063000 19 35 55.6 +71 14 27   0.013   1.002   80.4  98.9  12.2  203.57    286.7    202  +29   -46   0.52   089  -17        24 316.2 / Map / Offsets
2017 04 19 064500 19 25 37.9 +71 28 07   0.013   1.003   81.2  98.1  12.1  206.19    284.2    202  +31   -46   0.52   089  -14        24 313.6 / Map / Offsets
2017 04 19 070000 19 14 58.4 +71 39 45   0.013   1.003   82.0  97.3  12.1  208.76    281.7    202  +33   -46   0.52   090  -11        24 310.9 / Map / Offsets
2017 04 19 071500 19 03 59.0 +71 49 13   0.012   1.003   82.8  96.5  12.0  211.27    279.1    202  +36   -46   0.51   090  -08        24 308.2 / Map / Offsets
2017 04 19 073000 18 52 41.9 +71 56 22   0.012   1.003   83.6  95.7  12.0  213.72    276.4    201  +38   -46   0.51   090  -05        25 305.4 / Map / Offsets
2017 04 19 074500 18 41 09.8 +72 01 02   0.012   1.003   84.4  94.9  11.9  216.09    273.6    201  +40   -45   0.51   091  -02        25 302.5 / Map / Offsets
2017 04 19 080000 18 29 25.9 +72 03 07   0.012   1.004   85.3  94.0  11.9  218.39    270.8    200  +41   -44   0.51   091  +01        25 299.6 / Map / Offsets
2017 04 19 081500 18 17 33.7 +72 02 31   0.012   1.004   86.1  93.2  11.9  220.61    267.9    199  +43   -43   0.51   091  +03        25 296.7 / Map / Offsets
2017 04 19 083000 18 05 37.1 +71 59 08   0.012   1.004   87.0  92.3  11.8  222.73    265.1    197  +45   -41   0.51   092  +06        25 293.8 / Map / Offsets
2017 04 19 084500 17 53 40.0 +71 52 56   0.012   1.004   87.8  91.5  11.8  224.75    262.2    195  +47   -39   0.51   092  +09        26 290.9 / Map / Offsets
2017 04 19 090000 17 41 46.3 +71 43 53   0.012   1.004   88.7  90.6  11.7  226.67    259.3    193  +48   -38   0.51   093  +12        26 287.9 / Map / Offsets
2017 04 19 091500 17 30 00.0 +71 31 59   0.012   1.004   89.6  89.7  11.7  228.47    256.5    190  +50   -36   0.51   093  +14        26 285.1 / Map / Offsets
2017 04 19 093000 17 18 24.7 +71 17 16   0.012   1.005   90.5  88.9  11.6  230.15    253.7    187  +51   -33   0.51   093  +17        26 282.3 / Map / Offsets
2017 04 19 094500 17 07 03.6 +70 59 48   0.012   1.005   91.3  88.0  11.6  231.71    251.0    184  +51   -31   0.50   094  +19        26 279.5 / Map / Offsets
2017 04 19 100000 16 55 59.8 +70 39 37   0.012   1.005   92.2  87.1  11.5  233.14    248.4    181  +52   -29   0.50   094  +22        26 276.8 / Map / Offsets
2017 04 19 101500 16 45 15.5 +70 16 51   0.012   1.005   93.1  86.2  11.5  234.43    245.8    177  +52   -26   0.50   094  +24        26 274.3 / Map / Offsets
2017 04 19 103000 16 34 52.8 +69 51 37   0.012   1.005   94.0  85.3  11.5  235.58    243.3    174  +52   -23   0.50   095  +26        26 271.8 / Map / Offsets
2017 04 19 104500 16 24 53.2 +69 24 01   0.012   1.006   94.9  84.4  11.4  236.58    240.9    170  +52   -21   0.50   095  +28        26 089.4 / Map / Offsets
2017 04 19 110000 16 15 17.6 +68 54 12   0.012   1.006   95.8  83.5  11.4  237.44    238.7    167  +51   -18   0.50   096  +30        27 087.1 / Map / Offsets
2017 04 19 111500 16 06 06.5 +68 22 19   0.012   1.006   96.8  82.6  11.4  238.14    236.5    163  +51   -15   0.50   096  +32        27 085.0 / Map / Offsets
2017 04 19 113000 15 57 20.3 +67 48 30   0.012   1.006   97.7  81.7  11.3  238.69    234.4    160  +49   -12   0.50   096  +34        27 082.9 / Map / Offsets
2017 04 19 114500 15 48 58.7 +67 12 54   0.012   1.006   98.6  80.8  11.3  239.08    232.4    158  +48   -09   0.50   097  +35        27 081.0 / Map / Offsets
2017 04 19 120000 15 41 01.5 +66 35 40   0.012   1.006   99.5  79.8  11.2  239.31    230.6    155  +46   -06   0.49   097  +36        27 079.1 / Map / Offsets
2017 04 19 121500 15 33 28.0 +65 56 56   0.012   1.007  100.4  78.9  11.2  239.39    228.8    153  +45   -03   0.49   098  +38        27 077.4 / Map / Offsets
2017 04 19 123000 15 26 17.4 +65 16 51   0.012   1.007  101.3  78.0  11.2  239.31    227.1    151  +43   +00   0.49   098  +38        27 075.8 / Map / Offset
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