"Pseudo-MPEC" for 2015 GU = WG1A68B

Created 2015 Apr 11 21:26:40 UT using Find_Orb

Update: Since I announced this on MPML, the object has been well-observed and now has been MPECed as 2015 GU. As you will see, the uncertainties have shrunk considerably, and there is no risk of losing the object. It would still be good to have some more data, though, just in case the folks at Goldstone attempt radar observations. This is not very likely -- it's short notice, and they haven't been very interested in small objects of this sort anyway -- but it could happen, and it would certainly be a strong target. If they go for it, a few more observations would help (and a light curve and a rotation period would really help.) I've included a Goldstone-centric radar-based ephemeris, just in case.

If you get more observations and are willing to have them posted here, please send them to p‮ôç.ötulpťcéjôřp@otúl‬m.

Astrometry:
     K15G00U  C2015 04 11.22636 11 59 16.59 +06 36 11.2          18.7 VqEG036703
     K15G00U  C2015 04 11.23138 11 59 19.59 +06 34 42.5          19.0 VqEG036703
     K15G00U  C2015 04 11.23640 11 59 22.58 +06 33 12.2          18.6 VqEG036703
     K15G00U  C2015 04 11.24142 11 59 25.62 +06 31 41.9          18.8 VqEG036703
     K15G00U  C2015 04 11.38610 12 01 15.39 +05 39 38.7          18.2 VqEG036703
     K15G00U  C2015 04 11.38660 12 01 15.90 +05 39 26.1          18.1 VqEG036703
     K15G00U  C2015 04 11.38710 12 01 16.40 +05 39 14.1          17.9 VqEG036703
     K15G00U  C2015 04 11.38810 12 01 17.41 +05 38 47.9          17.9 VqEG036703
     K15G00U KC2015 04 11.44429 12 04 07.01 +05 48 13.5          18.1 RtEG036474
     K15G00U KC2015 04 11.44552 12 04 08.46 +05 47 42.3          17.4 RtEG036474
     K15G00U KC2015 04 11.44675 12 04 09.95 +05 47 10.7          17.7 RtEG036474
     K15G00U KC2015 04 11.44737 12 04 10.70 +05 46 54.2          17.2 RtEG036474
     K15G00U KC2015 04 11.53623 12 06 11.18 +05 02 58.0          16.5 RtEG036474
     K15G00U KC2015 04 11.53688 12 06 12.23 +05 02 36.2          16.0 RtEG036474
     K15G00U KC2015 04 11.53754 12 06 13.19 +05 02 13.6          17.0 RtEG036474
     K15G00U  C2015 04 11.60281 12 09 04.68 +03 38 41.1          17.8 RoEG036300
     K15G00U  C2015 04 11.60405 12 09 06.98 +03 37 46.2          17.4 RoEG036300
     K15G00U  C2015 04 11.60467 12 09 08.17 +03 37 17.9          17.6 RoEG036300
     K15G00U  C2015 04 11.60528 12 09 09.25 +03 36 50.4          17.5 RoEG036300
     K15G00U  C2015 04 11.60589 12 09 10.43 +03 36 23.0          17.6 RoEG036300
     K15G00U  C2015 04 11.60624 12 09 06.31 +03 35 53.6          18.1 VqEG036900
     K15G00U  C2015 04 11.61072 12 09 14.77 +03 32 29.1          18.0 VqEG036900
     K15G00U  C2015 04 11.61520 12 09 23.38 +03 29 02.1          18.1 VqEG036900
     K15G00U  C2015 04 11.61967 12 09 32.13 +03 25 31.8                qEG036900
     K15G00U KC2015 04 11.62748 12 10 43.34 +03 13 00.3          17.6 RqEG036O75
     K15G00U KC2015 04 11.62776 12 10 43.96 +03 12 46.6          17.4 RqEG036O75
     K15G00U KC2015 04 11.62804 12 10 44.60 +03 12 33.0          17.2 RqEG036O75
     K15G00U KC2015 04 11.62832 12 10 45.21 +03 12 19.2          17.2 RqEG036O75
     K15G00U  C2015 04 11.81045 12 23 37.85 -00 17 38.9          16.3 RoEG036461
     K15G00U  C2015 04 11.81071 12 23 39.12 -00 18 03.8          15.8 RoEG036461
     K15G00U  C2015 04 11.81097 12 23 40.42 -00 18 29.5          15.7 RoEG036461
     K15G00U  C2015 04 11.81123 12 23 41.74 -00 18 55.1          16.5 RoEG036461
     K15G00U  C2015 04 11.81149 12 23 43.10 -00 19 21.1          16.4 RoEG036461
     K15G00U  C2015 04 11.81175 12 23 44.41 -00 19 46.4          16.3 RoEG036461
     K15G00U  C2015 04 11.81227 12 23 47.00 -00 20 36.4          15.9 RoEG036461

Station data:
(300) Bisei Spaceguard Center-BATTeRS (N34.67201 E133.54444)  Japan.  1.0-m
    f/3.0 reflector + CCD.
(461) University of Szeged, Piszkesteto Stn (Konkoly)  (N47.9181 E19.8943)  Hungary.
      Observer K. Sárneczky.  0.60-m Schmidt + CCD.
(474) Mount John Observatory, Lake Tekapo (S43.98746 E170.46496)  New Zealand.
      Observers A. C. Gilmore, P. M. Kilmartin.  Measurer P. M. Kilmartin.
    1.0-m f/7.7 reflector + CCD.
(703) Catalina Sky Survey (N32.41712 W110.73264)  US/Arizona.   Observers E.
    J. Christensen, A. R. Gibbs, A. D. Grauer, R. E. Hill, J. A. Johnson, R. A.
    Kowalski, S. M. Larson, F. C. Shelly.  0.68 m Schmidt + CCD.
(900) Moriyama (N35.04980 E135.98994)  Japan.  0.25-m Schmidt-Cassegrain.
(O75) ISON-Hureltogoot Observatory (N47.86533 E107.05180)  Mongolia.
    Observers T. Namkhai, S. Schmalz.  Measurer S. Schmalz.  0.4-m f/2.3
    reflector + CCD.

Orbital elements (heliocentric):  2015 GU
   Perihelion 2015 May 13.175151 +/- 0.000669 TT =  4:12:13 (JD 2457155.675151)
Epoch 2015 Apr 12.0 TT = JDT 2457124.5   Earth MOID: 0.0004   Ma: 0.0093
M 349.942444 +/- 0.0027                                       Find_Orb
n   0.322614498 +/- 8.07e-5         Peri.  221.340887 +/- 0.0007
a   2.105459033 +/- 0.000351        Node    21.493533 +/- 0.000012
e   0.56601924 +/- 7.73e-5          Incl.    2.794857 +/- 0.00026
P   3.06                   H 28.5   G  0.15   U  6.4
q 0.913728711 +/- 1.06e-5    Q 3.297189355 +/- 0.000712
From 35 observations 2015 Apr. 11 (14.1 hr); mean residual 0".37

Orbital elements (geocentric):  2015 GU
   Perigee 2015 Apr 12.233399 +/- 3.05e-5 TT =  5:36:05 (JD 2457124.733399)
Epoch 2015 Apr 12.0 TT = JDT 2457124.5                        Find_Orb
q110518.3085 +/- 12.4
H   28.5  G 0.15                    Peri.  255.934088 +/- 0.00058
                                    Node     5.887351 +/- 0.00023
e  36.69122953 +/- 0.0119           Incl.   48.048930 +/- 0.00049
From 35 observations 2015 Apr. 11 (14.1 hr); mean residual 0".37
Residuals in arcseconds:
150411 703  .03-  .54+    150411 474  .59-  .26+    150411 O75  .13-  .03-
150411 703  .19+  .39+    150411 474  .00   .30+    150411 O75  .16-  .07-
150411 703  .02-  .34-    150411 474  1.0-  .07-    150411 O75  .11+  .01+
150411 703  .20+  .05-    150411 300  .10-  .08-    150411 O75  .09-  .09-
150411 703  .02-  .34-    150411 300  .12-  .66+    150411 461  .18-  .19+
150411 703  .07+  .18-    150411 300  .42+  .26+    150411 461  .60-  .60+
150411 703  .01-  .59+    150411 300  .45-  .26+    150411 461  .58-  .24+
150411 703  .07-  .02-    150411 300  .14+  .42+    150411 461  .28-  .01+
150411 474  .42+  .90-    150411 900  .13+  .58-    150411 461  .59+  .59-
150411 474  .01+  .13-    150411 900  .03+  .60-    150411 461  .70+  .47-
150411 474  .15+  .34+    150411 900  .10+  .18-    150411 461  .41+  .48+
150411 474  .18+  .05+    150411 900  .42+  .52-

Ephemerides (geocentric):
Date (UT)  HH   RA              Dec         delta   r     elong  mag " sig PA
---- -- -- --  ------------   ------------  ------ ------ -----  --- ---- ---
2015 04 11 21  12 29 12.593   -01 34 38.65  370928 1.0046 165.8 16.3  0.7 146
2015 04 11 22  12 34 59.696   -03 10 56.32  331901 1.0044 167.8 16.0  1.1 143
2015 04 11 23  12 42 20.149   -05 12 30.12  293422 1.0041 170.2 15.6  1.7 142
2015 04 12 00  12 51 56.287   -07 49 48.08  255750 1.0039 173.1 15.2  2.7 141
2015 04 12 01  13 04 59.317   -11 19 00.85  219310 1.0037 175.3 14.8  4.4 139
2015 04 12 02  13 23 36.837   -16 04 57.95  184852 1.0035 172.3 14.5  7.1 138
2015 04 12 03  13 51 53.506   -22 42 10.26  153743 1.0032 163.8 14.4   11 135
2015 04 12 04  14 37 59.389   -31 37 44.13  128482 1.0030 150.6 14.5   18 129
2015 04 12 05  15 56 23.215   -41 42 07.04  113116 1.0028 132.2 14.7   27 117
2015 04 12 06  17 53 19.396   -47 48 10.22  111848 1.0026 110.9 15.3   30  96
2015 04 12 07  19 46 55.575   -46 07 03.56  125109 1.0023  91.6 16.2   26  75
2015 04 12 08  21 00 43.138   -40 43 51.56  149040 1.0021  77.3 17.3   19  63
2015 04 12 09  21 44 02.995   -35 30 01.87  179386 1.0019  67.4 18.2   13  56
2015 04 12 10  22 10 48.193   -31 20 28.83  213399 1.0016  60.5 19.1    9  53
2015 04 12 11  22 28 32.232   -28 09 18.95  249568 1.0014  55.6 19??  7.2  51
2015 04 12 12  22 41 01.579   -25 41 58.64  287065 1.0012  51.9 20??  5.3  49
2015 04 12 13  22 50 15.093   -23 46 23.44  325423 1.0009  49.2 21??  3.9  49
2015 04 12 14  22 57 19.540   -22 13 55.28  364364 1.0007  47.0 21??  2.9  48
2015 04 12 15  23 02 54.838   -20 58 34.05  403715 1.0005  45.2 21??  2.1  48
2015 04 12 16  23 07 26.156   -19 56 08.21  443364 1.0003  43.8 22??  1.5  49

Ephemerides for (253) Goldstone DSS 14, Fort Irwin:
Assumes power=430.00 kW, Tsys=17.0 deg K, gain 0.94 K/Jy
Assumed rotation period = 0.30 hours, diameter 8.4 meters
Date (UT)  HH   RA              Dec         delta   alt  az  SNR " sig PA
---- -- -- --  ------------   ------------  ------  --- --- ---- ---- ---
................
2015 04 12 15  23 04 51.156   -21 40 37.06  .00268  +23 142 6084  2.3  36
2015 04 12 16  23 08 35.117   -20 35 48.44  .00294  +30 154 4200  1.7  36
2015 04 12 17  23 11 35.655   -19 40 32.98  .00321  +34 169 2979  1.3  36
2015 04 12 18  23 14 05.352   -18 52 48.59  .00347  +36 186 2164  0.9  37
2015 04 12 19  23 16 13.253   -18 11 06.91  .00374  +33 202 1604  0.6  40
2015 04 12 20  23 18 05.914   -17 34 23.02  .00402  +28 217 1211  0.3  45
2015 04 12 21  23 19 48.054   -17 01 48.56  .00429  +20 230  929  0.1  72