"Pseudo-MPEC" for 2018-017A

Created 2018 Feb 8 1:20:01 UT using Find_Orb

The following "observations" are synthetic, not real! I made these up in the process of coming up with a rough estimate of what the orbit would be. At the time, all I had was the time the second stage burn ended, orbital elements from before the burn, and contradictory data from Elon Musk's tweet. (Musk gave data indicating the object was headed out to near Ceres, but also gave a C3=12 km^2/s^2 value that indicated a considerably less energetic object.)

Based on these bits and bobs of information, I came up with an orbit that you'd get if the object accelerated to that C3 value at the time people reported seeing the second stage burn end. This seemed to be a reasonable guess. As with many reasonable guesses, it wasn't quite right.

Fortunately, Jonathan McDowell was able to get someone at SpaceX to cough up orbital elements for the roadster and second stage rocket (they're attached to each other). Based on that, I generated the observations below, which are where (E12) Siding Spring Observatory would have seen the object had they been looking, and had it been where SpaceX thought it would be.

As it turned out, the SpaceX orbit was good enough to tell you where to point a telescope, though not entirely correct. You can click here for real observations from many observatories, with elements and ephemerides based on those actual observations.

Astrometry:
2018-017A     C2018 02 07.51000 14 18 16.16 -26 47 49.1                 SynthE12
2018-017A     C2018 02 07.52000 14 18 49.58 -26 51 10.6                 SynthE12
2018-017A     C2018 02 07.53000 14 19 19.93 -26 54 26.1                 SynthE12
2018-017A     C2018 02 07.54000 14 19 47.35 -26 57 35.4                 SynthE12
2018-017A     C2018 02 07.55000 14 20 12.00 -27 00 38.3                 SynthE12
2018-017A     C2018 02 07.56000 14 20 34.02 -27 03 34.5                 SynthE12
2018-017A     C2018 02 07.57000 14 20 53.53 -27 06 23.7                 SynthE12
2018-017A     C2018 02 07.58000 14 21 10.66 -27 09 05.8                 SynthE12
2018-017A     C2018 02 07.59000 14 21 25.55 -27 11 40.4                 SynthE12
2018-017A     C2018 02 07.60000 14 21 38.33 -27 14 07.3                 SynthE12
2018-017A     C2018 02 07.61000 14 21 49.12 -27 16 26.4                 SynthE12
2018-017A     C2018 02 07.62000 14 21 58.04 -27 18 37.3                 SynthE12
2018-017A     C2018 02 07.63000 14 22 05.21 -27 20 40.0                 SynthE12
2018-017A     C2018 02 07.64000 14 22 10.77 -27 22 34.2                 SynthE12
2018-017A     C2018 02 07.65000 14 22 14.81 -27 24 19.8                 SynthE12
2018-017A     C2018 02 07.66000 14 22 17.47 -27 25 56.7                 SynthE12
2018-017A     C2018 02 07.67000 14 22 18.86 -27 27 24.8                 SynthE12
2018-017A     C2018 02 07.68000 14 22 19.10 -27 28 44.0                 SynthE12
2018-017A     C2018 02 07.69000 14 22 18.29 -27 29 54.3                 SynthE12
2018-017A     C2018 02 07.70000 14 22 16.55 -27 30 55.6                 SynthE12
2018-017A     C2018 02 07.71000 14 22 13.99 -27 31 47.9                 SynthE12
2018-017A     C2018 02 07.72000 14 22 10.72 -27 32 31.4                 SynthE12
2018-017A     C2018 02 07.73000 14 22 06.84 -27 33 06.0                 SynthE12
2018-017A     C2018 02 07.74000 14 22 02.46 -27 33 31.9                 SynthE12
2018-017A     C2018 02 07.75000 14 21 57.67 -27 33 49.1                 SynthE12
2018-017A     C2018 02 07.76000 14 21 52.57 -27 33 57.9                 SynthE12
2018-017A     C2018 02 07.77000 14 21 47.26 -27 33 58.4                 SynthE12
2018-017A     C2018 02 07.78000 14 21 41.82 -27 33 50.8                 SynthE12
2018-017A     C2018 02 07.79000 14 21 36.34 -27 33 35.3                 SynthE12
2018-017A     C2018 02 07.80000 14 21 30.92 -27 33 12.2                 SynthE12
2018-017A     C2018 02 07.81000 14 21 25.62 -27 32 41.7                 SynthE12

Station data:
(E12) Siding Spring Survey  (S31.273453 E149.064200)  Australia/NSW.
   Observers R. H. McNaught, S. Larson, et.al. Measurer R. H. McNaught. 0.5-m
   Uppsala Schmidt + CCD.

Orbital elements:  2018-017A
   Perigee 2018 Feb 7.107941 +/- 0.000163 TT =  2:35:26 (JD 2458156.607941)
Epoch 2018 Feb  8.0 TT = JDT 2458157.5                        Gray
q  7264.98505 +/- 1.55              (J2000 equator)
                                    Peri.  146.80547 +/- 0.019
                                    Node   285.83986 +/- 0.0014
e   1.2190924 +/- 0.000314          Incl.   29.05622 +/- 0.0015
From 31 observations 2018 Feb. 7 (7.2 hr); mean residual 0".033

Orbital elements (heliocentric):  2018-017A
   Perihelion 2018 Feb 4.200049 +/- 0.000358 TT =  4:48:04 (JD 2458153.700049)
Epoch 2018 Feb 10.0 TT = JDT 2458159.5   Earth MOID: 0.0002   Ma: 0.0009
M   3.68007 +/- 0.0013              (J2000 ecliptic)          Gray
n   0.63450090 +/- 0.000194         Peri.  177.28664 +/- 0.00059
a   1.34126487 +/- 0.000273         Node   317.45885 +/- 0.0007
e   0.2648281 +/- 0.00015           Incl.    1.09424 +/- 0.0007
P   1.55/567.36d      U  7.0
q 0.98606016 +/- 1.71e-7    Q 1.69646959 +/- 0.000546
From 31 observations 2018 Feb. 7 (7.2 hr); mean residual 0".033
Residuals in arcseconds: 
180207 E12 .060- .003+    180207 E12 .030+ .025+    180207 E12 .048- .004+
180207 E12 .021+ .027-    180207 E12 .040- .009-    180207 E12 .014+ .022-
180207 E12 .058+ .009-    180207 E12 .076+ .007+    180207 E12 .016+ .030+
180207 E12 .047- .016+    180207 E12 .013- .026+    180207 E12 .002- .008+
180207 E12 .059- .001+    180207 E12 .014- .026+    180207 E12 .041+ .010-
180207 E12 .045+ .008-    180207 E12 .014- .009+    180207 E12 .005+ .025-
180207 E12 .068+ .036+    180207 E12 .055+ .002+    180207 E12 .074- .010-
180207 E12 .012- .016-    180207 E12 .014+ .039-    180207 E12 .026+ .016-
180207 E12 .052- .008-    180207 E12 .023- .034-    180207 E12 .043+ .028+
180207 E12 .015- .030+    180207 E12 .051- .029+
180207 E12 .028+ .025-    180207 E12 .037- .014-

Ephemerides for (J95) Great Shefford:
Date (UTC) HH:MM   RA              Dec         delta   r     elong SM  alt  az
---- -- -- -----  ------------   ------------  ------ ------ ----- --  --- ---
................
2018 02 08 02:20  14 28 51.119   -28 19 58.13  363992 .98667  94.9  m +01
2018 02 08 02:30  14 28 50.649   -28 19 57.28  366142 .98667  94.9  m +02
2018 02 08 02:40  14 28 49.965   -28 19 54.94  368296 .98667  94.9  m +02
2018 02 08 02:50  14 28 49.083   -28 19 51.07  370453 .98667  94.9  m +03
2018 02 08 03:00  14 28 48.017   -28 19 45.64  372615 .98667  94.9  m +04
2018 02 08 03:10  14 28 46.781   -28 19 38.64  374782 .98668  94.9  m +05
2018 02 08 03:20  14 28 45.389   -28 19 30.03  376953 .98668  94.9  m +06
2018 02 08 03:30  14 28 43.856   -28 19 19.80  379129 .98668  95.0  m +06
2018 02 08 03:40  14 28 42.196   -28 19 07.93  381309 .98668  95.0  m +07
2018 02 08 03:50  14 28 40.424   -28 18 54.43  383495 .98669  95.0  m +08
2018 02 08 04:00  14 28 38.553   -28 18 39.27  385686 .98669  95.0  m +08
2018 02 08 04:10  14 28 36.599   -28 18 22.45  387882 .98669  95.0  m +09
2018 02 08 04:20  14 28 34.575   -28 18 03.99  390084 .98669  95.0  m +09
2018 02 08 04:30  14 28 32.494   -28 17 43.87  392291 .98669  95.0  m +09
2018 02 08 04:40  14 28 30.372   -28 17 22.12  394503 .98670  95.1  m +10
2018 02 08 04:50  14 28 28.221   -28 16 58.73  396722 .98670  95.1  m +10
2018 02 08 05:00  14 28 26.055   -28 16 33.74  398946 .98670  95.1  m +10
2018 02 08 05:10  14 28 23.887   -28 16 07.15  401175 .98670  95.1  m +10
2018 02 08 05:20  14 28 21.731   -28 15 38.99  403411 .98671  95.1  m +10
2018 02 08 05:30  14 28 19.598   -28 15 09.29  405652 .98671  95.1  m +10
2018 02 08 05:40  14 28 17.502   -28 14 38.06  407899 .98671  95.2 Am +10
2018 02 08 05:50  14 28 15.455   -28 14 05.35  410152 .98671  95.2 Am +10
2018 02 08 06:00  14 28 13.467   -28 13 31.19  412411 .98672  95.2 Am +10
2018 02 08 06:10  14 28 11.552   -28 12 55.61  414676 .98672  95.2 Am +10
2018 02 08 06:20  14 28 09.719   -28 12 18.65  416946 .98672  95.2 Nm +09
2018 02 08 06:30  14 28 07.980   -28 11 40.37  419222 .98672  95.2 Nm +09
2018 02 08 06:40  14 28 06.345   -28 11 00.79  421503 .98672  95.3 Nm +08
2018 02 08 06:50  14 28 04.824   -28 10 19.98  423790 .98673  95.3 Nm +08
2018 02 08 07:00  14 28 03.427   -28 09 37.97  426083 .98673  95.3 Cm +07
2018 02 08 07:10  14 28 02.162   -28 08 54.83  428380 .98673  95.3 Cm +07
2018 02 08 07:20  14 28 01.039   -28 08 10.60  430683 .98673  95.3 Cm +06
2018 02 08 07:30  14 28 00.065   -28 07 25.34  432991 .98674  95.3 Cm +05
................