Artemis II: magnitude estimates

Artemis II is scheduled for launch from KSC on 2026 Apr 01 at 22:24 UTC. Mission duration is 10 days.

JPL Horizons has ephemerides of the spacecraft. I did not check Horizons for any other pieces from
the launch.

https://ssd.jpl.nasa.gov/horizons/app.html

Horizons does not have magnitude estimates for Artemis II, so I have made rough estimates.

Based on dimensions published by NASA, I have estimated standard magnitude (1000 km range, 90 deg phase
angle) of 4.6 for the Orion spacecraft, and 3.9 for the final stage of the SLS booster plus spacecraft
adapter. The estimated uncertainty of both is 2 magnitudes.

Below are magnitude estimates for a variety of ranges, for 100% illumination and 50% illumination. Since
Horizons states range in astronomical units, I have done likewise and included the km equivalent.
Note: Horizons uses the term delta for range.

      Range       Estimated Magnitude
   AU        km   100% Ill.  50% Ill.
0.00001	  1496	 4.2     5.5
0.00002	  2992	 5.7     7.0
0.00003	  4488	 6.6     7.9
0.00004	  5984	 7.2     8.5
0.00005	  7480	 7.7     9.0
0.00006	  8976	 8.1     9.4
0.00007	 10472	 8.5     9.7
0.00008	 11968	 8.7    10.0
0.00009	 13464	 9.0    10.2
0.00010	 14960	 9.2    10.5
0.00020	 29920	10.7    12.0
0.00030	 44879	11.6    12.9
0.00040	 59839	12.2    13.5
0.00050	 74799	12.7    14.0
0.00060	 89759	13.1    14.4
0.00070	104719	13.5    14.7
0.00080	119678	13.7    15.0
0.00090	134638	14.0    15.2
0.00100	149598	14.2    15.5
0.00110	164558	14.4    15.7
0.00120	179517	14.6    15.9
0.00130	194477	14.8    16.0
0.00140	209437	15.0    16.2
0.00150	224397	15.1    16.3
0.00160	239357	15.2    16.5
0.00170	254316	15.4    16.6
0.00180	269276	15.5    16.7
0.00190	284236	15.6    16.9
0.00200	299196	15.7    17.0
0.00210	314156	15.8    17.1
0.00220	329115	15.9    17.2
0.00230	344075	16.0    17.3
0.00240	359035	16.1    17.4
0.00250	373995	16.2    17.5
0.00260	388954	16.3    17.5
0.00270	403914	16.4    17.6

Uncertainty = 2 magnitudes
Subtract 0.7 mag for rocket body

Happy hunting!
Ted Molczan




_______________________________________________
Seesat-l mailing list
https://lists.seesatmail.org/mailman/listinfo/seesat-l