C/2017 U1 => A/2017 U1
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Author:  t00fri [ Fri, 27-10-17, 7:13 GMT ]
Post subject:  C/2017 U1 => A/2017 U1

For those of you with an interest in C/2017 U1:

I quote from a brand new article in S&T (by Kelly Beatty, Oct 25 2017) ... lar-comet/

S&T wrote:
Its true character became clearer after Karen Meech (University of Hawaii) recorded a series of images with the Very Large Telescope that, when stacked, showed a perfectly starlike object. So it's a deep-space asteroid, not a comet, and consequently officials at the MPC changed its designation to A/2017 U1.


Author:  John Van Vliet [ Sat, 28-10-17, 0:14 GMT ]
Post subject:  Re: C/2017 U1 => A/2017 U1

here is a link to a bsp file from horizons telnewt service ... sp=sharing


BRIEF -- Version 4.0.0, September 8, 2010 -- Toolkit Version N0066
Summary for: A_2017_U1.bsp
Bodies   Start of Interval (ET)          End of Interval (ET)
-------  -----------------------------   -----------------------------
3788040  1900 JAN 01 00:00:00.000        2101 JAN 01 00:00:00.000

Author:  t00fri [ Sun, 29-10-17, 15:21 GMT ]
Post subject:  Re: C/2017 U1 => A/2017 U1

Thanks John for the link to the A_2017_U1.bsp file. Meanwhile I wrote the .ssc file etc for SPICE from scratch and added some comments about where the various parameters came from:
"A2017 U1" "Sol"
Class "asteroid"
Mesh "asteroid.cms" # default
Texture "asteroid.jpg" # default

Orientation [ 90 1 0 0 ]

Radius 0.08 # educated guess
Albedo 0.1 # guess

OrbitFrame { EclipticJ2000 { Center "Sol" }}

Beginning "1900 01 01 00:00:00.000" # from 'brief' Spice utility
Ending "2101 01 01 00:00:00.000" # 'brief *.bsp'

Kernel "A_2017_U1.bsp"
Target "3788040" # from 'brief *.bsp' command
Origin "0" # from 'brief -c *.bsp'
Period 0 # from celestia.Sci code to get aperiodic Spice trajectory
BoundingRadius 1 # not too big since used just for culling

Period 6 # guess

A few remarks: celestia.Sci and Celestia code expect Period = 0 for an aperiodic (hyperbolic) Spice trajectory. In one of the scholarly papers about A/2017 U1 some arguments are given for a relatively tiny size (0.16 km ) of the asteroid. Accordingly, the BoundingRadius (used for culling only) should be pretty small, too. Practically all other values came from using the 'brief' utility. As you can see, I used the default asteroid.cms and asteroid.jpg for now.

Here is a screenshot to show that things are working fine.

[by all means click on image and then hit F11 (Firefox)]
a2017_u1.jpg [ 187.65 KiB | Viewed 131 times ]

Important tests I did were checking the various positions found by the official observers between Oct. 19 and Oct. 25.
The accuracy is generally quite OK.


Author:  John Van Vliet [ Mon, 30-10-17, 0:46 GMT ]
Post subject:  Re: C/2017 U1 => A/2017 U1

links all over the place
added a zip to the cmod ,bsp,and ssc i posted in the spice kernel section
-- the gray colored texture and not the red one

Author:  symaski62 [ Mon, 13-11-17, 13:36 GMT ]
Post subject:  Re: C/2017 U1 => A/2017 U1

The origin of interstellar asteroidal objects like 1I/2017 U1

We find that about 1.3\,Myr ago 1I/2017U1 has passed within a distance of 0.16\,pc from the nearby star TYC4742-1027-1. It seems unlikely that 1I/2017U1 originated from an Oort-cloud around this star, but it simply trespassed on its way through.


1I/╩╗Oumuamua = A/2017 U1

Author:  symaski62 [ Wed, 15-11-17, 11:21 GMT ]
Post subject:  Re: C/2017 U1 => A/2017 U1

APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/'Oumuamua

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