2021-10-08, 06:34 PM
(This post was last modified: 2021-10-08, 06:36 PM by bigmasterdrago.)
Always use your observing location. I always use hour steps over what ever time span I'm interested in. And run with the close approach minimum distance time as the center. Like this set up for 48 hours:
Or change the "Ephemeris Type" to Osculation Orbital Elements which will let you copy and paste the full hourly element set from a specific time into SkyTools 4v. That give you the opportunity to create a precision ST finder chart for that rock at a time very near (couple hours) that set of osculating elements. This is specifically necessary due to ST not being able to predict an n-body plot. The chart (IA) has to be for the specific time near those elements.
Remember that when making a set of osculating elements to always use UT not UT-(time zone) as you would do for just a strict local time ephemeris.
In the example 2021 TQ1, the Horizons hourly ephemeris indicates the rock is not only too low during that 48 hour near Earth pass, but too faint.
However, 2019 XS on November 9, 3:48UT with an uncertainty of <1min and has good conditions from Nov 9, 23:00CDT to Nov 10, 03:00CDT:
see text file
So use Horizons to make an osculating element set for the hour of expected observation, then copy all of it and edit that rock, pasting that set into the complete field.
Unfortunately, when I copy those osculating elements for 23:00CDT on November 9th and then attempt to edit by pasting in the edit field, I get a (not Responding) then ST4 crashes and 2019 XS is no longer in the database. Maybe the date is too far in the future to predict or edit future elements. But I will try closer to the date of observations. I want a good finder chart so can wait. But for now, Horizons will predict the location or I'll turn to a stand alone gravitational simulator that takes todays elements (JPL epoch July 1, 2021 JD 2459396.5) and predicts the location on Nov. 9, 23:00CDT as RA 2h46m40s DEC -4°8'18s, azi 158°, el 53° moving 62.2"/min, mag 13.2, %ph 96.
Or change the "Ephemeris Type" to Osculation Orbital Elements which will let you copy and paste the full hourly element set from a specific time into SkyTools 4v. That give you the opportunity to create a precision ST finder chart for that rock at a time very near (couple hours) that set of osculating elements. This is specifically necessary due to ST not being able to predict an n-body plot. The chart (IA) has to be for the specific time near those elements.
Remember that when making a set of osculating elements to always use UT not UT-(time zone) as you would do for just a strict local time ephemeris.
In the example 2021 TQ1, the Horizons hourly ephemeris indicates the rock is not only too low during that 48 hour near Earth pass, but too faint.
However, 2019 XS on November 9, 3:48UT with an uncertainty of <1min and has good conditions from Nov 9, 23:00CDT to Nov 10, 03:00CDT:
see text file
So use Horizons to make an osculating element set for the hour of expected observation, then copy all of it and edit that rock, pasting that set into the complete field.
Unfortunately, when I copy those osculating elements for 23:00CDT on November 9th and then attempt to edit by pasting in the edit field, I get a (not Responding) then ST4 crashes and 2019 XS is no longer in the database. Maybe the date is too far in the future to predict or edit future elements. But I will try closer to the date of observations. I want a good finder chart so can wait. But for now, Horizons will predict the location or I'll turn to a stand alone gravitational simulator that takes todays elements (JPL epoch July 1, 2021 JD 2459396.5) and predicts the location on Nov. 9, 23:00CDT as RA 2h46m40s DEC -4°8'18s, azi 158°, el 53° moving 62.2"/min, mag 13.2, %ph 96.