2023-01-31, 12:22 AM
If we want to be prepared for planetary defense, we need to know the threats. 
Phil S.

Phil S.
Feature Request
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2023-01-31, 12:22 AM
If we want to be prepared for planetary defense, we need to know the threats.
![]() Phil S.
2023-01-31, 04:12 PM
I tend to agree with Phil's post #2. Although I would often find +/-15 days far too narrow. I very often like to see what a plot of a future NEA pass will look like in my sky. Maybe 48 hours either side of its closest approach. Unfortunately, using osculating elements fetched from Horizons is the only way to make ST do any sort of precision plotting over a several hour period in an IA.
What Phil, I think, is suggesting is to be able to load a "batch" set of those into an editor and save for any specific rock. As quick example, look at 2023 BN6 which has a 2LD pass on Feb. 4, 8:25UT at mag 14.8. If you edit the elements for a few days as: 2459978.500000000 = A.D. 2023-Feb-03 00:00:00.0000 TDB EC= 1.361361850160800E-01 QR= 9.176589058671051E-01 IN= 1.198273040869708E+01 OM= 1.341825605562988E+02 W = 6.782822053059083E+01 Tp= 2460039.055970014073 N = 9.002229335844819E-01 MA= 3.054861270277121E+02 TA= 2.915388320657171E+02 A = 1.062272652182088E+00 AD= 1.206886398497071E+00 PR= 3.999009429437242E+02 2459979.500000000 = A.D. 2023-Feb-04 00:00:00.0000 TDB EC= 1.373916635955650E-01 QR= 9.166394622812821E-01 IN= 1.198356129091044E+01 OM= 1.341822639829116E+02 W = 6.804448523075352E+01 Tp= 2460039.161668986082 N = 8.997600889833137E-01 MA= 3.063188114041699E+02 TA= 2.923457652918628E+02 A = 1.062636915963579E+00 AD= 1.208634369645875E+00 PR= 4.001066555494620E+02 2459980.500000000 = A.D. 2023-Feb-05 00:00:00.0000 TDB EC= 1.385784768618187E-01 QR= 9.153635681974311E-01 IN= 1.192101563919726E+01 OM= 1.341771407316324E+02 W = 6.842044677572754E+01 Tp= 2460039.393495740369 N = 8.997818258575129E-01 MA= 3.070087028717792E+02 TA= 2.930020633463932E+02 A = 1.062619801816348E+00 AD= 1.209876035435266E+00 PR= 4.000969897974008E+02 What you can easily discover is that the rock is brighter (mag 13.9) on Feb 3 15:24UT. SkyTools can quickly display this info having good elements. And make nice finder charts.
2023-01-31, 06:15 PM
Greg is suggesting adding the ability for ST4 to read a datafile of element sets in the HORIZONS format. You could select the interval between the sets, 1, 2, 4, 6, 12, 24 hours, for example in HORIZONS. ST4 would then use the elements closest in time for calculation of the positions. This is a fantastic option. It would give SkyTools the ability to make more accurate position predictions using osculating elements rather than needing to perform calculations using the equations of motion with perturbations as CNEOS does.
To clarify, the MPC has elements for the NEOs in datafiles for each day ±15 days around today's date. This option could be used to calculate ephemerides using elements 2 days in the future, for example. This is similar to what you can get using HORIZONS, but here you're limited to 1 day intervals. On the plus side, you get the elements for ALL of the NEOs for that future (or past) date. This capability would be most useful while screening the NEOs for upcoming close approaches to observe. In my case I use ST4v's DBPS function to search for MPs that will be within 0.05 AU 2 days in the future, then calculate the ephemeris for each MP to see if it will be bright enough to observe in the 13" scope. Having both of these functions would be great for asteroid hunters. Getting the MPC's elements for a future date would be great for screening all of the NEOs, then the datafile of HORIZONS elements could be used to calculate the positions during the close approach. Since ST4v reads the HORIZONS datafile, you wouldn't need to edit the MP DB for each element set during the pass - super cool! I'm looking forward to this update, Phil S.
2023-01-31, 07:07 PM
(This post was last modified: 2023-01-31, 07:49 PM by theskyhound.)
Phil, you mostly nailed it.
Phil, yes you could use HORIZONS to generate a set of elements with a custom epoch at a later date (months or years from now) and that will work with my plan, and it can be useful in some circumstances. But... there is an important reason why you usually need to wait until a date closer to the pass to plan for these things, and its not perturbations. Except for a few asteroids with very well-known orbits from previous close passes, what limits the accuracy of the plotted positions is how accurate the observational data is that the orbit is built on. The accuracy of the astrometry improves as the object gets closer. The accuracy required from the orbital elements also increases as it gets closer. The two work in lock step together. Usually, the most important factor in accurately plotting the position of an asteroid as it passes the earth is the accuracy of the astrometry, and that, in turn, is usually the most recent astrometry as it approaches. This is the main reason for releasing new orbital elements regularly for NEAs, rather than the perturbations from the earth. Phil--you can't tell from the epoch alone what observations are included in the orbit. A new orbit based on the same observations for an epoch ten days later isn't a useful improvement, because there is normally nothing to affect the osculating elements over such a short period of time. What's more useful is that new astrometry has been included that improves the orbit, not that the epoch has been updated. So here is what I believe is needed: 1. Download of elements updated more often than the 200-day epoch (e.g. the NEA Today elements) 2. Patience, as the asteroid approaches and the astrometry improves 3. For very close passes only, wait until the last minute and import sets of HORIZONS elements every couple of hours during the relatively short period of the pass and afterward 4. A way for SkyTools to pick the proper set of HORIZONS elements, based on the time, during the pass when plotting the path on the chart I am proposing making (3) easier, but mostly, I have a plan to implement (4) as a special case. Note: I previously mistakenly said I wanted to make (1) easier.
Clear skies,
Greg Head Dude at Skyhound
2023-01-31, 08:07 PM
(2023-01-31, 07:07 PM)theskyhound Wrote: Phil, you mostly nailed it.Hi Greg, Since you released the update that allows the NEAs at Today's Epoch to replace the elements from MPC's 'Standard Epochs', Condition #1 is no longer a problem for NEOs. #2 applies to newly discovered NEOs primarily. It's interesting to watch the error on close approach time shrink with additional observations on the CNEOS website; however, for some objects this can occur quickly. So quickly that the MPC's daily updates aren't able to keep up with the changes. This is where #3 comes in & being able to import element sets from HORIZONS will be a big help in combination with #4. As you keep emphasizing, the elements are only as good as the observations on which they're based whether from CNEOS, HORIZONS or the MPC. For new discoveries, there aren't many observations & the orbit arc is short, hence the high uncertainty for these objects. I'm aware of this though I don't always express it in forum posts. ![]() These improvements to SkyTools are much anticipated. TIA, Phil S.
2023-02-01, 04:38 AM
Please note that the original version of my post mistakenly labelled #1 as something to be made easier, but I meant #4.
Clear skies,
Greg Head Dude at Skyhound
2023-02-01, 02:10 PM
(2023-01-27, 05:09 PM)theskyhound Wrote: Xmas is coming in the form of version 4.1 later this year. If you guys could have one wish with SkyTools to make this process of observing close approachers easier, what would it be? If I could have a single Christmas gift in ST, it would be some sort of single click that I could make b4 I go have breakfast. The entire process of working with asteroids in ST is clunky, sometimes frustrating, & always time consuming. That single click would initiate a command to fetch all the latest elements of NEAs for the date I'm interested in - most likely the date on the computer clock. Then, I can run DBPS to refine my list for that day. Automate this process with a one click.... 1st click - wait for backup of supplemental data files 2nd click to download MP 3rd click to fetch & install 4th click to download wait..... while it downloads, reads, updates, creates 200 day epoch, writing epoch files, rebuild cross index files 5th click to close 6th click to accept
2023-02-01, 05:53 PM
(2023-02-01, 02:10 PM)bigmasterdrago Wrote:(2023-01-27, 05:09 PM)theskyhound Wrote: Xmas is coming in the form of version 4.1 later this year. If you guys could have one wish with SkyTools to make this process of observing close approachers easier, what would it be? That would be nice, but I like to examine the MPDB after Step #5 to see which MPs have been added to the DB. Sometimes the 'NEAs at Today's Epoch' file from MPC doesn't contain the most recently discovered NEOs & the close approach is upon us. In that case, I download the single NEO's elements from MPC. That info always uses the Standard Epoch, currently 2023 Feb 25 0000 UT. Phil S.
2023-02-01, 08:54 PM
(This post was last modified: 2023-02-01, 08:56 PM by theskyhound.)
Guys, I appreciate your enthusiasm, but I specifically asked not for your ideas of how to solve this problem, only what problem needs to be solved. Please let me do the design and programming. I know about constraints, limitations, and relationships within the software that you aren't aware of. Most of all, your own needs may not encompass those of others.
If you get a design idea locked into your heads, you are going to hate me when you don't get that exact thing. Seriously. Been down this road before.
Clear skies,
Greg Head Dude at Skyhound
2023-02-01, 08:57 PM
(This post was last modified: 2023-02-02, 04:03 AM by theskyhound.)
I will think about streamlining the process, but I can't guarantee anything.
Clear skies,
Greg Head Dude at Skyhound |
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