NEO Planner V5.0  -  Object Selection  -  Explanations

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NEO Planner Page

Within the picture, click on the zone that you want to be explained: (not in all browsers available)

Copyright: The data comes from official access to web services from MPC or the new API Web Service of the Horizons system of the JPL.

These settings are the third step in getting NEO Planner up and running.  

Here you define the Object Selection of NEO Planner.
In preparation for an observation session, so far you manually spend some of the time picking out the observable objects and weighing which objects are really suitable.
With the help of the settings made here, the objects are preselected analogous to the manual entries on the MPC homepage and the ephemeris are determined.
NEO Planner only selects non-numbered NEOs and all observable comets.
When loading or saving Object Selection, the associated current result of the CGI-query at the MPC is displayed due to the preset settings on the right in the window.

Plausibility checks or actions are usually only carried out after leaving the cursor in the input field.

IAU Observatory Code::

The active observatory is displayed

- Ephemeris selection: NEO and Comets:

Number of lines per object:

The result of the calculation of the observation night is completely dependent on good parameters.
Neo Planner needs the ephemeris of each object over the entire period of the coming night if possible.
This means that the number of ephemeris and the interval in minutes must be coordinated in such a way
that there are enough ephemeris for each object in order to calculate the optimal observation slot for position and time.

The MPC returns the ephemeris related to the Observatory Code. This means that the local altitude of the objects is included in the output.
Reaching the highest altitude is exactly the calculation goal for the best observation time.

A well-functioning combination of the number of ephemeris and the interval in minutes is number 40 and interval 20.
These suggested values should be used to ensure that the entire observation period of the coming night is taken into account.
In the months around  Summer solstice in higher latitudes around 45 degrees the number can also be set to around 30 to prevent an overflow to the following day.

Interval in minutes per object:

Please look at the previous explanation.

The time intervals of the ephemeris in these settings are only required for preselecting the objects and play no role in the final calculation of the observation ephemeris.
These are then determined to the minute, regardless of these settings.

Select objects from NEAM00.txt:

The determination of the observable NEO per observatory code is no longer carried out via the NEAm00.txt of the MPC,
but via the new API Web Service of the Horizons system of the JPL.
This significantly reduces the loading time of the NEO's ephemeris, which is good for the overall performance of the Execute process.
The loading of the observable NEO of the coming night is now carried out according to the parameters defined by NEO Planner
such as minimum altitude or limitation of magnitude.

Only those NEOs are taken into account whose last observation date is no longer than the specified days ago.
A period longer than one year makes sense if you also want to carry out recovery observations.



All NEO with V = xx.xx to xx.x:

The selection of the NEO can be narrowed down. It is possible to choose the brightness from ... to.

As a rule, every NEO observer has experience with the maximum NEO observable for him in relation to their brightness and
should therefore enter his personal experience value here.
NEO Planner will therefore only select those objects whose Vmag values are numerically below the settings value.
The apparent speed does not play a role at this point when considering the maximum usable brightness.

The following model is used to select the NEO:

First it is checked whether the Vmag of the ephemeris is maximum 0.4 mag weaker than the limit value in the settings. If so, the object will continue to be considered.

Second, if the apparent speed in the ephemeris is less than 100.00 s / min, the average Vmag of the last 10 observations is used for the selection of the object,
otherwise the Vmag of the ephemeris.

The reason for taking into account the apparent speed at the time of the ephemeris is a possible strong change in the Vmag compared to previous observations..
At speeds over 100 seconds / minute at the time of the ephemeris we always use MPC's designated Vmag of the ephemeris for selection.
Otherwise fast objects might not be taken into account.

In additon, during the calculation of the exposure times, the selected NEO are subjected to a special Vmag consideration.
See the explanations for the revise button in the Preparation / Execute Planning tab

Minimum s/min x.xx:   All objects, also NEOCP

Depending on the observation strategy, objects that move below a defined speed per minute can be sorted out: s / min = arc seconds per minute.
Extremely low speeds increase the number of images required for a measurement, even with bright objects.
Each individual measurement should be made at the distance of the FWHW value.

Maximum s/min xxxx.xx:   All objects, also NEOCP

Depending on the observation strategy, objects moving above a defined speed per minute can be sorted out: s / min = arc seconds per minute.

Sort out previously observed objects:

Mark the checkbox if previous own observations of objects are to be taken into account when planning the object selection
and enter the number of days in the past within which the objects are not selected until the current date.



- Ephemeris selection:  Comets:

Select Comets with V = xx.xx to xx.x:

The selection of the comets can be narrowed down. It is possible to choose the brightness from ... to.

With comets, compared to NEO, you have to apply slightly different standards with regard to the Vmag selection. Since comets usually appear spotty on the CCD image,
the maximum usable brightness should be set somewhat brighter than with NEO. In addition, comets move at far greater distances from the Earth,
which largely excludes a significant change in measured brightness.
29P SCHWASSMANN/WACHMANN with its regularly occurring outbursts in brightness is certainly an exception here just like outbreaks in other comets,
but is generally not taken into account.

The real brightness of comets is actually often very different from the brightness we find in the ephemeris of the MPC.
Therefore to calculate the exposure times, NEO Planner always uses the average Vmag of the last 10 observations,
which are computed from the last publishing by the MPC

Last observations since xx months:

Comets can lose their brightness very quickly, which means that they have not been observed lately.
It is therefore advisable to include only those comets in the planning that have been observed by observatories for a month.
However, if you intend to rediscover one in the coming orbit, you should increase the value here accordingly.



NEOCP settings and some additional explanations:

Most of the following settings represent a simulation of the manual entries on the NEOCP, which NEO Planner automatically determines using so-called CGI queries.
Both the MPC and JPL CNEOS Scout kindly offer such queries to motivated programmers.

The MPC delivers CGI results in text format, while Scout sends so-called JSON files, which all have to be parsed after receipt.
However, the Scout JSON queries are not used in the object selection at this point, only NEOCP objects are selected.

NEO Planner only uses the Scout JSON queries when calculating the observation positions to the minute during the calculation process,
which in contrast to the manual entries on the Scout website do not have to endure long waiting times.
(The reason for the long manual waiting times of ephermeris calculated with Scout, which every NEOCP observer knows, is, by the way,
the compulsory calculation of more than 1000 different orbital elements for each object. NEO Planner, on the other hand,
makes a quick Scout query request only with the first 30 orbits, which experience shows is sufficient for planning.)


- Ephemeris selection: NEOCP:

Not seen less than days::

Newly discovered objects usually show only a few observations.
Most of the objects listed on the NEOCP are too weak in terms of brightness or lie outside the observable range.
To make matters worse, many objects were observed more than a day ago, which makes it very difficult to find them again.
In the latter cases, the positions calculated by the MPC or JPL Scout can be very far from the real position.
Therefore, especially with the smaller field sizes of the CCD chip and longer focal lengths,
you should only target those objects that were observed no longer than a day ago.
This is of course only a recommendation and depends on the motivation and equipment of the observer.

Around the time of the full moon, it can make sense to include objects with the last observation time in the past, especially
if several observations were made earlier.

All NEOCP object with V = -30 to  xx.x:

Confirming NEOCP objects is both a motivation and a challenge. Experience has shown that observers pay special attention to these objects.
The confirmation of new objects, but also the follow-up observation, is important in order to allow as many measurements as possible to flow into
the calculation of the orbital elements for a retrieval in later orbits.

with Declination between +/-xx and +/-xx:

Entering the observable area in declination applies equally to NEOCP objects, NEO and Comets.
Enter exactly the values that you would enter on the NEOCP.
Enter values between -90 and approx. +30 in the southern hemisphere!

with a NEO disirability score  of xxx% and xxx%:

Usually from 0 to 100%

Ephemeris interval:

Entering interval 1 (30 minutes) usually ensures the required range of ephemeris over the entire night.

Display of the NEOCP Site:

The NEOCP query results are displayed when the window is loaded based on the parameters set.
In addition, the display adapts itself when you press the Save settings button
based on the settings made.


JPL Scout n-orbits  1 to 30  xx:

The Scout offered by JPL cneos shows the average (median) determined ephemeris of the NEOCP object
against the background of a high number  (>1000)
of possible orbits and a correspondingly long calculation time. Everyone knows this performance effect when using the Scout.
This very high-performance method provides the best positions of a newly discovered object and is therefore preferred by the NEO Planner.

However, NEO Planner does not calculate the ephemeris of NEOCP objects completely and controls the median result in the API call
using a freely selectable number of orbits between 1 and 30.
Experience has shown that the median of 30 orbits is sufficient for objects with arcs >= 8 hours,
to get a good positioning very close to the online Scout ephemeris.
As a result, determination of the ephemeris by the Scout API is reduced to around 4 seconds for these objects.

With arcs < 8 hours, NEO Planner uses an automated scaling of the orbits to be calculated.
The number of orbits given here is increased by a factor of 2 to 8 per arc hour approaching from 8 to 1.
This means that an arc of 7.xx hours n-orbits is increased by a factor of 2 =  60 n-orbits.
An arc of 4.xx hours increases the factor by 5 = 150 n-orbits, an arc of 1.xx hours increases the factor to 8 = 240 n-orbits.
Arcs of less than 1 hour, which often consist of individual detection measurements from an observatory, are treated as follows:
An arc between 0.5 and 0.99 hours increases the factor by 9 = 270 n-orbits, an arc < 0.5 hours increases the factor to 10 = 300 n-orbits.
For an object with an arc < 0.5 hours, reading out the ephemeris with Scout-API takes about 30 seconds.

You can choose the number of n-orbits as a basis for the median calculation of the Scout itself between 1 and 30. 30 is recommended.
With the checkbox you can choose whether NEO Planner should perform the scaling as just described or not.

So what does this mean for the accuracy of the NEOCP ephemeris in the NEO Planner?

The larger the arc of an object, the more precise positions are displayed. 
The shorter the arc of an object, the longer the planning takes.
Objects with a very short arc should be observed with caution, especially if confirmatory measurements have not yet been submitted.

Suggestion for the planning method:

When planning for the first time, the setting should be: n-orbits = 30, no scaling.
Selecting a scaling makes sense in the following scenario.
After planning, you find objects with short arcs in the Revise and want to find and confirm them.
Then you adjust n-orbits to e.g. 15 and click on scaling.
Re-planning will then determine the positions of the short-track objects closer to the online scout than without scaling.




Copyright: The author of NEO Planner and all sites of this web is Bernhard Haeusler, Dettelbach, Germany, all rights reserved