What is NEOCam's (now NEO Surveyor) strategy for scanning the sky? Need to consider in which coordinate system?

In Survey Simulations of a New Near-Earth Asteroid Detection System it can be seen that Infrared astronomer Amy Mainzer gave the scanning strategy of the horizon in a paper, but I am very confused whether the scanning strategy of the sky is the same? In addition, how to connect solar elongation with ecliptic latitude?

The main problem is that I cannot figure out which coordinate system to convert the position of the asteroid to.

Fig. 3.— The basic element of the survey cadence is a “quad,” which consists of four observations taken over ∼9 hours. The green rectangle indicates the starting position.

• Welcome to Stack Exchange! Can you add a link to, or cite the source of the image? It's better if you mention what you've read so far, it may be helpful as a starting point for answers. Thanks!
– uhoh
Commented Sep 14, 2021 at 19:16
• I've fixed your post; much of the text was missing because you had accidentally embedded it in the figure information. I've also added a link to Mainzer et al so people can read it.
– uhoh
Commented Sep 19, 2021 at 11:20

above: Profoundly not-to-scale illustration of NEOCam in an orbit around the Sun-Earth libration point L1, about 1.5 million kilometers from Earth. Presumably Sun-shield and Earth-shield block light (both infrared and visible) from the Sun and the Earth in order for the instrument to work at cold temperature necessary to detect the faint infrared light radiated from NEOs.

above: Infrared astronomer Amy Mainzer illustrates how asteroids warmed by the sun will stand out more brightly in the infrared compared to reflected visible light from the sun. One coffee cup is black the other white in the false-color infrared thermal image. From here.

If you move on to figures 5 and 6 of Mainzer et al 2015 Survey Simulations of a New Near-Earth Asteroid Detection System it seems it's fairly clearly explained.

NEOCam will be in a heliocentric orbit in resonance with the Earth, in other words, in a halo orbit around Sun-Earth L1.

The paper discusses how close it should look to the direction of the Sun.

The reference plane for these illustration is the ecliptic with the horizontal direction indicating angle to the left or right of the Sun. The vertical direction is perpendicular to the ecliptic.

Fig. 5.— The survey pattern over ∼6 days for the L1 survey. Green indicates the starting field.

Fig. 6.— The entire cadence takes ∼22 days to execute, switching back and forth on either side of the Sun for the L1 survey, and proceeding in a continuous sweep for the Venus-trailing survey.

• Thank you very much! For this paper, I have some things that I don't understand. First of all, why the solar elogation range of the scanning area is 45~110, why not 45~125? Secondly, if we scan according to the method in figures 5 and 6, how to judge whether there is an asteroid in each small grid during simulation? What information should be used for judgment? Commented Sep 22, 2021 at 13:22
• @ZhitongYu I will take another look at the paper in a day or two, but the best way to proceed is to ask a new question. We can ask as many questions as we like here, and the advantage of a new question is that everyone will see it and have a chance to write an answer. Just include a link to your previous question as part of the background.
– uhoh
Commented Sep 22, 2021 at 14:24