[Paper Review] Simultaneous LSST and Euclid observations - advantages for Solar System Objects

C. Snodgrass, B. Carry+18 more|arXiv (Cornell University)|Dec 3, 2018

Stellar, planetary, and galactic studies1 references4 citations

TL;DR

This paper proposes a coordinated mini-survey between LSST and Euclid to enable quasi-simultaneous observations of Solar System Objects (SSOs), leveraging the 0.01 AU parallax between Earth and the Sun-Earth L2 point to improve orbital determination and distance measurements. The method enables precise photometry, compositional analysis via near-IR colors, and detection of binarity or cometary activity, significantly enhancing SSO characterization beyond what either mission could achieve alone.

ABSTRACT

The ESA Euclid mission is a space telescope that will survey ~15,000 square degrees of the sky, primarily to study the distant universe (constraining cosmological parameters through the lensing of galaxies). It is also expected to observe ~150,000 Solar System Objects (SSOs), primarily in poorly understood high inclination populations, as it will mostly avoid +/-15 degrees from the ecliptic plane. With a launch date of 2022 and a 6 year survey, Euclid and LSST will operate at the same time, and have complementary capabilities. We propose a LSST mini-survey to coordinate quasi-simultaneous observations between these two powerful observatories, when possible, with the primary aim of greatly improving the orbits of SSOs discovered by these facilities. As Euclid will operate from a halo orbit around the Sun-Earth L2 Lagrangian point, there will be significant parallax between observations from Earth and Euclid (0.01 AU). This means that simultaneous observations will give an independent distance measurement to SSOs, giving additional constraints on orbits compared to single Euclid visits.

Motivation & Objective

• To improve the orbital determination of Solar System Objects (SSOs) discovered by LSST and Euclid through quasi-simultaneous observations.
• To leverage the 0.01 AU baseline between Earth and Euclid’s L2 position to enable independent distance measurements via parallax.
• To enable high-precision photometry by minimizing systematic effects from rotation of irregular SSOs through simultaneous visible and near-IR observations.
• To enhance compositional characterization of faint SSOs using Euclid’s broad visible and near-IR bands, breaking degeneracies present in visible-only surveys.
• To detect and study binarity and cometary activity in Centaurs and trans-Neptunian objects using Euclid’s high spatial resolution.

Proposed method

• Propose a LSST mini-survey to schedule observations in coordination with Euclid’s survey timeline, prioritizing fields where both telescopes observe the same SSOs nearly simultaneously.
• Utilize the 1.5 million km baseline between LSST (Earth) and Euclid (L2) to measure parallax, enabling independent distance estimates to SSOs.
• Combine LSST’s high-cadence, multi-epoch observations with Euclid’s single-visit, multi-band imaging to refine orbital arcs and reduce uncertainty.
• Use simultaneous visible (LSST) and near-IR (Euclid) photometry to derive accurate colors and break spectral degeneracies in asteroid taxonomy.
• Apply astrometric and photometric modeling to detect binary systems and extended features (e.g., cometary tails) in SSOs via differential motion and flux variations.
• Simulate LSST-Euclid overlap using known SSO ephemerides and Euclid’s fixed survey schedule to identify optimal observation windows.

Experimental results

Research questions

• RQ1 How can quasi-simultaneous observations between LSST and Euclid improve the accuracy of Solar System Object orbit determination?
• RQ2 To what extent does the parallax baseline between Earth and L2 enhance distance measurements for SSOs?
• RQ3 How does simultaneous visible and near-IR photometry reduce systematic errors from irregular SSO rotation in color measurements?
• RQ4 What is the potential of combined LSST-Euclid data to detect and characterize binary systems and cometary activity in trans-Neptunian objects?
• RQ5 How can coordinated observations improve the compositional classification of faint, distant SSOs compared to single-mission surveys?

Key findings

• The 0.01 AU parallax baseline between LSST and Euclid enables independent distance measurements to SSOs, significantly improving orbital solutions beyond single-visit data.
• Simultaneous observations reduce photometric systematics from unknown rotation lightcurves, enabling more precise color measurements for SSOs.
• Euclid’s near-IR bands (Y, J, H) combined with LSST’s visible band break degeneracies in asteroid taxonomy, enabling better compositional mapping of faint objects.
• The method allows for rapid recovery and follow-up of rare or fast-moving SSOs by providing early, high-precision orbit solutions via parallax.
• Euclid is expected to detect ~150,000 SSOs, with ~100,000 being newly discovered, and coordinated observations will greatly enhance the scientific return from these detections.
• The combination of LSST’s high-cadence coverage and Euclid’s diffraction-limited imaging enables detection of binarity and cometary activity in Centaurs with high sensitivity.