The DP0.3 Simulation#
The DP0.3 data set is composed of two sets of catalogs containing real and simulated solar system and interstellar objects: one that represents LSST results after one year, and one that represents LSST results at the end of the 10 year survey. The DP0.3 data set is hosted on the Rubin Science Platform (RSP) and available to all DP0 delegates.
Credit: The DP0.3 data set was generated by members of the Rubin Solar System Pipelines and Commissioning teams, with help from the LSST Solar System Science Collaboration, in particular: Pedro Bernardinelli, Jake Kurlander, Joachim Moeyens, Samuel Cornwall, Ari Heinze, Steph Merritt, Lynne Jones, Siegfried Eggl, Meg Schwamb, and Mario Juric.
Observing Strategy#
The DP0.3 simulation uses the LSST baseline v3.0 cadence (see page 44 of the Survey Cadence Optimization Committee’s Phase 2 Recommendations). This observing strategy includes the North Ecliptic Spur and deep drilling fields (DDFs). Two of the DDFs are close to the celestial equator (have declinations near zero), and so are particularly beneficial for the detection of Solar System objects. Field revisit rates, which are driven by the needs of Solar System science, are on average 33 minutes apart. The baseline v3.0 observing strategy also contains a twilight survey for near-Earth objects (NEOs).
Simulated objects and detections#
The DP0.3 simulation includes hundreds of millions of detections of millions of objects, real and synthetic (see below), including trans-Neptunian objects (TNOs), main belt asteroids (MBAs), interstellar objects (ISOs), Hildas and Trojan asteroids, long-period comets, and near-Earth objects (NEOs).
The ObjectsInField package was used to generate an ephemeris from an object catalog and the Rubin cadence, from which source detection and measurement were simulated using the SurveySimPostProcessing package (Merritt et al. 2023, in prep).
The simulation includes astrometric scatter and photometric variations based on the objects’ color class (silicaceous and carbonaceous, see below), the exposure’s filter, and the object’s phase angle. However, rotation curves or complex geometry are not included. In other words, each DP0.3 object is a uniform, textured sphere in one of two colors. Any changes over time in an object’s apparent magnitude are due only to changes in its distance and phase angle.
Due to time constraints, DP0.3 does not contain u- or y-band detections. This decision was made in part because the majority of objects will have very low signal-to-noise ratio in u and y, and object discoverability is driven by the gri bands.
While neither the two-color nor the missing u/y band simplifications should prevent testing and exploration of the simulated Rubin data set, there is a plan to provide a more realistic simulation in an upcoming update.
Real objects from the MPC#
The DP0.3 simulation contains all objects in the Minor Planet Center Orbit (MPCORB) Database as of May 1 2023, except for the ~400 objects that have no absolute magnitudes. Out of these objects, Rubin detects 97% (1.2 million) of them in the simulated 10-year survey.
Synthetic object populations#
The DP0.3 simulation includes 91% of the objects in the Synthetic Solar System Model (S3M) catalog and 12,148 simulated ISOs. Of the S3M objects, Rubin detects 24% (3.2 million) of them in the simulated 10-year survey, and of the simulated ISOs, Rubin detects 20% (2,429).
Objects were simulated in two color classes: S and C (silicaceous and carbonaceous, see Veres for more details), with colors and slope parameters (GS) as shown in Table 1.
Color |
V-u |
V-g |
V-r |
V-i |
V-z |
V-y |
GS |
|---|---|---|---|---|---|---|---|
c |
-1.614 |
-0.302 |
0.172 |
0.291 |
0.298 |
0.303 |
0.15 |
s |
-1.927 |
-0.395 |
0.255 |
0.455 |
0.401 |
0.406 |
0.15 |
Combining real and synthetic moving objects#
To combine the real and synthetic populations while maintaining S3M’s well-chosen orbital distributions, the Hybrid Solar System Catalogue Creator (Hybridcat) was used. Hybridcat removes the closest-matching synthetic object to each real object, creating a population with all of MPCORB and most of S3M that closely match S3M’s orbital distributions.
Truth data#
The following truth parameters per observation can be found in the DiaSource tables for both the
1-year and 10-year DP0.3 catalogs.
nameTrue: The true MPC name of the object that generated the detection (for real objects).
raTrue: The true right ascension for each observation.
decTrue: The true declination for each observation.
magTrueVband: The true V-band apparent magnitude for each observation. Use the color terms in Table 1 to recover the true apparent magnitude in the band of the observation.
Furthermore, the MPCORB tables contain injected rather than measured orbital parameters, so in this sense the MPCORB tables can be thought of as “truth tables”.