The crowded window, MJD 60850 to 60880, holds 77,231 labelled objects with tracklets on three or more nights. That is three quarters of the Phase 4 sample. The counts below are the claimed groups from that window.
| Outcome | Objects | Of eligible |
|---|---|---|
| Exclusive | 32,971 | 42.7% |
| Gathered, mixed with another catalogue object | 35,002 | 45.3% |
| Missed | 9,258 | 12.0% |
Three quarters of the misses are nights claimed inside a neighbor's group. The mixed groups are that same neighbor, kept for three nights. A separate fifth of the misses is a clean pair whose third night is a week away and moving several arcsec/hour differently.
Of the 9,258 objects with no group holding three of their nights, 6,929 already have a night inside a cluster that contains another catalogue object. 1,802 have a clean two-night pair and an unmatched third night. 527 never join another night of themselves.
| What happened | Objects |
|---|---|
| A night was claimed in a neighbor's group | 6,929 |
| Clean pair, third night unmatched | 1,802 |
| No cross-night link | 527 |
A night counts as claimed when it sits in a kept cluster that also holds another catalogue object.
Among those 6,929, the longest surviving piece is already mixed for 4,280. Another 2,062 still have a clean pair, and the third night was taken by an object a median 0.18° away whose rate agrees to about 3 arcsec/hour. 584 never keep even a pair. Their nights appear only inside someone else's group. A handful of the 6,929 also contain a planted tracklet, so the three pieces add to 6,926.
The 1,802 clean pairs span a median of 3 days. The night left out is a median of 10 days from that pair, and its rate differs by a median of 9 arcsec/hour. Only 65 of them are within 3 days, and only 345 agree in rate to 5 arcsec/hour. The velocity tolerance of the grid is 0.001 AU/day, about 3 arcsec/hour at 2.5 AU, so that night never enters the cluster. The 527 with no link at all look the same: a median gap of 9 days, and only three nights.
| Left-out night | Median | 90th percentile |
|---|---|---|
| Gap from the clean pair | 10 days | 16 days |
| Rate difference | 8.9 arcsec/hr | 14.8 arcsec/hr |
| Span of the pair itself | 3 days | 5 days |
The 6° patch margin accounts for 12 misses. No object in this window has more than 12 tracklets, so the cluster cap does not.
35,002 gathered objects share their group with another catalogue object. The companion is on the sky at a median 0.08°, shares a night in 94% of cases, and differs in rate by a median 1.7 arcsec/hour. Half of the groups contain exactly one other object. The rest contain two or more. 88% of the companions agree in rate to 5 arcsec/hour. Five further objects are mixed only with a planted tracklet.
| Separation of the companion | Objects |
|---|---|
| Under 0.05° | 9,454 |
| 0.05° to 0.1° | 11,937 |
| 0.1° to 0.2° | 9,787 |
| 0.2° to 0.5° | 2,735 |
| Over 0.5° | 1,084 |
Minimum on-sky separation between the object's tracklets and its nearest companion in the same cluster. 0.008 AU is about 0.2° at 2.5 AU.
| Other catalogue objects in the group | Objects |
|---|---|
| 1 | 18,428 |
| 2 | 10,138 |
| 3 | 4,186 |
| 4 or more | 2,249 |
Exclusive, mixed, and missed objects all have another tracklet a median 0.03° away on the same night. What differs is the rate match of the body that enters the cluster. The companion inside a mixed group differs by 1.7 arcsec/hour. The nearest tracklet to an exclusive object differs by 4.1 arcsec/hour, outside the velocity tolerance at main-belt distance. Most exclusive objects still share two or more nights with some similar-rate neighbor, so multi-night proximity is not enough. The propagated state has to keep the neighbor inside 0.008 AU.
| Class | Objects | Nearest tracklet | Rate difference |
|---|---|---|---|
| Exclusive | 32,971 | 0.034° | 4.1 arcsec/hr |
| Mixed | 35,002 | 0.032° | 3.2 arcsec/hr |
| Missed | 9,258 | 0.031° | 3.3 arcsec/hr |
Nearest other catalogue tracklet on the same night, median over objects. The mixed class's in-cluster companion, which is not always that nearest tracklet, is at 0.08° and 1.7 arcsec/hour.
Data: Rubin Observatory Data Preview 2, labelled
ssObjectId detections, linked with the Phase 1 HelioLinC grid
in one 30-day window.