Yesterday, over 16,000 new asteroids reported by Rubin received provisional designations from the MPC. These objects appear to have bypassed the usual MPC process for survey reports—where objects are first sent to the ITF, then identified as unique through orbital fitting before being assigned a provisional designation. Instead, it seems the MPC checked the orbits directly upon reporting and assigned provisional designations without going through the ITF.
Here’s the question: if all detected moving objects are being reported, then naturally there should be tracklets stored in the ITF without provisional designations. Objects detected only during a single night fall into this category. It is impossible for every object to be detected without fail over three or four nights. However, in reality, even in yesterday’s reports, and further back in the reports from the first look in June last year, Rubin observations sent to the ITF appear to be almost nonexistent.
Does this mean that Rubin reports only include objects identified (via HelioLinC, etc.) as the same object detected over multiple nights, out of all the moving objects detected?
If so, do you plan to report the detection of the single night that could not be identified with other tracklets until the end as an observation sent to the ITF to the MPC?
To add a few details: we do intend eventually to submit un-linked tracklets with some minimum number of sources – probably three or four. We’re still working out the details of this because it isn’t expected to be a major source of discoveries for LSST, for reasons I’ll explain below.
The LSST survey cadence dictates that most sky areas will be observed only twice per night, meaning that tracklets will consist of just two sources. In other words, the LSST will produce mainly ‘two-point tracklets’. This is a major departure from other surveys, which typically aim for four-point tracklets (or three-point tracklets at the very least). A four-point tracklet indicating ‘straight line’ motion on the sky at a constant velocity is a very good indication of real asteroid. By contrast, many two-point tracklets are random associations of unrelated things (different objects or noise detections of various kinds). For this reason, two-point tracklets cannot be submitted to the MPC without overwhelming the ITF (and the NEOCP) with spurious data. The best way to prove unambiguously that a given two-point tracklet does correspond to a real asteroid is to link it to other tracklets on other nights. That’s why the LSST discovery paradigm relies on multi-night linking rather than tracklet submissions: we need the multi-night linkages to know which tracklets correspond to real asteroids.
That said, we will sometimes observe a field more than twice per night, and a small minority of LSST-produced tracklets will have more than two points. These we intend to submit to the ITF – or the NEOCP if the object’s angular velocity is characteristic of a near-Earth asteroid. Many-point tracklets with NEO-like angular velocities will be submitted promptly. Many-point tracklets with angular velocities characteristic of main belt asteroids or more distant objects may not be submitted right away (we’re still deciding on the timescale) because it would be more efficient to incorporate them into a multi-night linkage prior to submission, if this is possible. In any case, all plausible many-point tracklets that do not form part of a multi-night linkage will eventually be sent to the ITF.
Thank you for the very, very clear explanation.!
I had completely assumed that since the Rubin survey began, numerous NEO candidates with only two points would be sent to the NEOCP every night, but that’s not actually the case. Does that mean the expectation that Rubin would monopolize many NEOs in the southern hemisphere isn’t necessarily correct?
And does the search range for links to two-point tracklets within Rubin only include objects observed by Rubin itself? For example, if an object is immediately identified as known, would it be reported even as a two-point tracklet? Also, if a link can be established with an object from another station stored in the ITF, would it be reported as a two-point tracklet or a two-point tracklet over two nights, and then the identification submitted?
For example, DECam has reported numerous MBAs of ~23 mag and Subaru has reported numerous MBAs of ~26 mag to ITF. Therefore, with just two nights of Rubin two-point tracklet data, it can link these to past observations and submit a provisional designation for a new object.
Hello! Are these 16,000 new asteroids given provisional designations part of the same Rubin First Look data spanning nine nights between 2025 April 21 and May 5?
If these are not yet in MPC X05, then how to find the photometry (magnitude) data of all these asteroids?
Thank you for these additional details, Ari. From your description, it sounds like there would be a window of time for other surveys (including amateurs) to perform follow-up observations of alerts that might correspond to asteroids before they are submitted by the LSST to the MPC. This would allow other surveys/amateurs to gain discovery credits on some of these objects, which would be, in my (very biased) opinion excellent news!
Mag 22 is not easy but feasible for amateurs. With my C11 F/1.9, I can reach that point with a stack of ~5 hours on a good night (using ATLAS V mag and SNR > 10). Those with bigger telescopes and darker skies can reach magnitude 22.5. That’s the beauty of synthetic tracking. While we spend 5 hours on just one field, we can go close to or as deep as the big surveys (ATLAS, CSS and PanSTARRs, but not Kitt Peak Bok or DECam who go much deeper).
But this is not even the most important point. Some NEOs detected by the LSST will be much brighter than mag 22 (and many will be detected around mag 23 but will become much brighter within a few days). If the LSST does not immediately submit these observations as tracklets to the MPC, there is an opportunity for amateurs (and other surveys) to perform follow up observations while receiving discovery credit. Imagine that on night N, the LSST emits an alert for something that looks like a NEO around mag 21. But with only two observations, this is not submitted as a tracklet to the MPC. Other surveys (including amateurs for the easiest ones) could attempt to perform follow up observations, and if these follow up observations confirm that this alert corresponds to a NEO, they would be the first to send a tracklet to the MPC, therefore receiving discovery credit. Sounds like a good way to incentivise other surveys and the amateur community to follow up on alerts from the LSST that could be from NEOs. If the two points tracklets are immediately submitted to the MPC, the lack of discovery credit as a nice reward for follow up observations would make these less likely. Just my 2 cts.
Yes, from an amateur’s perspective, there is hope.
However, from a planetary defense standpoint, it may not be cause for celebration. Small NEOs remain invisible in the night sky for days, making it difficult for Rubin alone to observe and report on them night after night.
but That said, observers tracking based on real-time alerts may emerge. Follow-up observers would likely monitor not only NEOCP alerts but also Rubin alerts.