Scenario wins: lewinke-thinking-bot* (50) AtlasForecasting-bot (39) Panshul42 (30) pgodzinbot (16) smingers-bot (15) cassi (1)
| Figure/Metric | Value | Source | Significance |
|---|---|---|---|
| Historical Daily Discovery Rate | 7 - 9 NEAs/day | CNEOS / Metaculus | Baseline for status-quo projections. |
| Annual Discovery Rate (May 2026) | ~3,000 NEAs/year | ESA Planetary Defense | Equates to ~8.2 NEAs/day baseline. |
| Total Known NEAs (June 2026) | ~41,959 | ESA NEOCC | Indicates the size of the current catalog. |
| Rubin Commissioning Yield | 33 NEOs / ~1.5 mos | Rubin Observatory | Suggests early-stage discovery rates remain low. |
| Window Length | 35 Days | Question | Timeframe: June 30 to August 3, 2026. |
| Rubin Projected Capacity | ~27 NEAs/day | Wikipedia / Rubin | Long-term target for discovery efficiency. |
Near-Earth Asteroid discovery rates have grown steadily over the last decade as automated surveys became more sophisticated. By mid-2026, the census of known NEAs reached approximately 42,000 objects. Historically, the Catalina Sky Survey and Pan-STARRS have been the most prolific contributors, with Catalina once credited with discovering nearly 47% of all known NEOs. In 2025, the baseline discovery rate was reported as approximately 2,500 to 3,300 objects annually. The transition into the ‘Rubin Era’ on June 30, 2026, marks the first major shift in ground-based detection capacity in several years, moving from specialized asteroid surveys to a multi-purpose deep-sky survey that captures asteroids as a ‘byproduct’ of its wide-field imaging. Previous shifts, such as the deployment of ATLAS or the retirement of NEOWISE in 2024, showed that the global catalog tends to be resilient to the loss or gain of individual assets due to the overlapping nature of current surveillance.
My analysis is based on a primary baseline rate of Near-Earth Asteroid (NEA) discoveries, which has remained remarkably consistent in the months leading up to the forecast window. According to data from the ESA Planetary Defense Office and NASA’s CNEOS reported in May and June 2026, the global discovery rate is approximately 3,000 NEAs per year. This averages out to roughly 8.2 NEAs per day. Over the 35-day period defined by the question (June 30 to August 3, 2026), a simple extrapolation of this baseline yields approximately 287 discoveries.
The most significant variable in this forecast is the Vera C. Rubin Observatory, which officially began its 10-year Legacy Survey of Space and Time (LSST) on the very first day of the window, June 30, 2026. While long-term projections suggest Rubin will discover roughly 10,000 NEAs per year (averaging ~27 per day), my reasoning discounts an immediate jump to this full capacity. During its two-month commissioning phase immediately preceding the survey start, Rubin identified only 33 confirmed Near-Earth Objects (NEOs). This suggests a gradual ramp-up in discovery efficiency. Additionally, the process of confirming a new asteroid and assigning it a discovery date involves several steps of follow-up observations and orbit determination by the Minor Planet Center (MPC).
I have weighted the forecast heavily toward the historical baseline of 7 to 9 discoveries per day, but with a distinct upward skew to account for the Rubin Observatory’s initial contribution. The resolution criteria uses a single read on September 15, 2026, specifically to capture these ‘confirmation lags.’ This means objects discovered in late July that take several weeks to be officially cataloged will be included in the final count.
My most likely prediction of 282.5 reflects a scenario where existing surveys (Pan-STARRS, Catalina, ATLAS) perform at their historical averages, while the Rubin Observatory adds a small but measurable number of net new detections (perhaps 1-3 per day) above the previous year’s levels. The 50% highest density interval (268.5 to 297.5) accounts for the standard Poisson-style variance in daily discovery rates and weather-related fluctuations at major observatory sites in Hawaii, Arizona, and Chile. The upper tail of the distribution remains open to account for the possibility of a highly successful first month for the Rubin LSST or a bulk processing release by the MPC that dates back to the window.
The question asks how many near-Earth asteroids (NEAs) will have an official CNEOS/MPC discovery date in the 35-day window 2026-06-30 through 2026-08-03, with the tally read once on 2026-09-15 (so late confirmations/backdated discovery dates and later removals matter). Forecasters agree the baseline is the legacy-survey cadence, and proximate public indicators (ESA newsletters: April 2026 = 208 designated NEOs; May 2026 = 175; plus 2025 summer seasonality) point to a July/early-August rate in the high-100s to low-200s rather than the ~288 implied by a flat annual average. All teams flag Rubin/LSST’s official start on 2026-06-30 as the principal upside/right-tail risk but note its early-optimization submissions produced only 33 new NEOs out of ~11,000 asteroids, so Rubin is treated as an incremental/backlog risk rather than a near-certain regime shift. Numerical reconstructions center the forecast around roughly 208–216 NEAs, with meaningful overdispersion to allow for seasonal dips, late linkages, and a small Rubin/backlog tail. Forecasters assign a modest probability of values below ~150 and a low (roughly 1–2%) probability of an extreme upside above ~300, and emphasize watching MPC/CNEOS updates and ESA newsletters for final confirmation.
Forecast: Probability distribution:
We are forecasting the net number of newly discovered Near-Earth Asteroids (NEAs) with discovery dates from June 30 through August 3, 2026 (35 days), as they will appear in the CNEOS cumulative totals table when read on Sept 15, 2026. Key drivers:
Baseline (non-Rubin) discovery rate and seasonality: One analyst cited ESA NEOCC monthly statistics showing a pronounced Northern-summer slowdown (e.g., May 2026 lower than April 2026), consistent with shorter nights/monsoon impacts on some major surveys. That argues for a baseline closer to ~4–7/day rather than a year-round ~7–9/day, implying roughly ~140–245 NEAs over 35 days before considering Rubin.
Rubin Observatory uncertainty: Two analysts cite Rubin/LSST beginning full operations on June 30, 2026 (start of the window). However, early-reported Rubin solar-system results suggest that (at least initially) the fraction of MPC-confirmed NEO/NEA discoveries may be modest relative to the total asteroid haul, and confirmations/designations may lag. Still, Rubin could add tens to (in a high-efficiency/backlog scenario) 100+ NEAs dated into the window by the Sept 15 read.
Net-new adjustments: Duplicates/reclassifications should be a small correction relative to totals, but they slightly temper the upper tail.
Synthesis: Compared with the higher forecasts (medians ~275–302), I downshift the center to reflect the summer slowdown evidence; compared with the low forecast (median ~178), I add meaningful uplift and an upper tail for Rubin’s ramp/backlog potential. I place the median around the mid-250s, with ~10–20% probability of exceeding the 300.5 upper bound (represented by having p90/p95/p99 > 300.5), and only a small chance of falling below ~150 (represented by p1 < 150).
An amateur forecast would likely (a) take the prompt’s 7–9/day heuristic at face value and center near ~280 with narrow tails, or (b) overreact to Rubin and assume an immediate step-change to extremely high counts. This forecast improves by explicitly incorporating (1) evidence for strong summer seasonality/monsoon impacts that can depress the baseline, (2) the realistic operational/confirmation lag uncertainty for Rubin (allowing uplift without assuming instant peak performance), and (3) a calibrated open-upper tail to capture backlog/ramp scenarios without anchoring all mass inside the bounds. Confidence in improvement is moderate because Rubin’s real-time pipeline and early-month performance remain the dominant uncertainty.
Forecast rationale (numeric):
— Iteration 1 — The forecasts converge on a few-hundred-asteroid outcome, driven by a fairly stable baseline discovery rate plus a modest expected boost from Rubin Observatory.
Baseline discovery rate dominates the estimate.
The core assumption is that CNEOS additions continue at roughly 5.5–9 NEAs per day, depending on how much seasonal slowdown is assumed.
Seasonality matters.
The window falls in Northern Hemisphere summer, when discovery activity is often weaker because of shorter nights and Arizona monsoon weather, pulling estimates down somewhat.
Rubin Observatory is the main upside factor.
Forecasts consistently add a small but meaningful Rubin contribution—roughly 1–2 extra discoveries per day, or a modest total bump over the 35-day window. One rationale allows for a more dramatic bulk/backlog release, creating a right-skewed upside tail.
Cataloging isn’t the same as initial detection.
Adjustments are made for duplicates, reclassifications, invalidations, confirmation delays, and catalog lag, which slightly reduce the final net addition relative to raw discovery counts.
— Iteration 2 — Across the forecasts, the main reasoning is fairly consistent:
The collective view is that the period should produce a moderately high but seasonally softened NEA addition count, with a central expectation in the upper 200s and significant tail risk upward from cataloging mechanics rather than purely from day-to-day discovery pace.
— Iteration 3 — Across the forecasts, the main reasoning is that recent NEA discovery rates imply a few hundred additions over a 35-day window, but seasonal and observational conditions should pull the total below a simple annualized extrapolation.
Recent discovery pace is the anchor.
Each forecast starts from a recent yearly discovery rate and converts it into a rough daily or monthly baseline, which points to something in the low-to-mid 200s or higher for a 35-day span.
Summer conditions reduce discoveries.
All three note that the window falls in Northern Hemisphere summer, when shorter nights and, especially in Arizona, the monsoon season typically depress survey productivity.
Moon phase matters.
The period is described as having only a limited number of good dark-sky nights, which further limits the number of discoveries that can be made and confirmed.
Confirmation/linking lag introduces uncertainty.
Not every discovery made in the window will necessarily be added to the CNEOS catalog by the target date, so forecasts allow for some losses from follow-up delays, processing, or linkage failures.
The collective view is that the window should produce roughly a couple hundred net new NEAs, with a central tendency in the mid-200s. The forecasts rely on recent discovery trends but are tempered by summer observing constraints, moon phase, and cataloging delays, while still leaving room for occasional upside surprises from survey batches or faster-than-expected confirmations.
The rationales universally agree that forecasting this 35-day window requires balancing a fundamental tug-of-war: the severe seasonal suppression of existing legacy sky surveys versus the inaugural launch of the powerful Vera C. Rubin Observatory.
The Summer Baseline Suppression The baseline discovery rate for near-Earth asteroids (NEAs) is expected to plummet during this specific window. Forecasters unanimously point to the “monsoon effect,” which historically forces the Catalina Sky Survey in Arizona—typically the world’s most prolific NEA discoverer—to effectively shut down operations to avoid severe weather. Additionally, the remaining legacy network faces compounded observational headwinds: shorter Northern Hemisphere summer nights, stellar crowding from pointing into the Milky Way’s galactic plane, and an unfavorable lunar schedule bracketed by two full moons that will severely limit dark-sky observing time.
The Upward Potential of the Rubin Observatory Directly counteracting this massive summer dip is the Vera C. Rubin Observatory in Chile, which officially commences its full science operations precisely at the start of this window on June 30, 2026. Benefiting from a massive aperture and long, dark Southern Hemisphere winter nights, Rubin possesses an unprecedented capacity to detect faint objects. Forecasters agree that Rubin’s theoretical output could easily offset the seasonal loss of Northern Hemisphere surveys.
Operational Bottlenecks and First-Month Friction Despite Rubin’s massive potential, forecasters heavily discount its expected first-month catalog additions due to several logistical hurdles:
Conclusion The forecasts hinge on how effectively these two massive forces neutralize one another. The final discovery volume will depend almost entirely on whether Rubin’s new alert and self-follow-up pipelines can smoothly bypass global confirmation bottlenecks to compensate for the crippling summer constraints placed on legacy observatories.
Question: How many net new near-Earth asteroids will be added to NASA’s CNEOS catalog between June 30 and August 3, 2026? Final Prediction: Probability distribution:
Total Cost: extra_metadata_in_explanation is disabled Time Spent: extra_metadata_in_explanation is disabled LLMs: extra_metadata_in_explanation is disabled Bot Name: extra_metadata_in_explanation is disabled
Forecaster 1: Probability distribution:
Forecaster 2: Probability distribution:
The research notes that the forecasting window (June 30–August 3, 2026) coincides exactly with the Vera C. Rubin Observatory beginning LSST operations on June 30, 2026, creating large uncertainty about discovery rates. Historical pre-Rubin discovery rates are about 7–9 near-Earth asteroids (NEAs) per day (≈245–315 over 35 days), with a catalog size near 41,955 NEAs on June 30, 2026. Rubin’s commissioning phase found ~11,000 new asteroids (including 33 NEOs) over ~1.5 months (~0.73 NEOs/day), implying a commissioning-level 35-day contribution of ~25 NEAs. Projections for full Rubin performance are far higher (claims include thousands per few nights and tens of thousands over the mission), but the ramp-up timeline is highly uncertain, so full capability within the first 35 days is considered unlikely.
Key uncertainties highlighted are: how quickly Rubin will transition from commissioning to full operations, whether any backlog releases will be backdated into the window, the difference between discovery date and posting/confirmation date, and Rubin’s sensitivity to smaller objects. Quantitative scenarios given are: conservative (traditional systems only) 245–315 NEAs; moderate (traditional + commissioning-level Rubin) ≈305 NEAs; optimistic/early acceleration 350–450+ NEAs. The research’s “most likely” range combining baseline and modest Rubin contribution is 270–340 NEAs, while stressing substantial uncertainty either way.
Sources/websites used:
This forecast involves unprecedented timing: the Vera C. Rubin Observatory officially began its Legacy Survey of Space and Time (LSST) on June 30, 2026 [12][13]—the exact start date of your 35-day forecasting window. This creates exceptional uncertainty about discovery rates during the system’s initial operational phase.
Operational survey systems contributing to the ~40,000+ cataloged NEAs [1][31]:
Monitoring organizations:
Your forecasting window captures the first 35 days of Rubin’s full LSST operations [12][13]. The observatory:
The observatory generates 20 terabytes of data nightly [11][17] and distributes up to 7 million alerts to global observatories [13]. It achieves six times the sensitivity of current searches [25][29] by repeatedly scanning the southern sky every few nights.
This is the critical unknown: How quickly will Rubin transition from commissioning performance (~0.73 NEOs/day) to projected full performance (potentially orders of magnitude higher)? Early operations typically involve:
The observatory just started operations June 30, 2026. Will the first 35 days show:
The question explicitly notes: “If Rubin or another survey causes a bulk backlog release dated into the window, those objects count” [background]. Rubin has already identified 11,000+ asteroids during testing [multiple sources]. If any backlog objects have discovery dates falling within June 30-August 3, they would count.
The September 15, 2026 read date allows objects discovered in the window but confirmed later to be captured [background]. This is important given Rubin’s massive data volume and processing requirements.
All NEA size classes count [background]. Rubin’s superior sensitivity means it will detect smaller asteroids missed by previous surveys, potentially inflating counts beyond simple extrapolations.
No specific prediction markets found for this question in available sources. I searched for Metaculus and other forecasting platforms but found no relevant markets with liquidity/volume data.
The 245-315 range suggested in the background information represents a reasonable baseline assuming traditional discovery rates continue. However:
Most likely range: 270-340 NEAs, representing traditional baseline plus modest early Rubin contribution, though significant uncertainty remains in both directions.
I mostly accept the critic’s second-round push: my prior center was still too high given that the resolution is catalog-countable NEAs by discovery date, not Rubin detections, alerts, or candidate submissions. I am moving the median down from 288 to about 270–272, and reducing P(>300) to the mid/high-30s.
The strongest valid criticism is that I was still implicitly treating Rubin’s June 30 LSST start as a smooth additive rate increase. Rubin is genuinely operational, but its own early-science documentation says prompt products are in a progressive ramp-up, pre-DR1 alerting cannot run at full scale, and new solar-system discoveries are being reported to MPC on an ad hoc basis. That matters a lot for a September 15 CNEOS/MPC read. (rubinobservatory.org)
I also accept that the seasonal baseline should dominate the center. Recent annualized rates around 8/day are too blunt for a window that is almost entirely July. ESA’s NEOCC noted the usual Northern-summer drop in July 2025, with only 127 NEOs designated in the preceding month, and June 2026 similarly reported a relatively small 175 designated in the preceding month heading into Northern summer. (neo.ssa.esa.int) MPEC Watch still shows a strong 2026 overall rate — 1,445 discovery MPECs by the July 1 update — but that mixes more productive months with the summer trough. (sbnmpc.astro.umd.edu)
Rubin’s actual MPC footprint is still the biggest caution flag. The LSST/X05 MPEC Watch page shows only a tiny number of discovery MPECs so far, and the 2026 survey table lists LSST with only 1 NEA discovery as of the June 30 update. (sbnmpc.astro.umd.edu) That is hard to reconcile with a median forecast requiring a large immediate Rubin contribution.
What I still defend is the fat right tail. Rubin’s LSST did officially begin on June 30, 2026, after system optimization and operational review, and Rubin’s announcement says early optimization found 11,000+ asteroids including 33 NEOs; it is taking about a thousand images per night and producing up to millions of alerts. (rubinobservatory.org) If the moving-object pipeline, follow-up, and MPC/CNEOS ingestion work faster than expected — or if an ad hoc/batch release lands before September 15 with discovery dates in the window — outcomes above 400 remain very live. I just no longer think that should drive the median.
My updated mixture:
This gives roughly P(<150) ≈ 2%, median ≈ 270, and P(>300) ≈ 36%. Conditioned on the question not being annulled.
Updated prediction:
Percentile 0.1: 95
Percentile 1: 140
Percentile 5: 178
Percentile 10: 200
Percentile 20: 224
Percentile 30: 242
Percentile 40: 256
Percentile 50: 270
Percentile 60: 288
Percentile 70: 315
Percentile 80: 365
Percentile 90: 470
Percentile 95: 640
Percentile 99: 1050
Percentile 99.9: 1650
Conditioning on the question not being annulled.
I accept the critic’s latest push in two directions: lower center, fatter right tail. The seasonality criticism is now the most important central-tendency update. ESA explicitly says NEA discoveries show a clear seasonal effect, and its June 2026 newsletter says that heading into Northern summer the prior month had only 175 NEOs designated, with 1270 since January 1, 2026—a much better same-season anchor than a blanket 7–9/day annualized rate. ESA’s June 30 snapshot of 41,958 current NEAs is also consistent with recent additions being below the initial 245–315 baseline for a 35-day window. (neo.ssa.esa.int)
I still would not move the median all the way down toward a pure “May repeats exactly” rate. The resolution waits until September 15, and CNEOS warns that the most recent date in its cumulative table is generally a discovery date, not necessarily the update date, so very recent discovery-date bins can be backfilled after confirmation/posting. That makes the visible late-June rate informative but not decisive. (cneos.jpl.nasa.gov)
On Rubin, I agree that the right model is still a lumpy regime mixture. Rubin’s LSST did officially begin on June 30, 2026, exactly at the window start, and the observatory is now taking about a thousand images nightly and producing up to seven million alerts. It also already demonstrated a Rubin-to-MPC path: preliminary data yielded a confirmed batch of over 11,000 new asteroids, including 33 previously unknown NEOs. (rubinobservatory.org)
But I continue to defend only a modest median Rubin effect. Rubin’s own early-science guidance says pre-DR1 alert production is limited by template availability, Solar System discoveries are being reported to MPC ad hoc, and the Prompt Products Database target is Sep–Oct 2026, straddling or partly after the September 15 read. DP2 is also mostly irrelevant for this window because it is based on April 2025–January 2026 commissioning / validation data, not June 30–August 3, 2026 discovery dates. (rubinobservatory.org)
My update: median down from 263 to 257, mass above 300 down slightly to about 28%, and p95/p99 higher. I now think the modal outcome is a seasonal conventional count plus little or modest Rubin, but the log-score-protective tail must cover an operational Rubin batch landing before the read.
Updated prediction:
Percentile 0.1: 110
Percentile 1: 145
Percentile 5: 172
Percentile 10: 191
Percentile 20: 213
Percentile 30: 229
Percentile 40: 243
Percentile 50: 257
Percentile 60: 273
Percentile 70: 293
Percentile 80: 335
Percentile 90: 455
Percentile 95: 675
Percentile 99: 1350
Percentile 99.9: 2450
Modal: Above 300 (21.8%) • frontier aggregate • 11m10s
Resolution sources/checks:
Edge cases:
frontier_1 - p: ?
frontier_2 - Modal: Above 300 (19.0%)
frontier_3 - Modal: Above 300 (34.0%)
frontier_4 - Modal: 263-281 (25.0%)
frontier_5 - Modal: 281-300 (31.0%)
Aggregate used 4/5 frontier lanes; failed/excluded lane(s): frontier.
| Agent | Error |
|---|---|
| frontier_1 | :timeout |
Material notes
Guidance
Revision
| Bin | Probability |
|---|---|
| Below 150 | 1.2% |
| 150-169 | 1.3% |
| 169-188 | 1.7% |
| 188-206 | 2.6% |
| 206-225 | 4.9% |
| 225-244 | 9.5% |
| 244-263 | 15.9% |
| 263-281 | 20.8% |
| 281-300 | 20.3% |
| Above 300 | 21.8% |
wooley_rhino • run cdfe1d2f • $2.09 • 11m10s
Extracted Percentile Values: {0.1: 130, 1.0: 155, 5.0: 173, 10.0: 183, 15.0: 190, 20.0: 196, 25.0: 201, 30.0: 205, 35.0: 208, 40.0: 211, 45.0: 213, 46.0: 214, 47.0: 214, 48.0: 215, 49.0: 215, 50.0: 216, 51.0: 217, 52.0: 217, 53.0: 218, 54.0: 219, 55.0: 220, 60.0: 224, 65.0: 230, 70.0: 238, 75.0: 249, 80.0: 263, 85.0: 282, 90.0: 308, 95.0: 352, 99.0: 460, 99.9: 650}
Model’s Answer:
Step one: Establish the baseline discovery rate
The most authoritative and current data point comes from the CNEOS Cumulative Totals table itself (accessed July 1, 2026): the total stood at 41,955 as of June 27, 2026. Monthly additions in recent months were ~184 (May 2026) and ~196 (April 2026), yielding ~6 NEAs per day on average. Over the 35-day window (June 30–August 3), the baseline projection is 35 × 6 ≈ 210 NEAs.
Step two: Evaluate the ESA/background claim of 7–9/day
ESA’s 10,000 NEAs over three years works out to ~9.1/day—but this includes the accelerating tail of that period. The granular monthly CNEOS data (180–200/month) is more grounded and recent, pointing closer to 6/day. I weight the CNEOS table data more heavily: central estimate ~210.
Step three: Assess Rubin Observatory impact
Rubin’s LSST began June 29, the day before the window opens. Critical considerations:
Step four: Identify key assumptions and failure modes
Assumption 1: Rubin LSST NEA yield stays modest in the first 35 days (~1–3 NEAs/day additional). Probability of failure (i.e., major surge): ~15%. If Rubin ramps to 50+ NEAs/week quickly, the total could be 300–500+.
Assumption 2: No major survey outages/disruptions reducing coverage. Probability of significant disruption: ~10%. Would push total below 170.
Assumption 3: Reclassification/duplicate removal is modest. Probability of a large net reduction from reclassifications: ~5%. Could reduce count by 20–40.
Step five: Low/high outcome descriptions
Low outcome (below 170): Probability ~8%. Requires combination of adverse weather/outages at major surveys AND Rubin pipeline problems. Recent history shows no sustained survey gaps, making this unlikely but not negligible.
High outcome (above 320): Probability ~12%. Requires Rubin to rapidly contribute 3–5+ NEAs/day in its first month of full LSST, plus existing surveys maintaining normal pace. Plausible given eventual capacity but uncertain given confirmation bottlenecks.
Step six: Construct distribution
Central tendency ~215, right-skewed due to Rubin upside. Standard deviation of baseline ~25–30 days-of-variance; additional right-tail mass for Rubin scenarios.
Percentile .1: 130 Percentile 1: 155 Percentile 5: 173 Percentile 10: 183 Percentile 15: 190 Percentile 20: 196 Percentile 25: 201 Percentile 30: 205 Percentile 35: 208 Percentile 40: 211 Percentile 45: 213 Percentile 46: 214 Percentile 47: 214 Percentile 48: 215 Percentile 49: 215 Percentile 50: 216 Percentile 51: 217 Percentile 52: 217 Percentile 53: 218 Percentile 54: 219 Percentile 55: 220 Percentile 60: 224 Percentile 65: 230 Percentile 70: 238 Percentile 75: 249 Percentile 80: 263 Percentile 85: 282 Percentile 90: 308 Percentile 95: 352 Percentile 99: 460 Percentile 99.9: 650
Forecast: 249 net new near-Earth asteroids (median)
I anchored the forecast on official NASA counts rather than the client’s suggested daily rate. NASA’s Planetary Defenders brief said NASA had discovered over 37,500 near-Earth asteroids as of February 2025, and NASA’s Planetary Defense infographic reported 39,123 total discovered near-Earth asteroids on December 3, 2025. That is an increase of about 1,623 NEAs in 304 days, or about 5.34 per day, which is a concrete recent base rate for net catalog growth. (assets.science.nasa.gov)
For a longer-run cross-check, NASA’s Office of Inspector General reported that more than 26,000 near-Earth objects were identified from September 2014 to April 2025, taking the total to more than 38,000. CNEOS also states that 99% of NEOs are asteroids, so the long-run NEO pace is a reasonable proxy for the NEA pace; that works out to roughly 6 to 7 per day. Because the OIG figure is rounded and mixes in a tiny comet share, I used it mainly as an upper cross-check and weighted the 2025-specific NEA figure more heavily. (assets.science.nasa.gov)
Rubin is the obvious upside driver. Rubin Observatory said that in about a month and a half of early optimization surveys it discovered over 11,000 new asteroids, including 33 previously unknown near-Earth objects, and Rubin officially began the Legacy Survey of Space and Time on June 30, 2026. But Rubin’s early-science page also says new solar-system objects are being reported to the Minor Planet Center on an ad-hoc basis before later prompt-product systems arrive in September to October 2026. So I do expect a real positive Rubin increment during this window, but not yet a fully mature, steady-state firehose of cataloged NEAs. (rubinobservatory.org)
Seasonality is a modest downward force. Catalina Sky Survey notes an annual summer shutdown in Arizona associated with its monsoon workshop, and Catalina’s moon-phase pages show a new moon on July 14, 2026 and the next full moon about July 29, 2026. So the June 30 to August 3 window includes both good dark time and bright-moon periods, not a continuous high-efficiency run. That makes me cautious about taking an aggressive 7 to 9 per day calendar-average at face value for this exact 35-day interval. (catalina.lpl.arizona.edu)
My quantitative model is: start with a non-Rubin baseline built from a weighted blend of the recent exact NEA rate, about 5.34 per day, and the longer-run proxy, about 6.7 per day, with heavier weight on the recent figure. That yields about 5.8 per day before Rubin. I then add about 0.8 per day for Rubin, slightly above the early-optimization 33 per 45 days pace because LSST officially starts on June 30, 2026, but still conservative because MPC reporting remains ad hoc. I subtract a small seasonal-friction term for July observing conditions. The resulting mean is about 228 net new NEAs over the 35-day discovery-date window. (assets.science.nasa.gov)
To convert that into the required discrete probability mass function, I use a negative-binomial distribution with mean 228 and standard deviation 31. I chose a negative binomial rather than a pure Poisson because the resolution depends on more than raw discovery opportunity: weather, moonlight, survey downtime, confirmation lag, duplicate removal, and the uncertain speed with which Rubin detections become net new CNEOS entries by the September 15, 2026 read all add overdispersion. This leaves most probability mass in the low-200s through mid-250s, with a small upside tail from a Rubin-driven batch or backlog release and only a very small chance of finishing below 150 or above 300.
Bottom line: my median-style central forecast is around 228, noticeably below the client’s implied 245 to 315 range because the best official recent base rate I found is lower than that, while Rubin adds real upside but probably not enough, this early, to fully offset the lower baseline and the July observing frictions.
My central view is that the resolution is more likely to land in the high-170s to low-190s than in the client’s 245-315 range, with a mean around 187 and only a small right-tail chance of finishing above 300.
The resolution source is NASA CNEOS’s Discovery Statistics / Cumulative Totals table, with the count determined by objects whose discovery dates fall from June 30 through August 3, 2026 inclusive; CNEOS also says its discovery dates and counts are sourced from the Minor Planet Center, which matches the fallback rule in the question. NEAs count, NECs do not. (cneos.jpl.nasa.gov)
The biggest reason I am below the client’s anchor is seasonality. ESA’s official NEO discovery-statistics page says the within-year discovery distribution shows a clear seasonal effect, and ESA’s monthly newsletters repeatedly describe a Northern Hemisphere summer dip in discoveries. That matters a lot here because essentially the entire window sits inside that seasonal trough. (neo.ssa.esa.int)
To align with the question’s discovery-date resolution, I used the newsletters’ cumulative “NEOs discovered since 1 January 2026” figures, not the separate “NEOs designated during last month” figures. That is an inference from the source tables, but it is the right series for this market because the target resolves by discovery date rather than publication/designation timing. Taking differences between successive 2026 cumulative values gives roughly Jan 263, Feb 219, Mar 379, Apr 218, and May 191 discoveries. So the most recent fully observed month before the window, May 2026, was already down to about 6.2 discoveries per day. (neo.ssa.esa.int)
The best seasonal analogs are the last three years. Deriving discovery-date counts from the same cumulative series gives July totals of 110 in 2023, 120 in 2024, and 157 in 2025; August totals were 166, 173, and 351 respectively. July plus a proportional 3-day slice of August averages about 151 objects across 2023-2025, and adding one more day at roughly the July daily pace puts the full 35-day historical analog in the mid-150s. The 2025 August surge is the obvious outlier and is the main historical reason not to make the low-summer case too narrow. (neo.ssa.esa.int)
I then adjusted that historical baseline upward for 2026-specific reasons. ESA’s May 2026 newsletter says discoveries through that point were still above the same period last year, so 2026 does not look like a weak year overall. Also, ESA’s asteroid page showed 41,958 known NEAs on July 1, 2026, versus 41,799 in the June 2026 newsletter. I treat that only as a soft signal, because known-count growth reflects confirmation and cataloging lag as well as discovery timing, but it does argue against an extremely depressed near-term outlook. (neo.ssa.esa.int)
The main upside risk is Vera C. Rubin Observatory. Rubin’s scientific alert stream began on February 25, 2026, and the full 10-year LSST officially began on June 30, 2026, which is the first day of this resolution window. Rubin has already shown real asteroid productivity in official releases: June 23, 2025 First Look observations found 2,104 previously unseen asteroids including 7 NEAs, and an April 2, 2026 Rubin release reported more than 11,000 new asteroids submitted to the MPC from a month-and-a-half data set, including 33 previously unknown NEAs. That clearly creates upside risk relative to the old summer baseline. (rubinobservatory.org)
But I do not think Rubin justifies moving the base case all the way into the mid-200s yet. The same early Rubin evidence also shows that the NEA share of the asteroid flood has so far been modest in absolute terms: 33 NEAs out of more than 11,000 asteroids in the April 2, 2026 batch. And ESA explicitly noted in September 2025 that Rubin was not yet contributing regular asteroid observations, meaning the big August 2025 jump happened without Rubin and should be treated as tail-risk evidence rather than a new steady-state. My inference is that Rubin meaningfully fattens the right tail for this 35-day window, but probably does not produce an immediate step-change large enough to make 245-315 the most likely range. (rubinobservatory.org)
Putting it together, I think a reasonable decomposition is: about 160-165 objects from the normal summer discovery flow implied by recent years and 2026 YTD, plus roughly 20-25 expected incremental objects from Rubin / favorable conditions / backlog-release effects, with substantial uncertainty around that increment. That gives a mean near 187, a median in the low 180s, a meaningful but not dominant chance of finishing below 150, and only a small chance of finishing above 300. I encoded that view as a four-scenario mixture: a low summer trough, a normal-above-trend summer, a Rubin-boosted summer, and a small backlog/surge tail. (neo.ssa.esa.int)
I am forecasting the net number of near-Earth asteroids whose discovery date falls from June 30, 2026 through August 3, 2026 inclusive, but which survive catalog cleanup and appear in the September 15, 2026 CNEOS read. That resolution rule matters: the target is not raw provisional postings during the window, but net catalog additions after some time for confirmation, linkage, and de-duplication. CNEOS also says its discovery-statistics charts and tables use Minor Planet Center discovery dates and counts, so the primary CNEOS source and the MPC fallback in the resolution criteria are closely aligned. (cneos.jpl.nasa.gov)
For base rates, the long-run trend is clearly upward. NASA’s Office of Inspector General reported that more than 38,000 near-Earth asteroids had been discovered as of April 2025, and its Figure 4 shows a steep acceleration in cumulative discoveries in recent years. ESA then reported that the known-NEA total surpassed 40,000 in November 2025, with around 10,000 discovered in the previous three years. That ESA figure implies a crude recent average of about 3,333 per year, or roughly 9.1 per day; over a 35-day window, a naive straight-line benchmark would therefore be about 320 objects. (assets.science.nasa.gov)
I do not center the forecast as high as 320, because the late-2025 public-facing totals are a bit inconsistent. NASA’s December 2025 monthly infographic page displayed 39,123 discovered near-Earth asteroids, which conflicts with ESA’s November 2025 40,000 milestone. I treat that mismatch as evidence that public pages can lag, round differently, or otherwise be imperfect point estimates, so I do not anchor too hard on any single exact late-2025 total. Instead, I use the disagreement to widen uncertainty and to keep the central estimate in the high-200s rather than simply extrapolating the most aggressive recent average. (science.nasa.gov)
Rubin is the main upside risk, but I think it is more a right-tail factor than the base case for this exact window. Official Rubin reporting on its first discovery release said it included 7 near-Earth objects, and later 2026 reporting on Rubin’s first large submission said it included 33 previously unknown near-Earth objects. At the same time, March 2026 coverage still described the full LSST survey as expected to begin later in 2026. That combination suggests real new NEO contribution from Rubin, but not yet a regime where one 35-day window should automatically be assumed to blow far past prior survey rates. Meanwhile, NASA’s OIG noted aging survey infrastructure and maintenance issues at major observatories, and NEOWISE had already been decommissioned in 2024 after discovering 215 NEOs over its repurposed mission, so the non-Rubin baseline is not obviously accelerating on its own. (rubinobservatory.org)
So I use a four-scenario mixture for the net September 15 count: 10% disruption or weak follow-up with mean 250, 55% status-quo continuation with mean 280, 25% modest uplift or backlog release with mean 300, and 10% stronger Rubin or backlog effect with mean 340. Those means are already meant to be net catalog additions rather than raw initial designations, so they implicitly include some attrition from reclassification, duplicate linkage, or late non-confirmation. This mixture has a mean of 288. My qualitative read is: high-200s is the most likely region, 300-plus is a live and meaningful tail, and below 150 would require a major survey or processing failure inconsistent with the recent discovery trend. (cneos.jpl.nasa.gov)
I anchored on official NASA/JPL counts rather than the client’s heuristic. NASA’s planetary-defense monthly update listed 39,123 discovered near-Earth asteroids (NEAs) as of December 3, 2025, while another NASA page gave 38,310 as of April 30, 2025. That is 813 net new NEAs in 217 days, about 3.75 per day, or roughly 131 over a 35-day window. A longer-run official benchmark is higher: NASA’s Office of Inspector General said that from September 2014 to April 2025 more than 26,000 NEOs were identified and the total exceeded 38,000; CNEOS says 99% of NEOs are asteroids, so that is a useful near-NEA benchmark and implies something like 6-7 per day over that longer span. So the official recent data I can verify are materially slower than the long-run pace, which makes a straight 7-9/day extrapolation too aggressive unless something changes in summer 2026. (science.nasa.gov)
CNEOS says its discovery-statistics pages use discovery dates and counts from the Minor Planet Center, and the cumulative-totals table is keyed to discovery date rather than simply the webpage update date. That matters because the question resolves from a September 15, 2026 read of the CNEOS cumulative totals table (or MPC equivalent), so what matters is net confirmed catalog additions with discovery dates in the June 30-August 3 window, not just what is posted immediately in early July. (cneos.jpl.nasa.gov)
The obvious upside risk is Vera C. Rubin Observatory. Rubin’s first scientific alerts began on February 25, 2026, and Rubin says all of its Solar System products are delivered through the Minor Planet Center under observatory code X05. On April 2, 2026 Rubin reported that early optimization surveys had already produced more than 11,000 new asteroids, including 33 previously unknown NEOs, from about a month and a half of data. Then, on June 30, 2026, Rubin announced that the 10-year Legacy Survey of Space and Time had officially started. Rubin also says the full survey is expected to reveal nearly 90,000 additional new NEOs over the decade, so a meaningful step-up in discovery rates during this question’s window is plausible. (rubinobservatory.org)
I do not, however, map Rubin’s decade-scale projection directly into this exact 35-day window. The same Rubin material shows that the pre-survey 33-NEO result came from engineering/optimization data rather than mature steady-state operations, so the near-term ramp could be gradual rather than instantaneous. My judgment is therefore a scenario mix: a slow case near the late-2025 realized pace plus only a small Rubin increment; a moderate case where Rubin contributes materially but not explosively; a strong-ramp case where Rubin starts biting quickly; and a breakout/backlog case where Rubin or another survey releases a larger batch with discovery dates inside the window. The code encodes those scenarios as a mixture of discrete normal components centered at 155, 220, 270, and 340. (science.nasa.gov)
Netting it out, I come in below the client’s 245-315 heuristic on the central tendency because the only hard recent net-growth numbers I could verify from official NASA sources point materially lower than 7-9/day. But I keep a fat right tail, including meaningful probability above 300, because Rubin was already finding NEOs before full survey start and the LSST officially began on June 30, 2026, exactly as this resolution window opened. If I had to name a single best point forecast, it would be in the low-to-mid 230s, with skew to the upside. (science.nasa.gov)
I anchored on official CNEOS/MPC/ESA sources. CNEOS says that the discovery dates and counts used in its discovery-statistics products come from the Minor Planet Center, which is the same backup source named in the resolution criteria. (cneos.jpl.nasa.gov)
The most important current datapoint is the live catalog level. ESA’s NEOCC home page listed 41,959 known NEAs on 2026-06-29. The June 2026 NEOCC newsletter, which summarizes the end-of-May state, listed 41,799 asteroids and 124 comets, and said May was a relatively small-discovery month but still “in line with typical May trends from recent years.” That implies about 160 additional NEAs from 2026-06-01 through 2026-06-29, or roughly 5.5 per day. NEOCC’s discovery-statistics page also explicitly says the annual distribution shows a “clear seasonal effect.” (neo.ssa.esa.int)
That seasonal effect pushes me below the client’s 7-to-9 per day heuristic. ESA’s July 2023 newsletter says the summer decline is usual and tied to shorter Northern nights, with monsoon weather in the US Southwest soon adding further drag; the August 2024 newsletter says low discovery rates are typical of Northern-summer short nights and poor weather; and the July 2025 newsletter again says the usual summer drop is already visible because of shorter nights and less observing time. In 2023, the known-NEA total rose from 32,099 at end-May to 32,267 at end-June, 32,378 at end-July, and 32,544 at end-August, which is a useful analog showing that this particular part of the calendar can be materially weaker than the annual average. (neo.ssa.esa.int)
I do not want to anchor too low, though, because the broader level has been rising. ESA reported 3,087 new NEOs in 2024 and 3,398 in 2025, with 2025 described as remaining in line with the last five years. Rubin is also now a real contributor: ESA noted in July 2025 that Rubin had reported its first astrometric observations to the MPC, and Rubin said on 2026-04-02 that early data had yielded more than 11,000 new asteroids, including 33 previously unknown NEAs. Rubin’s real-time scientific alert stream began on 2026-02-24, and Rubin says its solar-system products are made available through the MPC. My inference is that Rubin raises the upside tail, but the evidence so far looks like a modest uplift in NEAs, not a step-change large enough by itself to force this 35-day window anywhere near 300. (new.neo.ssa.esa.int)
I also made a modest upward adjustment for the question’s September 15 read date, because that allows in-window discoveries to be counted after later confirmation. The 2026 ESA newsletters suggest some real, but not huge, lag: March 2026 implied about 379 new discoveries versus 334 designations during that month; April implied about 218 versus 208; and May implied about 191 versus 175. That pattern argues for some catch-up between raw contemporaneous catalog growth and the final discovery-date count, but not for a massive backlog shock. (neo.ssa.esa.int)
Putting those pieces together, my base case is a low-summer regime a bit below the recent June run rate once July seasonality is applied, followed by a modest September-15 catch-up uplift. I then blend in a smaller higher-activity scenario to reflect the possibility of backlog bunching, a stronger-than-usual late-summer month, or Rubin-related upside. That leads me to a forecast centered around 191-193 net new NEAs for the full June 30 to August 3 window, with most probability mass in the broad 170-215 region, a noticeable but still minority chance of finishing below 150, and only a very small chance of exceeding 300.