Potential Interstellar Visitor Found in April-May 2026 LSST Data

[reductionista (Domino Valdano)]

Potential Interstellar Visitor Found in April-May 2026 LSST Data

Identified by linking unlinked LSST diaSources from the public alert stream.
Submitted to the Minor Planet Center on 2026-06-09; posting here for visibility
and to invite confirmation and image-level follow-up.

Hello all! I have some potentially exciting news to report, but please verify my data for yourself and offer any alternative hypotheses or caveats I should be aware of in case I’m missing something.

Summary

I’ve been using HelioLinC/Heliolinx with custom hypothesis grids to search for Interstellar
Visitors in Fink and Lasair Data, and found what appears to be a pretty strong candidate for
a new Interstellar Visitor (4I?). It has a strongly-hyperbolic trajectory, whose orbit has been
independently verified with Find_Orb. Both converge on the same retrograde hyperbolic
solution. The object is not present in the Rubin SSP linked output, or in the MPC database. If confirmed, it would also be the fastest known object to ever have been detected moving through our Solar System (148 - 170 km/s).

What I’ve tentatively labelled as DVAq1 appears to have entered our Solar System from the direction of Aquarius (bordering on Pisces), crossing the asteroid belt in early February, the orbits of Mars and Earth in mid-February, and whipping around the Sun at perihelion on February 28th, passing at almost exactly Mercury’s distance from the Sun (0.39 AU). It’s been climbing back out ever since, and today it’s expected to be located in the faint constellation of Sextans, just beneath Leo. If the hyperbolic orbit holds up, it’s on a one-way trip back into interstellar space.

Unfortunately, it is too faint now for any ordinary telescope to see, but it’s possible it could still be visible within the next 4-6 weeks if LSST or another high-powered observatory sweeps that part of the sky. It was not visible in February due to Solar Conjunction, and will be hidden again by the Sun at the beginning of August. If its current 43-day arc is not extended with at least one more night of observation, we may never know for sure whether it was a true ISO.

Astrometry Submitted to MPC on June 9, 2026

     DVAq1    C2026 04 07.07078 10 02 19.719+01 06 49.28         22.66i      X05
     DVAq1    C2026 04 07.07125 10 02 19.701+01 06 49.41         22.71i      X05
     DVAq1    C2026 04 07.07421 10 02 19.668+01 06 50.53         23.32g      X05
     DVAq1    C2026 04 09.07113 10 01 53.668+01 23 25.94         23.37g      X05
     DVAq1    C2026 04 09.07159 10 01 53.661+01 23 26.16         23.32g      X05
     DVAq1    C2026 04 09.07326 10 01 53.640+01 23 26.63         22.67i      X05
     DVAq1    C2026 04 09.07373 10 01 53.632+01 23 26.74         22.69i      X05
     DVAq1    C2026 05 19.98241 10 05 35.560+03 01 51.96         23.55r      X05
     DVAq1    C2026 05 19.99164 10 05 35.731+03 01 52.58         23.46r      X05

Orbit (Find_Orb, consistent with heliolinx)

element	value
epoch	2026 Apr 9.0 TT
eccentricity e	10.6 ± 0.13
perihelion distance q	0.387 AU
inclination i	171.7° (retrograde)
ascending node Ω	55.4°
arg. perihelion ω	162.9°
perihelion time	2026 Feb 28.3
v∞	≈ 148 km/s
abs. mag H	≈ 16.8 (~1.8 km at 10% albedo)
arc	2026 Apr 7 – May 19 (9 detections, 3 nights, 43 d)
mean residual	0.222″

Two further, lower-confidence candidates

Curiously, two more objects appear in the same field and epoch with similar retrograde
inclinations (DVAq2 i ≈ 167°, DVAq3 i ≈ 168°, vs DVAq1 i ≈ 172°). However, their
orbits are only weakly constrained by shorter arcs, and their mean residuals much higher (1.24″ and 1.58″). It’s tempting to think they may be related somehow (fragmented pieces of a larger object?), but the best fit of their orbits individually don’t match DVAq1 very well (e ≈ 5 and e ≈ 15), so these are possibly just unrelated observations that got linked together weakly due to statistical artifacts. I include
them for completeness, not as confident detections.

     DVAq2    C2026 04 09.07113 10 06 46.237+02 01 24.28         23.30g      X05
     DVAq2    C2026 04 09.07159 10 06 46.235+02 01 24.52         23.17g      X05
     DVAq2    C2026 04 09.07326 10 06 46.220+02 01 25.10         22.55i      X05
     DVAq2    C2026 04 09.07373 10 06 46.221+02 01 25.30         22.56i      X05
     DVAq2    C2026 04 12.06768 10 06 30.758+02 18 34.77         22.75r      X05
     DVAq2    C2026 04 12.07012 10 06 30.754+02 18 35.51         22.25z      X05
     DVAq2    C2026 04 16.08082 10 06 29.908+02 35 44.51         22.60r      X05
     DVAq2    C2026 04 16.09238 10 06 29.881+02 35 47.77         22.39z      X05
     DVAq2    C2026 04 16.17421 10 06 29.780+02 36 10.61         22.54i      X05

     DVAq3    C2026 04 08.07630 09 58 08.290+02 59 27.96         22.53r      X05
     DVAq3    C2026 04 08.07920 09 58 08.256+02 59 28.86         22.06z      X05
     DVAq3    C2026 04 08.07970 09 58 08.249+02 59 28.93         22.24z      X05
     DVAq3    C2026 04 09.07110 09 57 58.812+03 04 23.02         23.52g      X05
     DVAq3    C2026 04 09.07160 09 57 58.802+03 04 23.12         23.62g      X05
     DVAq3    C2026 04 09.07330 09 57 58.786+03 04 23.63         22.89i      X05
     DVAq3    C2026 04 09.07370 09 57 58.783+03 04 23.77         22.90i      X05
     DVAq3    C2026 04 30.00840 09 58 35.143+03 49 23.41         22.84r      X05
     DVAq3    C2026 04 30.07020 09 58 36.062+03 49 32.20         22.96r      X05

What would help

Confirmation, a designation, and image-level follow-up — in particular a check
for cometary morphology and verification of the point-source astrometry. If anyone
with access to the LSST images (or archival ATLAS/ZTF coverage of the March outbound leg, RA ~152–164°) can take a look, please let us know!

Also, if anyone involved in the LSST commissioning/observing plan could prioritize a visit to RA 10ʰ12ᵐ, Dec +03° (drifting ~0.5°/month eastward) in the coming weeks, or co-add whatever images of it do get taken, it could catch the object again before it fades and slides into Solar Conjunction.

Thank you for reading! And feel free to reach out with any questions or comments.

Domino Valdano, PhD
Independent Researcher

[aheinze (Ari Heinze)]

I’m sorry to dash some hopes here, but there’s almost no chance that the interstellar linkage found by Domino Valdano is a real object. The biggest problem is that the linkage includes only three nights of data, making it statistically easier to fit a spurious orbit to a set unrelated observations. Such a coincidental alignment is very improbable in itself, but the Vera Rubin Observatory produces such vast source catalogs that improbable alignments become common.

We (the LSST solar system team) have found hundreds of ‘interstellar’ linkages that look as good as this one. Most (probably all) of these must be false: there are numerous reasons why it’s impossible for that many real interstellar objects to be passing through our solar system. We’ve also found many instances of three-night linkages with normal solar system orbits that have similar time span and astrometric residuals to Domino’s linkage, and still have proven to be false, ‘mixed’ linkages containing observations of two unrelated asteroids. This is why we prefer to submit linkages with at least four nights of data to the Minor Planet Center, submitting three-night linkages only when they pass a long list of strict criteria we’ve designed to avoid false discoveries.

A real discovery of an interstellar object would require at least four nights of observations, and probably five. It would also have to have a mean astrometric residual less than the 0.222 arcsec found for Domino’s linkage. Rubin astrometry is so precise that we typically reject anything above 0.20 arcsec even when it’s a four-night linkage in a normal solar system orbit. Finally, the Earth encounter velocity of 145 km/sec found for Domino’s linkage, though not physically impossible, is improbably high at best.

In summary, though I congratulate Domino Valdano on successfully running heliolinx and producing linkages, this one is almost certainly not a real object.

Ari Heinze, PhD
Research scientist and heliolinx author

[reductionista (Domino Valdano)]

Dr. Heinze,

Thank you for your reply. I was just composing an email to Mario Juric to ask him to give this a SARC review. But in light of your comment, I think I will just withdraw my submission instead of wasting his time.

I feel a bit foolish for having posted about this publicly, rather than asking your opinion on it privately first–something I had considered. I was looking forward to thanking you for writing heliolinx if this turned out to be real, but I guess I got my hopes up too quickly.

I kept wondering why there didn’t seem to be any public discussion of this, or a mention that the LSST solar system team was even looking for interstellar candidates yet. I’m grateful that now I know what the bar is (4 nights, < 0.20 arcsec) if I run across anything new. And also it’s interesting to that your team is actively looking for hyperbolic candidates, so thanks for clarifying that.

If I had found more than one like this in the data I have access to, I would have been more inclined to suspect it was just statistics. But at least in all the data I analyzed (admittedly, just Fink and some Lasair, probably far less than you have access to), this was the only one that stood out as a good fit–I was convinced by that too easily that it must be something worth reporting.

Domino

[LienaDreams]

@reductionista Hi Domino, can you share diaObjectId for a few of the above detections? On May 19 maybe. Thank you.