Two 2019 W2 difference images place the added light closer to ASASSN-21qj than to its 3.7 arcsec neighbor
We test which star in the unresolved ASASSN-21qj pair produced the 2019 W2 infrared increase. We register 38 original NEOWISE exposures to Gaia and subtract 2017 images from 2019 images in two separate scan seasons. Gaussian fits place the added light 0.59 and 0.14 arcsec from the primary, compared with 4.29 and 3.72 arcsec from its visual neighbor. Signed moments, quadratic peak fits, and 29 sensitivity fits give the same location choice. We add sources at both star positions in field residuals and in artificial blends made from measured field images. All 400 fits stay closer to the input star. The tests share 20 field stars and are not independent. Some November blend errors reach 5.02 arcsec, so the tests do not give a universal position-error bound. The result supports the primary as the source of the large increase under these field tests. It does not establish a planet or a unique physical cause. The package preserves original image cutouts, source tables, provenance, code, figures, numerical tests, and offline reproduction instructions.
ASASSN-21qj · NEOWISE · W2 · difference images · infrared variability · source position · Gaia DR3 · blended stars · reproducible research
References
11- usesThe blended ASASSN-21qj source has infrared flux near its earlier level in three 2023–2024 NEOWISE visits sci:sha256:2111d70dce9993c8de3f8feda9b58c62a884ff88a94a03826971209354727b18
We reuse its verified target and field tables, query records, original field-star list, IPAC parser, and catalog quality cuts. We add original-image position measurements.
- Ten ASASSN-21qj infrared visits give a constant-colour p value of 0.028 under the stated error model sci:sha256:378e7fb1a635c429fc297c6e64f6b2a76c2e622b6e3dfac17e45603bf7272413
This prior work tests the color of the blended event. It does not measure the position of the added light.
- doi:10.1038/s41586-023-06573-9
This event study gives the proposed planetary-collision model and identifies the nearby visual star. We test the position of the added W2 light.
- doi:10.1038/s41586-023-06874-z
This correction identifies the independent event study.
- doi:10.3847/1538-4357/ace629
This independent event study gives a comet-breakup model. Our position test does not select between physical models.
- doi:10.48550/arXiv.2504.05401
This prior method uses NEOWISE catalog position shifts to separate variable sources in another close pair.
- usesdoi:10.26131/IRSA147
The final NEOWISE image archive supplies the original W2 intensity and uncertainty cutouts.
- usesdoi:10.26131/IRSA144
The source table supplies the exposure identifiers and selection values.
- usesdoi:10.26131/IRSA1
The AllWISE source catalog supplies the field-star selection values.
- usesdoi:10.5270/esa-qa4lep3
Gaia DR3 supplies reference positions, proper motions, and reference-star quality values.
- doi:10.1051/0004-6361/202243940
This paper describes Gaia DR3.
Cited by
3 publicationsPublic catalog entries on Sciscape.
- A grey thermal model with constant temperature fits ten selected 2018–2022 ASASSN-21qj visits better than a model with constant area under fixed baseline light and the stated errors
This prior source-location study describes the known close neighbor. The blended aperture remains a limit on physical interpretation.
- usesA fixed W2/W1 ratio fits added light in selected 2018–2022 ASASSN-21qj images under the stated errors
We reuse verified Gaia and AllWISE tables, some IRSA image bytes, and MIT code for field selection, proper motion, and reference-star image fits. We add W1/W2 visit images and aperture color tests.
- NEOWISE 2014–2024 shows one sudden >10% 4.6 µm brightening (TYC 9279-457-1, 2021) in 7,897 young cluster stars without IR excess; onsets are below 1.3e-4 per star-year for 2-yr exponential decays
It places the 2019 W2 increase on ASASSN-21qj and not on its 3.7 arcsec neighbour. We use the blended source as a positive control.