Sentinel-2 catalogue showing S2A and S2B transit on the same day?

On 28/03/2025 in UTM tile 32TMK the catalogue.dataspace.copernicus.eu gives me both S2A and S2B acquisitions.

To date the catalogue has only ever showed one or other of the pair on a single date.

Has anything changed?

Or is there a bug in the catalogue?

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In particular these two acquisitions:

S2B_MSIL2A_20250328T100559_N0511_R022_T32TMK_20250328T130415

S2A_MSIL2A_20250328T102031_N0511_R065_T32TMK_20250328T202117

Hello,

This can be an expected behavior and can occasionally occur. While Sentinel-2A and 2B are typically phased to image the same area on different days, overlaps may happen due to orbital geometry.

The two acquisitions you mentioned are about 15 minutes apart, which suggests this is a valid dual coverage scenario rather than a bug.

That said, I’ll look into it further and share an update here if I find anything unusual.

M h

Hello,
….That said, I’ll look into it further and share an update here if I find anything unusual.

Now I see that this realignment of S2A started on 18 March. And in the meantime the new S2C has begun providing acquisitions. IIRC S2C is the replacement for the ageing S2A.

My guess is that S2A has been manoeuvred to ‘join’ S2B. That way, while it still functions, it can act as a backup for S2B - just in case S2B has issues.

Okay so my Isola2 WebApp that shows one acquisition per tile on a single calendar date now prefers those from S2C over those from S2B over those from S2A. See here:

https://crs4.github.io/IsolaS2/src/