Brum
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It looks like 151 mm to me. 88.8 mm between adjacent holes and 143.6 mm between 'opposite". It can't be 144 BCD if it's already >140 mm between two bolts.
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Either measure between two bolt-holes that are next to each other and refer to Sheldon's crib sheet, or on that chainring you could measure from one bolt hole to the middle-centre of the banana-shaped slot between the bolt-holes exactly on the opposite side of the chainring.
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A pictorial approach using Corel Draw: the yellow circle is a 100mm reference with no allowance for foreshortening, red circle is an average of outer and inner perimeters of the bolt holes (line thickness was later increased to make it visible in the photo)
Most of the error is due to the camera having a relatively short focal length, but measuring your photo and scaling gives a BCD of 143.7mm - say 144mm with an error in measurement of 0.2%, which is probably as accurate as you'll get with a tape measure.
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frankenbike
ffm
MrE
https://www.sheldonbrown.com/cribsheet-bcd.html
Measuring between two adjacent holes can work. Bit hard to tell with your tape measure lining up on the imperial edge rather than the metric, but looks yours is 151mm or 144mm BCD?