# Alert production and exposure time

**URL:** <https://www.rubin.community/t/alert-production-and-exposure-time/6303>\
**Category:** Alerts & Brokers\
**Created:** [February 8, 2022, 8:02am UTC](https://www.rubin.community/t/alert-production-and-exposure-time/6303 "2022-02-08T08:02:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![JulienPeloton](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/julienpeloton/32/937_2.png) [@JulienPeloton](https://www.rubin.community/u/JulienPeloton)\
**Post date:** [February 8, 2022, 8:02am UTC](https://www.rubin.community/t/alert-production-and-exposure-time/6303/1 "2022-02-08T08:02:29Z")

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Hi – In the scenario of 2x15 second exposures, will the two be calibrated and differenced independently for producing alerts, or coadded before?

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**Author:** ![ebellm](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/ebellm/32/771_2.png) [@ebellm](https://www.rubin.community/u/ebellm)\
**Post date:** [February 8, 2022, 5:53pm UTC](https://www.rubin.community/t/alert-production-and-exposure-time/6303/2 "2022-02-08T17:53:02Z")

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Hi @JulienPeloton: alerts are only produced from the coadd of the two 15 second snaps.

However, the DPDD says we will report the snap-difference flux for those alerts as well.

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**Author:** ![JulienPeloton](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/julienpeloton/32/937_2.png) [@JulienPeloton](https://www.rubin.community/u/JulienPeloton)\
**Post date:** [February 9, 2022, 7:52am UTC](https://www.rubin.community/t/alert-production-and-exposure-time/6303/3 "2022-02-09T07:52:06Z")

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Thanks!