# LSST Mask Planes to Euclid Flag Maps **URL:** \ **Category:** Data Management\ **Tags:** dm-dev\ **Created:** [November 26, 2021, 12:09pm UTC](https://www.rubin.community/t/lsst-mask-planes-to-euclid-flag-maps/6130 "2021-11-26T12:09:22Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![rfahed](https://avatars.discourse-cdn.com/v4/letter/r/c68b51/32.png) [@rfahed](https://www.rubin.community/u/rfahed)\ **Post date:** [November 26, 2021, 12:09pm UTC](https://www.rubin.community/t/lsst-mask-planes-to-euclid-flag-maps/6130/1 "2021-11-26T12:09:23Z")
Hello, I am working for Euclid and have the responsability of the lsst data processing within the Euclid infrastruture. I was asked about the bit flags used in LSST, and saw that you are refering to **Mask Planes Number** whereas Euclid uses **Bit Mask Value** in their documentation. I guessed that the correspondance between the two was as follow : ```auto BIT_PLANE FLAGMAP_BIT BIT_VALUE 0 0x00000001 1 BAD 1 0x00000002 2 SAT 2 0x00000004 4 INTRP 3 0x00000008 8 CR 4 0x00000010 16 EDGE 5 0x00000020 32 DETECTED 6 0x00000040 64 DETECTED_NEGATIVE 7 0x00000080 128 SUSPECT ``` Can someone tell me if this is correct ? Thank you for your help. Rémi ---
**Author:** ![ktl](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/ktl/32/1373_2.png) [@ktl](https://www.rubin.community/u/ktl)\ **Post date:** [November 26, 2021, 3:11pm UTC](https://www.rubin.community/t/lsst-mask-planes-to-euclid-flag-maps/6130/2 "2021-11-26T15:11:20Z")
[LSST Applications: How Mask Planes are handled in @c afw](http://doxygen.lsst.codes/stack/doxygen/x_masterDoxyDoc/afw_mask_planes.html) gives some information. Basically, the mapping from name to bit and bit value is not fixed; it can vary between image types (and even theoretically from image to image). But it is always recorded so that code can reliably use names. ---
**Author:** ![DouglasLTucker](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/douglasltucker/32/1341_2.png) [@DouglasLTucker](https://www.rubin.community/u/DouglasLTucker)\ **Post date:** [November 29, 2021, 1:27am UTC](https://www.rubin.community/t/lsst-mask-planes-to-euclid-flag-maps/6130/3 "2021-11-29T01:27:29Z")
Dear Rémi, I am not sure if the following helps, but I have been doing some validation tests of the mask planes from test data processing sets for the Rubin LSST DP0.2 campaign. I “borrowed” some code from Brant Robertson and Alex Drlica-Wagner’s Rubin LSST Stack club jupyter notebook [AFW\_Display\_Demo.ipynb](https://github.com/LSSTScienceCollaborations/StackClub/blob/master/Visualization/AFW_Display_Demo.ipynb) and found the following for Rubin DP0.2-processed calexp image masks: ![Screen Shot 2021-11-28 at 7.24.22 PM](https://us1.discourse-cdn.com/flex002/uploads/rubin/original/2X/9/9e494e019d4aebaaf843d9282e29dabcd07581dd.png) As K-T Lim mentions above, mapping between the name to bit value is not fixed and can vary between image types; e.g., I suspect things may differ for the coadd images. I hope this helps!