# Reference image’s WCS compares inequal to the current image's WCS **URL:** \ **Category:** Support\ **Created:** [February 6, 2022, 3:22pm UTC](https://www.rubin.community/t/reference-image-s-wcs-compares-inequal-to-the-current-images-wcs/6297 "2022-02-06T15:22:30Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![mpaillassa](https://avatars.discourse-cdn.com/v4/letter/m/ed655f/32.png) [@mpaillassa](https://www.rubin.community/u/mpaillassa)\ **Post date:** [February 6, 2022, 3:22pm UTC](https://www.rubin.community/t/reference-image-s-wcs-compares-inequal-to-the-current-images-wcs/6297/1 "2022-02-06T15:22:30Z")
Hello, I am getting an error concerning reference image’s WCS being inequal to the current image’s WCS and I was told that it may be a long-standing bug. I am running the multiBandDriver on pdr2\_wide HSC data in which I added fake sources. I am using LSST pipelines 23\_0\_0 and running with doPropagateFlags=False in the measureCoaddSources task. It fails at the forcedPhotCoadd task with the attached traceback. [traceback](https://www.rubin.community/uploads/short-url/gvPm4Kqj6MAJNbiCqEoXkWh3QXt) (3.4 KB) Is this really a bug or something on my side ? Thanks, Maxime ---
**Author:** ![timj](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/timj/32/10_2.png) [@timj](https://www.rubin.community/u/timj)\ **Post date:** [February 7, 2022, 4:14pm UTC](https://www.rubin.community/t/reference-image-s-wcs-compares-inequal-to-the-current-images-wcs/6297/2 "2022-02-07T16:14:52Z")
The traceback doesn’t have a file extension so has to be downloaded before it can be seen. Here it is inline for others to comment on: ```auto Traceback (most recent call last): File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 112, in wrapper return func(*args, **kwargs) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 1069, in run while not menu[command](): File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 239, in wrapper return func(*args, **kwargs) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 1087, in reduce result = self._processQueue(context, func, [(index, data)], *args, **kwargs)[0] File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 546, in _processQueue return self._reduceQueue(context, None, func, queue, *args, **kwargs) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 572, in _reduceQueue resultList = [func(self._getCache(context, i), data, *args, **kwargs) for i, data in queue] File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/ctrl_pool/23.0.0+1611dd45d2/python/lsst/ctrl/pool/pool.py", line 572, in resultList = [func(self._getCache(context, i), data, *args, **kwargs) for i, data in queue] File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/pipe_drivers/23.0.0+476726adcc/python/lsst/pipe/drivers/multiBandDriver.py", line 464, in runForcedPhot self.forcedPhotCoadd.runDataRef(dataRef) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_base/23.0.0+1c9213783a/python/lsst/meas/base/forcedPhotCoadd.py", line 297, in runDataRef forcedPhotResult = self.run(measCat, exposure, refCat, refWcs, exposureId=exposureId) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_base/23.0.0+1c9213783a/python/lsst/meas/base/forcedPhotCoadd.py", line 328, in run self.measurement.run(measCat, exposure, refCat, refWcs, exposureId=exposureId) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_base/23.0.0+1c9213783a/python/lsst/meas/base/forcedMeasurement.py", line 369, in run self.callMeasure(measChildRecord, exposure, refChildRecord, refWcs, File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_base/23.0.0+1c9213783a/python/lsst/meas/base/baseMeasurement.py", line 337, in callMeasure self.doMeasurement(plugin, measRecord, *args, **kwds) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_base/23.0.0+1c9213783a/python/lsst/meas/base/baseMeasurement.py", line 367, in doMeasurement plugin.measure(measRecord, *args, **kwds) File "/work/mpaillassa/lsst_stack/stack/miniconda3-py38_4.9.2-0.7.0/Linux64/meas_modelfit/23.0.0+2ea42a5d58/python/lsst/meas/modelfit/cmodel/cmodelContinued.py", line 104, in measure raise lsst.meas.base.FatalAlgorithmError( lsst.pex.exceptions.wrappers.FatalAlgorithmError: CModel forced measurement currently requires the measurement image to have the same Wcs as the reference catalog (this is a temporary limitation). application called MPI_Abort(MPI_COMM_WORLD, 1) - process 2 ``` ---
**Author:** ![jbosch](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/jbosch/32/12_2.png) [@jbosch](https://www.rubin.community/u/jbosch)\ **Post date:** [February 8, 2022, 5:19pm UTC](https://www.rubin.community/t/reference-image-s-wcs-compares-inequal-to-the-current-images-wcs/6297/3 "2022-02-08T17:19:16Z")
Yes, this is a known issue: [DM-15181](https://jira.lsstcorp.org/browse/DM-15181), though it also seems like something similar happened earlier and was fixed on [DM-10105](https://jira.lsstcorp.org/browse/DM-10105). We haven’t seen it all all recently, so it fell off everyone’s radar. There is a commit on the branch for the former that you may be able to checkout, rebase, and build to work around the problem. ---
**Author:** ![price](https://sea2.discourse-cdn.com/flex002/user_avatar/www.rubin.community/price/32/488_2.png) [@price](https://www.rubin.community/u/price)\ **Post date:** [February 8, 2022, 5:33pm UTC](https://www.rubin.community/t/reference-image-s-wcs-compares-inequal-to-the-current-images-wcs/6297/4 "2022-02-08T17:33:43Z")
Oh, I now recall that this gets triggered when the forced measurement is done on a different machine (architecture?) than originally created the reference WCS.