What are the latest parameters for the filter changer?

filter
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(Matthew Penny) #1

The best information I can find on the filter changer is on the following webpage:
https://www.lsst.org/about/camera/features

Changer/Carousel Design

Carousel holds five filters:g-r-i-z-y
Rail-type changer engages carousel for automatic changing; 
Maximum filter change time of two minutes;
Can change filters up to four times per night; 
Manual load-lock changer for inserting a 6th filter (u-filter);
Operational lifetime of 2 x 104 cycles

Is this information still current? The operational cycle does not make sense to me, unless there is a typo and it should be 2x10^4?


(Tim Jenness) #2

Of order 20,000 sounds about right if you look at the camera requirements in LSE-59 (see CAM-REQ-0070). @sritz will know for sure.


(Antilogus) #4

The requirements on the filter exchange system are :

https://docushare.lsst.org/docushare/dsweb/Get/LCA-49

so it is 100 000 filter exchanges on 15 years , corresponding per day to 20 filter changes (on sky + calib) + 1 test + 2 swap of filter per month …

For example , in the current call on LSST cadence , you can propose cadence up to 17 filters changer per night .

Remark : in many document you see the number 4 filter changes per night ( ex LSE-59 ) ,but it is more a minimal number associated to the LSST cadence initially considered , and for sure it’s not the allowed limit .