The HMI instrument is retuned on a regular basis to compensate for drifts in the Michelson interferometers. The instrument retuning is performed by loading new mechanism position tables to the flight instrument and selecting a new wavelength tuning set. HMI retunings were initiated at the following dates and are indicated by the change in the wavelength tuning id (WTID) value. Most retunings were performed during EVE cruciform maneuvers in order to allow the mechanism adaptive position control to settle into optimal mechanism delay values during non-science observing periods. The first table shows the retuning times, FSNs at the retuning, observing framelist FTSID at the time, and the change in wavelength tuning ID. The second table shows the motor positions for the center wavelength. ***************************************************************** T_OBS FSN FTSID WTID ------------------------- -------- ----- ---- 2010.12.13_19:45:08.35_UTC 15049882 1001 10 2010.12.13_19:45:10.21_UTC 15049883 1001 10 2010.12.13_19:45:12.10_UTC 15049884 1001 11 2010.12.13_19:45:13.97_UTC 15049885 1001 11 2011.07.13_18:35:23.35_UTC 24812717 1021 11 2011.07.13_18:35:25.21_UTC 24812718 1021 11 2011.07.13_18:35:27.09_UTC 24812719 1021 14 2011.07.13_18:35:28.97_UTC 24812720 1021 14 2012.01.18_18:15:08.35_UTC 33508227 1021 14 2012.01.18_18:15:10.22_UTC 33508228 1021 14 2012.01.18_18:15:12.10_UTC 33508229 1021 17 2012.01.18_18:15:13.97_UTC 33508230 1021 17 2013.03.14_06:42:07.35_UTC 52877107 1021 17 2013.03.14_06:42:09.22_UTC 52877108 1021 17 2013.03.14_06:42:11.10_UTC 52877109 1021 20 2013.03.14_06:42:12.97_UTC 52877110 1021 20 2014.01.15_19:13:37.35_UTC 67002794 1021 20 2014.01.15_19:13:39.22_UTC 67002795 1021 20 2014.01.15_19:18:11.10_UTC 67002796 1021 23 2014.01.15_19:18:12.97_UTC 67002797 1021 23 2015.04.08_18:51:07.35_UTC 87614596 1021 23 2015.04.08_18:51:09.22_UTC 87614597 1021 23 2015.04.08_18:53:26.12_UTC 87614598 1021 26 2015.04.08_18:53:27.98_UTC 87614599 1021 26 2016.04.27_18:56:21.36_UTC 105328287 1022 26 2016.04.27_18:56:23.23_UTC 105328288 1022 26 2016.04.27_19:03:55.11_UTC 105328289 1022 29 2016.04.27_19:03:56.98_UTC 105328290 1022 29 2017.04.19_19:57:50.35_UTC 121696089 1022 29 2017.04.19_19:57:52.23_UTC 121696090 1022 29 2017.04.19_20:05:24.10_UTC 121696091 1022 31 2017.04.19_20:05:25.98_UTC 121696092 1022 31 2019.04.23_18:27:50.35_UTC 155480547 1022 31 2019.04.23_18:27:52.23_UTC 155480548 1022 31 2019.04.23_18:45:54.11_UTC 155480549 1022 32 2019.04.23_18:45:55.98_UTC 155480550 1022 32 2020.10.21_18:03:50.36_UTC 180664284 1022 32 2020.10.21_18:03:52.23_UTC 180664285 1022 32 2020.10.21_18:14:24.11_UTC 180664286 1022 33 2020.10.21_18:14:25.98_UTC 180664287 1022 33 2021.07.14_18:08:20.36_UTC 192908452 1022 33 2021.07.14_18:08:22.24_UTC 192908453 1022 33 2021.07.14_18:18:54.11_UTC 192908454 1022 34 2021.07.14_18:18:55.98_UTC 192908455 1022 34 2023.10.25_17:21:50.36_UTC 231248958 1022 34 2023.10.25_17:21:52.24_UTC 231248959 1022 34 2023.10.25_17:39:54.11_UTC 231248960 1022 35 2023.10.25_17:39:55.98_UTC 231248961 1022 35 ***************************************************************** Retuning Date WT ID Lyot WB NB ----------------- ----- ---- -- -- 30 Apr 2010 22:24 10 36 58 82 13 Dec 2010 19:45 11 37 56 82 13 Jul 2011 18:35 14 37 54 82 18 Jan 2012 18:15 17 37 53 81 14 Mar 2013 06:42 20 37 52 81 15 Jan 2014 19:13 23 37 51 80 08 Apr 2015 18:51 26 37 50 80 27 Apr 2016 18:56 29 37 50 79 19 Apr 2017 19:58 31 38 49 79 23 Apr 2019 18:28 32 38 48 79 21 Oct 2020 18:10 33 38 48 78 14 Jul 2021 18:10 34 38 47 78 25 Oct 2023 17:30 35 38 46 78