I took over the vent prep: I'm going through the list in [ELOG 15649] and [ELOG 15651]. I will also look at [ELOG 15652] at the day of venting.

1. IFO alignment: Two arms are already locking. The dark port beam is well overlapped. We will move PRM/SRM etc. So we don't need to worry about them. [Attachment 1]
   scripts>z read C1:SUS-BS_PIT_BIAS C1:SUS-BS_YAW_BIAS
-304.7661529521767
-109.23924626857811
scripts>z read C1:SUS-ITMX_PIT_BIAS C1:SUS-ITMX_YAW_BIAS
15.534616817500943
-503.4536332290159
scripts>z read C1:SUS-ITMY_PIT_BIAS C1:SUS-ITMY_YAW_BIAS
653.0100945988496
-478.16260735781225
scripts>z read C1:SUS-ETMX_PIT_BIAS C1:SUS-ETMX_YAW_BIAS
-136.17863332517527
181.09285307121306
scripts>z read C1:SUS-ETMY_PIT_BIAS C1:SUS-ETMY_YAW_BIAS
-196.6200333695437
-85.40819256078339
    
2. IMC alignment: Locking nicely. I ran WFS relief to move the WFS output on to the alignment sliders. All the WFS feedback values are now <10. Here is the slider snapshots. [Attachment 2]
    
3. PMC alignmnet: The PMC looked like it was quite misaligned -> aligned. IMC/PMC locking snapshot [Attachment 3]
   Arm transmissions:
   scripts>z avg 10  C1:LSC-TRX_OUT C1:LSC-TRY_OUT
C1:LSC-TRX_OUT 0.9825591325759888
C1:LSC-TRY_OUT 0.9488834202289581
    
4. Suspension Status Snapshot [Attachment 4]
    
5. Anchal aligned the OPLEV beams [ELOG 16407]
   I also checked the 100 days trend of the OPLEV sum power. The trend of the max values look flat and fine. [Attachment 5] For this purpose, the PRM and SRM was aligned and the SRM oplev was also aligned. The SRM sum was 23580 when aligned and it was just fine (this is not so visible in the trend plot).
    
6. The X and Y green beams were aligned for the cavity TEM00s. Y end green PZT values were nulled. The transmission I could reach was as follows.
   >z read C1:ALS-TRX_OUTPUT C1:ALS-TRY_OUTPUT
0.42343354488901286
0.24739624058377277
   It seems that these GTRX and GTRY seemed to have crosstalk. When each green shutters were closed the transmissino and the dark offset were measured to be
   >z read C1:ALS-TRX_OUTPUT C1:ALS-TRY_OUTPUT
0.41822833190834546
0.025039383697636856
>z read C1:ALS-TRX_OUTPUT C1:ALS-TRY_OUTPUT
0.00021112720155274818
0.2249448773499293
   Note that Y green seemed to have significant (~0.1) of 1st order HOM. I don't know why I could not transfer this power into TEM00. I could not find any significant clipping of the TR beams on the PSL table PDs.
    
7. IMC Power reduction
   Now we have nice motorized HWP. sitemap -> PSL -> Power control
   == Initial condition == [Attachment 6]
   C1:IOO-HWP_POS 38.83
   Measured input power = 0.99W
   C1:IOO-MC_RFPD_DCMON = 5.38
   == Power reduction == [Attachment 7]
   - The motor was enabled upon rotation on the screen
   C1:IOO-HWP_POS 74.23
   Measured input power = 98mW
   C1:IOO-MC_RFPD_DCMON = 0.537
   - Then, the motor was disabled
    
8. Went to the detection table and swapped the 10% reflector with the 98% reflector stored on the same table. [Attachments 8/9]
   After the beam alignment the MC REFL PD received about the same amount of the light as before.
   C1:IOO-MC_RFPD_DCMON = 5.6
   There is no beam delivered to the WFS paths.
   CAUTION: IF THE POWER IS INCREASED TO THE NOMINAL WITH THIS CONFIGURATION, MC REFL PD WILL BE DESTROYED.
9. The IMC can already be locked with this configuration. But for the MC Autolocker, the MCTRANS threshold for the autolocker needs to be reduced as well.
   This was done by swapping a line in  /opt/rtcds/caltech/c1/scripts/MC/AutoLockMC.init
# BEFORE
/bin/csh ./AutoLockMC.csh >> $LOGFILE
#/bin/csh ./AutoLockMC_LowPower.csh >> $LOGFILE
--->
# AFTER
#/bin/csh ./AutoLockMC.csh >> $LOGFILE
/bin/csh ./AutoLockMC_LowPower.csh >> $LOGFILE
   Confirmed that the autolocker works a few times by toggling the PSL shutter. The PSL shutter was closed upon the completion of the test
    
10. Walked around the lab and checked all the bellows - the jam nuts are all tight, and I couldn't move them with my hands. So this is okay according to the ancient tale by Steve.