Displaying reports 56101-56120 of 83091.Go to page Start 2802 2803 2804 2805 2806 2807 2808 2809 2810 End
Reports until 08:13, Wednesday 15 June 2016
H1 AOS
bubba.gateley@LIGO.ORG - posted 08:13, Wednesday 15 June 2016 (27747)
E X Wind Fence
Progress on the E X Wind Fence. We will continue work on this project today also.
Images attached to this report
H1 ISC
terra.hardwick@LIGO.ORG - posted 03:11, Wednesday 15 June 2016 - last comment - 17:01, Wednesday 15 June 2016(27743)
PI ITMY actuation adventures

Carl, Terra, Rich A.

1. We used the never-before-tested LVLN ITMY ESD driver to ring up and damp two mechanical modes of ITMY, 15072 Hz and 14979 Hz. Below is the amplitude evolution of the 15072 Hz peak as we rang it up, allowed it to ring down naturally, rang it up again, and then damped it down fully with a gain sign flip. 

We drove and damped similarly for the 14979 Hz peak. 15072 Hz is the vertical differential drumhead mechanical mode; 14979 Hz is the horizontal version. For both cases, we tightly bandpassed the H1:OMC-PI_DCPD_64KZ_A/B signal, added a +60deg damping filter, and added gain to the damping filter until saturation. Positive gain drove up, negative damped down. 

I've fit the natural ring down with f(x) = a * exp(bx), where tau = - (1/b). Then Q = pi * 15072 * tau = 31.5 million.

2. Interestingly, we realized after the above tests that we had not turned the ESD bias on for either ITM. After turning on both to 100K cts (to DC offset), we just had time to ring back up the ITMY 15072 Hz mode before a lockloss. Below is a comparison of the ring ups (note we lost lock and did not damp for the ring down portion below). Green trace is the 15072 Hz ring up without bias, blue trace is with bias (time shifted for ease of comparison).  

A slight slope difference is visible but we'll look into this more. Thoughts are that we could use the difference in responses to measure test mass charge coefficients as discussed here and here.

3. We turned ring heaters off and on for future mode-mass identification analysis. For the record (since RH messing with violin modes was a concern tonight):

Images attached to this report
Comments related to this report
carl.blair@LIGO.ORG - 13:59, Wednesday 15 June 2016 (27753)

We were also driving the ITMX mode at 15077Hz before and after the bias was turned on.  The data is a little more confusing.  As the phase was being varied before hand to try find the optimum damping phase.  In the plot the amplitude is made to coincide when the damping phase with no bias had the largest response.  There was no attempt to optimise the phase in the case where the bias was on other that to try the positive and negative of the previous 'best' phase.   Interesting points are: 
For the 15077Hz mode the phase that excited the mode was flipped whent he bias was engaged.  
The response with the bias engaged is relatively larger when compared to the ITMY 15072Hz mode.  
For the 15077Hz mode the amplitude response with bias is about twice the amplitude response without bias.

Images attached to this comment
carl.blair@LIGO.ORG - 17:01, Wednesday 15 June 2016 (27762)

Mode identification.  
In the attached plot the relative change in frequency of the four likely drum head modes around 15200Hz is plotted as a function of time.  The ring heaters were adjusted as follows:

ETMX 0.5W per segment to 0W  02:29
ETMY 0.5W per segment to 0W  03:00
ITMX  0W to 0.5W per segment  03:33
ITMX  0.5W per segment to 0W  04:02
ITMY  0W to 0.5W per segment  04:06
ITMY  0.5W per segment to 0W  04:36

The response in frequency shows that the 15218Hz mode is a cooling ETMX, 15219Hz is a cooling ETMY, 15197Hz a heating ITMX and 15192 a heating ITMY mode.  
As we were only operating at 2W input the signal to noise ratio of modes is a lot lower and many fewer modes are visible compared to Livingston measurements T1600141.



The following is the list of modes identified.

Measured Frequencies   Simulated Frequency        
ITMX ITMY ETMX ETMY ITMX ITMY ETMX ETMY Shape description
6044 6042 6055 6054 6057 6054 6053 6053 Butterfly  
8162 8160 8161 8158 8194 8190 8189 8188 Drumhead  
9812 9809 9829 9831 9827 9827 9832 9832 Drumhead Vertical
9860 9863 9881 9882 9879 9881 9885 9885 Drumhead Horizontal
  10415     10437 10434 10433 10432 3 point ripple  
10423 10419 10428 10426 10462 10460 10463 10462 Drumhead  
12992 12988 12999 13000 13022 13026 13035 13036 Drumhead Differential
15077 15072     15093 15096 15102 15103 Drumhead Horizontal
15197 15192 15218 15219 15227 15227 15232 15231 Drumhead  
    15540   15545 15541 15544 15544 Drumhead Vertical
  15627     15635 15632 15634 15634 Drumhead Horizontal
19555 19553     19589 19588 19595 19594 Drumhead  
Images attached to this comment
H1 SUS (ISC)
nutsinee.kijbunchoo@LIGO.ORG - posted 01:21, Wednesday 15 June 2016 - last comment - 14:04, Wednesday 15 June 2016(27745)
Violin Mode damping work (cont.)

Stefan, Nutsinee

A very quick summary: ITMY modes rung up tonight. All the damp settings has been changed. I suspect ETMX damp phase might have been changed as well. ITMX didn't seen to have a problem. We suspect the ring heater changed the violin mode frequency.

 

Below I attached a screenshot of what works on ITMY modes tonight.

Images attached to this report
Comments related to this report
stefan.ballmer@LIGO.ORG - 14:04, Wednesday 15 June 2016 (27754)

We looked at the frequency of mode 8 last night, two nights before around GW151226 and after a O1 power ouitage (20151025 9UTC). (attached)

Two days ago the mode was heavily damped, so the frequency estimate might be a bit off. At any rate, all frequencies are within 3mHz (or 22deg of feed-back phase in the current band-pass filter). So we ough to be able to damp this mode consistently.

Images attached to this comment
LHO VE
kyle.ryan@LIGO.ORG - posted 21:43, Tuesday 14 June 2016 - last comment - 16:11, Wednesday 15 June 2016(27741)
CP5 LLCV %open seems high


			
			
Comments related to this report
chandra.romel@LIGO.ORG - 16:11, Wednesday 15 June 2016 (27761)
Chandra, Gerardo

-Adjusted CP5 Dewar pressure regulator 1/4 turn CW to raise Dewar pressure (nominally at 15 psi). Will wait hours/days to see results. 
-Measured Dewar vacuum jacket pressure = 20 microns, satisfactory.
-Magnehelic readout is noisy - jumps from 35-40 in. of H20, even when CP5 is in manual mode.
-Manually tested full range of stroke of electronic actuator - looks OK.
-Tightened actuator support/brace nuts along unistrut.
-Noticed needle of valve has wiggle (more than CP6). Verified packing nut is adjusted properly and coupling nut and needle are fully threaded.

So now we wait to see if adjusting pressure of Dewar has an impact.
kyle.ryan@LIGO.ORG - 21:58, Tuesday 14 June 2016 (27742)
Not able to trend - was sitting around 100% but maybe just big swing?
H1 General (Lockloss)
haocun.yu@LIGO.ORG - posted 19:01, Tuesday 14 June 2016 - last comment - 15:30, Wednesday 15 June 2016(27739)
Locklosses

Sheila, Haocun

We had lots of locklosses today, and some were probably caused by the side OSEM driving of the beamsplitter M1, as shown in the figures attached.

(H1:SUS-BS_M1_MASTER_OUT_SD_DQ & H1:SUS-BS_M1_DAMP_T_IN1_DQ)

Images attached to this report
Comments related to this report
sheila.dwyer@LIGO.ORG - 15:30, Wednesday 15 June 2016 (27758)

It seems to have happened again at 22:20:12 UTC June 15th

Images attached to this comment
sheila.dwyer@LIGO.ORG - 22:25, Tuesday 14 June 2016 (27744)CDS, Lockloss, SUS

Tagging SUS and CDS. 

Tonight I had a look at several other of these locklosses, and other than the one at 23:57:59 that Hoacun plotted, it seems mostly like the glitch in the side osem comes after the lockloss.  Many of these locklosses seem to happen durring the CM board switching.

It does seem like it would be worth investigating this side osem issue, since we know that it causes at least some locklosses. 

H1 CAL (ISC, SUS)
jeffrey.kissel@LIGO.ORG - posted 18:31, Tuesday 14 June 2016 - last comment - 10:25, Tuesday 21 June 2016(27733)
Individual Stage Calibration Line Oscillators for QUADs; Other DARM Loop Params Time-Dependence Upgrade CAL-CS; DELTAL Channels Now Double Precision with No Whitening
J. Kissel 
WP #5932

Today's model modifications come in three parts: 
(1) Independent Synchronized Oscillators for each isolation stage of the QUAD for calibration lines
(2) Updated CAL-CS model with better demodulation scheme that spits out coherence and uncertainty
(3) Changed all CAL-DELTAL and CAL-DARM channels to double precision and removed whitening
Below are all the details.

------------- Part (1)
In order push the PCAL vs. SUS actuation calibration line cancelling scheme for ER9/O2 forward (see T1600218 and T1600215), I've installed independent, longitudinal, synchronized oscillators in each of the UIM/L1, PUM/L2, TST/L3 stages of all of the QUAD models. See first attachment for screenshot of the QUAD OVERVIEW screen that now has the CAL_LINE block beneath every LOCK bank. Sadly, due to the recent split in QUAD library part models, I'd forgotten to add the needed EPICs channel for GPS synchronization to the ITMs. We'll install them tomorrow morning. 
I've committed the following new models: 
/opt/rtcds/userapps/release/sus/common/models/
Sending        FOUROSEM_DAMPED_STAGE_MASTER_WITH_DAMP_MODE.mdl    <-- Used in PUM/L2 stages
Sending        FOUROSEM_STAGE_MASTER_OPLEV_TIDAL.mdl              <-- Used in UIM/L1 stages
Sending        QUAD_MASTER.mdl                                    <-- Added EPICs record for GPS sync time on TST/L3 stage for ETMs

and accordingly modified MEDM screens:
M       SUS_CUST_QUAD_ITM_OVERVIEW.adl
A  +    SUS_CUST_QUAD_ISTAGE_CAL_LINE.adl
D       SUS_CUST_QUAD_L3_CAL_LINE.adl
M       SUS_CUST_QUAD_OVERVIEW.adl


------------- Part (2)
In addition, as a continuation of the improvements to using those calibration lines to track changes in the DARM loop parameters, I've followed Joe's instructions (see LHO aLOG 26491) and updated the CAL-CS model to demodulate PCAL and DARM error signals at given frequencies and produce parameter estimates, coherence estimates, and even uncertainty estimates. 

Darkhan will be working on commissioning the infrastructure with Joe.


------------- Part (3)
Finally, I've converted all of the calibrated DARM channels to double precision. *EXCEPT* for DELTAL_EXTERNAL, which is needed to display on the wall in the control room via DTT (which sadly, cannot yet handle double precision; see CDS Bug 1003).  

As a result, and as per Joe's advice I've turned OFF all dewhitening filters that condition the following (new) channels stored in the frames: 

H1:CAL-DARM_CTRL_WHITEN_OUT_DBL_DQ 
H1:CAL-DARM_ERR_WHITEN_OUT_DBL_DQ 
H1:CAL-DELTAL_CTRL_DBL_DQ  
H1:CAL-DELTAL_CTRL_PUM_DBL_DQ  
H1:CAL-DELTAL_CTRL_TST_DBL_DQ 
H1:CAL-DELTAL_CTRL_UIM_DBL_DQ  
H1:CAL-DELTAL_RESIDUAL_DBL_DQ  

We need to investigate if we're now happy with the signal fidelity without whitening or if we just need to re-assess the whitening. Again, I've retained single precision on H1:CAL-DELTAL_EXTERNAL_DQ, so its whitening filter remains ON.

Images attached to this report
Comments related to this report
jeffrey.kissel@LIGO.ORG - 13:52, Monday 20 June 2016 (27854)
J. Kissel, J. Betzwieser

Joe called to let me know that I'd misinterpreted the fixed oscillator part that we chose to use (of the two; see T1600143). Turns out this version of the fixed phase oscillator automatically synchronizes to GPS time 0 (i.e. Jan 4 1980), so there's no need for the extra EPICs record input to the oscillator that specifies the GPS time. 

So, in opposition to what's said above, the ITM models are fine; we need to take the GPS EPICs record *out* of the ETMs. Will do so tomorrow.

jeffrey.kissel@LIGO.ORG - 10:25, Tuesday 21 June 2016 (27882)
J. Kissel

All QUAD Models have been restarted sans EPICs record for synchronization (the ITMs needed a restart to absorb the removal from the L1 and L2 stage common library parts). MEDM screen has been updated as well. I've committed the following to the repo. 
/opt/rtcds/userapps/release/sus/common/medm/quad/
Sending        SUS_CUST_QUAD_ISTAGE_CAL_LINE.adl

/opt/rtcds/userapps/trunk/sus/common/models/
Sending        FOUROSEM_DAMPED_STAGE_MASTER_WITH_DAMP_MODE.mdl
Sending        FOUROSEM_STAGE_MASTER_OPLEV_TIDAL.mdl
Sending        QUAD_MASTER.mdl
Images attached to this comment
H1 ISC (SUS)
carl.blair@LIGO.ORG - posted 18:24, Tuesday 14 June 2016 (27738)
ITMY PI path ESD measurements

The ITMY PI path was measured during maintenance day driving from CDS and measuriung the quadrant outputs to the ESD. WP#5931
Specifically driving H1:SUS-ITMX_PI_OMC_DAMP_MODE2_DAMP_EXC, and measuring P2-P5 of D1600122 directly with an SR785.

Generally behaves well.  The LR channel has slight excess noise (about twice the other channels) which is a ~65kHz signal.  It goes away when the DAQ input to the box is removed.   There was no evidence of the glitchy behaviour of ETMX LR channel.
Other than that it looks just like the ETMX.  The electronics TFs slightly over estimating the HF voltages. 

Images attached to this report
LHO VE
kyle.ryan@LIGO.ORG - posted 16:54, Tuesday 14 June 2016 (27737)
~1400 - 1430? hrs. local -> started scroll pump in old bake oven lab (adjacent to LVEA change room)
Anticipate running this pump for then next week or two.
H1 CDS
patrick.thomas@LIGO.ORG - posted 16:46, Tuesday 14 June 2016 (27736)
Test Conlog process
I've started a test Conlog process on conlog-test-replica connecting to the same channels as the production Conlog process on h1conlog1-master.
H1 SEI (CDS, ISC, SEI)
krishna.venkateswara@LIGO.ORG - posted 16:45, Tuesday 14 June 2016 (27735)
Effect of BRS Sensor Correction on the Interferometer in 20-40 mph winds

Michael, Jim, Krishna

We had 20-40 mph winds for most of the day yesterday. In the evening we tested a couple of different ISI configurations at the Corner Station (ITMX, ITMY) and the End-Stations. We tested the following two configurations:

1. 90 mHz Blends on ST1 and no sensor correction (SC) on all test-mass chambers -  The standard configuration used for most of O1 which works well in low microseism.

2. 250 mHz Blend and BRS SC on ST1 at the End-Stations and 90 mHz blends and no SC on ITMX, ITMY - The idea is to use the tilt-subtracted ground seismomter in feedforward more and rely less on the tilt-contaminated ST1 seismometer.

Quick Answer: The effect on some of the Interferometer channels we looked at was a small but uniform improvement of a factor of ~1.5 or so over the 90 mHz blend configuration. Near 0.1 Hz we were limited by ITMY chamber motion.

Details: The first attached pdf shows some of the Interferometer channels in Config 1 (Dashed) versus those in Config 2 (Solid) in units of ADC counts. The red line is equivalent to H1:DARM_CTRL_OUT_WHITEN_DQ which for some reason was not available today. The other three lines are some of the Angular Control Signals, all of which show small improvements. The second page shows the ASD of the wind-speed in both Configs showing that wind-speeds were comparable during the two measurements.

The second pdf shows data from some of the ISI local sensors. The first plot shows the ground motion near each chamber - note that the ITMY seismometer sits in the 'bier garten'  which is far away from the walls of the building. Also shown are the tilt-subtracted super-sensor signals (dashed lines). It is worth noting that the secondary microseism becomes visible after tilt-subtraction and is consistent with what the ITMY seismometer measures. The next plot shows the CPS signals which at low frequencies, are representative of the motion of ST1. The combination (ETMY-ITMY)-(ETMX-ITMX) should roughly correlate with DARM_CTRL at low frequencies, since the translational ground motion is small below the microseism. The third plot shows the ST1 seismometer(T240) motion. In all these plots, notice that despite the apparently quieter ground motion, ITMY moves nearly as much as ETMY. This is also seen in the fourth plot - which shows the coherence of the DARM_CTRL with the various CPS sensors. ITMY shows significant coherence between 60 to 200 mHz.

I think this suggests that the ITMY seismometer may not be a good measure of the tilt of the ITMY chamber, which is closer to the walls of the building. Thus our assessment that the Corner tilts significantly less than the End Station may not be valid. But if ITMY seismometer acts as a nearly tilt-free seisometer we can use it for sensor correction just as we do at the End-Stations and gain another small factor of ~1.5-2 in low frequency DARM_CTRL.

Non-image files attached to this report
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 16:23, Tuesday 14 June 2016 (27734)
X-End Signal Cable for BSC5 AIP Landed

(Richard, Gerardo)

Landed cables at rack and at the controller for annulus ion pump 525 (BSC5 AIP), gettind data now.

For future reference at the rack for both X-end and Y-end:

F37 ------- 011(+)

F38 ------- 012(-)

H1 CDS
patrick.thomas@LIGO.ORG - posted 16:03, Tuesday 14 June 2016 (27732)
Updated Conlog channel list
Added 231 channels. Removed 74 channels. (see attached)

The following channels are still unmonitored:
H1:GRD-TCS_ITMX_LOGLEVEL
H1:GRD-TCS_ITMX_MODE
H1:GRD-TCS_ITMX_NOMINAL_S
H1:GRD-TCS_ITMX_REQUEST
H1:GRD-TCS_ITMX_REQUEST_S
H1:GRD-TCS_ITMX_STATE_S
H1:GRD-TCS_ITMX_STATUS
H1:GRD-TCS_ITMX_TARGET_S
Non-image files attached to this report
LHO General
corey.gray@LIGO.ORG - posted 16:02, Tuesday 14 June 2016 (27731)
DAY Ops Summary
H1 ISC (CAL)
evan.hall@LIGO.ORG - posted 15:55, Tuesday 14 June 2016 (27675)
0.5° of SRC detuning can explain O1 anomaly in DARM plant

Kiwamu, Jeff, Evan

The calibration group has known since O1 that Hanford (but not Livingston) has an anomalous loss of gain in the DARM optical plant at 10 Hz and below. This can be explained by 0.5° of positive (antispring) SRC detuning away from pure RSE.

The first attachment shows a loop-corrected pcal sweep from O1, calibrated into mW/pm. On top of this I have plotted my guess at what theory curve this corresponds to (from Rob Ward's thesis), using 700 W of beamsplitter power, an arm pole of 42 Hz, an SRM transmissivity of 37 %, a homodyne angle of 90°, and a one-way SRC carrier phase of 90.5°. (The theory curve is pretty much insensitive to variations in the homodyne angle at the few-degree level, and we know that the homodyne angle deviates from 90° by less than 3°, since we ran with 20 mA of dc offset light and there is less than 1 mA of contrast defect light.)

To test this, I took a new set of pcal sweeps at 10 W of input power, with several different SRC detunings. The result is shown in the second attachment, again with guesses about the theory curves. All are with 350 W of beamsplitter power, 42 Hz arm pole, 37 % SRM transmission, and 90° homodyne angle. 0 ct of SRCL offset corresponds to the green (90.8°) curve, –200 ct corresponds to the blue (90.1°) curve, and +200 ct corresponds to the red (91.5°) curve. The implied calibration (0.1 ct / pm for the SRCL error point) is consistent with SRCL OLTF budgeting. The fact that 0 ct of SRCL offset produces a nonzero RSE detuning is perhaps not surprising, since we have never had good angular control of the SRM.

Non-image files attached to this report
LHO General (OpsInfo)
corey.gray@LIGO.ORG - posted 15:46, Tuesday 14 June 2016 (27717)
Maintenance Day Summary

With the list of items on our plate and the need to give more time to getting H1 ready for ER9, we did our darnedest to limit Maintenance Day to 4hrs today.  Jeff helped from the Detector Engineer side, and Ed was recruited whenever the waves of activities were too much.

With Maintenance starting at ~8:00, we were complete by around 12:39pm.  At this point, it was noticed that the Quads were pretty misaligned.  I restored their pointing via Oplev trends, and then since there were big changes, I went ahead and performed an Initial Alignment.  

Ops Note:  Only issue with alignment was when doing the last step (SRC_ALIGN_OFFLOADED).  For some reason, the IMC would break lock and Guardian would loop through this step repeatedly.  Not really sure what the issue was here.  Sheila & Jenne were notified of this.

Alignment took from 12:39pm - 1:44pm & then handed over to Commissioners.

A log of all activities are attached as a pdf (vs posted in this alog......thought of reducing alog real estate with the many lines of each activity during the day---input on preference on how Operators should post logs like this would be nice).

Non-image files attached to this report
LHO VE (VE)
gerardo.moreno@LIGO.ORG - posted 15:13, Tuesday 14 June 2016 (27728)
CP3 liquid level control

At 18:00 utc I decreased the LLCV valve setting to 18%, previous setting was 20%.  Due to LN2 delivery today.

H1 PSL (PSL)
patrick.thomas@LIGO.ORG - posted 15:11, Tuesday 14 June 2016 (27727)
Weekly PSL Chiller Reservoir Top-Off
Added 300 mL H2O to the H1 PSL crystal chiller. There were no fault alerts on either chiller. Both canister filters appear clear.
H1 ISC (ISC)
terra.hardwick@LIGO.ORG - posted 02:18, Thursday 09 June 2016 - last comment - 20:16, Tuesday 14 June 2016(27659)
PI: Driving ITMX modes with newly installed LVLN ESD

Carl, Terra, Ross, Tega

Tonight we used the freshly installed LVLN ITMX ESD driver to ring up and damp two mechanical modes of ITMX, 15063 Hz and 15077 Hz. 

After sorting out some phase settings, we drove the ITMX ESD close to saturation in a differential drumhead pattern. Negative gain rang up 15063 Hz. Flipping the gain sign to postive then damped this mode and rang up 15077 Hz. The amplitude plateaued as a the saturated drive signal approched a square wave. Figure below tracks amplitude of 15063 Hz and 15077 Hz (seen in OMC trans), with gain sign flip occuring around the 0.15 time mark. 

Also attached is a spectrum of H1:OMC-PI_DCPD_64KHZ_A_DQ during no gain, negative gain, and positive gain times, i.e. on either side of the 0.15 time mark from the plot above. 

At about 0.23 hours the gain was turned off and the mode rangdown.  The fit to this ringdown indicates the mode has a Q factor of (omega_o)/(2alpha) = 1.2 million.  

Settings: Power 1.9 W, DC bias 100k, butterworth BP filter, iWave bypassed, -60deg damp filter, damp gain 300,000. 

Images attached to this report
Comments related to this report
rich.abbott@LIGO.ORG - 11:18, Thursday 09 June 2016 (27667)ISC, SUS
Such a wonderful conclusion to the installation and commissioning of this system.  Much thanks for the great support I received from all involved.
slawomir.gras@LIGO.ORG - 09:12, Tuesday 14 June 2016 (27718)
I suspect that 15077 Hz mode is an aliased 48923 Hz mechanical mode (64 - 15.077) kHz. The FEA gives an interesting mode at 48944 Hz (mode shape attached). Observation of the analog channel PSD on transmission is required to confirm if this is a case. The 15077 Hz mode is only 14 Hz above known  15063 Hz mode. I am not very familiar with linetracking filter but I assume that the two resonant lines 15063 HZ and 15077 Hz cannot be sufficiently separated and the signal with higher resonant peak will be eventuality phase-locked. It may be interesting to observe the transition from one mode to another.  
If this all is true you measured the Q-factor of one of the modes in the range were PI may also show up at higher circulating power than during O1.
It looks to me that the 48923 Hz mode is very sensitive to off-center position of optical TEM00 (that's probably why can be seen on OMC) and can be used for centering of TEM00 on ITMs.   
Images attached to this comment
carl.blair@LIGO.ORG - 20:16, Tuesday 14 June 2016 (27740)

In the Q estimate 'f' was used in place of 'omega_o' introducing a 2 pi error.  The corrected estimate of the Q factor of the 15077Hz mode is 7.4million.

Displaying reports 56101-56120 of 83091.Go to page Start 2802 2803 2804 2805 2806 2807 2808 2809 2810 End