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Telemetry GUI Manual (First Draft)

Warning: Under construction. Some information might be out of date or incorrect.

This document provides a description of SISPI Telemetry-Viewer GUI.

Introduction

DECam Observers will want to know that the instrument is functioning properly. We have many sources
of information available from instrumentation, from the images, and from computer processes that allow us to monitor
the status and performance of DECam. The common name for this collection of information is telemetry. SISPI records this information in the telemetry database and different tools are provided to view this data in the form of time history charts. The Telemetry-Viewer GUI displays predefined plots of critical variables arranged in several pages. The information is updated automatically. A second tool, also called Telemetry Viewer to keep things interesting, can be used to query the telemetry database outside the SISPI framework. It also provide access to every telemetry variable, not just the predefined set used by the GUI. This document describes the Telemetry Viewer GUI. A description of the other tool can be found here add link

Start-Up and Control

Describe how to start the gui. Describe the controls (cycle, update period)
In addition to the SISPI Observer1 Console, you can access the telemetry information at
http://system1.ctio.noao.edu:7001/apps/telemetry_viewer/ using a web-browser other than IE.

  • 1. Refresh the plots manually
  • 2. Stop the automatic refreshing of the plots (press again to resume)
  • 3. The slider controls the time between the automatic plot refreshes
  • 4. The tabs sort the plots by sections. Clicking on a tab opens its set of plots. The blue one is currently open. Which plot is open will cycle regularly.
  • 5. Pause (and resume) the cycling of tabs.
  • 6. List of current alarms, press for information. There will be a red circle with a number for warning, alert, or critical alarms (The number is the number of alarms.
    There is a green circle with a number if all alarms are event alarms.
  • 7. Click to see a list of currently active sessions.
  • 8. Press to logout of the viewer
  • 9. Press to change your access level

Focal Plane Cooling

The above images are on the same page of the viewer, if the plot
you are looking for is not visible, try scrolling down.

CCD Temperature, DECam Vacuum, & DECam Total Heater Power

There are four RTD’s that measure the temperature of the DECam Focal Plane. Three of them are
plotted in the first chart in units: degrees Centigrade. They should be at a constant temperature within a
couple degrees of ‐100 deg C. It is important that they don’t vary by as much as 1⁄2 deg C as that could
affect the QE at the red end of the sensitivity.

An ion gauge measures the gas pressure within the DECam Dewar. It’s very important that the vacuum
be maintained at all times that the Focal Plane is cold. The chart shows the ion gauge reading in units:
Torr. The pressure is normally less than 2x10‐7 Torr and is very steady.

The DECam Total Heater Power is the sum in Watts of the power deposited by the temperature controls
system onto 10 Cu heater braids. It should be steady within about five Watts (the above exaples show
a situation when this isn't true). Turning off the power to the RO Crates will cause it to drop quickly;
it will take a couple hours for the control loop to settle down if the temperature has varied by more
than a couple degrees C.

LN2 Pump Speed, LN2 Tank Level, and LN2 Pressure

The DECam Focal Plane is cooled using LN2 pumped from a tank on the roof of the old Console Room (C‐
floor) to the camera. It is a closed‐loop system so the nitrogen returns to the tank as a mixture of liquid
and gas. We have been operating the pump at 80 RPM. The chart seems to jump around from 50 to
120 RPMs during normal operation.

The LN2 Tank liquid level chart shows the tank level in unit percent. It varies by 1% to 3% over the
course of a day. As this is a closed‐loop system, we would be concerned if there was a steady loss of LN2
product.

The LN2 Tank pressure chart has units PSI. The pressure is controlled by heaters within the tank. The
pressure should be steady. A variation of a few % is expected.

Since this is a closed‐system, there is a relation between the Tank Level and the Tank Pressure. If the
pressure goes up the level tends to drop. Heaters within the tank receive less power. The LN2 gets
colder and more LN2 is made by the two cryo‐coolers. The pressure goes down and the level goes up.

Should add information about LN2 Heater Power

DECam Cage Temperatures

These monitors are now implemented. Should have bounds for normalcy

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

VSUB Values

Backplane 1, 3­-5, F, & G

Photons that hit the CCDs create electron‐hole pairs in the silicon substrate. The CCD substrate voltage
(Vsub) drives the holes onto the nearest pixel and eats the electrons. The charts are Vsub for the 2kx4k
CCD RO crate backplanes (1 and 3‐5) and for the guide and focus CCD backplanes (2 and 6, respectively).
The units of the plots are volts. Vsub should be at 40V for observing. The first image after Vsub is
turned‐up will be a trashed image.

Vsub slew is related to how fast Vsub transitions up or down. We usually set it at the maximum value,
which is 10V. In the telemetry this has a factor of 4 applied. It takes about 1 second to make a transition.

Vsub limit is the maximum voltage swing, set to either 0 or 40V.

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

Board Temperatures

Backplane 1, 3­-5, F, & G

We monitor the temperature on various boards within each backplane. The charts are the
temperatures for the 2kx4k CCD RO crate backplanes (1 and 3‐5) and for the guide and focus CCD
backplanes (2 and 6, respectively). It is normal for them to be in the range 30‐37 deg C. If these start to
climb it is possible that the electronics crate cooling system (NESLab chiller) has stopped pumping cold
glycol to the crates.

“No Data” is probably a bad thing. Do we have any new information on what this is?

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

Cooling System (LN2 Recirculation System)

The above images are on the same page of the viewer, if the plot
you are looking for is not visible, try scrolling down.

LN2P, CryoCoolers, Heaters, & Pump Speed

LN2P seems to be a time counter. It monotonically increases.

Cryocoolers displays the temperature of the cold head of each of the two cryocoolers in the LN2 Tank on
the Old Console roof. These should be in the neighborhood of ‐173 deg C during normal operation.
They tend to move around together.

There are two heaters in the LN2 Tank. The chart shows the temperature of the block that the heaters
are embedded‐in.

Pump Speed indicates the rate in units RPM. We have been operating the pump at 80 RPM. The chart
seems to jump around from 50 to 120 RPMs during normal operation.

Pressure, LN2 Differential Pressure, Heater Power, & Level

The pressure chart shows the pressure, in units PSI, in the LN2 Tank. The two cryocoolers are so cold
that they can condense the N2 gas in the tank, raising the liquid level, and lowering the pressure. We
are maintaining the pressure at 100 PSI using two heaters in the tank. Under normal circumstances the
pressure is steady within a few PSI.

The LN2 differential pressure chart shows the difference between the pressure on the return and
pressure in the supply line of the LN2 system. Some of the Ln2 will have vaporized to cool the focal
plane, so the return pressure is typically 10 PSI higher. Note: This is not reflected in the above
graphs. Has this changed, or are the graphs irregular?

The Heater Power chart is the total power, in units Watts, deposited by the two heaters in the LN2 tank
into the N2 in the tank. Typically is 80 Watts.

The LN2 Tank liquid level chart shows the tank level in unit percent. It varies by 1% to 3% over the
course of a day. As this is a closed‐loop system, we would be concerned if there was a steady loss of LN2
product.

Since this is a closed‐system, there is a relation between the Tank Level and the Tank Pressure. If the
pressure goes up the level tends to drop. Heaters within the tank receive less power. The LN2 gets
colder and more LN2 is made by the two cryo‐coolers. The pressure goes down and the level goes up.

Ion Gauge & Flow Rate

An ion gauge measures the gas pressure within the DECam Dewar. It’s very important that the vacuum
be maintained at all times that the Focal Plane is cold. The chart shows the ion gauge reading in units:
Torr. The pressure is normally less than 2x10‐7 Torr and is very steady. The Ion Gauge plot seems to be
missing from this screen capture.

Flow Rate is probably the flow in units gallons‐per‐minute for one of the chillers. But in order to be sure
we need to actually see the plot work.

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

SISPI

It is important to note for this section that the charts above show a set of domeflats, followed by a period of inactivity, followed by exposures taken as usual.
The domeflats are marked in red, the usual exposures in green.

Image Builder (seconds) & Exposure Queue

The chart records the amount of processing time required for the different stages of Image Handling. It
starts with time to build the image (put together the pieces from the different backplanes), perform
Image Health, perform the data compression, and transfer the data. The total is the sum of the
components.

The chart showing the exposure queue is simply indicating the depth of the queue that is currently in‐
place. Naturally, as long as we are taking exposure from the queue it will decrease. In these graphs,
the domeflats were all queued at once, and let run. The usual exposures were queued gradually by ObsTac.

DHS & Image Builders

The DHS chart shows how long it takes to get the images off of the PANVIEWs.

The Image Builder chart shows the available number of those. Typically that runs from two to five.

This page has changed - when there are new screenshots there need to be updated descriptions

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

Image Health

The above images are on the same page of the viewer, if the plot
you are looking for is not visible, try scrolling down.

Mean Seeing & Median Ellipticity

The Mean Seeing chart displays the mean of the calculated seeing based on analysis of the images. The
units are FWHM in arc‐seconds.

The Median Ellipticity chart shows the ellipticity of stars in the image. This should be close to zero
because stars should be round.

No Star CCDs

Image Health identifies stars in the image. The CCDs should have stars. Flat‐fields and Bias images won’t
have stars.

Describe additional plot (gradient)

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

RASICAM

The above images are on the same page of the viewer, if the plot
you are looking for is not visible, try scrolling down.

It is important to note that when the above charts were made, the weather conditions were very poor,
with much more cloud cover than usual.

Global Clear Flag & Local Clear Flag

The Global Clear Flag chart provides a single bit, a 0 or a 1, to describe whether‐or‐not the sky is clear. It
is based on the overall standard deviation of the RASICAM image. A score of 1 means the sky is clear.

The Local Clear Flag chart provides a single bit, a 0 or a 1, to describe whether‐or‐not the sky is clear in
the field where the Blanco Telescope is pointing. It is based on the overall standard deviation of the RASICAM image.
A score of 1 means the sky is clear.

Local Hot Fraction & Global Hot Fraction

The Local Hot Fraction is the fraction of pixels that exceed the threshold for cloudy in the region of sky
where the Blanco Telescope is pointing. Changes in this quantity indicate whether clouds are “inbound”
or “outbound”. This measurement was only taken later in the night, accounting for the part of the
chart above without data.

The Global Hot Fraction is the fraction of pixels that exceed the threshold for cloudy in the whole sky.

As can be seen in the charts above, the first part of the night was very cloudy (and still was again later).

Local Variation & Global Variation

These quantities are sensitive indicators of the presence of clouds.

The Local Variation chart shows the standard deviation of the counts in the RASICAM image in the field
where the Blanco telescope is pointing, normalized for position on the focal surface. In clear sky
conditions this is a small number. This measurement was only taken later in the night, accounting for
the part of the chart above without data.

The Global Variation chart shows the standard deviation of the counts in the RASICAM image,
normalized for position on the focal surface. In clear sky conditions this is a small number.

Normalized Power

A unit‐less quantity unique to RASICAM, nominally any value above zero indicates a source of thermal
radiance. This value can be used to quantify the cloud radiance. The image shown on the RASICAM
display is a false‐color representation of this quantity. This measurement was only taken later in the night,
accounting for the part of the chart above without data.

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

Guider

Guider code

The code describing the state of the guider. The codes are:
0: not used
1: used
2: used, lost a star
3: used, lost all stars

Max correction in x and y, mean in x and y

The max correction in x and y is the maximum guider provided correction for a given image.

The mean correction in x and y is the mean of all guider corrections in a given image.

No. CCDs Used

The number of guider CCDs used in tracking.

Needs information on Seeing and on Auto Correlation

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

AOS

Needs information on AOS Components

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.

Environment

The above images are on the same page of the viewer, if the plot
you are looking for is not visible, try scrolling down.

Needs information on what is normal/expected and what
isn't

Lowdome and Pmas temperature

The temperature measured in the lower section of the dome, and the
primary mirror above surface temperature

Pointing

new section - need to add

What to Watch For

Write here what would appear on the graphs that would be worthy of
note or action

What to Do

Write here what to do if something worthy of action were to appear on
the plots.