Differential Image Motion Monitor (DIMM) User’s Guide LBT PROJECT

Differential Image Motion Monitor (DIMM)  User’s Guide LBT PROJECT
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Differential Image Motion Monitor (DIMM)
User’s Guide
Prepared
Reviewed
Approved
Signature
Tom Herbst & Johannes Schmidt
Date
7 June 2009
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1. Revision History
Issue
0.1
Date
5-Jun-09
Changes
First draft
Responsible
Tom Herbst, Johannes Schmidt
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2. Table Of Contents
1.
2.
3.
4.
Revision History....................................................................................................... 2
Table Of Contents .................................................................................................... 3
List Of Abbreviations ............................................................................................... 4
About this document................................................................................................. 5
4.1. Reference Documents ........................................................................................ 5
5. Introduction and General Principles.......................................................................... 6
6. Quick Start Guide..................................................................................................... 9
6.1. Starting Up the DIMM....................................................................................... 9
6.1.1. Login to Workstation .................................................................................. 9
6.1.2. Switch on DIMM Power ............................................................................. 9
6.1.3. Start Webcam ........................................................................................... 10
6.1.4. Start DIMM Software ............................................................................... 11
6.1.5. Establish Communication with Mount and Camera ................................... 12
6.2. Measuring the Seeing....................................................................................... 14
6.2.1. Identify a Target Star ................................................................................ 14
6.2.2. Center the Target Star ............................................................................... 14
6.2.3. Initiate Measurement................................................................................. 16
6.3. Shutting Down the DIMM ............................................................................... 17
7. Control Interface .................................................................................................... 19
7.1. Menus.............................................................................................................. 19
7.2. Main Control Window ..................................................................................... 20
7.2.1. Menu Area ................................................................................................ 21
7.2.2. Button Bar ................................................................................................ 21
7.2.3. Info Panel ................................................................................................. 22
7.2.4. Log Panel.................................................................................................. 23
7.2.5. Status Panel .............................................................................................. 23
7.3. Move Mount Window...................................................................................... 24
7.3.1. Position Panel ........................................................................................... 24
7.3.2. Slew to Star Panel ..................................................................................... 25
7.4. Settings Windows ............................................................................................ 27
7.4.1. Camera Settings ........................................................................................ 27
7.4.2. Mount Settings.......................................................................................... 28
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3. List Of Abbreviations
CCD – Charge-Coupled Device (image sensor)
DIMM - Differential Image Motion Monitor
GUI – Graphical User Interface
LBT – Large Binocular Telescope
LBTO – Large Binocular Telescope Observatory
OTA – Optical Tube Assembly
PC – Personal Computer
SVC – Subversion version control system (check spelling)
TCS - Telescope Control System
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4. About this document
This document provides a quick-start guide to operating the Differential Image Motion
Monitor (DIMM) on the LBT. It also includes a complete description of the DIMM
control interface. Further information on DIMM hardware, troubleshooting, etc. appears
in the Reference Documents and in the online twiki:
http://wiki.lbto.arizona.edu/twiki/bin/view/Operators/DIMMOperatingProcedureAndManuals
4.1.
Reference Documents
All of the following reference documents are either at the observatory in paper form or on
the LBTO DIMM wiki accessible on the Operators Web at wiki.lbto.arizona.edu. Note
that in some instances, the “Reference Document” may be several individual PDF files
grouped together in a single directory.
RD
1*
2*
3
4*
5*
6
7*
8*
9*
10*
11*
12*
13*
14*
Title
DIMM Operating Principles and Hardware Manual (116g001a)
LBT DIMM Operating and Software Manual (wiki only)
Celestron 14 Optics Tube model C14-A XLT manual
Paramount ME manual
DVC 1412 AM Camera manual
Hartmann Mask construction drawing
EDT Cameral Link Interface Card manual
JMI Smart Focus manual
Intellinet webcam manual
Moxa NPort 5400 Switch manual
DIMM Electronics Enclosure power distribution
DIMM Pier construction drawing
Onboard Electronics Box documentation
Design and Implementation of a Seeing Monitor for the Large Binocular
Telescope (Johannes Schmidt, Diplom Thesis)
*available in electronic form on the DIMM wiki
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5. Introduction and General Principles
RD1 provides a description and references to the principle of differential image motion
tracking for seeing measurement. Here, we focus on the general operating principles of
the LBT DIMM.
The DIMM sits at the upper inboard side of the right C-ring of the LBT (figure 1), and its
control computer resides in the lower right tree house (figure 2). Only power and two sets
of dedicated fibers for Ethernet and Camera Link connect the DIMM with its control
computer (figure 3).
Figure 1: The DIMM on the inboard side of the right C-ring.
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Figure 2: The Dell 2950 control computer in the lower right treehouse.
Figure 3: General configuration of the DIMM and its control and display components
(figure from RD1).
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The control computer is an LBT-standard Dell 2950. All of the code and middleware has
been designed to be compliant with LBT internal standards, and the software is
maintained within the LBT version control system (SubVersion?).
The user interacts with the DIMM by opening windows on an X-terminal in the control
room. This usually means logging into one of the control room machines (for example,
lbtmu06) then connecting to the DIMM control computer via ssh.
Two major software modules on the control computer drive the DIMM. The first is the
DIMM Server, which is the primary control software for the instrument. The user
controls the DIMM via the second module, the DIMM Client, which presents a Graphical
User Interface (GUI) and communicates with the DIMM Server. This server-client
architecture has a number of advantages and has become standard for instrument control.
The results of the seeing measurement appear in the LBT Telescope Control System
(TCS) Data Dictionary and are available to other software systems. For example, science
instruments can access the current seeing value and record it in file headers. A software
module running within the TCS also presents the seeing value on a large display in the
control room. (NOTE: As of this writing – June 2009 – neither the Data Dictionary
access nor the control room display have been tested).
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6. Quick Start Guide
6.1.
Starting Up the DIMM
6.1.1.
Login to Workstation
Identify a suitable workstation in the control room (ask an operator if you are unsure).
You can operate the DIMM comfortably on a single screen, so using your current
workstation is a viable option.
• Login if necessary. Username: dimmuser Password: (ask operator)
NOTE: at this writing (June 09), the dimmuser account had not yet been created on the
control room workstations.
6.1.2.
Switch on DIMM Power
The DIMM hardware is powered by a single 110 V connection through an Ethernet
power switch. Normally, the DIMM will be switched off at the end of each night. To
begin measurements, you need to switch on the power.
• Start Firefox (button at bottom of screen or firefox in a command line)
• Navigate to the DIMM power switch web page (should be in Bookmarks):
dimmpower1.lbt.as.arizona.edu (10.144.0.47)
• Login to control power… User: admin Password: (ask operator)
• Click the radio button to turn on the DIMM power (port 1) and click Apply (fig. 4)
The DIMM power is now on. You may have to return to this page to cycle the power in
case of difficulty.
Figure 4. The Ethernet power interface for the DIMM.
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Start Webcam
A small commercial webcam rides around on the back of the DIMM to provide a view of
the current look direction. The field of view is approximately 4.5° x 3°, considerably
larger than that of the DIMM. The webcam is invaluable in terms of monitoring DIMM
operations, since it can indicate whether the DIMM mount (or the LBT itself) is moving,
whether stars are visible, and so forth. In combination with a plastic overlay (see below),
it also helps ensure that DIMM pointing is working correctly.
• Open a new tab in Firefox (ctrl-t)
• Navigate to the webcam address: 10.144.0.52 (does this have a text name?)
This address should also be in the bookmarks menu or tab
• Login to the webcam server: User: admin Password: admin
(the admin account lets you change brightness and contrast, etc.)
• A webpage showing the live webcam view should appear (fig. 5).
• Ask the operator for the DIMM plastic overlay and attach it to the screen using
adhesive tape. There should be alignment markings on the overlay to help.
Note that due to network peculiarities it may take two or three attempts to get through to
the webcam server. You can press the Try Again button until you get through. Note also
that the webcam has a number of hot pixels. These are easy to distinguish from stars,
since the stellar images are a few pixels across.
Figure 5. (top) CHECK – need this image!! The webcam shows a live view of the DIMM
look direction. The small box shows the approximate location and size of the DIMM field
of view (this box does not appear onscreen – use the overlay). The Administrator Menu
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option at left lets you adjust brightness, contrast, and other parameters. (bottom) The
webcam even lets you look at the inside of the dome!
6.1.4.
Start DIMM Software
As mentioned in section 5, two software modules control the DIMM: the Server and the
Client. You will need to start both before making measurements. Note that you must
always start the DIMM Server first!
• Open two new terminal windows on the desktop (right click: Open Terminal)
• Establish an X-windows session on the DIMM computer in each window:
ssh –X [email protected]
(Note capital X!)
The operator can tell you the password
• In the first window, start the DIMM Server by typing:
dimmServerStart
A number of log messages should appear.
• If you want a detailed log (i.e. for debugging), an alternative to this is:
dimmServerStart 1>MyLogTodaysDate.txt 2>&1
This will create a log file named MyLogTodaysDate.txt.
• In the second window, start the DIMM Client by typing:
dimmClientStart
The main DIMM control window will appear (fig. 6), along with a number of
log messages.
Section 7 contains a complete description of all the controls and fields in this window.
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Figure 6: The main DIMM control window at startup
6.1.5.
Establish Communication with Mount and Camera
Two critical subsystems of the DIMM, the mount and the high speed camera, have their
own communication channels. You need to connect to these channels before proceeding.
Connect to Mount
First, connect to the DIMM mount.
• In the DIMM GUI, click Connect in the mount control area (fig. 7) or select
Connect from the Mount menu
Figure 7: The Connect and Go to/Move buttons are in the mount control area
A number of messages should appear in the log window as the mount initializes. If you
have just powered up the system, the mount must self-calibrate by slewing to its internal
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reference position and returning. This can take a couple of minutes, during which time
the Mount status at the bottom of the GUI will read “Slewing.” You may see stars and
dome/telescope structures moving through the webcam view (a good sanity check that
things are working). At the end of the initialization process, the status should read
“Connected” and the Go to / Move button for the mount should be enabled.
• In the DIMM GUI, click Go to / Move in the mount control area (fig. 7) or
select Go To / Move from the Mount menu. The Move Mount window should
appear (fig. 8)
Figure 8: The Move Mount window at startup CHECK – weird entries - replace
Connect to Camera
Connect to the high speed DIMM camera. You can do this while the mount is initializing.
• In the DIMM GUI, click Connect in the camera control area (fig. 9) or select
Connect from the Camera menu
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Figure 9: The Connect and Preview Camera buttons in the camera control area
A number of messages related to camera initialization will appear in the log window. The
camera takes longer than the mount to initialize, but after 20-30 seconds the Camera
Status at the bottom of the main GUI window should reflect that the operation is
complete. The Preview Camera button (fig. 9) should also now be enabled.
6.2. Measuring the Seeing
Seeing measurements involve a sequence of three steps: identifying and slewing to a
suitable target star, centering the star, and initiating the measurement. As of this writing
(June 2009), we are attempting to automate these procedures, a process that is
complicated by the fact that the LBT, to which the DIMM is mounted, can slew or offset
at any moment.
6.2.1.
Identify a Target Star
The DIMM requires fairly bright target stars, since the entrance apertures are small (ca. 7
cm – see RD1) and the exposures are short (typically 5 or 10 ms). The Move Mount
window (fig. 8) will have identified and ranked potential targets by brightness and
distance from the zenith. You must select one of these stars.
• In the Move Mount window, click on a target star. Unless you have a good reason
to do otherwise, you should pick a star high up in the list (i.e. number 1).
• Click the Go To button on the lower left. The DIMM should start moving (check
the webcam – you should see stars moving past).
• After a few to 10-20 seconds, the DIMM should arrive at the target star, and it
should be visible within (or very near) the target box on the plastic overlay.
6.2.2.
Center the Target Star
The field of view of the DIMM is considerably smaller than that of the webcam (as is
obvious from the plastic overlay). Before making a measurement, you may have to center
the star more accurately. There are several ways to do this.
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Center with Plastic Overlay
This is the simplest technique, and once you get used to it, the fastest.
• Use the arrow keys to move the star to the center of the DIMM field in
the plastic overlay. Use the appropriate slew speed (see below), typically
8-32x, to prevent overshoot
The Move Mount window has manual controls for fine-tuning the pointing (fig. 10). You
can use the speed drop-down menu to adjust the offset rate and the four arrows to center
the star (the star moves in the direction of the arrows).
Figure 10. The manual offset controls for DIMM pointing
Center with High Speed Camera Preview
The high speed CCD has a preview mode that lets you see what the DIMM will see. The
preview is full frame (1392x1040 pixels – see RD1) and considerably slower than the
sub-array measurement rate.
• In the main control window, click the Camera Preview button (fig. 9). A
preview window should pop up, and you should see background noise (fig. 11).
• You may also see the two star images, split by the wedges at the entrance of
the DIMM (see RD1). If not, use the manual offset controls to center the star
(see section 6.5.1 to learn about the manual offset controls).
Figure 11. (CHECK – need this one!) The camera preview window showing background
noise and the dual stellar images
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The Camera Preview mode is an excellent way to check on the centering and drifting
performance of the mount. In order to execute successful measurements, the star images
should not drift out of the frame for at least a minute or so. Rapid drifting or inability to
keep the stellar images in the frame may indicate a problem. See the Troubleshooting
documents on the wiki page for help.
Center with Spiral Search
The final centering technique is the most automatic, but also often the slowest. If the
stellar images are not in the field, the DIMM can execute a raster scan of the nearby sky
to locate them (yes, the name Spiral Search is inaccurate). Note that seeing measurements
are initiated automatically as soon as the Spiral Search finds the star.
• Click on the Spiral Search button above the manual offset controls (fig. 8).
The DIMM should move in a raster pattern – you can watch this on the
webcam – and initiate measurements as soon as it locates the star.
6.2.3.
Initiate Measurement
If you have made it this far, initiating a seeing measurement is straightforward (this step
is automatic in the Spiral Search mode – see section 6.2.2).
• If it is not already open, the Camera Preview window provides a sanity
check that the star is in the DIMM field of view and that the DIMM is
tracking well. See section 6.5.2.
• In the main control window, click the Start Measuring button (fig. 12)
Figure 12. The Start Measuring button and seeing information areas
of the main control window
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The software will automatically set a sub-array and exposure time and begin making
measurements. The camera preview window should show the sub-array and the two
stellar images. Green circles around the stars indicate successful identification (fig. 13). If
the images drift toward the edge of the frame, the software should re-center them (to be
implemented).
Figure 13. The camera preview window during a seeing measurement. Note the dual
stellar images and the green circles showing successful identification.
The software has a buffer of the 300 most recent measurements, from which the seeing
value is calculated. After initiating the measurement, it can take ten or more seconds for
the buffer to fill and for the first measurement to appear. Look carefully at the dropped
frames value in the seeing information area (fig. 12). This will tell you how many frames
were dropped due to the software’s inability to locate the stellar images. A very high
value (greater than 20% CHECK) could indicate a problem, and if the percentage rises to
near 100%, the measurement aborts.
Large offsets and slews of the LBT will cause an interruption in measurements. We are
currently (June 2009) working to recover and restart automatically from such events.
6.3. Shutting Down the DIMM
The DIMM needs to be shut down in an orderly fashion to ensure that the mount does not
continue tracking and hit a hard stop (there is a document in the Troubleshooting wiki to
explain recovery from this condition).
• Click the Go Home button in the Move Mount window. The DIMM
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should return to its home position (co-pointing with LBT)
• Close the Move Mount window by clicking its close box or clicking
the Go To / Move button in the main control window
• Disconnect the Mount by clicking the Disconnect button in the main window
• Disconnect the Camera by clicking the Disconnect button in the main window
• Click the Exit button in the main window. This terminates the Client
• Hit ctrl-c in the terminal window from which you launched the Server (see
section 6.1.4). This terminates the Server
• As a precaution, you can then issue the command:
dimmKillServices
This will ensure complete termination of both Server and Client
• VERY IMPORTANT – Switch off the power to the DIMM, following the
procedure in section 6.1.2 (obviously selecting Off instead of On…)
• You should verify that the power is off by refreshing the webcam tab in
Firefox. With no power, the webcam will not respond.
This ends the Quick Start Guide. Turn to the next section to learn about the GUI controls
in detail.
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7. Control Interface
This section provides a reference to all the menus, buttons, and displays in the DIMM
control software.
7.1.
Menus
The menu bar appears across the top of the main control window (fig. 6). Essentially all
of the menu entries have button equivalents, and you will probably use the buttons
instead.
DIMM Menu
Start
- This command starts seeing measurements and is equivalent to the Start
Measuring button (see section 6.6)
Exit
- This command exits the DIMM client and is equivalent to the Exit button
Camera Menu
Connect
- This command connects to the high speed camera. Equivalent to the
Connect Button
Preview
- This command opens the Camera Preview window. Equivalent to the
Preview Camera Button
Settings
- This command opens the Camera Settings dialog. Equivalent to the
Settings Button (see section 7.4.1 for a description of this dialog)
Mount Menu
Connect
- This command connects to the DIMM mount. Equivalent to the
Connect Button
Go To/Move - This command opens the Move Mount window. Equivalent to the
Go To / Move button (see section 7.3 for a description of this dialog)
Tracking
- Switches the mount tracking on and off. Equivalent to the Tracking
button (see section 7.2.2 for more information)
Settings
- This command opens the Mount Settings dialog. Equivalent to the
Settings button (see section 7.4.2 for a description of this dialog)
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Focuser Menu
The Focuser menu is not currently used.
Help Menu
Contents
- Not yet implemented
Index
- Not yet implemented
About
- Pops up a window showing the current version of the software
7.2.
Main Control Window
Figure 14 shows the main control window during a seeing measurement. The following
sections explain each of the panels of this window, from top to bottom.
Figure 14. The main control window during a seeing measurement.
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Menu Area
This area at the top of the window contains the menus for controlling the DIMM. See
section 7.1 for a description of the menus.
7.2.2.
Button Bar
The most important buttons for controlling the DIMM appear in the Button Bar (fig. 15).
Note that the buttons fall into three broad groups separated by gray cross-hatching:
Overall Control, Camera Control, and Mount Control. Note also that some buttons may
be grayed out and inaccessible in some operating states.
Figure 15. The Button Bar at the top of the main control window.
Overall Control
Exit
This button exits the DIMM Client and closes all windows. Make sure that the DIMM is
pointing close to the LBT pointing direction before Exiting the Client (see Go Home in
section 7.3 below).
Start/Stop Measuring
Initiate or halt a seeing measurement (the button toggles automatically, depending on the
current state). You should ensure that the star is in the DIMM field of view before
initiating a measurement (see section 6.2).
Camera Control
Connect / Disconnect
This button opens or closes the communication channel to the high speed DIMM camera.
The current connection state appears in the status panel at the bottom of the main control
window (see section 7.2.5 below). See section 6.1.5 for further information on connecting
to the camera and section 6.3 for instructions on disconnecting.
Preview Camera
Opens the Camera Preview window and initiates full frame exposures on the high speed
camera. Preview is useful for verifying proper camera operation and for centering /
checking stellar images (see section 6.2.2). If the Camera Preview window is open,
clicking this button closes it. This may be necessary prior to starting a seeing
measurement.
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Settings
Opens the Camera Settings dialog. See section 7.4.1 below. Closes the Camera Settings
dialog if it is already open.
Mount Control
Connect / Disconnect
Opens the communication channel to the DIMM Mount. The current mount connection
state appears in the status panel at the bottom of the main control window (see section
7.2.5 below). Sections 6.1.5 and 6.3 explain how to connect and disconnect, respectively.
Go To / Move
Opens the Move Mount window (see section 7.3). If the Move Mount window is already
open, clicking this button closes it.
Tracking
Switches the tracking on and off. When tracking is on, the DIMM should follow the
current position on the sky. When off, the DIMM motors do not move and any motion is
due to the LBT. Note that a diagonal red line through the button indicates that tracking is
ON.
Mount Settings
Opens the Mount Settings dialog. See section 7.4.2 below. Closes the Mount Settings
dialog if it is already open.
7.2.3.
Info Panel
Figure 16. The Info panel of the main control window.
The Info panel presents information about the current LBT pointing, the target pointing,
and the seeing.
LST
This is the local sidereal time as read from the Telescope Control System. If all is well,
the LST should be increasing.
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LBT
The Right Ascension (RA), Declination (DEC), Azimuth (AZ), and Elevation (EL) of the
LBT. Note this is the pointing of the LBT, not the DIMM. You can and should crosscheck these value with the telescope operator display if you suspect a problem.
Seeing
The current seeing measurement. Zero or negative values indicate a problem. The
software writes the seeing value to the TCS Data Dictionary, from which it is available to
other subsystems (i.e. science instruments, wall display, etc. – to be tested as of June
2009).
Dropped Frames
The number of DIMM frames dropped because the software could not find the stellar
images. For bright stars in good conditions, the fraction of dropped frames should be very
low. See section 6.2.3 for more information.
Target
The Right Ascension (RA) and Declination (Dec) of the DIMM target star. This
information appears in the Move Mount window as well (section 7.3) and is presented
here as a convenience for comparing DIMM and LBT pointing.
7.2.4.
Log Panel
Figure 17. The Log panel of the main control window.
The log panel presents ongoing time-stamped status messages reported by the DIMM
Server. Error conditions will appear in red. It is very worthwhile keeping an eye on this
panel, particularly if you notice unusual behaviour. A scroll bar on the right side of the
window allows you to review earlier messages.
7.2.5.
Status Panel
Figure 18. The Status panel of the main control window.
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The Status Panel reflects the current status of four main DIMM subsystems:
Measuring Status
Camera Status
Mount Status
Focuser Status
- Measuring / Not Measuring
- Disconnected / Connected / Measuring
- Disconnected / Connected / Slewing
- Disconnected
Note that the Focuser is not currently used and hence the Focuser is always Disconnected.
7.3.
Move Mount Window
Figure 19 shows the Move Mount window during a measurement. The following sections
explain each of the panels of this window, from top to bottom.
Figure 19. The Move Mount window during a seeing measurement
7.3.1.
Position Panel
This panel contains information on the current pointing and tracking of the DIMM.
NOTE: Do not confuse these values with those of the LBT in the main control window
(section 7.2). These numbers are for the DIMM.
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RA, DEC
The Right Ascension and Declination of the DIMM look direction (not the LBT look
direction!).
Elevation, Azimuth
The Elevation and Azimuth (horizon coordinate system) of the DIMM look direction (not
the LBT look direction!).
Up-Down, Left-Right
The current up-down and left-right angles of the DIMM mount. Document RD1 provides
a complete explanation, but here is a short version:
up-down is the axis which rotates the DIMM up and down the LBT dome slit
left-right is the axis which rotates the DIMM left and right across the LBT slit
Because the DIMM is mounted to the LBT itself, the transformation from up-down/leftright to sky coordinates is not straightforward (see RD1).
NOTE: Due to peculiarities and constraints on the DIMM mounting location, the updown axis is horizontal in the webcam and high speed camera views, and the left-right
axis is vertical. Thus “up-down” and “left-right” refer to the physical relationship of the
mount to the dome slit, not to the direction on the onscreen views.
UDrate, LRrate
The tracking rates of the DIMM mount in the up-down and left-right axes. Because the
mount must point at and track a target that is almost always different from the LBT
science target, non-zero correction rates must be applied. These rates will be zero when
the DIMM co-points with the LBT (assuming the LBT is tracking the sky). Document
RD1 provides full information on these issues.
7.3.2.
Slew to Star Panel
The Slew to Star panel (fig. 20) provides a number of controls for pointing the DIMM.
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Figure 20. The Slew to Star panel of the Move Mount window
Target Star List
The Target Star List appears at the top of the Slew to Star panel. Based on the current
LBT pointing direction, the software selects and sorts stars according to magnitude and
zenith angle. You can click on a star entry to have its values entered in the target
coordinate fields (see below). NOTE: If the LBT slews to a new science target, it may be
necessary to refresh the Target Star List for the new position. The easiest way to do this is
to close and re-open the Move Mount window by clicking on the Go To / Move button in
the main control window.
Recent Stars
For convenience, the software provides a drop-down list of the X most recent DIMM
target stars. Selecting a star from this list enters its location in the target coordinate fields
(see below).
Go Home Button
The Go Home button instructs the DIMM mount to return to its home position, which is
co-pointing with the LBT. This also turns off the tracking. You should click the Go Home
button before closing down the DIMM software.
Spiral Search Button
The Spiral Search button executes a raster scan search for the target star as described in
section 6.2.2. If the star is found, seeing measurements are initiated automatically. The
Abort button (see below) will interrupt a Spiral Search.
Target Coordinate Fields
The Target Coordinate Fields receive input from the Target Star List and the Recent Star
List (see above). You can also enter coordinates directly. The Go To button (see below)
instructs the DIMM to slew to the current location in the Target Coordinate Fields.
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Go To Button
The Go To button causes the DIMM to slew to the location in the Target Coordinate
Fields. You can follow progress with the webcam – the target star should end up inside or
very close to the DIMM field of view box on the plastic overlay (see section 6.2.1). The
Abort button (see Below) will interrupt a Go To operation.
Abort Button
The Abort Button stops any DIMM mount motion and turn off the tracking. This can be
used if you make an error selecting a source or if the mount is not doing what you expect.
It will also interrupt the Spiral Search procedure.
Sync Button
The Sync button allows you to tell the software that the DIMM is now pointing at the
chosen target. This generates offsets for the DIMM axes which are applied to future
pointings. NOTE: Until further notice, users should use the Sync button with care.
Manual Offset Controls
The Manual Offset Controls allow the operator to adjust the DIMM pointing. The Speed
drop-down menu sets the rate, while the four arrows allow accurate positioning. Note that
the arrow directions correspond to the view in the webcam and Camera Preview
windows. In other words, clicking on the up arrow moves the star up, and so forth. Some
users experience difficulty with these arrow buttons if they click too quickly. This is due
to latency between the DIMM Client and Server. Patience pays.
7.4.
Settings Windows
The DIMM has two setting windows to adjust system parameters, one for the high speed
camera and one for the mount.
7.4.1.
Camera Settings
The Camera Settings window lets you adjust parameters associated with the high speed
DIMM camera and the Camera Preview display. Normally, you should never need to
adjust these settings. The parameters are largely self-explanatory, with the exception of
ROI, which refers to the Region Of Interest, in other words, the sub-array used for seeing
measurement. Also, the unit of the Exposure Time is milliseconds.
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Figure 21. The high speed Camera Settings window
7.4.2.
Mount Settings
Figure 22. The Mount Settings window
The Mount Settings window lets you perform two functions, Set Origin and Reset.
Set Origin - CHECK What does this do?
Reset
- Re-writes the internal flash memory of the mount with the factory defaults
NOTE: You should not use these options unless you know what you are doing!
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