Finder Users Manual

This manual documents operational aspects of using finder: an overview of its design, how to launch it, the meanings of the  toolbar and menu items and methods of target acquisition. Finders mounted permanently in COAST telescopes and standalone portable finders are all documented. For a condensed summary, refer to the quickstart guide . In-depth documentation of finder's hardware and software design is in the reference manual .

Introduction

Design Overview

Launching Finder...
...Using the window manager menu (COAST finders) 
...From an xterm (COAST finders)
...From an xterm (DIMMWITs)
User Interface Layout
Online Help
The  Menus and Toolbar
File  Menu
fileopen icon Open Config...
filesave icon Save Config
Save as...
prefsdlg icon
Data Parameters...
scopeconnect icon
Connect Telescope
scopedisconnect icon
Disconnect Telescope
Exit
View Menu
Toolbar
Statusbar
CCD Menu
ccdconnect icon Connect CCD
ccddisconnect icon Disconnect CCD
fullscreen icon Fullscreen
dimm 1D icon 1D  DIMM Mode
dimm 2D icon 2D  DIMM Mode
dimm 2D icon Transverse  DIMM Mode
Tracking  Menu
target icon Select Target
selectregion icon Select Region
subframe icon Subframe
track icon Start Tracking
stoptrack icon Stop Tracking
spiral icon Manual Control
movie icon Save Movie
stopmovie icon Stop Recording Movie
Help  Menu
  About...
The Panel Controls and Indicators
CCD Readout
Binning
Exposure
Clear Charge
Video Display
Stretch Contrast
Correct Gamma
Fast 1D Grid
Fast 2D Grid
Fast Trans Grid
Show Scale
Status
X and Y Offset Signals
Telescope Secondary and Beam Splitter Status
Progress Bars
Data Saved
Max Flux
Status Bar

Introduction


Design Overview

Each telescope at COAST contains:

Finder Overview



Inside the bunker:
DIMMWITs are slightly different:
For more information on the construction of Finder please refer to the reference manual . In particular, instructions on how to set up a computer to interface with and store data from a DIMMWIT are here.

Launching Finder...

Recommendations for COAST finders:
Recommendations for COAST finders and DIMMWITs:

...Using the window manager menu (COAST finders only)

Finder can be launched from the popup "Utilities" menu on any of the X consoles in the bunker.
Make sure you are logged in as "coast", then move the mouse cursor away from any open applications. Menu Image

The window placement is the same as for the autoguider display:
Finder Layout

...From an Xterm (COAST finders)

Firstly you will need to know the network name of the single board computer you wish to contact. A table of finder computer names versus telescopes is here .

Make sure you're logged in as "coast" and then type

ssh cstfindern finder &

where n=1..5 . Repeat for all the finders you want to run. No password is required.

Your X server will decide where to place the finder displays but you can drag them to convenient locations.

...From an Xterm (DIMMWITs)

To launch finder when using a DIMMWIT:
ssh coast@dimmwit finder

User Interface Layout


Finder GUI Layout

Online  Help

Finder offers the following forms of online help:

The  Menus and Toolbar

This section describes all the menu actions. The toolbar actions are a subset and hence also included. The finder menus incorporate the same features as most contemporary menus:
Each action is described here in the way it appears in finder, that is, by:

File  Menu

fileopen icon Open Config...
The single board computer at each telescope contains a configuration file that lists aspects of finder operation that are unique to that telescope. Finder running on each telescope configures itself according to this file. The contents of the file are described in more detail here .

The default file name is "finder.conf" but with this menu item the user can choose to load a different configuration as long as it has a " .conf" suffix.
filesave icon Save Config
Saves the current configuration under the filename finder.conf . NOTE: If the crosshair position changes while finder is running, finder will automatically update finder.conf when quitting
Save as...
Saves the current finder configuration under a new name. This might be useful if the user wants to record the current crosshair position before doing experiments where it will be temporarily changed.
prefsdlg icon Data Parameters... Shift+P
Invokes the data file dialog, which tells finder (or DIMMWIT) how to save files when the "movie icon Save Movie " action (in the tracking menu) is chosen. The file format depends on whether finder or DIMMWIT is in 1D DIMM mode or not. Normally, the file is a 3D FITS file with the image stored in the x and y dimensions and successive images in time in the z dimension. In 1D DIMM mode, the file is a 2D FITS file with spatial information in x and successive snapshots in time in the y axis. See "movie icon Save Movie " and "dimm icon 1D DIMM Mode" for more information.

Data File Dialog

In the file parameters section:
In the FITS parameters section:
scopeconnect icon Connect Telescope Shift+T
(NOTE: This command will not work with DIMMWIT unless it is on the COAST network.)

Connects this finder to the telescope controller via local ethernet. If the connection is successful the "scopedisconnect icon Disconnect Telescope" menu item and button will become available, otherwise there will be an error dialog and you should refer to the   troubleshooting guide for suggestions as to what to do next.

The telescope controller IP address and the port number to use are determined by the configuration file . The port number is important because the telescope controller uses it to distinguish which finder it is talking to. The appropriate port numbers are here . It is important to get the port number right, as it is otherwise possible to have a finder feeding signals back to a different telescope!

NOTE: If finder can't find or does not understand its configuration file, it will default to port 2700 (the centre telescope). So if a finder is unexpectedly communicating with the centre telescope, look for a missing or broken finder.conf.
scopedisconnect icon   Disconnect Telescope Shift+D
Disconnects finder from the telescope controller. If finder is connected to the telescope controller and the latter program forces disconnection (for example, by quitting), finder now also disconnects gracefully .
Exit Ctrl+Q
Quits finder. If the configuration has changed (new crosshair position) finder will inform you before exiting.

NOTE: Finder is reasonably robust when told to quit unexpectedly while connected to everything and tracking. However, it is best not to tempt fate and to shut it down gracefully:

View Menu

Toolbar
Hides/shows part of the toolbar. Of limited use.
Statusbar
Turns status messages (at the bottom of the display) on/off.

CCD Menu

ccdconnect icon   Connect CCD Ctrl+C
Connects finder to the CCD controller. If all is well, readout will begin immediately. If not, you will be informed and should refer to the troubleshooting guide for ways to rectify the problem.

NOTE: If the camera head does not have power (for example, a telescope beam splitter is out) the display will remain dark.
ccddisconnect icon   Disconnect CCD Ctrl+D
Disconnects finder from the CCD controller. If you try to quit finder before doing this you will see an error message asking you to disconnect first.
fullscreen icon   Fullscreen Ctrl+F
Causes finder to start reading out the entire CCD. The following operations are cancelled if they were running:
This is a good button to press if something has gone wrong, as all feedback is cancelled and the entire field of the CCD is displayed.
dimm 1D icon   1D DIMM Mode Alt+1
Initiates high speed CCD readout in a way that is suitable for one-dimensional DIMM measurements.

1D DIMM mode tries to maximise readout rate for seeing measurements:
Note:
DIMM mode diagram

1D DIMM mode also differs from normal readout in other ways:
Dropouts in acquisition files can occur if acquisition is disturbed. Hence:
dimm 2D icon   2D DIMM Mode Alt+2
Initiates high speed CCD readout in a way that is suitable for two-dimensional DIMM measurements.

NOTE: This mode works with both MX516 and HX516 cameras whether they have had the the hardware modification described above or not.

2D DIMM mode tries to maximise readout rate for seeing measurements:
Note:
2D DIMM mode also differs from normal readout in other ways:
Dropouts in acquisition files can occur if acquisition is disturbed. Hence:
dimm transverse icon   Transverse DIMM Mode Alt+T
Initiates high speed CCD readout in a way that is suitable for two-dimensional transverse DIMM measurements.

  Transverse DIMM mode tries to maximise readout rate for seeing measurements:
Note:
Transverse DIMM mode also differs from normal readout in other ways:
Dropouts in acquisition files can occur if acquisition is disturbed. Hence:

Tracking  Menu

target icon   Select Target Alt+A
Changes the cursor into the target selection shape. If it is then clicked in the video display area:
If you are using a COAST telescope finder, the crosshair marks the position on the CCD image plane that the telescope controller will guide stars to.
selectregion icon   Select Region Alt+R
Changes the cursor into the region selection shape. To select a region in the CCD image:
In normal use a region is selected around the image of a star that is to be acquired. When that region is later subframed it reads out much more quickly than the full CCD field. The region can also be used to exclude stars that are not of interest.
subframe icon   Subframe Alt+U
If a region has been selected, this action initiates subframing - that is, only the region of the CCD that has been selected is read out. Tracking is not initiated.

Subframing improves the readout rate, as less time is required to clock the CCD and to transfer the data over the USB cable. This is useful in situations where visual real-time feedback is important,  or as a precursor to tracking or acquisition of 3D DIMM files.
track icon   Start Tracking Ctrl+T
If used on a COAST telescope finder, this is the action used to automatically steer a star image to the crosshairs and hence hopefully within autoguider range.

If a region has been selected, this action initiates subframing (if that is not already occurring) and tracking. Tracking consists of the following actions:
Hence, as the star image moves the subframe region moves with it. The star can be tracked across the entire field without resorting to slow full frame readout. Subframing in this way also allows the user to exclude stars that are not of interest.
stoptrack icon   Stop Tracking Ctrl+S
Stops any ongoing tracking. The most recent subframe region is retained and continues to be read out. However, no valid data is sent to the telescope controller. To recommence tracking:
spiral icon   Manual Control Shift+C
If the finder is connected to a COAST telescope, this action allows the user to make manual adjustments to the telescope pointing by clicking and dragging on the star field. To use it:
All this action really does is send a fake error signal to the telescope, which then tries to correct it using pointing changes. As with a real error signal, a conversion is done by the telescope controller into Az and El components. Hence dragging vertically should result in image motion that also appears vertical. 
movie icon   Save Movie Shift+M
Initiates the saving of a sequence of one or more consecutive FITS files, each consisting of a set of one or more consecutive images. To change the file saving parameters invoke the data file dialog using "prefsdlg icon Data Parameters" first.

The files you get after you select this option depend on whether you are in 1D DIMM mode or not.

If you are acquiring normally or are in 2D or transverse DIMM mode:
If you  are in 1D DIMM mode:
In either case:
stopmovie icon   Stop Recording Movie Shift+H
Interrupts the recording of a sequence of FITS files.

NOTE: Using this button is not recommended:
You may be able to recover the saved data manually:

Help  Menu

About...
Displays a brief message about Finder.

The Panel Controls and Indicators

CCD Readout

The CCD readout panel controls how the CCD is clocked during readout, prior to digitisation of data.

CCD panel image
Binning
Changes the amount of charge binning in the X and Y directions.

Binning is the adding together of charge from neighbouring pixels prior to readout.
Binning can be changed "on the fly" even while subframing or tracking. The binning parameter is ignored in either DIMM mode.
Exposure
Sets the exposure time between frames.
Clear Charge
This option clears CCD charge prior to an exposure.

Unchecking it reduces readout time. However, image artefacts are also introduced:

Video Display

The video display panel controls how digitised data is displayed. Changes made here do not affect data that is saved to file.

Display panel image
Stretch Contrast
This option linearly maps the scale of intensities in the image to the full range of the display:
Correct Gamma
Corrects for the nonlinear intensity response of a cathode ray tube display. Hence a linear relationship between photon flux and displayed intensity is produced.

Turn this option off if you have a linear display (such as an LCD monitor) or your display hardware already compensates for monitor gamma (if you are using a Silicon Graphics computer, a Macintosh or some PC display adaptors).
Fast 1D Grid
Displays a red grid in the video display area that marks the fast readout regions useful in 1D DIMM mode . As long as all star images in a DIMM set are in the same valid rectangle of the grid and are separated horizontally, useful data will be obtained.

DIMM grid
Fast 2D Grid
Displays a blue grid in the video display area that marks the fast readout regions useful in 2D DIMM mode. As long as the star images in a DIMM image set are in the same rectangle, useful data will be obtained.

2D DIMM grid
Fast Trans Grid
Displays a blue grid in the video display area that marks the fast readout regions useful in Transverse DIMM mode. As long as the star images in a DIMM image set are in the same rectangle, useful data will be obtained.

Transverse DIMM grid
Show Scale
Displays the angular sky scale on the video display area.

Not yet implemented and disabled.

Status

On COAST telescope finders, the status area informs the user of the feedback being sent to the telescope controller and the status of the telescope secondary mirror and beamsplitter. Messages to the user are also occasionally displayed.

status panel image
X and Y Offset Signals
Display of the offset being sent to the telescope controller (if it is connected to finder).
Telescope Secondary and Beam Splitter Status
When finder is connected to the telescope controller, the positions of the telescope secondary mirror and beam splitter are displayed:
Status
Secondary
Beamsplitter
Out
Secondary Out
Splitter Out
Moving
Secondary Moving
Splitter Moving
In
Secondary In
Splitter In


Progress Bars
Data Saved
"Data Saved" progress bar
Max Flux
"Max Flux" progress bar
Status Bar
At the lower left of the finder user interface, messages to the user are sometimes displayed.

This page last updated 19th October 2004 by bodie@mrao.cam.ac.uk