Large Format Camera (LFC) Commands
View the original commands guide.
LFC commands follow this syntax:
command <argument [optional argument]>
Commands issued without a necessary argument will
simply display the current value. Commands may be
abbreviated to the shortest
length necessary for completion.
mcdcom — This starts the LFC program.
Once started, mcdcom will start writing data into the
current directory. Mcdcom recognizes the Unix commands ls and cd ,
and will write to any new directory that you
point to. You can issue any Unix command with the standard ! escape.
mosaic <mode> — This downloads
the appropriate code to the DSP controller and
configures mcdcom. The mode sets the clocking parameters. Currently, there are 5 modes:
Example mosaic lfc2 — This will
setup Mcdcom to readout the entire mosaic, binned 1 × 1.
Example mosaic lfczero — This
will setup Mcdcom to readout only chip 0, binned 1 × 1.
Example mosaic lfcfind — This
will setup Mcdcom to readout only chip 0, binned 2 × 2; useful for a quick find exposure.
The DSP code files are found in the environment variable
LODPATH , which is normally /usr/ccd/dsp
for the LFC. These files contain the binary arrangement for the DSP
controller, and they are specified by the configuration file in MOSCONFIG .
Currently there are 3 DSP files that can be used; one
for readout of the full mosaic, one for readout of the central
four chips, and one for readout of just chip 0.
The DSP files cannot be edited or created, so we get one of these 3 options.
The Binning Value and Raster Value configuration parameters can be
changed should the above mode options not meet your needs
(again, the chip numbers read out cannot be changed).
The configuration file location is taken from the MOSCONFIG
environment variable, and the <mode>
argument is appended to form a filename for reading
configuration files. For the lfc, MOSCONFIG is
normally /usr/ccd/config/mos_config .
The mos_config files currently available for LFC are in this directory.
To change binning and/or raster parameters, a new mos_config
file will need to be created for you with a FORMAT
line added. These are the 7 parameters for the FORMAT line:
binx |
biny |
starting offset x |
starting offset y |
number save x |
number save y |
number save bias |
The other variables that are set in the mos_config file MUST match
up with the corresponding DSP file. In
other words, if you want to change the binning and raster values
while reading out just chip 0, you MUST make
sure that you are using the proper DSP binary code for the single
chip0 readout. A good way to do this
would be to copy the mos_config file that uses the mode you want,
and then edit the copy to include the
FORMAT instructions. You won't have file permission to edit the
mos_config FORMAT line, so you will need to ask
for mountain staff help to do this.
Mcdcom takes exposures and writes data files according to various
parameters that you can set. The basic sequence that mcdcom
follows is:
- Clear the chip
- Open the shutter and wait for the predetermined exposure time
- Readout the guide chip during the exposure and forward to the guide display at intervals
- Close the shutter
- Readout the CCDs into memory
- Write the contents of memory into FITS format data files
- Put the CCDs into idle mode
Not all of these above steps need be taken. The actual sequence
followed depends on how the "automatic actions" are set, as described below.
There are seven ways to set the basic parameters which govern what mcdcom does:
bias <time [name]> — Setup for a
bias exposure. bias prepares mcdcom to take a bias frame
exposure. bias ignores any exposure time arguments.
You can specify a name as the second argument. If
you don't specify a name, the previous value for bias
is used. bias sets the automatic actions to:
Autowipe = ON |
Shutter = OFF |
Readout = ON |
Write = ON |
Idle = OFF |
Example bias 0 bias — Ignores any integration time argument and
sets the name to bias.
comp <time [name]> —
Setup for a comparison lamp exposure. comp
prepares mcdcom to take
an exposure of a comparison arc for a spectrograph. You can specify
the integration time as the first
argument. If you don't
specify a time, the previous value for comp is used. You can
specify a name as the second argument.
If you don't specify a name, the previous value for comp is used.
comp sets the automatic actions to:
Autowipe = ON |
Shutter = ON |
Readout = ON |
Write = ON |
Idle = OFF |
Example comp 1 Hg-Ne —
Sets the integration time to 1 second and the name to Hg-Ne
dark <time [name]> —
Setup for a dark field exposure. dark prepares
mcdcom to take an exposure of the dark field. You can specify the
integration time as the first argument. If you don't specify
a time, the previous exposure time is used. You can specify a
name as the second argument. If you don't specify a name,
the previous value for dark is used.
dark sets the automatic actions to:
Autowipe = ON |
Shutter = OFF |
Readout = ON |
Write = ON |
Idle = OFF |
Example dark 10 dark — Sets
the integration time to 10 seconds and the name to dark
flat <time [name]> — Setup
for a flat field exposure. flat prepares
mcdcom to take an exposure of a flat field. You can specify the
integration time as the first argument. If you don't specify a
time, the previous exposure time is used. You can specify a name
as the second argument. If you don't specify a name, the previous value for
flat is used. flat sets the automatic actions to:
Autowipe = ON |
Shutter = ON |
Readout = ON |
Write = ON |
Idle = OFF |
Example flat 10 domeflat —
Sets the integration time to 10 seconds and the name to domeflat
focus <time [name]> —
This was a command to set the exposure time for a focus image. The
current default exposure time is 5 seconds. If you would like to
change the exposure time you may do so by editing the first line of
the focus scripts, focus (N) focus_fine .
object <time [name]> —
Setup for a general exposure. object prepares
mcdcom to take an exposure of a general target. You can specify the
integration time as the first argument. If you don't specify a time, the
previous exposure time is used. You can specify an object name as
the second argument. If you don't specify a name, the
previous value for object is used.
object sets the automatic actions to:
Autowipe = ON |
Shutter = ON |
Readout = ON |
Write = ON |
Idle = OFF |
Example object 0.18 — Sets the integration time to 0.18 seconds
Example object 300 N3031 — Sets the integration time to 300 seconds
and the name to N3031
auto — Prompts, and then sets
the automatic actions as described above. You can tailor your exposures
to suit your needs in this manual way if the preconfigured options above don't meet
your needs. The automatic actions are:
- Number of times to wipe chip before exposure [1]:
- Open shutter for exposure? [yes]:
- Read CCD after exposure? [yes]:
- Write data to file after read? [yes]:
- Turn on continuous wipe after readout? [no]: PLEASE DON'T CHANGE
THIS OPTION FOR THE LFC. It can cause problems with the filter
wheel as of 2000/03/20."
There are three more commands that you can use to setup
your exposures. These do not change any of the
automatic actions described above.
et <seconds> — Sets
the exposure time. Any floating point value is
accepted. The accuracy of
the exposure timing is somewhat better than 0.01 seconds, but
is ultimately limited by the mechanics of the
shutter (currently the mechanics of the shutter are good to 0.6 seconds).
et uses Unix to compute the exposure time.
An exposure that is based on Unix timing can be interrupted reliably with a
^C . For example, if you start an exposure of 300
seconds and decide to change that to 600 seconds, you would do a ^C to stop the
exposure, issue an et 600 command, and
restart the exposure with the go command (see below).
Changing the exposure time with et will
NOT change any of the automatic actions listed above.
If,
for example, you are running a bias frame, you won't be able to
change the exposure time with et
since
the
bias mode ignores the exposure time (shutter automatic action is OFF).
name <objname> —
Sets the object name into the FITS header. You can
change
the name of the
current exposure by closing the shutter with ^C ,
issuing the name <objname> command, and then
restarting the
exposure with go .
status <> —
Shows the current parameters that the next exposure will take.
clear <[num]> —
Clear (wipe) the CCDs. This flushes any charge existing
in the CCDs. The chips
are good about not retaining residual images, but you can give
clear an argument if you want to wipe
it several times.
Some of the CCDs may require several wipes to clear bled charge
from near the bottom of the chip if the CCD
is saturated. We've seen the need for a clear 5 once or twice
after a very bright (3 mv) star.
If the LFC has been sitting for a long period of time, especially
in the bright dome, several clear
commands may not be
sufficient to clear the chip. You may need to execute an
rm command to read
the mosaic before attempting an exposure. Note that
rm will write the 6 FITS files and
increment the file number. You can set the write data option to off
with the auto
command.
go <[num]> —
Starts the exposure. Depending on the automatic actions that are previously set
(see above), go may wipe the chip, open the
shutter, close the shutter, read out the CCDs into
memory, and write the data
to disk. An exposure that has been started with go
can be interrupted by a ^C . This will close the
shutter and return you to the mcdcom command level. You can then alter the exposure with
et ; you can change the
eventual output file name with fp or fn . If you want to
continue the exposure, reissue a go . If you want to
readout the CCDs, issue an rm command. If you want to abort the exposure,
issue a clear command. You can set the number of consecutive
exposures to take with the fist argument [num] .
If you receive a "camera not responding " or a similar
warning when trying to take an exposure, you will need
to start a Cold Boot sequence.
fn <#> —
Sets the incrementing file number to ###. The default
value is 1.
Mcdcom writes files of the form "prefix###.chip ",
where ### is an incrementing file number.
fn allows you to
specify this file number. Mcdcom uses the current file number
as the program prompt (example: ccd.###> )
and automatically increments the file number as each file is written.
fp <prefix> —
Sets the output file name prefix . The default value
is ccd. (note
the trailing dot ("."). Mcdcom writes files of the form
"prefix###.chip ", where "prefix" is the file name
prefix. fp allows you to specify this file name prefix.
If you don't want a dot (".") between the prefix and the file number, simply omit it.
Note that an exposure is written to disk in the form
prefix###.chip , where chip is a number
(0-5) that corresponds to the CCD number.
Example: For an fn set to
1 at the start of the night, and an fp set to
mylfc , the 33rd
exposure of the night would produce six FITS files (17 Megabytes each) that looked like:
mylfc033.0 |
mylfc033.1 |
mylfc033.2 |
mylfc033.3 |
mylfc033.4 |
mylfc033.5 |
fs <suffix> —
Sets the file number suffix (ex: .fits ).
Clear this with fs "" .
iraf — Toggle
IRAF format for FITS file.
IRAF (among others) is finicky about dealing with 16-bit FITS
images, but the dynamic range and A/D converters for our CCDs are such
that we want to save all 16 bits. The "iraf" option causes
ccdcom to scale all FITS images to pack 16-bits of unsigned data
(so-called "ushort") into standard FITS signed 16-bit integers
("short" or BITPIX=16 FITS format).
Specifically, this the FITS header parameter BZERO is set to 32768, and
the image is written as a FITS-standard 16-bit integer data file. IRAF
et al. use the value of BZERO in the FITS header to restore the pixel
values to those provided by the camera.
By contrast, the old "not IRAF" format images stored pixel data as
unsigned 16-bit integers, resulting in a non-standard FITS format image
(a "ushort" image in IRAF parlance) that most FITS readers cannot read
without special handling.
rm — Readout the
CCDs ("read the mosaic"; not to be confused with the Unix
r emove command).
If you pause an exposure with ^C , you can readout
the contents with rm . If the
automatic action Write = ON (it's on, unless you specify it to
OFF with the auto
command), rm will write the resulting image to a disk file.
wf <[filename]> —
Write FITS file. Mcdcom reads out the CCDs into memory and maintains the
image there (if there is a full disk or if the automatic action
Write = OFF); or Mcdcom continues on and writes to disk (if the
automatic action Write = ON). The wf command
puts together FITS headers for the images and writes them
to disk files. If the write fails (say the disk is full), wf will
abort but mcdcom will keep the data in memory, and
you can save your data
with the wf command after fixing the problem
that prevented the write.
The LFC shutter is operated by two motor controllers.
The communication to the motor controllers (plus the
filter wheel motor) is
via a serial connection. The shutter has two blades which
open and close in the same direction, providing a
very uniform
illumination. The shortest reliable exposure time is 0.6 seconds.
General shutter status and configuration is accomplished via
the shutter command. The supported
subcommands:
shutter blades —
This reads the current motor encoder positions and reports the
status of the shutter.
shutter home —
This command re-initializes the shutter blade positions to
nominal. This must be done
if the power to the LFC motors is cycled. It also doesn't
hurt to run this once at the beginning of each
night, to take out any
small amount the motors may have drifted.
shutter startup —
This command re-initializes the I/O to the motors, and sends
some configuration
parameters to the motors. This should be executed each time
mcdcom is started (as described above).
shutter stat —
Reports a different status of the blades, based on the Hall
effect sensors.
shutter oneblade —
This mode was implemented in case of the failure of one of the
two blades. This mode
opens and closes the shutter using one blade only, instead of
using two blades coming from the same
direction
as is the norm.
Don't use this unless you know what you're doing; it also
reduces the uniformity of the exposures.
If you receive a "camera not responding" or a shutter error
when trying to take an exposure, you will
need to start a Cold Boot sequence.
The LFC has a 4-position filter wheel that holds 6.2 inch
square filters in custom holders. The wheel is driven via friction
drive, and has Hall effect sensors to read the filter position.
There are two sensors that encode which filter is in the beam,
and a fine-position sensor to achieve precise alignment.
The wheel is controlled by the filter
command. Positions are encoded as 0, 1, 2, and 3.
The names for each filter are read from a file, usually
/usr/ccd/config/filters.def . If you
change filters in the wheel, update this file to correspond.
You will need to restart Mcdcom in order to update
the filter table.
filter —
Reports the current status of the filter wheel, including the current
position and the names
of the filters in the wheel (the "estoff" value should read
0 after a filter move). The names are read from a file,
usually /usr/ccd/config/filters.def . If you
change filters in
the wheel, update this file to correspond.
You will need to restart Mcdcom in order to update the filter
table.
filter home —
Move the filter wheel to the "home" position, which is filter
position 3. This attempts
to spin the wheel all of the way around until position 3 is
located, then the wheel is stopped and backed
into position. If you
see the warning "filter wheel didn't make it into fine lock",
you can try a filter move 3 command to
re-adjust the fine
lock position. Or simply try a filter home again.
filter move <#> —
Move the wheel to position #, where # is 0, 1, 2, or 3. The
wheel moves in only one direction, and goes 3-2-1-0. So moving
from filter 1 to filter 2 requires a motion
of 3 steps. Sometimes, the servo will fail to converge and a
warning, "filter wheel didn't make it into fine
lock" will result. If this happens,
just issue the filter move # command again
until the filter wheel has seated properly. Pay attention to
the estoff= value. This value should be 0 before you
take an exposure.
Pay close attention to the response from the mcdcom
program after issuing a filter move command; make sure that
the filter wheel is seated properly before starting your exposure
(ie: estoff=0). Make sure that the filter wheel is where you think
it is after doing a cold boot (ie: estoff=0) by typing
filter .
If the filter wheel fails to locate position 0
(or the filter reports that it is lost when moving to
position 0), but it can move to position 1, 2, and 3;
you need to issue another filter subcommand, filter bump that will allow
you to bump the filter wheel in incremental amounts.
filter bump <#> —
Move the filter wheel by # encoder units. #
should generally be negative. There are about 330,000 encoder
units between adjacent filters. A bug currently in the filter
servo code crops up rarely: when moving to filter position 0, the servo will
occasionally report, erroneously, that the filter
wheel is "lost". If this happens, and you are sure the wheel isn't truly lost,
the command "filter bump -1000 " followed by
re-issuing the move will sometimes get around this problem. If that does not work, the
wheel is truly lost, and you should try the
filter home command.
If you receive a "camera not responding " warning when
trying to move the filter, you will need to start
a Cold Boot sequence.
The guider maintains the communication to the telescope;
LFC issues telescope commands and receives
telescope information (headers) through the guider. If LFC
is not communicating with the telescope, make sure the
guider is running. If the TCS is rebooted, you need to quit and
then restart the guider.
The LFC guider runs from a Tek 512x512 CCD in the mosaic
focal plane that sits behind the filter and shutter.
It is read out periodically during exposures, and the image is sent to
the guider GUI. Integration times and other guiding
parameters are set
with the guider GUI. Corrections are sent from the guider
program directly to the telescope. Since the
guider runs with the
shutter, you can only view the guide field either during an
exposure or in a special find mode that
opens the shutter and reads the chip.
The guider program is started in one of two ways.
When you logged into oasis, you should have
logged in with 2 terminals;
one for mcdcom and one for the guider. In the guider
terminal, you can start the guider by typing
lfcguide
& , in which case
all of the guider output is written to the standard output
(the terminal itself). If you want to send the guider output to
a file (useful in the early debugging days of the guider), you can use
lfcguide >& ~/lfcguide.out & .
This output file will be written to the oasis home directory
(/scr6/home/lfc ); make sure there is enough free space in this
directory to accomodate the long text file that
will result.
If you have a question about the operation of the guider,
use the Help button on the right hand side of the guider GUI.
Most (if not all) of the guider parameters will be set
from the guider GUI, but you can issue three guider
commands from mcdcom:
find — Opens the shutter
and puts mcdcom into a loop reading out the guide chip
and sending the resulting image to the GUI, but without actually
taking an exposure. The parameters for the display are
set with the guider GUI.
Find runs for 5 minutes and stops automatically,
or it can be interrupted via ^C . Note that this opens the
shutter, so charge can accumulate on the science CCDs. This is
not ordinarily a problem, as the mosaic is
cleared before a
science exposure. However, if the mosaic becomes saturated during
a find the ordinary clear
may not fully wipe the chip, in which case a clear 5
is advised before starting a science exposure.
Note 1: If guiding is enabled on the guide GUI,
the telescope will move (guide) during the find.
Note 2: Typically you will not use find
to get guide stars except in troublesome cases. Start your
science
exposure, locate a star in the GUI, move both the sky
and the signal boxes over the star, and
click Start.
This usually works fine, as the 200-inch tracks like a champ for
60-120 seconds.
guide <on|off> —
Set whether to read out the guide chip during exposure. If
guide is off, guiding
is impossible. You will want to leave this in the ON state; don't
turn it to OFF here unless you have a very good reason.
rg — Read guide ccd
once and send to the guide GUI.
synch — Ping the DSP
by sending it data and asking it to send it back. This is
useful to check to see
whether the CCD is alive and receiving commands properly from
mcdcom, or if the electronics may need a hardware reset.
utility init —
Initialize the utility board. You must execute this once if the
power in the electronics box has been cycled. The utility
board is largely independent of the rest of the Leach
electronics, so changing
the mosaic configuration will not affect the utility board.
Because of a bug in the utility ROMs,
executing this command again
on an already running board may cause the board to hang,
so use this only for a cold power reset.
utility status —
Display the status of utility board. This command tells you
the power supply
voltages, the CCD temperature, and the status of the heater which
regulates the CCD temperature. You might see
a display like:
Utility board status:
+40 V at +34.4 CCD temp at -391.6
+15 V at +16.1 CCD set temp at -391.6
-15 V at -15.8 Electronics temp at +25.8
+5 V at +5.1 % overcharge 2%
The temperature inside the electronics box is 25 C.
We do not use the utility board for temperature control,
so that part of the display is not useful.
If you receive a "camera not responding " or unreasonable
values for a utility status , you will
need to start a Cold Boot sequence.
Some other useful LFC commands:
! — This is the
standard shell escape to execute unix commands.
^C (control-C) — Use this
keystroke to interrupt any mcdcom function. Especially
useful for pausing an
exposure (see the discussion above for a complete description).
^D (control-D) — Quit mcdcom.
This will return you to the Unix oasis%
prompt.
cd — Change directories within
mcdcom. Once your path has changed, all future
exposures will be written to the new directory.
help — This will list the
currently recognized commands.
istat — Print some statistics of
chip 0. Useful for a quick-look at chip 0,
especially the mean count level during sky flats.
quit — Quit mcdcom. This will
return you to the Unix oasis% prompt.
ls — List the contents of the
current working directory.
sound — Toggle fancy sounds.
Mcdcom will use distinctive sounds for various
operations. If you want
to listen to them you can turn them on with the sound command. The sounds are:
- shutter open - dog bark
- shutter close - drip
- commence readout - toilet flush
- finish readout - gong
- finish writing file to disk - rooster crow
- failure writing file - crash
Note that the sounds emanate from the oasis computer located in
the computer room downstairs. You'll have
to
go downstairs in
order to hear them.
source <file [line]> Execute commands
from file . This is how you execute a script in
Mcdcom (see the Cookbook for script information).
There are a number of commands that you can use to
control the telescope. Note that the guider must
be running for telescope commands to work.
telescope focbump <dfocus>
— Move the current telescope focus by the
amount dfocus in
millimeters. Positive value moves focus out, negative value moves focus in.
telescope focgo <focusmm>
— Move the current telescope focus to the
absolute position
focusmm in millimeters. A typical
summer LFC focus value is 28.00 millimeters. A typical winter LFC
focus value 33.00 millimeters.
telescope gobase —
Go back to the previously defined base position (RET in the TCS lingo).
telescope goffset <dra" ddec">
— Move (dither) the telescope AND the
guider box in arcseconds
for both right ascension and declination. Positive values move
the telescope and guider box east and north respectively.
Negative values move the telescope and guider box west and
south respectively. Note that your guide field is
about two arcminutes across. Take care to keep your guide
star within the guider field.
telescope home —
Go back to the last telescope slew position (F in the TCS lingo).
telescope offset <dra" ddec">
— Move (dither) the telescope in arcseconds
for both right
ascension and declination. Positive values move the telescope
east and north respectively. Negative values
move the telescope west and south respectively. Note that you
are NOT moving the guide box with this command.
telescope ping —
Check to see if the LFC guider is alive.
telescope setbase —
Set the current position as the base position.
When this is done, the
telescope dra and ddec offsets (from the display monitor) will go
to zero (Z in the TCS lingo).
telescope status —
Report the current telescope position.
telescope goff —
Turn the LFC guider off (you will only want to use this command in
a script). Same as the guider OFF button.
telescope gon —
Turn the LFC guider on (you will only want to use this command in a
script). Same as the guider Start button.
telescope gres —
Resume guiding with the autoguider (you will only want to use
this command in a script). Same as the guider Resume button.
telescope lowlamp — Turn on the lowlamp.
telescope highlamp — Turn on the highlamp.
telescope arclamp — Turn on the arclamp.
telescope lampsoff — Turn off the lamps.
At some point during the night, you may find it necessary to
restart mcdcom. If you accidentally quit the
program, if the camera stops "talking", or if there is any other
unusual problem; follow the same
Start-up Sequence that you used to start
mcdcom. If you are not already out of the LFC program,
quit mcdcom.
Enter the following commands in this order to re-start
the LFC program (the order is crucial):
oasis% mcdcom —
This starts the LFC program. Pay attention to the directory that
you are in once you quit an Mcdcom session (any directory changes
done while in the Mcdcom program are lost).
ccd.001> mosaic <mode>
— See mosaic for the
current list of available modes. If you are changing
your mode, you need to do a cold
boot.
ccd.001> shutter startup
— This initializes the shutter
ccd.001> shutter home
— This sends the shutter to the home position
ccd.001> filter home
— This homes the filter wheel; make sure estoff = 0!
ccd.001> utility stat
— This displays and tests the current status of the utility
board
- Charge accumulates on the chips during a cold boot. The only
way to fully remove this charge is to readout the chips with either
rm or a 0 second bias exposure.
Note that all 6 chips are written to disk when you do this.
Note that the incrementing file number (fn)
has been reset to the default value of 001
upon restarting mcdcom. You will want to set fn
to your last exposure file number + 1.
If a Warm Boot has not solved your problem, try a
Cold Boot (below).
If a Warm Boot did not solve your problem, then you will
need to do a Cold Boot by resetting the
power to the electronics in the Prime Focus cage. This is done
by having the TO issue commands from the TCS Console. Follow
these steps (the order is crucial): NOTE: It is
recommended to have the telescope at zenith during a cold boot.
lfc_208> quit
- Have the TO issue the "
ir_off " command to turn off the
power to the LFC system. The TO will then wait 30-45 seconds
and issue the "ir_on " command to turn the power back on.
oasis% mcdcom
ccd.001> mosaic <mode> —
See mosaic for the
current list of available modes.
ccd.001> clear
ccd.001> util init —
Do this only once for a cold boot; more may lock up
the utility board and require another power down.
ccd.001> shut startup
ccd.001> shut home
ccd.001> filter home —
You may need to run this more than once. Make sure estoff = 0!
ccd.001> util stat — Make
sure that the utility board is alive.
- Charge accumulates on the chips during a cold boot. The only
way to fully remove this charge is to readout the chips with either
rm or a 0 second bias exposure.
Note that all 6 chips are written to disk when you do this.
If your problem isn't fixed or if there are any new problems,
cycle the power again and restart the cold
boot procedure. Do as many times as necessary to get you back
into service. Note that the incrementing
file number (fn ) has been reset to the default value of
001 upon restarting mcdcom. You will
want to set fn to your last exposure file number + 1.
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