MOSOCS

A simple "observation control system" for Mosaic II

An informal study suggests that more than 80 percent of Blanco observers use "mosocs". Read why and here below.

Mosocs is a script that allows astronomers to create a file completely describing a whole sequence of observations. Each observation is defined on one line, and this definition includes the telescope pointing, guide star position, filter, and exposure time. The script reads the file one line at a time, sending instructions to the telescope, guide camera, and instrument to control all the necessary parameters. The file can also be used to generate a list of positions to be read into the TCS, but under the current implementation this is not necessary because the script itself sends the slew requests to the telescope.

Mosocs was originally designed to to provide better support for programs that repeatedly image the same field. It is especially useful for programs that need to return to exactly the same location repeatedly (such as asteroid searches, supernovae searches, and the Super MACHO Survey), since it stores the position of the guide stars used for each pointing. This allows observers to return rather precisely to the same spot on the sky for repeat observations.

The "observing plan" file

The mosocs observing script is driven by an "observing plan" file, which specifies on one line everything the observer would normally specify at the prompt when observing in normal, interactive mode. An example mosocs observing plan looks like:

 # This is a

comment, to describe the file

# fields or columns are numbered below to aid following description

Comment lines begin with #, and are completely ignored by the script. The columns are space delimited, so only order is important, not column numbers. The order of fields on each line is:

1. field reference name: this is your field name (no spaces allowed)

2. RA

3. Dec

4. Epoch

5. Guider camera (either N or S)

6. Guide star x coordinate (from guider monitor)

7. Guide star y coordinate (from guider monitor)

8. Exposure time (decimal not required)

9. Filter

10. Title of image (no spaces allowed)

The first time you run mosocs, you should simply enter 0 0 for the guider x y coordinates. You will update these the first time you run the script.

Another example of an observing plan, this one specifically for two pointings at a standard star field in multiple filters, looks like:

# Landolt standard field SA 107

# 107S puts stds in 4 S CCDs, 107N puts stds in 4 N CCDs

 This and other useful sample observing plan files can be found at the telescope in the ocsfiles directory in the home directory of the mosaic user account.

The mosocs parameters

The first step to using the mosocs script is to set the parameters, most importantly the name (and location) of your observing plan file. An epar of the mosocs script looks like:

I R A F

Image Reduction and Analysis Facility

the filename parameter should be set to the full pathname of your observing plan file.

the addstar parameter determines whether or not the script will ASK the observer for the guider box x y coordinates. See below for use.

the stdname parameter can be used to change the naming scheme of the FITS files written to disk. The default naming scheme of the Arcon software is objNNNN.fits. Alternatively the observer can define some other root in the template parameter of obspars. Either of these are enabled by stdname=yes, depending on whether the template parameter of obspars is blank or not. With stdname=no, the FITS files are named as fieldname.ut_time.fits, where the ut_time is the time at the START of the exposure (when the observe command is given).

the resume parameter can be used to resume an aborted or interrupted sequence of observations at a specified position.

The other parameters (doit, ingcam, ingx, ingy, quit; and obspars, detpars, instrpars, telpars) are all variables or psets used by the script, and should not be modified.

Using the mosocs script

Once you've set the parameters as desired, you can type mosocs at the ARCON Acquisition IRAF prompt. The observing plan file will be read one line at a time, prompting for needed parameters or input.

You can exit out of the mosocs script any time to e.g. re-focus, repeat an observation, etc. To do this, say "no" to observe this field, and then "yes" to quit observing sequence.

To resume where you left off, type "mosocs res+".

You can also type "mosocs res+ pos=##, where ## is the number of observation from the top of the ocs file that you want to start on.

You could also comment out the lines/observations you have already completed, and type "mosocs". The script will then start from first uncommented line.

The first time / Adding guide star coordinates

If you are interested in using the guide star recovery feature of mosocs, the first time you run the script is unique, since it is the first time you will be observing the fields and hence you will be identifying the guide stars (and their guider x y coordinates) as you go. To help keep track of the guider x y coordinates, you can set addstar=yes. With this setting, mosocs will prompt you for the guide star x y coordinates, and write them out in a new observing plan file (NEWOCSFILE) with all of your other observing configuration, so that you can use this new observing plan file for all subsequent observations, setting addstar=no and allowing mosocs to set the guider box on the previously noted x y position.

Here is an example run of mosocs with addstar=yes:

cl> mosocs addstar=yes

Observing Plan File (/ua80/mosaic/ocsfiles/temp.in):

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Moving to position 1:

Field = field1

20:12:00.22 -30:00:00.00 2000

Add guider box x,y coords to file

Guide camera: N

Guide box x coord: 150

Guide box y coord: 175

Polling environmental computer for temperature. Please wait...

Truss temps: 6.9 6.9 6.9 6.6 at UT 03:55:00 on 08/08/2002

Median upper truss temp is = 6.9

Temperature has been set in instrpars.

Best guess at R-band focus:15515.5

Observe field1 title=Field1_title texp=5. filt=B

Observe this field (yes):

Focus calculation:

Filter1 = B                        Telfocus = 15457.000

Image obj054

Mosaic2 [1:8192, 1:8192] bin=[1:1], gain 2

Single character sub-commands:

A Abort exposure

P Pause exposure

R Resume paused exposure

S Stop exposure

T Change exposure title (current exposure ONLY)

X Change exposure time (current exposure ONLY)

Q Interrupt task (optionaly aborting exposure)

Field field1 observed

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Moving to position 2:

Field = field2

            20:14:00.00          -31:00:00.00 2000

Add guider box x,y coords to file

Guide camera (N): S

Guide box x coord (150.): 300

Guide box y coord (175.): 250

Polling environmental computer for temperature. Please wait...

Truss temps: 6.9 6.9 6.9 6.6 at UT 03:55:00 on 08/08/2002

Median upper truss temp is = 6.9

Temperature has been set in instrpars.

Best guess at R-band focus:15515.5

Observe field2 title=Field2_title texp=6. filt=R

Observe this field (yes):

Focus calculation:

Filter1 = R                     Telfocus = 15480.0000

Image obj055

Mosaic2 [1:8192, 1:8192] bin=[1:1], gain 2

Single character sub-commands:

A Abort exposure

P Pause exposure

R Resume paused exposure

S Stop exposure

T Change exposure title (current exposure ONLY)

X Change exposure time (current exposure ONLY)

Q Interrupt task (optionaly aborting exposure)

Field field2 observed

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Observations finished.

The file NEWOCSFILE has been created with all of your

guide star information from this run. You may now

copy and edit that file for your observing plan for

following nights.

The rest of the time

Once you've run mosocs once with addstar set to yes, OR if you're not interested in using the guide star recovery feature, you should set addstar=no.

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