European Southern Observatory
New Technology Telescope

General :
Observations :

MOS Operations

2 MOS operation

2.1 Setup of the instrument
       2.1.1 MOS plate mounting
       2.1.2 Punching head mounting
       2.1.3 Offsets adjustment
2.2 Plate punching
       2.2.1 The MOS User Interface
       2.2.2 Operational procedure
2.3 Check the punching
2.4 Trouble shooting
2.5 Summary of operations
       2.5.1 Setup
       2.5.2 Plate punching

2.1 Setup of the instrument

2.1.1 MOS plate mounting

Use EMMI configuration panel.

To put the desired location of the starplate wheel on the load point, do the following:

select the slit position and press the move to load button

PLEASE BE SURE THAT YOU INSTALL A THIN PLATE IN THE STARPLATE WHEEL,
OTHERWISE YOU MIGHT BREAK THE PUNCHEAD

Physically mount a virgin MOS plate on the position located at the load point. Then update the configuration doing the following:

select the position number and not aligned option, then press Enter Starplate button

Check the display on the right part of the GUI to check that the configuration is correct.

NOTE: it is important to declare that position 1 is punchable. This is the default but you can double check on the right part of the GUI.

2.1.2 Punching head mounting

Use EMMI configuration panel.

Install the requested punching head inside EMMI. Then update the configuration:

select the head number and press enter head button

Also, as the size of the punch head is a parameter for the MIDAS context emos, the following file on wg5ops should updated:

/midas/[Midas version]/contrib/emos/dat/emominslit.dat

example: in july 1997, the Midas version used is 96NOV

/Midas/96NOV/contrib/emos/dat/emominslit.dat

This file contains the width and the heigth in microns of the punch head. Those data are given in paragraph 1.3 as a function of punching head number.

IMPORTANT: At that point, execute emiBackup command to save your configuration (this command can be executed directly from the emouifConfig panel as an option in the File pull-down menu).

2.1.3 Offsets adjustment

Once the MOS plates have been loaded and the requested punching head mounted, the setup procedure consist in adjusting the punching offsets. Those offsets are set so that the punches performed on the plate are done exactly at the place where they were requested.

To this end, do the following:

Start emos Midas context on wg5ops, account nttastro.
Define a mask containing 2 short slits at two edges of the punchable area.
Send the mask.
From wemmi (directory /data/INSROOT/SYSTEM/MOS), ftp the file *.mask from wg5ops. This file is located in the sub-directory EMOS-MASKS and its name is given in the Midas window at the moment the 'send mask' command is executed.
At that point, follow the punching procedures detailed in the next section.
Once the plate is punched, check the punching by taking an exposure following the procedure given in the specific MOS manual. Loading the image from directory /data/raw on wg5ops, overlay the mask that served to define the punches. Using the zoom option, measure precisely the offsets (if any) in pixels between the hole and the defined slit. The error in pixel can be converted into error in encoder units by using the following formulae:

At that point you can modify in the emmi configuration panel the current punching offsets by adding to them the errors previously calculated. At that point you should repeat the process to make sure that the slits punched are located where they were intended to.
Once the adjustment is finished, execute emiBackup to save the configuration.
Finally write in your daily log book the punching offsets values you found as well as the punching head ID for trend analysis purpose.

As an example, these offsets have been adjusted on July 01st, 1997 when using punching head #7 and we got:

offset_X (enc) = -1488
offset_Y (enc) = -361

IMPORTANT: As you have punched a plate to perform the setup, always remember to replace it with a new one and update the EMMI configuration panel.

2.2 Plate punching

2.2.1 The MOS User Interface

From EMMI OS GUI under the tools menu, select the MOS option. This action will "pop-up" the MOS GUI.

[Click the image to enlarge]

Table 1 : MOS GUI Widget elements

Widget Element	Description
Position	To select wheel position were plate to be punched will be loaded (Only positions 2 to 5 are available for holding plates. Position 1 is always free)
File	Name of file containing the coordinates of position where to punch.
Overpunch/No_overpunch	To enable or disable the possibility to punch a plate already punched
Step	This element tells how many slits have already been punched
Total	This shows how many slit positions will be punched
STRX position	encoder position of STRX EMMI function
STRY position	encoder position of STRY EMMI function
Position	starplate position
Punchable	show if this position is available for punching or not
Punched	show if this position was already punched
Mask Filename	shows name of file containing the data of positions used to punch this particular plate
Date	Date when this plate was punched
Time	Time when this plate was punched
Online	to set MOS functions to online. Initializes & enables STAP STRX STRY STRZ & STRL functions
Load	Load file with position data. Name of this file was given in File element
Start	Start the punching procedure
Stop	Stop punching (punching cannot be restarted again)

2.2.2 Operational procedure

Put the module ONLINE by pressing the "Online" button at the lower part of the MOS GUI. Wait for the initialization of all units (the state of strx stry strz units should change to ONLINE).

Enter the name of the file containing the position of the slits to be punched by pressing the "Load"
button. This files should be in the following directory:

/vltdata/tmp/EMOS-MASKS

The files will have an extension ".mask"

On the MOS GUI select the position that will be punched. In case that the plate is already punched and new slits need to be added, select the "over-punch"option.

Start the punching procedure by pressing the "Start" button.

The punching procedure has the following steps:

reads from the input file the number of positions of slits to be punched and updates the Total widget.
moves the starplate to the punching position
moves X and Y arm of the punching unit to the first set of coordinates
punches a slit
increments the Step counter widget
goes to next punching position until all slits have been punched. (i.e. Step count will be equal to Total count)

In case you want to interrupt the punching process before it finishes, press "Stop" button.
Once all slits have been punched, and if no other plate has to be punched quit the MOS module. The state of strx stry strz units will remain ONLINE, but if the mask has been punched correctly to the end, this will not cause problems. If you wish to have them in "Standby" anyway the only way to do so is to re-initialize EMMI.

2.3 Check the punching

The plate that has been punched should be examined to make sure that all the slits have been done.
This cannot be made directly as once punched, the MOS plate cannot be removed from the starplate wheel (the alignment would be lost as warned in section 1.4). Therefore the check has to be done by taking an exposure with an internal calibration lamp. This can be done either with a suitable calibration template if you have one available or simply directly on the EMMI OS panel.

On the adapter B GUI:

check that adapter is online
put calibration unit in position IN

On the calibration lamp GUI

check that the unit is online
select lamp FFred
press ON button

On EMMI OS GUI:

select RILD mode
select starplate position were the MOS plate is located
fill in file exposure name (test_mos for example) & exposure time (1 sec)
Press SETUP
when setup has replied correctly, START the exposure

The image you get should contain all the slits previously defined. For an easier check, check the image on /data/raw/YYYY-MM_DD on wg5off to display it within xm and overlay the mask that served to define the punches (you'll have to ftp it from wlmos) or simply compare with a finding chart you have printed when you finished the mask drawing.

2.4 Trouble shooting

The troubles you might run into can be divided into 2 classes; the one that have never been reported before and the ones that are olf rriends of us (altough we are chasing them). A list is given here of those known problems and a suggested workaround.

When starting the punch, a pop up window appears indicating that the starplate function (STAP) cannot be moved or gave a time out. It is likely that one of the MOS plate installed has not been put correctly in position and prevent the motion of the starplate wheel. To solve the problem, open EMMI and reposition the MOS plate.
When punching a MOS plate, the process suddenly stalls after having punched some slits. If the display of STAP interlock on the MOS interface indicates 'Lock pin OUT and STRY parked, the workaround is to restart the punching (this is a quite common situation).
If you got an error at some point and the STAP interlock does not display the previous message, it is very likely that an HW interlock is set (either the one of the lock pin or the one of the STRY unit). You have to go up in the EMMI room, switch on the leds on the electronic board above EMMI and look at the corresponding leds. If one of those 2 leds is OFF, an HW interlock is set. In this case, the handset has to be used to drive manually STRY to trigger the HW switch (the interlock is set when the led is switched OFF).

2.5 Summary of operations

2.5.1 Setup

Here are the steps to be followed when one is performing a setup:

Install the virgin MOS plates
Install the requested punch head
Update EMMI configuration control (starplates and punch head)
Backup the EMMI configuration
Update parameters of emos Midas context (on wg5ops)
Adjust the punching parameters
Re-install a virgin plate and update the EMMI configuration
Backup the EMMI configuration
Log the adjusting parameters on your daily log

2.5.2 Plate punching

Start MOS user interface
Put online the MOS sub-system
Perform the punching
Take a calibration exposure to make sure the punching process was successful

[Index] [Page1] [Page3]

Send comments to: Emanuela Pompei & Paul Le Saux <epompei@eso.org>, <plesaux@eso.org>
Last Update: Mar. 17, 2004 (GM/EC)