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SPUPNIC

Revision as of 16:53, 21 January 2016 by Lisa (Talk | contribs) (→‎Setting up the slit position on the TCS - using the SpUpNIC Control GUI)

SpUpNIC User Manual

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Introduction

Here we provide a preliminary, and hopefully temporary, user manual for SpUpNIC (Spectrograph Upgrade: Newly Improved Cassegrain) - the recently upgraded spectrograph at the 1.9-m telescope's Cassegrain focus. We plan to produce instructive video clips and a more comprehensively illustrated wiki in future, but for now this will have to do!

The spectrograph's collimator and camera optics have been replaced, the instrument has a new detector, all of the mechanisms are now under PLC control and the software (both for instrument control + quick-look data reduction) has been completely re-written.

The instrument has two sub-systems, the PLC sub-system (controlling all the things that move) and the detector sub-system (controlling the data acquisition process). The drivers for these sub-systems run as stand-alone processes, and the user interface runs as a separate process on top of these. Typically, users will connect to the graphical user interface (GUI), although certain diagnostic functions can only be accessed using the command line interfaces.

We hope that you'll enjoy using SpUpNIC and that you'll be willing to provide the instrument team with feedback and suggestions by emailing lisa(at)saao.ac.za.

Change Log

The SpUpNIC software evolved substantially during the week of 16-23 December 2015. The wiki has been adapted to reflect these changes.

Quick Start

This is a basic overview of taking data; if you're unsure about anything, the Advanced User Guide section contains more information.

  • If the instrument control and quick-look interfaces are not running, they may be started from the panel on the left edge of the left screen. The instrument control GUI is started with the absorption spectrum icon, and the quick-look GUI from the emission spectrum icon.
  • Ensure that the grating you require is inserted (see the grating change instructions in the Start of Run Section), and then set the grating to the required angle.
  • Run a Hartmann routine (see the Advanced User Guide) to establish the best focus for the spectrograph.
  • Set the required spectrograph camera focus.
  • Set the slit width.
  • Check that the required filter is in the beam (or left open if required).
  • Select the exposure type (ARC, BIAS, SCIENCE, FLAT, TEST).
  • If appropriate, set the exposure time and number of exposures.
  • Select a target from the target catalogue file so that the object name and coordinates will go into the fits header.
  • If taking a science image, acquire the target, and ensure that it is visible through the slit and in focus.
  • If taking an arc, ensure that the arc mirror is in-beam, and the required arc lamp is on.
  • Select the SCIENCE exposure type after taking an arc, this will turn off the arc lamp and remove the arc mirror.
  • Start the exposure with the Expose button.
  • The countdown timer will show the time remaining, and the progress bar will first show the exposure completion state, and then the readout state.

PLC Subsystem

Detector Subsystem

SpUpNIC User Interfaces

SpUpNIC's displays are labelled "Monitor 1" and "Monitor 2", and are located to the right of the TCS monitor in the warm room. To launch the SpUpNIC Control GUI, click on the absorption spectrum icon in the menu bar on the left-hand-side of Monitor 1. All of the spectrograph sub-systems (e.g. grating angle, slit width, arcs, exposures, guide mirror) are controlled from this GUI.

There's an accompanying SpUpNIC Quick-Look GUI, which displays each spectrum after readout and allows basic extraction and wavelength calibration. To launch the SpUpNIC Quick-Look, click on the emission line icon below the absorption spectrum icon on the left-hand edge of Monitor 1.

The Instrument Schematic

Normal operations are performed in the Main View tab of the SpUpNIC Control interface. On the right-hand-side is a graphical representation of the instrument, which shows the light path through the various components controlled by the GUI. You can click on the guide mirror, arc mirror, rear-of-slit mirror and Hartmann shutters to move them in and out of the beam, and on the arc lamps and slit illumination to switch them on and off. A blue border surrounding the graphic indicates that the spectrograph is configured for acquisition or calibration, i.e. some component is in the beam that would obstruct its path to the science detector. If the system is correctly set up for a science exposure, there will be no coloured frame and the red light-path will go through to the detector.

Advanced Users Guide

  • The SpUpNIC Control interface has a number of tabs:
    • The Main View tab, in which you'll spend most of your time.
    • The Advanced tab, used at the start of the run, and which may be used if things go wrong.
    • The Engineering View tab, which displays various diagnostic settings.
    • The Config tab, which you should not need for the most part.
  • The panel on the right is an interactive schematic of the instrument. Components with in/out or on/off states can be toggled by clicking on the relevant part of the image. The light path is shown in red so that one can easily verify the instrument configuration.

Start Of Run

Setting name and run number

In the SpUpNIC Control GUI:

  • At the start of your run, click on the Advanced tab. In the Observer Info box, enter your name and run number. You can determine your run number from the triplicate "CCD and Unit Spectrograph" log book (stored in the "Log Books" section of the bookcase - behind you, if you're sitting at the SpUpNIC interface). Your run number will be one greater than the previous observer's run number, listed in the log book.

Setting up the grating

Note that the wavelength ranges and resolutions listed in the table below are only approximate, the new values are still to be determined from the recent instrument commissioning data!

Grating Order Blaze (A) Res (A) Range (A) Star Filter Arc Lamp Arc Filter Approx Angle
4 1 4600 1 800 None CuAr None 5
5 1 6800 1 800 GG495 CuNe GG495 -3
5 2 3400 0.5 350 BG39 CuAr BG39 5
6 1 4600 2 1600 None CuAr None 11
7 1 4600 5 4200 None CuAr BG38 15
8 1 7800 4 2300 GG495 CuAr GG495 12
8 2 3900 2 1150 BG39 CuAr BG39 8
9 1 7800 1.5 960 GG495 CuAr GG495 4
9 2 3900 0.7 480 BG39 CuAr BG39 -4
10 1 10000 1 800 GG495 CuAr GG495 -9
11 1 10000 2 1600 GG495 CuAr GG495 7
12 1 10000 5 3200 GG495 CuAr GG495 14
  • If a grating is mounted in the spectrograph, it will be indicated at the bottom of the Instrument Setup pane, e.g. gr8 in the Grating field shows that Grating 8 is installed. Above that is the Grating angle field.
  • If you need to change to a different grating, follow the steps below - being EXTREMELY careful not to touch, or even breathe on, the optical surface!
 GRATING CHANGE INSTRUCTIONS: 
 * set the grating angle to 0 deg in the SpUpNIC control GUI
 * set the telescope vertical 
 * position the ladder on the north side (so that you ascend from the south)
 * undo the two quarter-turn fasteners on the grating hatch
 * hold the grating handle at all times while undoing the 3 orange knobs that secure the grating
 * the bolts are captive so they will unscrew and slide back, but not fall out
 * carefully retract the grating, keeping it level as you do so (you may need to wriggle it slightly if it seems tight)
 * take the grating that was in the instrument to the grating room on the NW side of the dome and replace it in its box
 * back at the telescope, check that the grating is orientated correctly (2 bolts on 1 side, 1 on the other) before attempting to insert it
 * keep the grating level as you insert it, applying firm but gentle pressure until it's flush with the edges of the grating holder frame
 * keep hold of the handle and apply gentle upward pressure while you tighten the bolts
 * if any of the bolts feel stiff or awkward during tightening, gently wiggle the grating a bit (the bolts should turn quite easily)
 * continue tightening until all 3 bolts are fully secure (and can turn no further)
 * with all 3 bolts screwed in fully, close the hatch and lock the quarter-turn fasteners
 * remove the ladder
 * go to the Advanced tab on the control GUI and click the grating angle initialise button (in the bank of buttons on the left)
  • Once you have the correct grating in the spectrograph, enter the approximate starting angle (given in the grating table above) in the Grating angle box and click Go. Compare the resulting arc spectrum with the arc maps in Chapter 10 of the old spectrograph manual. Automated grating angle determination is on the way, but has yet to be implemented in the Quick-Look GUI.
  • The software knows which order-blocking filters should be used with each grating, but it is still a good idea to check that the correct filter is selected (refer to the table above). If necessary, select the required filter from the drop-down menu at the bottom of the Instrument Setup pane and click Go.

Arc lamp and filter selection

  • Two arc lamps are permanently mounted in the spectrograph - you no longer need to swap out a lamp - but the arc lamp filters are still changed manually. On the spectrograph, the CuNe lamp (Lamp 1) is in the horizontal housing, with two slots for filters in the light path. The vertically housed CuAr lamp (Lamp 2) is above it, similarly with slots for two filters at the bottom. Filter requirements are listed in the table above and the filters are stored in a small, labelled wooden box on the bench in the grating room (North-West corner of the dome).
  • The software now decides, based on which grating is in use and the angle at which it is set (whether the grating is being used in first or second order), which lamp to switch on once ARC is selected from the Exposure type drop-down list on the Exposure/CCD info pane.
  • Alternatively, click on the appropriate lamp icon in the instrument schematic - this will switch on the lamp and insert the arc mirror into the beam. Having taken the arc, simply click on the arc mirror icon in the schematic to remove the arc mirror and switch the lamp off. One can also control the lamps using the Lamp/Mirror Settings pane of the SpUpNIC Control GUI. Click the appropriate Change state button to switch the desired lamp on/off, and to move the arc mirror into the beam to take an arc exposure.

Focusing the spectrograph

Before each night's observations, you should focus the spectrograph. This is done using a scripted Hartmann sequence run from the SpUpNIC Control GUI. The process moves a shutter halfway into the beam, takes an arc exposure; then blocks the other half of the beam and takes a second arc exposure. The arc lines are then cross-correlated to measure the shift between the two. The procedure is repeated at a range of camera focus positions until the line shifts are minimised, indicating best focus. This procedure may be performed manually, but is typically run automatically, as follows:

  1. Take an arc to check that the grating angle is correct and to get an idea of the required exposure time (aim for at about 1000 counts in the weaker lines): in the Exposure/CCD info pane on the Main View tab, select "Exposure type" = ARC from the drop-down menu, and enter e.g. 10 seconds in the "Exposure time" box.
  2. If satisfied with the arc obtained, locate the Hartmann focus sequence panel in the Instrument Setup pane on the Main View tab of the SpUpNIC Control GUI (if not, adapt the exposure time and grating angle as required before proceeding).
  3. Select the Auto tab and enter the parameters for the Hartmann sequence: 3.75 for the initial focus position, 0.05 for the focus increment and 9 for the number of steps - with the system still set up as it was for the test arc (lamp on, arc mirror in beam), click Run.
  4. The slit width will automatically be set to 1.05" and the exposure type will switch to HARTMANN, then the GUI will grey out and not be available during the focus sequence (although you will see the Current Camera Focus field changing and the Hartmann shutters indicate Moving.
  5. On completion of the sequence: in the SpUpNIC Quick-Look GUI, in the log box to the left of the spectrum display window, you will see a list of focus positions and their corresponding pixel shifts. Best focus corresponds to a shift of zero.
  6. Enter the best focus into the Requested Camera Focus box on the SpUpNIC Control GUI's Instrument Setup pane and click Go.
  7. The Hartmann sequence ends with the shutter out of the beam, but for some reason it sends the slit width to zero! So select the desired slit width in the Instrument Setup pane and click Go. Check that it goes to the required position, click Go again if it does not do it the first time.
  8. Select "Exposure type" = ARC and take an arc to confirm that the focus looks good.
  9. Click on the arc mirror in the schematic to switch off the arc lamp and move the arc mirror out of the beam.

Observing Setup

Target Catalogue File

Target names and coordinates get propagated into the fits headers by loading a target catalogue file into the Target Info pane and then selecting the appropriate target.

  • Open a terminal on the SpUpNIC PC and use your favourite text editor to produce a simple text file (e.g. Run007.txt) with the format shown below:
 Target_1_name HH:MM:SS.S -DD:MM:SS.S J2000
 Target_2_name HH:MM:SS.S -DD:MM:SS.S J2000
 Target_3_name HH:MM:SS.S -DD:MM:SS.S J2000

(Note: do not include spaces in the target names and use single spaces between the object name, RA, Dec and Equinox)

  • Click on the Load Target Catalogue button, then navigate to, and select, your catalogue.
  • Select the appropriate target name from the drop-down list that appears after the catalogue file has been loaded.
  • If you edit the catalogue file, you'll need to reload it into the GUI before the changes will appear in the drop-down list.

Setting up the slit position on the TCS - using the SpUpNIC Control GUI

The purpose of this step is to figure out where on the acquisition image you need to place your star, in order for it to land close to the ideal spot on the slit. Very bright stars can be seen reflected on the slit jaws, and can be placed on the slit directly, but this is not the case for fainter stars, which need the superior reflectivity of the guide mirror in order to be seen on the acquisition camera.

  • # Move the guide mirror into the beam, either by setting the Acquisition state in the Lamp/Mirror Settings pane of the SpUpNIC control GUI (if it says Guide Mirror Science, click Change), or by clicking on the guide mirror in the instrument schematic.
  • # Acquire a bright star (e.g. ~4 mag from the Bright Stars chapter of the Sutherland Almanac, available in the warm room), roughly centre it on the acquisition camera and continue exposing.
  • # Move the guide mirror out of the beam.
  • # Move the rear-of-slit mirror into the beam (Lamp/Mirror Settings pane, RoS mirror change from Out of beam to In beam).
  • # Turn on the slit illumination (in the "Instrument Setup" pane, "Change" to turn on the lamp). Tune the exposure time/LUT sliders on the TCS until you can clearly see the slit running horizontally across the acquisition image, approximately halfway up.
  • # Using the hand paddle, move the telescope to place the star on the slit, approximately one third of the image width away from the right-hand edge.
  • # Turn off slit illumination.
  • # Open a terminal on Monitor 1, and run the following commands 
 * ssh -Y tcs@172.17.1.224
 * password ******* (you should have been supplied with the password)
 * sudo ./1X1_thread_forms -depth 24
 * password *******
  • # An image window for the rear-of-slit camera will pop up. This looks up at the slit from behind, to enable you to check that your star is centred on the slit. Move the telescope such that the star falls on the centre of the slit image in both x and y.
  • # Move the rear of slit mirror out of the beam and take a test spectrum (e.g. 20 seconds) of the bright star (in the Exposure/CCD info pane, select Exposure type = SCIENCE from the drop-down menu, enter 20 in Exposure time and click Expose).
  • # The resulting image will be displayed on Monitor 2. You are aiming for the spectrum to fall on approximately the central row of pixels. If the spectrum is too high or low, move the telescope slightly in RA, iterate until the star is well positioned.
  • # Once you are happy with the position of the spectrum on the image, on the TCS, add a red marker over the position of the star on the slit (TCS "Pointer" pane: "Markers", "Add a red marker").
  • # Finally, move the guide mirror into the beam, and add a second red marker at the position of the star. This marker will be used to approximately position stars on the slit that are too faint to be seen reflected off the slit jaws.

Focusing the telescope

  1. Acquire a ..... mag star with the guide mirror in the beam

Focusing the acquisition camera

  1. With the guide mirror out of the beam (either set the Science state in the Lamp/Mirror Settings pane of the SpUpNIC Control GUI -- if it says Guide Mirror Acquisition, click Change -- or click on the guide mirror in the instrument schematic to allow the beam through the hole in the guide mirror.
  2. Turn on the slit illumination, either by clicking on the Slit illumination icon in the schematic, or by clicking Change in the Instrument Setup pane.

On the TCS:

  1. Start exposures with the acquisition camera and tune the exposure time/LUT sliders/slit illumination to allow good contrast of the scratches on the lower slit jaw.
  2. Adjust the acquisition camera focus in the bottom right Camera Focus box until the scratches on the slit jaw appear as sharp as you can get them.

User's Troubleshooting Guide

Technician's Guide

Mounting the instrument

Testing the instrument

Unmounting the instrument

Technician's Troubleshooting Guide