Revision as of 13:38, 31 May 2016

SpUpNIC User Manual

NOTE: If slewing the telescope from the TCS, please watch from the dome floor! Care must be taken to ensure that SpUpNIC does not run into the piers.

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SpUpNIC Call list

SpUpNIC Instrument software: Carel van Gend 076 818 1312

Rear-slit-viewer camera & images: Steve Potter

Commissioning/general issues: Lisa Crause 082 498 4780

Telescope software issues: standby **113 (0829034869) or 9118

Electronics Issues: standby **103 (0767895131) or 9117

Mechanical Issues: standby **104 (07678951232)

Introduction

Here we provide a 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 should suffice!

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

• 26-27 May 2016: A mechanical brake was placed on the grating mechanism. Inside of lower box covers coated with resin to prevent dust.
• early May 2016: Lower box optics cleaned (black dust was coming from the covers).
• 16-23 December 2015: The SpUpNIC software evolved substantially during this week. The wiki has been adapted to reflect these and other subsequent 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.
• Check that the required filter is in the beam (or left open if required).
• 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.
• Select the exposure type (ARC, BIAS, SCIENCE, FLAT, TEST).
• If appropriate, set the exposure time and number of exposures.
• Load your target catalogue file.
• 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.

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

• Warning: During your start-off you will have been told about the grating instability problem. We applied a mechanical fix when the instrument is off the telescope in early April. This improved the situation, but did not completely resolve the issue - so until such time as we have completely fixed the problem, we urge users to bracket all target observations with arcs (to be taken immediately before and after the object exposures) to minimise the impact of the declination-dependent movement of the grating.

• The angles listed in the right hand column of the table are just to get one into the range where lines are visible for a given grating. One then needs to adjust the grating angle to obtain the desired wavelength range - consult the arc maps in the old spectrograph user manual (a hard copy is available in the warm room).

• 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 - running a Hartmann sequence

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:

• 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.
• 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).
• 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. For some unknown reason, this routine might not work the first couple of times - in which case you should close and restart the SpUpNIC control GUI and try starting the Hartmann sequence again.
• 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.
• 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.
• Enter the best focus into the Requested Camera Focus box on the SpUpNIC Control GUI's Instrument Setup pane and click Go.
• 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.
• Select "Exposure type" = ARC and take an arc to confirm that the focus looks good.
• 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.
• Click on the icon for the rear of slit camera (on the left-hand panel).
• 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 (the RA- button moves the spectrum downwards in the image), 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

• Acquire a ~11th mag star (e.g. one of the spectrophotometric standards) with the guide mirror in the beam.
• Position the star on the appropriate red box on the acquisition image.
• On the instrument schematic, set the guide mirror to Science (so that light reaches the slit).
• Also insert the rear-of-slit mirror into the beam to direct the light to the Lodestar (rear-of-slit) camera.
• View the stand-alone rear-of-slit software window.
• Click on the "continuous" button for an ongoing series of 2 second exposures.
• Open the slit wide, to about 4".
• Adjust the slider bars at the bottom of the image (both most of the way to the left) to set the brightness and contrast.
• Use the hand-paddle to position the star near the centre of the slit (in both X and Y).
• Adjust the telescope focus with the hand-paddle in steps of 3-5 units and assess how the star image changes.
• The star will move around due to the translation of the secondary mirror, so adjust it back into view with the hand-paddle if necessary.
• Astigmatism in the system extends the star image diagonally and the orientation indicates whether the focus is too high or too low.
• Best focus is where the star is as round and sharp as possible.

Focusing the acquisition camera

• Having focused the telescope as described above, one needs to focus the acquisition camera.
• The star used to focus the telescope may be too bright, so aim for something fainter (e.g. a guide star that needs a ~1 sec exposure).
• Adjust the acquisition camera focus with the up/down buttons in the lower right corner of the TCS GUI to get the stars as sharp as possible.

User's Troubleshooting Guide

Please be sure to inform the instrument team of any technical issues you encounter during your run, either by emailing lisa(at)saao.ac.za, or by means of the SAAO's online fault forum.

If the slit runs anything but horizontally across the rear-of-slit image, the camera needs mechanical relocation

• The rear-of-slit camera has a spring-loaded kinematic mount which can move slightly if the USB cable snags or the camera gets bumped somehow
• If this happens, the slit image will be displaced, making acquisition difficult
• Insert the rear-of-slit mirror and turn on the slit-illumination to confirm that this is indeed the case
• Go out and grip the rear-of-slit camera assembly and gently jiggle it - the camera will pop back into its required position
• Use the slit illumination to verify that the slit runs horizontally across the image again

If the rear-of-slit camera window does not produce any images (though the exposures seem to count down), it probably needs a reset

• Check that you've got the light path right: guide mirror centred and the rear-of-slit mirror in the beam
• Then check that it's not an image scaling issue, by turning on the slit illumination (which is bright enough to show up under most circumstances)
• If you still don't see anything, go out and gently unplug the black USB cable that goes in to the back of the camera (look for the red LED on the small camera that pokes out of the south side of the instrument's lower box) and plug it back in again
• Start the exposures again and check with the slit illumination