Difference between revisions of "Lesedi"

Revision as of 01:10, 11 June 2021

Lesedi is a 1-metre, Alt-Az, f/8, Ritchey-Chretien telescope built by APM Telescopes, and installed in the dome that previously housed SAAO's 30-inch Grubb Parsons equatorial. There are two Nasmyth foci, each with an instrument rotator and identical corrector optics. This page describes the facility and its operation.

Current status and issues

Things to be aware of at the current time (updated 20/11/2020):

1. If you encounter a loss of dome or shutter function, please report the symptoms and the time it occurred so we can check the logs for the cause. The fix will be to ask the IT technician/electronics technician/Hannah to restart the SiTech software. The shutters can be closed manually from the dome floor (with lockout switched on) if you need to close up in a hurry and it turns out to be quicker to find someone to press a button than restart the software.
2. The alt-az slew command has a liiittle bug and can't be used from the browser TCS just yet (this doesn't affect observations).

Contact numbers

To receive calls, the phones in the warm room and on the observing floor can be reached by the following numbers:

Extension number: 9109 (to phone from within the observatory)

To make calls if you have a problem that isn't addressed in this wiki or the fault forum (remember to dial the ** where given):

1.9m/74-inch observer: 9107

1.0m/40-inch observer: 9108

Cape Town remote observing station: 7027

Standby electronics technician: **103

Standby mechanical technician: **104

Standby IT technician: **113

A guided tour of the dome

The purpose of this section is to introduce you to the facilities and equipment you will need during your run. The tour begins at the front door of Lesedi's dome. To aid orientation, the domes of MeerLICHT, Lesedi, and the 40 inch are aligned East-West, perpendicular to the main road that passes SALT at the Northern end of the plateau and leads to the "Robotic Row" of telescopes in the South. A code (which you can obtain from the standby technicians/your support astronomer/other observers) is required to open the door.

Main lighting circuit switch

Just inside the entrance on the left-hand wall is a master switch to control all the lighting circuits in the building. Switch it on if you are working in the building, and always ensure that it is switched off when you leave, especially if people are observing remotely.

Light switches

• Foyer and stairwell light switches can be found on the right-hand wall as you enter the dome, just around the corner to the right, at the foot of the stairs (foyer light switch on the right, stair lights on the left). There is a second switch for the stairwell lights at the top of the stairs.
• Light switches on the left at the top of the stairs. The left-hand switch is for the stairwell lights; the other for the observing floor incandescents.
• The switch for observing floor fluorescent lights is located up the ladder on the observing floor, on the dome control console mounted on wall above the North end of the pier. These are also under software control.
• The slew lights on the ring beam are under software control only.

Ground floor facilities

As you enter the dome on the ground floor, you will find the following facilities:

• Fire extinguisher: mounted on the left-hand wall as you enter.
• First aid kit: on a shelf to the right as you enter the dome.
• Toilet: through the first door on the left as you enter the dome. The light switch is outside the door on the right. The right-hand switch operates an extractor fan(!).
• Kitchen:, second door on the left. It has a microwave, coffee maker, kettle, toaster, snackwich and an array of cutlery and crockery in the cupboard under the sink. There are jars of teas, coffees, hot chocolate and sugar. If these jars become empty, return them to the hostel kitchen in your night lunch bag for refilling. The kitchenware is cleaned daily by the hostel staff, except at weekends.

The control room

The control room, or "warm room", is the door on the right-hand side, opposite the kitchen. It contains an air-conditioned server room and has the following resources at your disposal:

• A PC ("lesedi-nuc") for running the telescope and instrument control systems.
• Several network cables and power sockets for use with laptops.
• Lights on a dimmer switch (push and hold to adjust the brightness) and a desk lamp.
• An air conditioner to heat or cool the room.
• A stereo compatible with iPods and iPhones, and plays CDs, MP3s from DVDs and USB devices, and has a radio.
• A phone (you'll need a PIN from IT to dial out).

The Observing Floor

At the top of the stairs, be careful not to trip over the raised hatch in the floor (this is for lowering the primary mirror for aluminising). You will find Lesedi on a raised pier, surrounded by a metal grid floor, accessed by a ladder. The North end of the pier is nearest the stairs. Familiarise yourself with the following:

• Dome control console at the North end of the pier.
• Dome lockout switch beside the dome control console at the North end of the pier. Note that this does not lock out the telescope hardware. It disables the dome and the browser TCS functions. The lockout should be switched on (a red light on the box will flash) if people are working on the dome, otherwise left off.

The Telescope

The Nasmyth ports are identified as left and right, defined from the point of view of someone standing behind the parked telescope, i.e. looking at the back of the primary mirror cell. SHOC is mounted on the right-hand port, and Sibonise will be commissioned on the left. Future instruments (Mookodi (a low-resolution spectrograph incorporating a high-speed imager to replace SHOC) and a fibre-fed echelle) will be co-mounted on an instrument selector on the right-hand port. A motorised tertiary mirror allows an instrument on either port to be selected in seconds.

The telescope is parked facing East, the dome to the West. There shouldn't be any need for manual interaction with the telescope during the night, but you should ensure that the observing floor is clear of ladders and other obstacles before moving the telescope, and that the mirror covers are closed before opening the dome.

Labelled layout of the telescope and observing floor with telescope and dome both parked, as seen from the Mobotix webcam.

Webcam

There are currently two webcams to use to keep an eye (and an ear) on the telescope:

• The Mobotix camera sees the full observing floor, but has no sound.
• The UniFi camera sees the shutters, the top half of the telescope and half the observing floor. The UniFi webcam must be viewed in Chrome/Chromium (not Firefox) for the sound to work.

Both webcams are mounted on the dome, which can be rotated to view specific areas of the observing floor.

Observing limits

Meteorological constraints

The dome must be closed when any of the following weather limits is reached:

• Humidity: T_external - T_dew ≤ 1.5
• Wind speed: 60 km/h
• Heavy cloud

In case of strong wind and rain, please park the dome shutters facing into the wind. This can be done remotely by rotating to the required azimuth in the TCS "Advanced" tab, or on-site by putting the dome in lockout and rotating left or right using the dome control console.

Meteorological information

The following should be used for regular monitoring of external conditions while observing:

• DIMM seeing data and all the weather stations on the plateau are summarised on this page
• For assessing sky conditions, SALT and LCO operate all-sky cameras, also available on the website above.

Telescope pointing limits

Lesedi can safely point between 30° and 89° above the horizon, at any azimuth. There are no obstructions in the dome to be aware of (assuming the observing floor has been checked for ladders etc).

If the telescope reaches an altitude limit, it will simply stop tracking and can be pointed to a new position. Note that the TCS will not warn you that the limit has been reached. The azimuth rotation is limited to a range of 400° in order to avoid twisting the cables that pass through the pier. It is therefore possible to encounter an azimuth limit while tracking, but this should be rare because the limits are in the West. If a limit is reached, the telescope should automatically "unwind" by 360° in azimuth and continue tracking (if it doesn't, simply repoint the telescope). If the telescope with within 40° of an azimuth limit when slewed to a target, it will "unwind" to avoid the limit.

TCS Overview

The user interface is a web browser that communicates with Lesedi's underlying control software. The browser-based software will be referred to as the "TCS" and the back-end software as the "SiTech software". The SiTech software consists of seven GUIs that must be running in the background for the TCS to function. Ideally, these GUIs will remain running at all times and the user will only interact with the TCS.

The TCS user interface runs in a web browser. The functionality for routine observing is accessed from the Controls tab, while a second tab provides access to more Advanced functions. Warnings requiring action pop up in orange, and messages appear in white bubbles that can be cleared by clicking the "x". The emergency stop button, startup/shutdown button, timing info and dome schematic are always visible on both tabs.

Safety

Note that there is no hardware lockout for the telescope (except for brackets that can be fitted to hold the telescope vertical for e.g. primary mirror removal). All the subsystems' motors are brushless DC motors and remain powered up all the time; powering down the motors would leave the telescope and subsystems free to move under gravity or external forces (e.g. leaning on it). There is a dome lockout, which is a physical switch in the dome that prevents the shutters and dome from moving. As a safety feature, the TCS disables all actions when the dome lockout is on and displays the warning shown in the image below. Before the telescope can be used from the TCS, you must ensure that it is safe to turn off the lockout, then do so using the switch at the North end of the pier in the dome. If observing remotely, you will need to call a technician to do this for you.

This message on the TCS indicates that the dome is locked out and the TCS cannot be used. The dome must be checked for safety before switching off the lockout and continuing.

The Controls Tab

Below is a screenshot of the main "Controls" tab of the TCS, where everything required for routine observing is located. There is one other tab, for more rarely used "Advanced" functions. The Controls tab is split into four main panels: command of the telescope and instrument selection on the left; the status of each subsystem in the middle; time and positional information on the upper right; and important buttons that need to be easily accessible on the bottom right.

The main Controls tab of the TCS indicates the status of all subsystems; displays the time, telescope and dome position; gives access to a target catalogue; and allows the user to slew and offset the telescope, adjust the focus focus and select the required instrument.

Clicking on the three vertical dots beside a subsystem displays a drop down list of further subsystem status info, as can be seen below "Dome" and "Rotator 1" in the central panel of the screenshot above. The meaning behind the colour coding of subsystem status is as follows:

• Green: a subsystem or state is either selected (e.g. in the screenshot above, the telescope is tracking at the sidereal rate, and the SHOC instrument is selected), or is in the correct state for observing (e.g. mirror covers open, dome shutters open, telescope tracking, dome tracking, rotator 1 (SHOC) tracking).
• Orange: a subsystem is in an inappropriate state for observing. If the mirror covers or dome shutters are closed, their indicators would turn orange; likewise if the lights are switched on their indicators would be orange. In the screenshot above, Rotator 2's indicator is orange - this is acceptable because SHOC (selected in green on the left) is mounted on Rotator 1, so only Rotator 1 needs to track with the telescope.
• Blue: a parameter that has a numerical value but no right or wrong state is indicated in blue, e.g. azimuth or airmass.

Emergency Stop

It is important to note the Emergency Stop button on the lower right of the TCS display. It is always visible on both tabs, and will stop the motion of the dome, shutters, telescope, rotators and secondary mirror. It will not stop the autoguider XY-slides, the mirror covers or the tertiary mirror. The Emergency Stop button should be clicked if anything that is moving is going to cause a hazard. Once clicked, the Emergency Stop button will be toggled to read Reset, and you must ensure that it is safe to reset all the subsystems before pressing this button to continue.

The Startup button

The Startup button is not a "power-up" button, as all telescope subsystems should be powered up at all times. The Startup button should be used only when you intend to open up to observe, as it opens the dome and the mirror covers.

If you don't want to run the full Startup procedure (e.g. because it's daytime and the dome should not open), but do need to interact with the telescope, individual subsystems can be commanded from the Advanced tab. Buttons on the Controls tab will work without running Startup (with the exception of Shutdown), though the telescope will need to be "unparked" from the Advanced tab before it can slew.

The Startup button runs a script that performs the following tasks in this order:

1. Take remote control of the dome
2. Switch off fluorescent lights
3. Switch on slew lights
4. Open dome shutters
5. Open mirror covers
6. Unpark telescope so it can slew
7. Set dome to track telescope
8. Select SHOC rotator
9. Switch off the slew lights

You can watch the startup procedure from the webcam. While the procedure is running, the button displays a revolving circle and the status panel on the Controls tab is updated as each subsystem is activated. Don't try to perform any other operation until the procedure is complete, when the text on the Startup button will be replaced with "Shutdown". The SHOC rotator is selected on startup to ensure that observations are not made with the tertiary mirror in an unknown position, so to use Sibonise you will need to select the instrument after the startup procedure has completed.

The Shutdown button

Once the Startup procedure is complete, the button will read Shutdown, and should be used to close everything at the end of observing. The shutdown script essentially reverses the Startup procedure:

1. Set the dome to remote control (in most scenarios it will already be in remote, but just as a precaution)
2. Switch on slew lights
3. Close mirror covers
4. Close dome shutters
5. Stop dome from tracking telescope
6. Park dome at az=270°
7. Park telescope at az=90°, alt=50°
8. Park rotators
9. Switch off slew lights
10. Switch off fluorescent lights (likely to be off, but as a precaution)

Control of the dome is not given up, but it can be "taken" using the lockout in the dome. It is not necessary to lockout the dome after use; staff will use this function when working in the dome.

The Advanced Tab

The Advanced tab is made up of four panels, one for telescope-related functions including mirrors and covers; one for the rotator in current use; one for the dome, including lights; and the panel containing positional and timing information and vital buttons, replicated on the Controls tab.

Green buttons indicate a state appropriate for observing. Below is an explanation of the features of the Advanced tab:

Telescope panel:

• Park (alt=50° az=90°) or unpark the telescope (also turns tracking on) to enable it to slew.
• Slew the telescope to specified alt-az coordinates. The telescope will then start tracking.
• Start/stop the telescope tracking. Tracking should be on while observing, otherwise off.
• Open/close the mirror covers. Covers should be open when observing, otherwise closed.
• Put the altaz, secondary and tertiary mirror motors in Auto mode. Motors should always be in Auto unless there is a fault.

Rotator panel:

• Turn tracking on/off for the rotator on which the instrument currently in use is mounted. Tracking is automatically disabled for the other rotator. Tracking "on" does not necessarily mean that the rotator is moving, but that it will move if the telescope is tracking. Rotator status can be found on the Controls tab, where the angle will be updating if the rotator is tracking.
• Put the motor in Auto for the rotator currently in use. The motor should always be in Auto unless there is a fault.

Dome panel:

• Take control of the dome (needed for all dome functions except controlling the slew lights)
• Rotate the dome to a specified azimuth
• Set the dome to start or stop tracking the telescope. Tracking should be on while observing, otherwise off.
• Switch the "Lights" on/off. This refers to the fluorescent lights mounted high in the dome.
• Switch on/off the slew lights. This refers to the dimmer lights mounted on the ring beam, that can be used to check on the telescope using the webcam.
• Park the dome (az=270°).
• Open/close the dome shutters.
• Stop the dome rotation or shutter movement.

Position/timing/vital functions panel:

• The schematic shows the shutter status (red=closed or moving, green=open) and position, and the telescope status (slewing=red, tracking=yellow) and altaz position. No indication of telescope presence implies that it has not tracked or slewed for the past 30 minutes.
• The time is displayed in SAST, UT, LST and Julian Date.
• Emergency Stop.
• Startup or Shutdown, whichever is the opposite of the current status.

Start-up recipes

Start-up in Sutherland

Follow this procedure to prepare the telescope and dome for observing in Sutherland:

1. Check the weather conditions here. If windspeed <60km/h and T-T_dew > 1.5 (see observing limits), continue with step 2.
2. Check the observing floor and clear any obstacles (e.g. ladders) that may obstruct the telescope.
3. Switch off the lights everywhere except in the warm room.
4. Log into lesedi-nuc in the warm room (address, username & password in the User Resources google doc), open a browser and navigate to the webcam and click "Live Feed". Adjust the PC's volume to ensure that you can hear the ambient noise in the dome.
5. Open a second browser window and navigate to the TCS (URL, username & password in the User Resources google doc).
6. Click the STARTUP button on the TCS. This will switch on the slew lights so you can watch it open the dome, baffle and mirror covers, and set the dome to follow the telescope, then switch off the slew lights. A blue progress circle will rotate on the button while all the commands are executed - don't try to send any other TCS commands until it disappears, indicating that the startup procedure is complete.
7. Select the Instrument you require by clicking either SHOC or SIBONISE to the mid-left of the display. The selected instrument name will turn green.

Start-up remotely

On-site technical staff should have checked the facility in the afternoon, clearing any obstacles, turning off the dome lockout and any lights that are not under software control.

1. If you are not working on site at SAAO in Cape Town, enable your SAAO VPN.
2. Check the weather conditions here. If windspeed <60km/h and T-T_dew > 1.5 (see observing limits), continue with step 2.
3. Open a Chrome or Chromium browser, navigate to the Unifi webcam, click "Live Feed" and check your volume level so you can hear sounds from the dome. Also open this [https:10.2.50.12 webcam] which gives a wider view of the observing floor.
4. Open another browser window and navigate to the TCS (URL, username & password in the User Resources google doc).
5. Navigate to the "Advanced" tab of the TCS, and in the central "Dome" section, turn the Slew Lights ON and check the webcam to see if observing floor is clear (if not, call the standby technician). Switch the Slew Lights OFF.
6. Click the STARTUP button on the bottom right of the screen. This will switch on the slew lights so you can watch it open the dome, baffle and mirror covers, and set the dome to follow the telescope, then switch off the slew lights. A blue progress circle will rotate on the button while all the commands are executed - don't try to do anything else until it disappears, indicating that the startup procedure is complete.
7. On the TCS "Controls" tab, check that the Instrument you require is selected (highlighted in green to the mid-left of the display), and if not, click either SHOC or SIBONISE. SHOC is automatically selected on startup.
8. On the central panel of the TCS "Controls" tab, check for green indicators showing the status of each subsystem: Mirror covers = Open; Secondary & Tertiary mirror motors = Auto; Dome: Control = TCS and Tracking = On; and the relevant rotator for your chosen instrument Tracking = On and Motors = Auto.

Instrument start-up

Follow the instructions on the SHOC wiki and note the Lesedi-specific SHOC info further down this page.

LCU start-up

There is a local control unit (LCU) that monitors the weather and the connection of the remote user, which can shutdown the facility if the connection is lost for a certain length of time, or the weather reaches the operational limits. The LCU will be incorporated into the TCS browser, but for now we need to run it in a terminal using the following commands:

     ssh lcutest@10.2.100.92
     cd programming/lesedi-lcu/lcu/
     . ~/.pyenv/lcuenv/bin/activate
     python lcu.py

Keep the terminal visible at all times. It will issue a 60 second warning before commencing a shutdown in the case of bad weather, and if you don't want to shutdown (e.g. if it has misjudged the weather), you can Ctrl-C to exit the LCU (and hence not shutdown).

Sky flat recipe

If the sky is clear during morning/evening twilight, you will be able to take sky flats.

1. (a) If you're starting with the facility closed:

• Follow the start-up procedure.
• Follow the appropriate instrument setup procedure.

This will result in a stationary telescope pointing out of the open shutters with open mirror covers.

Or,

1. (b) If the telescope is already up and running, dome and mirror covers open: On the TCS Advanced tab:

• On the central Dome panel, make sure Tracking is switched ON,
• On the left-hand Telescope panel, click Park Telescope.

Then:

2. On the instrument PC, select the required filter. If you need flats in a variety of filters, be sure to cycle through them in the correct order (e.g. UBVRI during evening twilight; IRVBU in the morning). This also applies if you need a range of prebin settings (i.e. start with low binning in the evening; high to low binning in the morning).

3. You can easily take a minimum of 15 flats in each filter/prebin setting with SHOC; Sibonise has longer readout times.

Observing recipes

Acquiring a target

1. Follow the facility start-up procedure.

2. Check that the selected target is within the pointing limits. If you're not sure, or want to find out the exact altaz of your target, you can enter the coordinates into the input boxes on the upper left panel of the Controls tab, then click "Visibility...". This brings up a panel that shows the altitude and azimuth of the target at that moment and the times at which the target rises and sets at the 30° altitude limit.

Then/or, either:

3(a) In the TCS Controls tab enter the RA, Dec (you can use spaces for delimiters, i.e. hh mm ss, though colons will work too) and Equinox into the boxes on the upper left panel and click Go.

or:

3(b) In the TCS Controls tab click on the box labelled Targets, then select the desired object from the dropdown list. To populate the dropdown list, see the catalogue instructions.

The telescope will slew to the target, and its movement will be plotted in red dots on the schematic in the right-hand panel. The "Go" button will become a "STOP" button, which you can click to stop the telescope. Once it reaches the target coordinates, the telescope will start to track and yellow dots will show the track progress on the visibility plot. If nothing happens, the target is probably outside the observing window - return to step 2.

4. The telescope will track the target until you click STOP, or until it reaches the lower altitude limit (note that the TCS will not warn you if this happens, so keep an eye on the visibility plot). To run SHOC, follow the instructions on the SHOC wiki.

5. Lesedi's pointing is excellent, so your target should land very close to the centre of the SHOC image. The image orientation with no "flips" applied in the SHOC software (check the Advanced tab of the SHOC control) is usually North up, East to the left with SHOC, but will change to North down, East to the right for a short time after passing through the meridian.

To adjust the pointing (e.g. to position a target and comparison star in the field), in the TCS Controls tab, click on the three dots beside "RA offset" (to shift the image horizontally) or "Dec offset" (for a vertical shift), enter the size of the required offset in arcsec, then click on the North, South, East or West button to move the telescope in the desired direction. When you're done, clicking the three dots again will hide the offset boxes.

6. The focus position is reported in the central status panel on the Controls tab. A reasonable starting point for SHOC focus with a filter in the beam is ~2000μm, or ~1800μm without a filter. Once you're close to focus, a reasonable increment for small adjustments is ~10μm. Focus the telescope using the Adjust Focus... button, which brings up a box in which you can enter the focus increment, then click + or - to add or subtract e.g. 10μm to the focus position.

Autoguiding

As of February 2021, there is a web browser interface to the standalone autoguider control GUI run on 1ms1, so users no longer need to VNC to Lesedi-NUC. Note that the original autoguider software does need to be running on Lesedi-NUC in order to operate the guider, but you shouldn't need to interact with it directly. The procedure for autoguiding via the browser is described below.

Open a web browser and navigate to:

  10.2.2.31:5001

The autoguider control interface looks like this:

The web browser interface for Lesedi's autoguider (click to enlarge).

The autoguider camera image is displayed on the top right, with the finderchart image below. There will be a green "Online" indicator at the top left if all is well; if it's red ("Offline") the web server may not be running (see instructions above)+++++++ or the autoguider control software might not be open on Lesedi-NUC. If it looks ok, continue reading this section, otherwise skip to the next section+++++++.

To acquire a guide star, do the following:

In the "X-Y Slides Control" section in the bottom left:

1. Check that "Error = 0". If "Error = 1" click "RESET".
2. Click "INITIALISE" to initialise the XY slides. Confirmation of a successful initialisation is indicated with "Initialised = 1".
3. Enter the RA and Dec of your target on the two lines below "Fetch DSS image". Use space delimiters, not colons, then press the "Fetch DSS image" button.
4. A catalogue image of your field will load in the bottom right. Click on a fairly bright star in the top half of the image to use as a guide star. The closer to the top of the image the better, to avoid vignetting the SHOC field (central) with the Lodestar camera pickoff arm.
5. Click "GOTO GS" to the left of the finderchart. You will see the XY slide coordinates updating and the status "Moving = 1".
6. In the upper-left "Exposure Control" section, enter an exposure time in milliseconds (e.g. 2000) and click "Start Continuous".
7. The Lodestar image will continuously update. Your guide star should be visible - click on it, then click "Search guide star" in the "Guiding Control" section, and watch for the message box below it to be populated with numbers and a time stamp, beginning with e.g. "zmax = 12345". The zmax value is counts on the star, so make sure it isn't saturated (<65536), else reduce the exposure time.
8. Click "Guide". If successful, the guide button will turn green, and the star will continuously be pulled back towards the red cross that appears on the image.

If guiding fails at any point during a track (e.g. due to cloud), the button will turn red. Try increasing the exposure time (change the value and click "Start Continuous") and click "Guide" if the star is sill near the red cross. If the star has drifted, you can either offset the telescope to bring it back to its original position and then click "Guide", or if it is not important to you to keep the target in the original position on the science image, you can repeat the guide star selection procedure to resume guiding in the new position.

To stop the autoguider at the end of the night:

1. Click "GUIDE" to stop guiding.
2. Click "Stop Continuous" to stop exposing.
3. Click "INITIALISE" to return the XY-slides to the home position.
4. In the terminal running the web server, press CTRL-C to kill the process.

Backup Autoguiding Procedure

Some users have encountered repeated loss of connectivity issues that make it very difficult to use the browser control for autoguiding. In this case, you can interact directly with the backend software by following the instructions below.

1. Connect to the NUC via remote desktop, e.g. for Linux use the Remmina client, set the server to lesedi-nuc.suth.saao.ac.za and enter the username and password from the Lesedi User Resources Google document.

1. Once connected to Lesedi-NUC, the autoguider software should be running. If it isn't, or if it fails to respond, follow these instructions.+++++++

To start guiding:

1. On the main autoguider GUI, if using SHOC select Slide 0; or Slide 1 for Sibonise.
2. If the status of any of the error codes (Err, XLL, XUL, YLL or YUL) is 1, click RESET, then INITIALISE. "FAKE" should always be a green "Fake is OFF" button while guiding - this is a test function for engineering purposes.
3. To start continuous exposures with the autoguider Lodestar camera, enter a number (~2 seconds) in the box on the right, and click CONTINUOUS. Binning should be set to 2x2. To get a workable look-up table, on the left-hand side of the main autoguider GUI, move the uppermost vertical slider ~1/6 of the way from the bottom. Leave the other two sliders in their default positions (lower vertical slider halfway up; lower horizontal slider all the way to the left; upper horizontal slider all the way to the right).
4. Enter the target coordinates (using spaces as delimiters, e.g. 12 34 56 -76 54 32) in the separate GS_FC window and click "Set".
5. Check that a finder chart loads showing your field. Guide stars are to be selected from outside the green box in the finder chart image. When North is Up in the SHOC/Sibonise image, click on a star in the upper half of the image to use as a guide star.
6. On the XY Slide Control section of the main GUI, click "Goto GS". This will send the XY slides to the position you clicked on the finder chart.
7. Click the "Pick G_Star" button in the "Guiding" panel, which will turn dark blue to indicate that it's ready to receive your guide star selection.
8. Choose a star in the Lodestar image and click on it. The "Pick G_Star" button will turn green if it recognises the star. If the button turns grey, your selection has been unsuccessful and you will need to click the "Pick G_Star" button again and then try clicking on a different star.
9. Click the red GUIDE button - it should turn green to indicate that it has started guiding.

If guiding fails at any point during a track (e.g. due to cloud), the button will turn red. Try increasing the exposure time (change the value and click "CONTINUOUS") and click GUIDE if the star is sill near the box. If the star has drifted, you can either offset the telescope to bring it back to its original position and then click GUIDE, or if it is not important to you to keep the target in the original position on the science image, you can repeat the guide star selection procedure to resume guiding in the new position.

To stop the autoguider:

1. Click "GUIDE" to stop guiding.
2. Click "STOP CONT." to stop exposing.
3. Click "Initialize" to return the XY-slides to the home position.

Autoguider troubleshooting

If the autoguider GUI isn't already running (or is not responding), open a terminal, login to 1ms1 (username & password in the google doc) and check for any autoguider jobs already running:

         ssh -Y observer@1ms1.suth.saao.ac.za
         ps aux | grep readPLC

If there are outstanding jobs, the result will be something like:

        root      1310 99.8  0.1  39384 13016 ?        R    Jun21 5284:08 python readPLCandLesediV1.py
        root     14103  0.0  0.1  39384 13040 pts/11   S+   14:41   0:00 python readPLCandLesediV1.py
        root     20411 99.9  0.1  39384 13092 ?        R    Jun23 1187:37 python readPLCandLesediV1.py
        observer 25808  0.0  0.0  14224  1032 pts/12   S+   17:49   0:00 grep --color=auto readPLC

These processes remain "hanging" if the xyslides software was not closed properly using the EXIT button. You need to kill them using their IDs given above, e.g. in this case:

        sudo kill -9 1310 14103 20411

Then in the same terminal, check that the Lodestar cameras are connected:

        observer@sa1:~$ lsusb
        Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
        Bus 001 Device 079: ID 1278:0507 Starlight Xpress Lodestar autoguider
        Bus 001 Device 081: ID 1278:0507 Starlight Xpress Lodestar autoguider

If you do not see the Starlight Xpress listed then the cameras are not detected on the USB ports and the icron devices probably need power cycling.

Once any rogue processes are killed and the cameras are connected, start the autoguider GUI:

         cd /home/observer/xyslide_lodestar_GUI_testing
         sudo ./main_prog -depth 24

If you intend to run the autoguider from the browser you don't need the next step, but follow it if you will be interacting with the backend software. To run the finder chart software, open a new terminal (or a new window in the same terminal with CTRL-SHIFT-T) and login again to 1ms1:

         ssh -Y observer@1ms1.suth.saao.ac.za
         cd /home/observer/GS_FC
         python genfinderLesediFeb2020.py

This brings up a finder chart and a coordinates box.

SHOC on Lesedi vs. other SAAO telescopes

If you notice any funny effects with the SHOC interface running in Chrome (e.g. image not displaying, red lines being deposited in the plot area by the cursor), run SHOC from Firefox and these should be resolved.

SAAO has two Andor cameras, interchangeably referred to as SHOC. The one largely dedicated to Lesedi is "shocndisbelief" ("shocnawe" is usually on the 1.9- & 1.0-m). Shocndisbelief has a roving bias issue in the 1MHz mode (a differential count level occurs, the number of rows affected varying with time) so it is recommended to operate in 3MHz readout. SHOC's field of view is larger on Lesedi than on the other telescopes (5.7x5.7 arcmin²), with a platescale of 0.33"/pixel, so the appropriate binning is usually 1x1 or 2x2.

On the Advanced tab of the SHOC control browser, set both "Flip X Axis" and "Flip Y Axis" to OFF to set SHOC's image display to North up and East to the left on Lesedi.

The login for SHOC on Lesedi is given in the Lesedi User Resources google doc.

Filters

At present, SHOC has one 8-position filter wheel, containing UBVRI, a clear filter to match the focus of the Bessell filters, and two empty slots. The SHOC software identifies the filter in each position. Filters must not be removed from the filter wheel.

Data

To retrieve your data from the SHOC PC during your run, use this command from the PC on which you which to view the images:

           rsync -avzP shoc1m@shoc1m.suth.saao.ac.za:/data/lesedi/shd/YYYY/MMDD/SHD_YYYYMMDD.nnnn.fits .

where YYYY is the year, MMDD the month and day, and nnnn the filenumber.

Shutdown recipes

Shutting down using the SHUTDOWN button

1. Ensure that you can see the feed from one of the webcams.
2. Click the SHUTDOWN button on the bottom right of the TCS screen. This will switch on the slew lights so you can watch the mirror & baffle covers close, the dome shutters close, the telescope and dome park, then the slew lights switch off. A blue progress circle will rotate on the button while all the commands are executed; it will disappear once the shutdown procedure is complete.
3. On the central panel of the TCS "Controls" tab, check for grey or orange indicators showing the status of each subsystem: telescope Tracking = Off (grey); Mirror covers = Closed (orange); Dome (orange) Tracking = Off (grey) and Shutters = Closed (orange) [the arc indicating the shutters on the schematic will also turn red].
4. On the left-hand panel of the Controls tab, there should be a message in orange stating "Unpark telescope to slew", indicating that the telescope is parked.
5. If any of the above is not in the correct state, you can rectify it using the relevant buttons on the Advanced tab.
6. Logout of the TCS and close the webcam browser windows.
7. Stop the autoguider exposures and initialise the XY slides.
8. Make sure the instrument (SHOC or Sibonise) is not exposing and turn off the camera.

Shutting down without the SHUTDOWN button

If you woke up the telescope with the STARTUP button, it will have turned into a SHUTDOWN button (these will be changed to independent buttons in a later version of the software). If there has been a failure in the nighttime that has resulted in the web server being restarted but the telescope remaining open, the software will forget that the startup procedure was run before the crash, so there will be no shutdown button. Here you have two choices: if there is no urgent reason to close (e.g. bad weather), you can press STARTUP and wait for the commands to execute (even though everything is already running), then close up using the subsequent SHUTDOWN button. The alternative is to shutdown each subsystem individually from the Advanced tab of the TCS:

1. Ensure that you can see the feed from one of the webcams. On the TCS Advanced tab:
2. In the central Dome panel, turn the Slew lights "ON".
3. In the left-hand Telescope panel, click Mirror Covers "CLOSED" and wait for the "OPEN" button to turn grey.
4. In the central Dome panel, click "CLOSE".
5. In the left-hand Telescope panel, click "PARK TELESCOPE".
6. In the lower left Rotator panel, click Tracking "OFF".
7. In the central Dome panel, click "PARK DOME".
8. Check the webcam image for a closed dome and a parked telescope.
9. In the central Dome panel, turn the Slew lights "OFF".
10. On the Controls tab of the TCS check for grey or orange indicators showing the status of each subsystem: telescope Tracking = Off (grey); Mirror covers = Closed (orange); Dome (orange) Tracking = Off (grey) and Shutters = Closed (orange) [the arc indicating the shutters on the schematic will also turn red].
11. If any of the above is not in the correct state, you can rectify it using the relevant buttons on the Advanced tab.
12. Logout of the TCS and close the webcam browser windows.
13. Stop the autoguider exposures, initialise the XY slides and close the remote session to lesedi-nuc.
14. Make sure the instrument (SHOC or Sibonise) is not exposing and turn off the camera.

Troubleshooting