• Use your favorite vncviewer to connect to alpha.pepsi.lbto.org (IP
    • display :1 contains the User Interface
    • dispay :2 contains the PEPSI instrument telemetry

Startup Instrument Interface

The User Interface desktop is typically populated with all GUI's needed to run the instrument. If there is an issue of if the GUI's are closed for any reason they can be brought up by:
  • Open by clicking Activities in the upper right corner. There is a menu with the PEPSI logo. Select that logo to open the program
  • Preferred: From a terminal on pepsi@alpha type

Pepsi PFU User Interface Desktop 1:

Pepsi Telemetry on Desktop 2:

Make sure the LBT telescope is selected to bring up LBT PEPS GUI:

Start of night Setup

Load the program for the night

  • In the Observing Programmes window, Open the desired dated program from the "Tables" menu.
Details about generating program plans and modifying on the fly can be found on the Planning PEPSI Observations Wiki

Put PEPSI in Observing Mode

  • At the bottom of the PEPSI LBT GUI, select the Engage radio button for both SX and DX (or for the side of interest if observing monocularly)
    PEPSI LBT GUI for Preset:
  • This will open the hatch, set up the ADC's and move mechanisms to put PEPSI in Observing Mode

Start the Guiders

  • This is typically done once slewed to the first target of the night.
  • At the bottom of the PEPSI LBT GUI, select the Guider radio button for both SX and DX (or for the side of interest if observing monocularly).
  • This will open the guider windows
    Pepsi Guider Windows:
    PEPSI Guider Windows.png

Sending Presets and Starting Science

  1. Select the OB
    -The Target (OB) is selected in the Observing Programmes GUI.
    -The airmass can be verified in the TargetVisibilityPlots. Selecting the target will highlight that target in the plot.
    -The Instument Configuration can be verified or altered by selecting "Edit Observing Blocks" in the Observing Programmes. This will open the Edit Observing Blocks Gui with the Instument configurations.
    Edit Observing Blocks GUI:

  2. Send the OB
    -Sending the OB will configure PEPSI and populate the PEPSI LBT GUI with the target information in preparation for a telescop preset.
    -Select the desired target from the Observing Programmes GUI. The target is sent to the PEPSI LBT GUI by selecting this.
    -For non-sidereal targets the OB should have coordinates close to the target. The NSIGUI will still be used to hijack the telescope.

  3. Sent the Telescope Preset and Start Science
    • Verify the target information. Once Confirmed ok with TO, select Preset send telescope preset.
    • Once preset complete, will see light in pinhole (otherwise pointing check may be required)
    • WFS will converge to set RMS
      PEPSI LBT GUI.png
    • Once WFS is acceptable click START (red circle) on PEPSI Control Interface
      PEPSI Spectrograph Control Interface GUI:
      NOTE: PEPSI does not automatically start exposures when collimation reacheaches acceptable range
    • STOP will readout the current CCD integration
  4. Optimizing Guiding
    • If target is too faint (poor seeing, clouds, etc) to converge,
      • The operator can adjust the guider filter on the fly (second to bottom row on the PEPSI LBT GUI)
      • the operator can increase the guider binning. Selecting a higher binning on one side will automatically update the other side.
      • If target is too faint, use BS4 to get more photons on the WFS. The optimal Beam splitter configurations are as follow:
        0-14 BS#1 BS#1 BS#1 BS#1 BS#1 BS#1
        14-17 BS#2 BS#2 BS#3 BS#2 BS#2 BS#3
        17-20 BS#4 BS#4 BS#5 BS#4 BS#4 BS#5
      • if one side loses guiding, can resend preset by selecting side lost in the PEPSI LBT GUI and click Preset to resend (similar to recovering from one side loss in MODS Bino observing).

Adjust Exposure times if Needed

This can be done one of two ways.
  1. If an OB is in progress, the Exposure time can be adjusted directly in the PEPSI Spectrograph Control Interface while the OB is in progress. This will update in real time for the exposure currently being taken. This has the advantage that a new preset is not required.
    If in the above example the exposure time is adjusted from 30 min to 20 min, the progress bar down below will immediately update to show 9 min of 20 min (~50% complete).
    Adjusting exposure times can be necessary if:
    1. Object is saturating or not acheiving the desired SNR
    2. Inclement weather is imminent
    3. To adjust for night plan, to ensure high priority objects are reached.
  2. Exposure times can be adjusted before an OB is sent directly in the "Edit Observing Block" Gui for that target. Once adjusted in the "Edit Observing Block" there is no need to save (there is no save). The new updated times will be sent to the PEPSI Spectrograph Control Interface when the preset is sent.

Viewing the data

To Check S/N:
  • click on box - press 'Alt' + 'c' or draw with mouse (with Macs use 'Cmd' in place of 'alt').
  • Draw box across a single order to estimate S/N
  • In the extracted spectra, draw a box from the max to the overscan, then hit the sun to measure the Gain/SN
  • The resultscan be saved to the header will be displayed in the Fits Image Browser GUI table
  • Viewing Data and calculating the S/N:

To check for Saturation:
  • click on box - press 'Alt' + 'c' 3 times (with Macs use 'Cmd' in place of 'alt'). The first time centers a box on the full frame, the second brings up a horizonal line cut, and the thrid will bring up a vertical line cut
  • Select the sideways sigma - extract one dimesional cross cut in veritcal direction - to plot the counts in the cross cut.
  • Counts should ideally be below 20K .
  • Check images for saturation:
    Check Image Saturation.png

Images can be added and analyed from the "FITS Images Browser". Double clicking our using the "Display Selected Image Button" will send the image to the active display, not necessarily red or blue display orientations.


  1. Click CALIB button in PEPSI Control Interface. This will launch the Calibration sequencer.
    Launching the Calibration Sequencer:
    PEPSI Calibration Sequencer:
  2. In the calibration Sequencer select the radio buttons for the relevant calibrations. Typically ThAr and Traces are executed daily.
  3. Select the Calibration of interest in the Pepsi Control Interface and select the desired Cross Dispersers and fiber combination. This will correlate to the Calibration Sequencer.

    The Calibration Sequencer Gui must be left open when running calibrations

  4. When ready click START. Cals aren't impacted by dome lights or telescope motion, etc.

The following example will setup and run calibrations for the 200 fiber CD 2 & 4 followed by the 300 fiber CD 3&5 and CD2 &4, traces and ThAr.
  • Set up Calibrations setup for 300 fiber CD3 &5, CD2 & 4 traces:
  • Set up Calibrations setup for 300 fiber CD3 &5, CD2 & 4 ThAr:
  • Set up Calibrations setup for 200 fiber CD2 & 4 traces:
  • Set up Calibrations setup for 200 fiber CD2 & 4 ThAr:
  • Hit Start and this will execute all of the calibrations sequentially.

Images generated are summarized in the FITS Image Browser.
  • Press insert on what was observed to Mark those items.
  • Select the printer to make a list. This will bring up a pop-up that will ask what columns to print.
  • In the pop up there is a radio button to "Pint All" or "Print Selected", make sure the correct one is selected. Review the ticked parameters that will be printed in the summary. Select or deselect as needed (default is typically good). Print to 'list' which prints to a standard text file 'list' in the home directory. It is ok to overwrite.
  • Copy the list to your directory from the pepsi machine. The list can be put in the partner google shared drive and linked in the log.

-- JenniferPower - 07 Sep 2021

I Attachment Action Size Date Who Comment
200ThAr.pngpng 200ThAr.png manage 101 K 09 Nov 2021 - 19:43 JenniferPower Calibrations setup for 200 fiber CD2 & 4 ThAr
200Traces.pngpng 200Traces.png manage 103 K 09 Nov 2021 - 19:42 JenniferPower Calibrations setup for 200 fiber CD2 & 4 traces
300ThAr.pngpng 300ThAr.png manage 101 K 09 Nov 2021 - 19:41 JenniferPower Calibrations setup for 300 fiber CD3 &5, CD2 & 4 ThAr
300Traces.pngpng 300Traces.png manage 107 K 09 Nov 2021 - 19:41 JenniferPower Calibrations setup for 300 fiber CD3 &5, CD2 & 4 traces
Check Image Saturation.pngpng Check Image Saturation.png manage 787 K 22 Oct 2021 - 04:27 JenniferPower Check images for saturation
EditObservingBlocks.pngpng EditObservingBlocks.png manage 96 K 07 Sep 2021 - 18:42 JenniferPower Edit Observing Blocks GUI
FITSImageBrowser.pngpng FITSImageBrowser.png manage 180 K 08 Sep 2021 - 20:17 JenniferPower Fits Image Browser
ObservingProgrammes_EditBlocks.pngpng ObservingProgrammes_EditBlocks.png manage 282 K 07 Sep 2021 - 18:40 JenniferPower Observing Programmes -> Edit Observing Blocks
PEPSI Guider Windows.pngpng PEPSI Guider Windows.png manage 258 K 07 Sep 2021 - 18:36 JenniferPower Pepsi Guider Windows
PEPSI LBT GUI.pngpng PEPSI LBT GUI.png manage 1 MB 07 Sep 2021 - 18:35 JenniferPower PEPSI LBT GUI
PEPSICalibrationsLaunch.pngpng PEPSICalibrationsLaunch.png manage 275 K 07 Sep 2021 - 20:06 JenniferPower Launching the Calibration Sequencer
PEPSICalibrationsSequencer.pngpng PEPSICalibrationsSequencer.png manage 109 K 07 Sep 2021 - 20:06 JenniferPower PEPSI Calibration Sequencer
PEPSIControlInterface.pngpng PEPSIControlInterface.png manage 191 K 07 Sep 2021 - 18:55 JenniferPower PEPSI Spectrograph Control Interface GUI
PEPSI_PFU_GUI.pngpng PEPSI_PFU_GUI.png manage 6 MB 07 Sep 2021 - 18:31 JenniferPower PEPSI PFU User Interface Desktop 1
PepsiTelemetry.pngpng PepsiTelemetry.png manage 7 MB 07 Sep 2021 - 18:32 JenniferPower PEPSI Telemetry on Desktop 2
PepsiUserInterfaceDesktop.pngpng PepsiUserInterfaceDesktop.png manage 6 MB 07 Sep 2021 - 18:34 JenniferPower PEPSI PFU User Interface Desktop 1
Saving_list.pngpng Saving_list.png manage 123 K 10 Nov 2021 - 18:20 JenniferPower Saving list of observed items
SelectLBT.pngpng SelectLBT.png manage 151 K 22 Oct 2021 - 04:33 JenniferPower Make sure the LBT telescope is selected to bring up LBT PEPS GUI
SendingPresets.pngpng SendingPresets.png manage 283 K 07 Sep 2021 - 18:46 JenniferPower Sending Presets from Observing Programmes GUI
TargetVisibilityPlots.pngpng TargetVisibilityPlots.png manage 147 K 07 Sep 2021 - 18:37 JenniferPower Target Visibility Plots
ViewingData.pngpng ViewingData.png manage 907 K 07 Sep 2021 - 20:01 JenniferPower Viewing Data and calculating the S/N
Topic revision: r8 - 10 Nov 2021, JenniferPower
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback