There are 4 Interfaces required for the generation and editing of PEPSI OB's:
  1. Observing Programmes GUI
    • This GUI summarizes the date, targets, basic configuration information, start and finish time for each target, and the ProjectID 's.
    • This GUI is brought up from the "Program" button in the lower right of the PEPSI Spectrograph Control Interfact GUI
      Observing Programmes GUI:
  2. Edit Observing Blocks
    • This GUI is used to Edit the Instrument Configuration
    • Opened from the "Edit Observing Blocks" button on the Observing Programs GUI (the left most Icon at the top)
    • Sets the Exposure Time, Cross Disperser, Number of Exposures, Fiber, Beam Splitter, Mirror, Guider Filter, FPE, Instument (PFU, POL, etc), Number of Cycles, and Overhead Time (the planning nominally assumes 2 minutes of overhead per target for preset.).
      Edit Observing Blocks GUI:
    • A single line exposure line across dictates the configuration to be executed at one time.
    • So in the above example the instrument will be configured with the 300 image slicer, PFU, and ND3 for the guider. The first exposure will be 4min with CD I and CDIV simultaneously, second will be 4 min CD II & CD V, and third will be 4min with CD III and CD VI. The cycle of 3 will be repeated 34 times.
  3. Target Visibility GUI
    • Allows the users to visible see the taget airmass on the night. Target selected will be highlighted.
      Target Visibility Plots:
  4. Observing Targets GUI
    • The Observing target GUI is a master list of all available PEPSI targets. It is opened via the "+" icon in the top of the Observing Programmes GUI.
      Observing Targets GUI:
    • Targets can be added, edited (for additional information, Project ID's, etc).
    • Target seaches will recognize and populate with SIMBAD recognized ID's.
    • When executing searches it is important to "Clear" fields between queries since populated field will not overwrite with blanks if information is unknown with the next query.
      Observing Targets Target Search:

    • The PEPSI ETC is also used for verification purposes, to check that requested exposure times will produce the desired SNR


The PEPSI Readme files should contain the insformation necessary to generate the PEPSI OB. Ilya has some historical knowlege of many programs so it is useful to run generated OB's by him in these early days.

The PEPSI README's are located in the PEPSI observing shared drive: Queue and Service Observing-> PEPSI

It is useful to verify whether the SNR requested will be reached in the requested time. Use the PEPSI ETC to quickly verify given the target information. Note that exposure times determined through the PEPSI etc should be increased by a factor of 1.33 to account for the fiber loss.

Planning Programs

  • Filter is selected automatically according the brightness of the target. However, it can be altered on fly to adapt to any changing conditions (e.g. clouds).
  • PFU beam splitter is selected automatically according the brightness of the target and cross-disperser used. Optimal combinations are as follow:

    Optimal configurations for Beam splitters are:

    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

    • BS1 - grey - 2% of science light reflected to guider
    • BS2 - for blue - 10% of science light reflected to guider
    • BS3
    • BS4 - for red - 50% of science light reflected to guider
  • The blue mirror us the default setting
    • Red mirror can be used in a special case with 100 μm fiber
  • Observations requiring good radial velocity stability may request simultaneous fabry-perot-etalon (FPE) on

Generating a New OB

  1. In the Observing Programmes GUI, "Open or Close" table
    Open_Close OB.png
  2. Select the dated OB or select default.ob to open a blank template. If starting with a fresh blank template, adjust the date in the bottom of the Observing programs and then resave with the dated OB name in the Open/Close File GUI by entering the new date in the File name and hitting "Save"
  3. Set the Starting time at the bottom of the Observing Programmes GUI. These times are in UT. A typical start time is 40 minutes after sunset, but can be dependent on the brightness of the first target.
  4. Bring up the Observing Targets list to add targets using the "+" in the Observing Programmes GUI. Search for Targets with the "?" or "Create a New Table Record" (the blank sheets of Paper icon) to add new targets. Targets are then sent to the OBserving Programmes GUI using the Right Facing Arrow in the Observing Targets GUI.
    In the Observing Programs GUI - Open necessary panels to edit program:
  5. Once a Target has been added, the Instrument Configuration should be set. Open the Edit Observing Blocks GUI
    1. Set the image slicer - 100, 200, or 300.
    2. Verify the ND filter. This is set automatically by the magnitude of the target. ND3 for the birtghtest of the bright, ND2 for <6mag, and ND0 for anything else.
    3. Select FPE on if requested, POL if designing for PEPSI pol otherwise PEPSI PFU.
    4. Select the Cross Dispersers. Remember that CD3 and CD4 cannot be observed simultaneously, but all other combinations are valid. The sequence of observation will execute each line sequentially, so the cross dispersers selected in the first line will be executed simultaneously first, then the second line, followed by the third. The cross Dispersers in each obs line can be adjusted/selected from a dropdown menu.
    5. Adjust the Exposure times
      1. Number of Exposures indicated the number of times that obs line will be executed before moving on to the next.
      2. Number of Cycles indicates how many times all 3 obs lines will be executed serially
      3. Expusre times are given in HH:MM:SS.SS (HH: Hours, MM: Minutes, SS.SS: Seconds)
      4. A standard overhead time of 2 minutes is allocated to each observation (lower left). For fainter objects, or objects with challenging acquisitions, this maybe adjusted to ensure the overall OB remains accurately on time. For the most part 2 minutes is reasonable.
    6. Verify the Beam Splitter for each Cross Disperser combination:

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
The next target to be added to the observing plan will have the same instrument configuration as the one above it. This is contrary to many observer beliefs that PEPSI remember the instrument confirguations associated with the targets themselves. You must rebuild the configuration on a target by target basis. In many cases the observing configurations in a program are the same for all targets with only small changes. So it is easiest to load the first target, make the configuration adjustments to that target, then load the remaining program targets knowing the first target configuration will be copied the those targets. Adjustments can then be made on a case by case basis at the end.

A full printout of a night plan can be made by selecting the printer in teh Observing Programmes Gui. This will print the targets and their estimated start and end times, but not their instrument configurations so those will need to be checked manually.

Adjusting night plans on the fly

There are 3 parts to adjusting observing programs on the fly
  1. Adjusting the times of an exposure in progess
  2. Adjusting the plan overview times to project the night overview and start/finish times of future targets.
  3. Adjusting the times or configurations for upcoming targets.

Adjusting exposure in progress

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.

There is no need to Stop, or Start the exposure while making this adjustment.

Adjusting the plan overview

The Observing Programmes GUI provides a nice summary of the targets planned for the night in order with Start, End, and Duration times. Sometimes there are techinical issues, weather loss, or other observing adjustments that need to be made that can impact the schedule. It is useful to ensure start and end times align with reality. There are 2 ways to do this:
  1. Ideally you just want to see the start and end time for the targets progressing from the current time and don't care about what has already been executed. The user can adjust the Starting Time in the lower right of the Observing Programmes GUI such that the current start time of the current object matches the real time.


  2. Sometimes its easier to just apply the known overheads directly to the Target OB. If Object overheads accumulate, then they can be added directly into the "Edit Observing Block GUI" in the Overhead time. These will propogate directly to the start/end times in the "Observing Porgrammes" GUI. This can be a useful way to track later where and when overheads occured, and what targets in the future may require additional time, but is not necessary if this was a one off event.
Having accurate start and end times allow for effective use of the visibility charts and ensures that any unreachalbe targets will be flagged.

-- JenniferPower - 07 Sep 2021
I Attachment Action Size Date Who Comment
AdjustingPlan_Overview.pngpng AdjustingPlan_Overview.png manage 316 K 10 Nov 2021 - 19:24 JenniferPower  
EditObservingBlocks.pngpng EditObservingBlocks.png manage 96 K 07 Sep 2021 - 21:24 JenniferPower Edit Observing Blocks GUI
ObservingProgrammesGUI.pngpng ObservingProgrammesGUI.png manage 116 K 07 Sep 2021 - 21:28 JenniferPower Observing Programmes GUI
ObservingTargetsGUI.pngpng ObservingTargetsGUI.png manage 280 K 07 Sep 2021 - 21:26 JenniferPower Observing Targets GUI
OpenToEditProgram.pngpng OpenToEditProgram.png manage 36 K 22 Oct 2021 - 05:48 JenniferPower In the Observing Programs GUI - Open necessary panels to edit program
Open_Close OB.pngpng Open_Close OB.png manage 419 K 08 Sep 2021 - 00:14 JenniferPower Open or Close OB
PEPSI_README_v3.pngpng PEPSI_README_v3.png manage 111 K 10 Nov 2021 - 17:03 JenniferPower PEPSI Readme v3
TargetSearch.pngpng TargetSearch.png manage 403 K 07 Sep 2021 - 21:45 JenniferPower Observing Targets Target Search
TargetVisibility.pngpng TargetVisibility.png manage 150 K 07 Sep 2021 - 21:24 JenniferPower Target Visibility Plots
Topic revision: r9 - 10 Nov 2021, JenniferPower
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