How to prepare CONCATENATION container

This tutorial provides a step-by-step example of the preparation of a concatenation scheduling container, one of the new features of P2PP version 3. To follow the tutorial you should have a P2PP installation on your computer and be familiar with the essentials of the use of P2PP (version 3). Please refer to the P2PP Webpage for detailed installation instructions and the latest P2PP version to be used. To the P2PP User Manual for a general overview of P2PP and generic instructions on the preparation of Observing Blocks.

Because the scope of this tutorial is to show how to prepare a concatenation container in general, it is meant to be instrument independent hence it will not give you a detailed description on how to make an OB for a given instrument. Specifically devoted tutorial for each VLT instruments can be found in the Service Mode guidelines Webpage, under the Manuals and Tutorials tab section.

What is a concatenation container?

A concatenation container consists of two or more OBs that must be executed back-to-back without breaks. The sequence of the execution of OBs in a concatenation cannot be specified.

If the execution of one OB within a concatenation fails, then the whole concatenation fails too and it must be repeated, irrespective whether any other OBs of the concatenation has been successfully executed or not.

The typical use of concatenation may be envisaged in the case of observations of science targets which should be immediately followed by the observations of a calibrator source (i.e. NACO: science target and PSF calibrator; CRIRES: science target and telluric standard; HAWK-I: science target and photometric standard star etc.).

0. Goal of the run

Your goal here is to obtain with NACO K-band images of a science field and then an additional source for PSF modeling.
After checking the Exposure Time Calculator you find out that you need about 20 and 7 minutes of exposure time on target and PSF calibrator, respectively to achieve the necessary signal-to-noise.

Because the observation of the PSF star should occur immediately after the execution of your science OB you decide to create a concatenation containing first  the science OB and then the calibrator.

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1. Getting started

We assume that you have started the P2PP session, logged in and selected the run within the P2PP main GUI for which the OBs should be prepared. For the sake of this tutorial we will use the P2PP special tutorial account that ESO has set up so that users who do not have their own P2PP login data can still use P2PP and prepare example OBs. You cannot use this account to prepare actual OBs intended to be executed.

After starting P2PP and logging in using the tutorial account (i.e. login: 52052, password: tutorial), the P2PP main GUI will appear as follows:

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2. Create a concatenation

In what follows we will create first a concatenation container and then we will proceed to fill the container with 2 OBs. However, it might be the case that you have already prepared the OBs and only after that you realize that the observing strategy would benefit if you group them together in a concatenation container. In this case you can skip what follows below and jump directly here.

The first step now is to create a container which will contain the OBs for a the science field and for the PSF calibrator. To do so click on the C purple icon on the upper bar of the P2PP main GUI. This creates an entry under the Observing Runs area that look like as follow:

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Next step is naming the concatenation and because there is no special requirement on the concatenation's name we will call it c1. Select the concatenation with the mouse, press Enter and type c1 in the New Concatenation field. The P2PP main GUI should then appear as follows:

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3: Define an OB within a concatenation

To create an OB within the concatenation c1, click on the OB blue icon on the upper left side of the P2PP main GUI. This creates an entry under the Observing Runs area. The red dot next to the OB name means that the OB fails to pass some fundamental verification criteria, as may be expected from the fact that no template has been attached to the OB yet.. At this point your P2PP main GUI looks like the figure here below:

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3.1: Naming the OB

In this tutorial we decide that the first OB is for the science target. To name the OB, as done previously in case of the concatenation container, select the OB, press Enter and type sci-target in the field No Name.
The P2PP main GUI now looks like this:

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3.2 Define the OB acquisition template

Double click on the OB name to have access to the main OB window where you define the contents of your OB. Because this OB will define standard imaging observations through the K-band filter, we decide to name the Observing Description as imaK. Thus type imaK in the OD Name field.

The first template that must be part of any science OB is the acquisition template, so now you need to choose it and specify the appropriate parameters. In the Template Type field make sure that the acquisition entry is selected. This will list all the acquisition templates available for NACO in the Template list below to it. In this example, our NACO observations are in standard imaging NGS mode, hence from the Template list select the NACO_img_acq_MoveToPixel template and then press add button to add it to the OB.

In what follows we assume that you have already prepared the NAOS configuration file (see NACO P2PP tutorial for more detailed description) containing all the information regarding the source to be used as NGS. Your decision for the values of DIT and NDIT depends on the brightness of the target. Since we assume here that sci-target is fairly bright and easily identifiable in a short exposure of 5 seconds long, you type 5 in the DIT field and 1 for the NDIT values. You then select the following parameters:

  • Type of AO Observation (LGS/NGS): NGS
  • Filter: Ks
  • Camera: S27
  • NAOS parameter file: sci-target.aocfg

The remaining parameters can be left as their Default values.
At this point the OB main GUI should appear as follows:

 

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3.3: Define the OB science template

Now it is time to insert the science template. On Template Type, select now science and the existing NACO science templates will appear. In this tutorial we will use the NACO_img_obs_AutoJitter template that allows you to randomly move the target within a given box whose width is defined by the user. Select the aforementioned template from the list and then click on the Add button on the right side. After consulting the Exposure Time Calculator you decide to use a DIT of 15 sec, NDIT of 10 and to take 9 exposures. The science template has thus the following parameters:

  • DIT: 15
  • NDIT: 10
  • Readout mode: Double_RdRsRd (Default)
  • Window side: 1024 (Default)
  • Observation Category: SCIENCE (Default)
  • Store Data Cube?(T/F): F (i.e. False, default)
  • Jitter box width: 7
  • Number of exposures per offset position: 1
  • Number of offset positions:9
  • Return to Origin? (T/F): True (Default)
  • Filter: Ks
  • Neutral density filter: Full (Default, i.e. no filter)
  • Camera: S27

The OB main window should look like this:

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3.4: Inserting the Target information

To access the view window where the Target information are, click on the Target icon in the top left of the main OB window. As shown below, in case of NACO all but one parameter (i.e. the Class field) are automatically extracted once the NAOS configuration file is uploaded in the acquisition template. In case of NACO observations, do not EVER edit these parameters!

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3.5: Filling the constraints set

As for the case of the Target information, the Constraints set are automatically filled once the NAOS configuration file is uploaded in the acquisition template. You can check that in the related OB view window which you can display by clicking on the Constraint Set icon. Once again, in case of NACO you should not EVER edit any of those parameters!

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At this point you can create the OB for the PSF calibrator following all the steps describe in this section 3. Remeber that the OB for the PSF observation should be named with the prefix PSF_ and that in the acquisition template the field PSF reference? (T/F) must be checked (i.e. True).

4: Concatenation and OBs priority

If you have followed all the instructions given so far, then in your P2PP main GUI you should see two OBs within a container as shown here below:

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As can be seen in the P2PP main GUI. under the Schedule tab and priority column, the priority is associated only to the container and not to the OBs within that given container. This implies that all the OBs of a given concatenation share a unique priority and, as mentioned earlier, there is no possibility to choose the sequence of execution of the OBs.

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5: Adding OBs into a concatenation

Here we assume that you have already prepared 2 independent OBs for your science target and for your PSF calibrator. Your P2PP main GUI should then look as below:

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Now you realize that your observing strategy would benefit from having these 2 OBs scheduled within a concatenation container. The quicker way to proceed is hence to create a new empty concatenation container. You click on the C purple icon on the upper bar of the P2PP main GUI.
The P2PP main GUI appears as follows:

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Now to fill the New Concatenation container with the OBs you have already prepared, with the mouse you can select them and then drag them into the container. If you have done so, then in the P2PP main GUI now the OBs appear directly under the concatenation container as shown here below:

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6. README, Finding Chart and Submission

With the completion of the concatenation we consider this tutorial to be finished. However, the Phase 2 package preparation is completed only after providing the finding charts and the README file. The reader can refer to the following pages for a more detailed description of the final three steps:

  1. Attaching the Finding Chart
  2. Filling the README file
  3. Submitting OBs and containers

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