Note: links to the manuals and references are available a the end of this page.

1. Introduction

All La Silla Telescopes work using pre-defined exposures. For service observing, the exposures should be defined well in advance using the P2PP tool (detailed info is available on the P2PP page). For "neo-classical" observing, the observations are defined at La Silla on the day and night preceding the observations, with the help of the support scientist. They can easilly be modified during the observations.

Exposures are defined using templates or Observation Blocks (OBs). An OB is one observation, or group of observation, that constitute a logical entity which should not be interrupted. Typical examples are a UBVRI sequence, a Red and a Blue spectrum, or a sequence of dithered K images.

An OB is constituted by

• a Target Package (defining the position of the object),
• an Acquisition Template (defining how to point the telescope to the target, e.g. by taking a short exposure to center the object in the spectrograph's slit)
• an Observation Description, which in turn is consituted by a series of Observation Templates (e.g., a V 600s exposure, a R 400s and a I 500s).

In addition to the series of Observation Templates (for all the possible modes of the instruments), there are also some Calibration Templates (for biases, flats, wavelength calibration, focus, etc..). All these templates are described in the Template Signature File Manuels (see Refs. below).

These OBs are defined in advance, and can be executed in a very flexible way. For instance, some of the templates can be skipped, or the whole OB can be paused between templates.

A number of different OBs are defined, for different kind of observations, such as, bias, darks, dome flat fields, twilight flat fields or a set of science exposures. A number of templates can be combined in an observing block, which is the smallest schedulable entity. Each observing block begins with a telescope preset to the desired position (acquisition), followed by one or more templates to be executed at this position. The defined Observation Blocks can be saved in a local directory ("local cache") from where they can also be recovered for further editing.
 
 

2. P2PP and creation of Observation Blocks

P2PP is described in details in the detailed and complete P2PP home-page. This section is meant as a short introduction to P2PP.

P2PP can be run on the off-line system (on kila, the main server at La Silla), to prepare your OBs before your observing run. P2PP is also run at the telescope for modifying the prepared OBs, or adding some new ones. Your support scientist will assist you with this; the preocedure is outlined in the next paragraph (that you can skip unless you enjoy this kind of reading)

The Login to P2PP window (screen copy) requesting for the log-in user validation: user id and password can be obtained from the observer support. After entering, the login window disappears and the user id appears in the second screen: the P2PP main window (screen copy).

The P2PP main window is divided in three sub windows, called Observation Blocks, Observation Descriptions, and Targets. Observation Blocks contains the list of defined observations. Observation Descriptions lists pre-defined instrument configurations, and Targets pre-defined targets; Observation Blocks are generated by combining a predefined target (target package) with an instrument set-up. The top buttons can be used to define new entries in the sub windows.

Before starting to define your OBs, you will have to set the program ID (recover your program number(s) from the [File] [Observing Program] menu), set the Period (small Period window) and select your instrument ([Instrument] button).

• Target definition: Under the File button on the P2PP window, open Target definitions. Enter the number of the period and click on Phase I. A list of all targets defined in your original proposal appears. Select one by double-clicking on it. A new window opens showing you the full information for this target. Information can be edited if required (check especially the equinox). Comments can also be entered.
• New targets can also be defined. Pull down the Targets menu on top of the proposal preparation window and select new. An empty target package appears in the Targets sub window. Double click on it to call up the edit window. Change the name in the top field. To delete a target package, select unload in the pull down menu.
• Observation Description: in the Observation Description subwindow, click the menu and select "new". An item will be entered in the Observation Description window. Click it to open the editing window and change the name. The available observing templates are listed under Observing and Calibration: select the desired one which will be entered under the Templates sub window. Open the template in the usual way and edit the parameters: you have to define readout mode, binning and CCD window, filter and exposure time. The verify option allows you to check that the parameters as entered fall in allowed ranges. Several filled out templates (called template signature files, cf TSF Manuals listed below) can be created, to be executed one after another.
• Observation Blocks: Select the Target and the Observation Description you want to associate, and select [new] in the Observation Block menu.
• Acquisition Template: at the bottom of the OB subwindow, selecte the Acquisition Template you want to use, and attach it.

That's it! Don't forget to save often your work, as if P2PP crashes for some reasons, all the unsaved work would be lost.
 

3. References