P2PP: tutorial for Finding Charts and Ephemerides

This tutorial provides a step-by-step example to manage finding charts and ephemerides files for your OBs prepared with P2PP. To follow it, you should have a P2PP installation on your computer and be familiar with the essentials of the use of the software. Please refer to the instructions in order to install it, and to the P2PP User Manual for a general overview of P2PP and generic instructions on the preparation of Observing Blocks.


Since version 2.7 of P2PP, the finding charts related to your Observation Blocks can be attached directly when building them. The finding charts must imperatively be provided as Jpeg images. Currently, the allowed maximum file size in P2PP for such an image is 1 Mbyte. Once your finding charts are attached, they will be sent to the ESO database when you decide to check-in the corresponding OBs.

Likewise, if you are using version 2.9 of P2PP (or a more recent release), you can attach your ephemeris files directly to your OBs, for your moving targets.

In the following, we will not detail how to prepare your finding charts and ephemeris files, as this information is detailed elsewhere. Please read the following pages:

From this point, we thus assume that you have prepared the necessary finding charts for your OBs, and that you have the corresponding Jpeg files at your disposal on your computer. If you have some moving targets, we will also assume that you have prepared your ephemeris file(s) beforehand.

Managing Finding Charts with P2PP

The Finding Charts menu in P2PP holds all the commands that you need to attach, detach or view your finding charts. This menu is available from the main window:

The finding chart menu in the main P2PP window

...as well as from the "OB view" window, which allows you to edit a single OB. This window pops up when you select an OB in the main window, and then click on the View button.

The Finding Chart menu in the OB view window

Both menus are identical, and call exactly the same functions. We will thus make no distinction between these two use cases. Although the illustrations of the next sections show the case of the main window, the explanations remain perfectly valid when using the Finding Charts menu from the "OB view" window.

Attaching finding charts to your OB

First of all, let's see how to attach one or several finding charts to a given OB. The command Attach Finding Charts of the FC menu is the one to be used to achieve this. If you are using it from the main window, first make sure to select the right OB with the mouse. The currently selected OB is the one which is highlighted. If you are using the "OB view" window, this step is obviously irrelevant.

Note: if you select several OBs at the same time in the main window (hold the Ctrl or Shift key while clicking on the individual OBs), you can attach the same finding chart(s) to all OBs at the same time.

Once you have called the command Attach Finding Charts, a file browser will pop up, as depicted on the image below:

the finding chart selection dialog

Navigate to the folder where you have stored your finding charts. This is done with the leftmost part of the file browser. Double-clicking on a folder's name will display the Jpeg files found in this directory. The file browser will only display files that have a .jpg extension. You can move back to the parent directory by double-clicking on the ".." entry.

Then, select one or several Jpeg files in the rightmost list window. Selection of multiple files is possible by holding the Ctrl key while clicking on the filenames. Your selection is highlighted. The first selected image will be shown as a thumbnail at the right of the file browser, and its name appears in the area labeled Enter file name. Please note that, although this area displays only one filename, it is the selection you made in the Files area that actually counts when you click on the button Attach finding charts.

Once you have clicked on this button, the file browser disappears. The main window then shows how many finding charts you have attached, and their filenames, for the OB(s) that was (were) selected:

list of finding charts attached to an OB

Clearing all finding charts

Should you need to start all over again, and you want to detach all finding charts at once, proceed as follows:

  • select the relevant OB(s). If you want to clear finding charts for several OBs at a time, you must do a multiple selection from the main P2PP window (use the Ctrl or Shift key while clicking).
  • Call the function Clear Finding Charts from the Finding Charts menu.
  • You are asked to confirm your action to avoid any mistake.

The corresponding column in the main window is cleared out accordingly.

Detaching selected finding charts

If you need to detach one or several particular finding charts from an OB, choose the function Detach Finding Charts. This will pop up a window showing you the list of finding charts currently attached to the selected OB. You can then select one or several finding charts to detach. Please note that if you select several OBs from the main window, before calling this function, it will only affect the first one in the list.

Detaching finding charts from an OB

Viewing the attached finding charts

Finally, it is possible to visualize the finding charts that you have attached to a given OB. Select the OB, and call the command View Finding Charts. The following picture viewer will be shown:

the finding chart viewer

The buttons labeled Next and Previous allow you to navigate through the set of attached finding charts, while the Cancel button simply dismisses the window. Please note, that if the pixel size of your finding chart is too large, it will be downscaled -- and thus slightly degraded, as in the example above -- for the display only. Your original finding chart will always be the one which is checked-in with your OB.

Managing Ephemeris Files with P2PP

It is also possible to attach an ephemeris file to your OB(s), should you be observing a moving target. The detailed requirements for the creation of your ephemeris file(s) are given on the page describing the procedures for moving targets. For this part of the tutorial, we assume that the file(s) you need have already been prepared, and available from the local disk of your computer.

The commands available for the management of ephemeris files are logically gathered in a single menu, labeled Ephemeris Files, which you can find in the menu bar of the main P2PP window, next to the one dedicated to finding charts. Contrary to what happens for finding charts, the menu is not repeated in the "OB view" window.

Menu for ephemeris files in P2PP main window

The tasks that you can perform are completely similar to the ones available for finding charts, so that we will not detail everything here, and we ask you to refer to the above sections for complete details. One notable difference is that you can attach only one ephemeris file to an OB. Naturally, attaching the same file to several OBs at the same time is possible, in the same way as for finding charts. Please note that the selection dialog will only show files with a .eph extension, when you attach an ephemeris file.

Finally, the command View Ephemeris File will allow you to see the contents of the file you have attached to a given OB. The view window looks like the example below:

the viewing window for ephemeris files

Instrument selector

This page is valid for all instruments

P2PP Documentation