How to create VLT-compliant Finding Charts

In general, a finding chart has to be attached to each OB. Exceptions are given in the instrument-specific rules. Please read the P2PP3 User Manual for a detailed description on attaching finding charts to OBs. Users of La Silla instruments should consult the P2PP version 2 User Manual. There also exists a online tutorial on the attachment of finding charts to OBs in the "old" version 2 P2PP and a video tutorial for P2PP3.

General Finding Chart Requirements

Regardless of the instrument, finding charts must have all the following characteristics:

  • Clearly indicate the Observing Run ID.
  • Clearly indicate the PI Name.
  • Clearly indicate the OB Name or Target Name, as used in the OB to which it is attached.
  • The target(s) position(s) must be clearly indicated.
  • The entire instrument field-of-view must be shown.
  • North and East must be clearly indicated.
  • The scale must be indicated by drawing a bar and writing the bar length in arcseconds or arcminutes.
  • The wavelength range of the image must be indicated. Whenever possible, finding charts should have similar central wavelength to observations (e.g. DSS charts are often inappropriate for IR observations near the galactic equator).
  • The images should be negative, i.e. dark objects on light background.
  • The output files must be in JPEG format and their size must be less than 1 Mbyte.
  • Positions of spectroscopic acquisition reference stars, if any, should be marked.
  • Spectroscopic finding charts must indicate the slit(s) position(s) clearly (unless slits are aligned along parallactic angle)

Please verify that finding charts have sufficient quality and resolution. This can be easily done from within P2PP by using the View Finding Chart option in the Finding Charts menu of the main P2PP interface (see also the P2PP User Manual).

Skycat Finding Chart tool

Although in most cases valid finding charts can be produced with any software tool able to produce output files in JPEG format, ESO recommends the use of the SkyCat-based finding chart tool. This tool provides a user-friendly interface to easily produce finding charts with the general characteristics described above.


Additional rules for X-SHOOTER finding charts

The acquisition in X-Shooter is performed through an optical, technical CCD. Therefore, although your observations may focus on the NIR part, you need to provide finding charts produced using optical images. For faint targets (V>22.5mag, B>22mag) or extended objects, offset stars have to be used to define the precise slit position. In addition to the standard Service Mode finding chart requirements, the finding charts for X-Shooter have to be provided in the North up -East left convention with a field size of 2x2 arc minutes and the target clearly identified. If offset stars are used for target acquisition, a corresponding 2x2 arcminute chart for the offset star has to be provided, too. Finding Charts are not Searching Charts. They are used for target identification in case of close multiple objects or crowded fields. No searches for targets will be performed if the object cannot be identified with the provided finding chart. If in the acquisition templates the slit is oriented with a specific position angle, the slit orientation has to be indicated on the finding chart, too.

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