About p3d

p3d is a general data-reduction tool that is intended to be used with data of fiber-fed integral field spectrographs (IFSs). This tool can be useful for people who have access to astronomical data of such an instrument. Data-reduction tasks, which are performed by p3d, convert raw data of CCD detectors into extracted spectra that can thereafter be used for scientific purposes.

Version 2.2.1 was released 21.1.2013.

The aim with p3d is and has been to write a user-friendly tool that will reduce the time that is spent performing repetitive tasks in IFS data-reduction. p3d can combine several images (exposures) into one image, clean single images of cosmic-ray hits, can extract spectra using three different methods, does full error propagation through all steps, and provides graphical tools for inspection of both intermediate and final results. Release 2.2 of p3d contains tools to handle the following tasks:

• Creating a master-bias image – prescan and overscan regions can, if available, easily be used instead.
• Cleaning raw data of cosmic-ray hits.
• Find and trace spectra on the detector, automatically.
• Creating a dispersion mask for wavelength calibration.
• Creating a dataset that is used to normalize (flat field) extracted spectra.
• Extracting science-object data, using different extraction methods.
• Creating a sensitivity function from a summed standard-star spectrum – this can be done either automatically or interactively. That sensitivity function is then used for flux calibration.
• Flux calibrating extracted data using a sensitivity function.
• Combining extracted images of separate detectors to one image (VIMOS).
• Correcting data for effects of differential atmospheric refraction (DAR; PMAS/Larr, Spiral, VIMOS, FLAMES/Argus, and MPFS).
• Converting RSS-formated output of p3d to data cubes – for PMAS/Larr, Spiral, VIMOS, FLAMES, MPFS, and ERA2 – or the E3d-format (all instruments).
• Combining several extracted images using the same or different exposure times, where all exposures target the same region.

p3d also provides graphical tools to inspect raw data and outcome of the different tasks. Flux calibration can be done both with the routines of p3d, or with, for example, IRAF (instructions on necessary steps in this case are available at the documentation WIKI).

Primary Reference
The primary reference regarding the functionality, the methods, and the implementation of p3d is:
"p3d: a general data-reduction tool for fiber-fed integral-field spectrographs", C. Sandin, T. Becker, M.M. Roth, J. Gerssen, A. Monreal-Ibero, P. Böhm, and P. Weilbacher 2010, Astronomy & Astrophysics, 515, pp.A35.

This is also the reference that should be used in publications that have made use of p3d for the data reduction. Additional references and links to those references are provided on the references page; please have a look at this page to see which other references you will want to cite.

In October 2010, at the STScI-workshop "IFUs in the era of JWST", Christer Sandin gave a presentation with the title "Integral-Field Spectroscopy Data Reduction Made Easy with p3d". Please, follow this link and watch the presentation.

p3d is written in the IDL language of EXELIS Visual Information Solutions. While p3d is licensed under GPLv3 and can be used freely with the help of provided tools, IDL is in itself a proprietary program.

We refer to p3d as a general tool since it has been developed to work with any fiber-fed integral field unit (IFU) of any IFS. Currently the software has been configured and tested with the following instruments:

• PMAS – that is mounted on the 3.5m telescope at the Calar Alto Observatory in southern Spain. p3d supports data of both the old 2kx4k CCD and the new 4kx4k CCD.
• The Mitchell Spectrograph [VIRUS-P] – that is mounted on the 2.7m Harlan J. Smith telescope at the McDonald Observatory in western Texas.
• VIRUS-W – that is, currently, mounted on the 2.7m Harlan J. Smith telescope at the McDonald Observatory in western Texas.
• SPIRAL and SAMI of the AAOMEGA spectrograph – that is mounted on the 3.9m telescope at the Anglo Australian Observatory. Note that fiber position tables are, currently, missing to evaluate any outcome of SAMI data.
• VIMOS – that is mounted on the third unit telescope (UT3) at the VLT in Chile. p3d supports data using the medium- and the high-resolution (MR and HR) gratings. Data sampled both before and after the instrument refurbish about October 2010 are supported. Data sampled using the new HR-blue setting will be supported as soon as we get a request for this (soon in any case).
• FLAMES – that is mounted on the second unit telescope (UT2) at the VLT in Chile. p3d supports data using the ARGUS IFU as well as the two mini-IFU configurations. Data sampled both before and after the instrument refurbish in 2007 are supported.
• MPFS – that is mounted on the 6m SAO Big Telescope Alt-azimuth (BTA) near Mount Pastukhov in the Caucasus Mountains in Russia. p3d has been setup to work with the newer CCD.
• GMOS-N and GMOS-S – that are mounted on the Gemini North telescope on top of Mauna Kea on the Big Island of Hawaií, and the Gemini South telescope on top of Cerro Pachon in Chile; both telescopes belong to the Gemini Observatory. p3d supports data using the two one-slit modes; i.e. the red and the blue slits. The two-slit mode is (logistically) more complex to handle, which is why it is not (yet) supported.
• INTEGRAL, which is a set of IFUs that are connected to the WYFFOS spectrograph at the 4.2m William Herschel Telescope (WHT) (of the Isaac Newton Group of Telescopes) at the Roque de los Muchachos Observatory on the island of La Palma. p3d supports both the older single-detector as well as the newer two-detector configurations.
• ERA2, which is an life-sciences integral-field spectrograph in development at AIP.

A tool as complex as p3d is never finished. There are several parts of p3d, which could be extended and improved upon. Additional tools could be written in order to optimize the control and analysis of the outcome. p3d can also, if required, be configured for more instruments. If and how this will happen at large depends on the interest of the community. Please, tell us if there is some functionality missing, in your opinion, or if you need support for another instrument. We are scientists with limited resources, but we will do what we can to help you out. We do consider taking on people with a suitable expertise in our development team.

The p3d team
sixth version, for release 2.2: 13.12.2012
fifth version, for release 2.1.2: 23.4.2012
fourth version, for release 2.1: 24.11.2011
third version, for release 2.0: 20.6.2011
second version, for release 2.0a: 26.1.2011
first version: 4.2.2010