III Worked Examples

This part of the cookbook provides a set of worked examples of reducing fibre spectroscopy observations from various instruments. The examples are:

The example of reducing Hydra data is available as part of the documentation for IRAF. The procedure is similar to, but simpler than, the procedure for reducing FLAIR data. Consequently it is sensible to work through the Hydra example before trying the FLAIR one.

All the examples assume that the requisite software is already installed at your site and ready for use. If the software is not available at your site then Section 7 describes how to obtain it. Note, however, that you will often require the assistance of your site manager to install the software.

Copies of the data files used in the examples are provided so that you can work through them yourself. On Starlink systems they are kept in directory:

Alternatively they can be retrieved by anonymous ftp from Edinburgh. The details are as follows:

Reply anonymous to the ‘Name’ prompt and give your e-mail address for the password. Set ftp to binary mode before retrieving the file. The file is a compressed tar archive and should be decompressed with the Unix command uncompress (sic).

In order to work through the examples you should use a display capable of receiving X-output (typically an X-terminal or a workstation console). Strictly speaking the software will run on a black-and-white device, but realistically you need a colour display. Before starting you should ensure that your display is configured to receive X-output.

Finally, the examples show only some of the features of the various packages used. In all cases they have additional features which are not described here. You should see the appropriate user manuals for full details.

11 Reducing Hydra Data Using IRAF

Hydra is a fibre spectrograph available at the Kitt Peak National Observatory (KPNO), Tucson (see, for example, Barden et al.[7]). Observations acquired with it are usually reduced using the IRAF task dohydra. dohydra is very similar to the IRAF task dofibers which is used to reduce FLAIR and WYFFOS/AUTOFIB2 data. A worked example of using dohydra is available as part of the IRAF documentation. This example is similar to, though simpler and easier than, the example of reducing FLAIR data given in Section 12, below. Thus, it is sensible to work through the Hydra example before trying the FLAIR one, even though you are unlikely to observe with Hydra.

Before trying the Hydra (or FLAIR) example you should already be familiar with the rudiments of IRAF and have an ‘IRAF directory’ prepared which you will use for running IRAF. If you are not au fait with IRAF then you must familiarise yourself with it before proceeding; SG/12: An Introduction to IRAF[34] is a convenient starting point.

You can simply follow the instructions given and there is no need to repeat them here. There are, however, a couple of caveats which you should be aware of.

12 Reducing FLAIR Data Using IRAF

FLAIR observations are usually reduced using IRAF (see Section 7.3.1) and this example is a simple demonstration of the procedure. The reduction of FLAIR data is documented in the manual FLAIR Data Reduction with IRAF[20]. The present example gives all the steps involved in a simple reduction but nonetheless you will find it useful to have a copy of the manual to hand as you work through it for further explanation of each step and future reference.

The example assumes that you are familiar with the rudiments of IRAF and already have an ‘IRAF directory’ prepared which you will use for running IRAF. If you are not au fait with IRAF then you must familiarise yourself with it before proceeding; SG/12: An Introduction to IRAF[34] is a convenient starting point. Reducing FLAIR observations with IRAF is similar to, but more complicated than, reducing Hydra observations, which was described in the previous example (Section 11, above). Consequently, it is sensible to work through the Hydra example before trying the present one.

The data used in this example are observations of some early-type stars in the direction of the Galactic centre. The stars are in the magnitude range 12 to 16 and the spectra cover the wavelength range 4000–4600Å. These data are unusual in that most FLAIR observations are of external galaxies. Nonetheless they can be used to illustrate the reduction procedure, which is as follows.

12.1 Setup file customisation

The FLAIR setup script flairsetup.cl, is, of course, just a simple text file which can be listed or edited from the Unix shell. In order to use the file with your own data there are a couple of items which may need to be changed.

You should set the items combine.rdnoise and dofibers.readnoise to the readout noise of the CCD chip. The value can be obtained from the FLAIR Web pages.

You may also need to alter the extents of the bias and trim regions (ccdproc.biassec and ccdproc.trimsec respectively). If you are unsure about the appropriate values then the FLAIR support staff should be able to advise.

13 Reducing 2dF Data Using 2dFDR

This example demonstrates the use of the 2dFDR (2dF Data Reduction) package for reducing 2dF observations. 2dFDR was written at the AAO specifically for the reduction of 2dF data and it is the usual way to reduce these data. The example works through a complete simple reduction but nonetheless only shows a few of the features of the 2dFDR package. For a full description you should see the 2dF User Manual[3]. You need a colour display to use 2dFDR.

A sample dataset is available from the AAO and it is used in the present example. It is not included in the usual example directory for the present cookbook, but rather you should download it from the AAO along with 2dFDR (see below). The data comprises observations of galaxies with

$B_{j} < 19.7$ and quasars with

$B_{j} < 21$ . They were acquired in January 1998 using 2dF plate 0 and spectrograph 1 and include arcs, flat fields, offset skys and target galaxy and quasar spectra. Though the observations are genuine the celestial coordinates have been randomised to preserve the proprietary rights of the original observers. The data are provided courtesy of the 2dF Bright Galaxy Survey and 2dF QSO Survey teams.

Acknowledgements

I am grateful to numerous people who contributed their time, expertise and data during the preparation of this cookbook. Nigel Hambly provided the data used in Section 12 and demonstrated the reduction of FLAIR data with IRAF. Dave Bowen provided the data used in Figures 3 and 4 and demonstrated the reduction of WYFFOS/AUTOFIB2 data with IRAF. Martin Clayton did much of the preliminary work on which the document is based. I had extremely useful discussions with Malcolm Currie and Quentin Parker. All the above and also Karl Glazebrook, Fred Watson, Don Pollacco, Jim Lewis, Harvey MacGillivray, Martin Bly and Rodney Warren-Smith either answered queries and/or provided useful comments on the draft version of the cookbook.

Bibliography

[1] J. Allington-Smith, P. Bettess, E. Chadwick, R. Content, R. Davies, G. Dodsworth, R. Haynes, D. Lee, I. Lewis, J. Webster, E. Atad, S. Beard, R. Bennett, M. Ellis, P. Hastings, P. Williams, T. Bond, D. Crampton, T. Davidge, M. Fletcher, B. Leckie, C. Morbey, R. Murowinski, S. Roberts, L. Saddlemyer, J. Sebesta, J. Stilburn and K. Szeto, 1997, in Kontizas et al. op. cit. ([28]), pp73-79.

[2] S. Arribas, E. Mediavilla and F.G. Watson (eds), 1998, Fiber Optics in Astronomy III, Astronomical Society of the Pacific Conference Series, 152.

[3] J.A. Bailey and K. Glazebrook, 1997, 2dF User Manual (Anglo-Australian Observatory: Sydney).

[4] S.C. Barden (ed), 1988, Fiber Optics in Astronomy, Astronomical Society of the Pacific Conference Series, 3.

[5] S.C. Barden (ed), 1995, Fiber Optics in Astronomical Applications, Proc. SPIE, 2476.

[6] S.C. Barden 1998, in Arribas et al. op. cit. ([2]), pp14-19.

[7] S.C. Barden, T. Armandroff, P. Massey, L. Groves, A.C. Rudeen, D. Vaughnn and G. Muller, 1993, in Gray op. cit. ([21]), pp185-202.

[8] J. Barnes, 1993, A Beginner’s Guide to Using IRAF (National Optical Astronomy Observatories: Tucson). See SG/12 op. cit. ([34]) for details of obtaining IRAF manuals.

[9] D.V. Bowen, M. Pettini and B.J. Boyle, 1998, Mon. Not. R. Astron. Soc, 297, pp239-250.

[10] R.D. Cannon, 1997, in Kontizas et al. op. cit. ([28]), pp33-40.

[11] J.W. Chamberlain, 1961, Physics of the Aurora and Airflow, International Geophysics Series, 2, (Academic Press: New York).

[12] Y. Chu, 1997, in Kontizas et al. op. cit. ([28]), pp67-72.

[13] M.J. Clayton, 1998, SC/7.2: Simple Spectroscopy Reductions (Starlink).

[14] M.J. Currie and D.S. Berry, 1998, SUN/95.13: KAPPA – Kernel Application Package (Starlink).

[15] M.J. Currie, 1998, SC/4.2: C-shell Cookbook (Starlink).

[16] M.J. Currie, G.J. Privett, A.J. Chipperfield, D.S. Berry and A.C. Davenhall, 1998, SUN/55.10: CONVERT – A Format-conversion Package (Starlink).

[17] A.C. Davenhall, 1998, SUN/190.6: CURSA – Catalogue and Table Manipulation Applications (Starlink).

[18] A.C. Davenhall, G.J. Privett and M.B. Taylor, 1999, SC/5.2: The 2-D CCD Data Reduction Cookbook (Starlink).

[19] P.W. Draper, 1998, SUN/139.9: CCDPACK – CCD Data Reduction Package (Starlink).

[20] M. Drinkwater and B. Holman, 1996, FLAIR Data Reduction with IRAF (Anglo-Australian Observatory: Sydney).

[21] P.M. Gray (ed), 1993, Fiber Optics in Astronomy II, Astronomical Society of the Pacific Conference Series, 37.

[22] W.D. Heacox and P. Connes, 1992, Astron. Astrophys. Rev, 3, pp169-199.

[23] J.Hecht, 1998, Understanding Fiber Optics, (Prentice Hall: Saddle River, New Jersey).

[24] J.Hecht, 1999, City of Light, (Oxford University Press: Oxford).

[25] J.M. Hill, 1988, in Barden op. cit. ([4]), pp77-92.

[26] J.M. Hill, J.R.P. Angel, J.S. Scott, D. Lindley and P. Hintzen, 1980, Astrophys. J. Lett, 242, ppL69-L72.

[27] D.C. Kay and J.R. Levine, 1995, Graphics File Formats, second edition
(Windcrest/McGraw-Hill: New York). See in particular Chapter 18, pp235-244.

[28] E. Kontizas, M. Kontizas, D.H. Morgan and G.P. Vettolani (eds), 1997, Wide-Field Spectroscopy (Kluwer Academic Publishers: Dordrecht).

[29] J.R. Lewis, 1996, WYFFOS Data Reduction Manual (Royal Greenwich Observatory: Cambridge).

[30] C. Lissandrini, S. Cristiani and F. La Franca, 1994, Publ. Astron. Soc. Pacific, 106, pp1157-1164.

[31] S.J. Maddox and A. Aragón-Salamanca (eds), 1995, Wide Field Spectroscopy and the Distant Universe, the 35th Herstmonceux Conference (World Scientific: Singapore).

[32] P. Massey, 1997, A User’s Guide to CCD Reductions with IRAF (National Optical Astronomy Observatories: Tucson). See SG/12 op. cit. ([34]) for details of obtaining IRAF manuals.

[33] P. Massey, F. Valdes and J. Barnes, 1992, A User’s Guide to Reducing Slit Spectra with IRAF (National Optical Astronomy Observatories: Tucson). See SG/12 op. cit. ([34]) for details of obtaining IRAF manuals.

[34] R. Morris, G.J. Privett and A.C. Davenhall, 1998, SG/12.1: IRAF – Image Reduction Analysis Facility (Starlink).

[35] R. Morris and G.J. Privett, 1966, SUN/166.4: SAOIMAGE – Astronomical Image Display (Starlink).

[36] G.W. Nelson, 1988, in Barden op. cit. ([4]), pp2-22.

[37] Q.A. Parker, 1997, in Kontizas et al. op. cit. ([28]), pp25-31.

[38] Q.A. Parker and M. Hartley, 1997, in Kontizas et al. op. cit. ([28]), pp17-23.

[39] Q.A. Parker, F.G. Watson and S. Miziarski, 1998, in Arribas et al. op. cit. ([2]), pp80-91.

[40] I.R. Parry, 1997, in Kontizas et al. op. cit. ([28]), pp3-16.

[41] I.R. Parry, 1998, in Arribas et al. op. cit. ([2]), pp3-13.

[42] I.R. Parry and E. Carrasco, 1990, in Instrumentation in Astronomy VII, Proc. SPIE, 1235 pp702-708.

[43] K.T. Shortridge, H. Meyerdierks, M.J. Currie, M.J. Clayton, J. Lockley, A.C. Charles, A.C. Davenhall and M.B. Taylor, 1998, SUN/86.16: FIGARO – A General Data Reduction System (Starlink).

[44] F. Valdes, 1992, Guide to the Multifiber Reduction Task DOFIBERS (National Optical Astronomy Observatories: Tucson). See SG/12 op. cit. ([34]) for details of obtaining IRAF manuals.

[45] F. Valdes, 1992, Guide to the Slit Spectra Reduction Task DOSLIT (National Optical Astronomy Observatories: Tucson). See SG/12 op. cit. ([34]) for details of obtaining IRAF manuals.

[46] G. Walker, 1987, Astronomical Observations – An Optical Perspective (Cambridge University Press: Cambridge).

[47] R.F. Warren-Smith, 1998, SUN/33.6: NDF – Routines for Accessing the Extensible N-Dimensional Data Format (Starlink).

[48] F.G. Watson, 1995, in Maddox and Aragón-Salamanca op. cit. ([31]), pp25-32.

[49] F.G. Watson, A.R. Offer, I.J. Lewis, J.A. Bailey and K. Glazebrook, 1998, in Arribas et al. op. cit. ([2]), pp50-59.

[50] D.C. Wells, E.W. Greisen, and R.H. Harten, 1981, Astron. Astrophys. Suppl, 44, pp363-370.

[51] F.G. Wyse and G. Gilmore, 1992, Mon. Not. R. Astron. Soc, 257, pp1-10.

site:	`ftp.roe.ac.uk`
directory	`/pub/acd/misc`
file	`sc14.tar.Z`

target astronomical object	1
sky	0
broken or ‘blanked off’ fibre	-1 or 1

Part III
Worked Examples

10 Introduction

11 Reducing Hydra Data Using IRAF

12 Reducing FLAIR Data Using IRAF

12.1 Setup file customisation

13 Reducing 2dF Data Using 2dFDR

Acknowledgements

Bibliography

Part IIIWorked Examples

10 Introduction

11 Reducing Hydra Data Using IRAF

12 Reducing FLAIR Data Using IRAF

12.1 Setup file customisation

13 Reducing 2dF Data Using 2dFDR

Acknowledgements

Bibliography

Part III
Worked Examples