ASTRONOMY & ASTROPHYSICS DECEMBER II 2000, PAGE 361 SUPPLEMENT SERIES Astron. Astrophys. Suppl. Ser. 147, 361–628 (2000) The Asiago Database on Photometric Systems (ADPS)? I. Census parameters for 167 photometric systems D. Moro1,2 and U. Munari1,3 1 Osservatorio Astronomico di Padova, Sede di Asiago, I-36012 Asiago (VI), Italy 2 Osservatorio Astrofisico di Asiago, Dipartimento di Astronomia, Universit`a di Padova, I-36012 Asiago (VI), Italy 3 CISAS, Centro Interdipartimentale di Studi ed Attivit`a Spaziali, Padova, Italy Received May 9; accepted August 14, 2000 Abstract. The Asiago Database on Photometric Systems Bessell (1993), in the books by Golay (1974) and Strai˘zys (ADPS) is a compilation of basic information and refer- (1995) and on the world wide web by Mermilliod et al. ence data on 167 optical, ultraviolet and infrared photo- (1997). The latter focuses mainly on the data collected in metric systems. Thirty-four additional systems are briefly various photometric systems (with entries for more than described. In compiling this census we have relied on pub- 2105 stars). At the same time, the Mermilliod et al. www lished information only. In Paper II the photometric sys- version available at the time of submission of the ADPS tems will be inter-compared, calibrated and parameterised provides a census of photometric systems by listing and by means of synthetic photometry using uniform criteria describing 82 of them. Even if our compilation was inde- and the same set of input spectra and extinction laws. pendent, we undoubtedly benefited by checking against Mermilliod et al.’s work. Key words: photometry — astronomical data bases — In compiling the ADPS we have tried to be as com- surveys plete as possible for the optical region (from 0.3 to 1.0 µm, where GAIA is currently planned to collect data), but ef- fort has also been made to include ultraviolet as well as infrared photometric systems (even if at a lower degree 1. Introduction of completeness). The ADPS www site will be regularly updated as new information becomes available. When we became involved in the design of the photomet- In this paper we rely only on data from literature (in- ric system for GAIA, which is under evaluation by ESA strumental set-ups, transmission curves, calibration and as the next Cornertone 5 mission, we realized how use- transformation functions, zero points, etc.), with prefer- ful it would have been to have a nearly complete census ence for those provided by the authors of the photomet- of the existing ground-based and space-born photometric ric systems in the original papers. Unfortunately, accu- systems. The completion of the Asiago proposal for the rate and complete information is available only for a small GAIA photometric system (Munari 1998) was originally minority of the surveyed systems. We have been able to conceived to follow the realization of the Asiago Database locate in literature (or derive ourselves from published on Photometric Systems (ADPS), but actually the reverse graphs) the tabular band transmission profiles for 105 sys- happened because the preparation of ADPS has been a tems. Calibration and transformation functions with any tougher task than anticipated. This paper intends to sum- kind of accuracy have been published only for a fraction marise this extensive census in an interesting way for the of the 167 surveyed systems. Even when calibration and general reader. transformation functions are available, it is not always Some compilations of photometric systems have al- easy to inter-compare them because of the heterogeneous ready been presented, among others by Lamla (1982), methods adopted by the different authors (see Sect. 2). As Send offprint requests to:U.Munari; a contribution toward a clarification of the whole issue, in e-mail: [email protected] a forthcoming Paper II we will inter-compare, calibrate ? The ADPS is reachable at and parameterise the systems by means of synthetic pho- http://ulisse.pd.astro.it/Astro/ADPS/ or via tometry using uniform criteria and the same set of syn- http://www.pd.astro.it/ thetic and observed input spectra and extinction laws. 362 D. Moro and U. Munari: The Asiago Database on Photometric Systems (ADPS). I. GAIA is a candidate ESA Cornerstone 5 mission confused when it comes to the width of the bands: the designed to obtain extremely precise astrometry (in authors have used values ranging from the FWHM of the micro-arcsec regime), multi-band photometry and a Gaussian approximation to the band, to something re- medium/high resolution spectroscopy for a large sample sembling the full width at zero transmission, or half of of stars. The goals as depicted in the mission Red Book the total width at 50% transmission, or even unspecified call for astrometry and broad band photometry to be concepts as “band-width”, “band-pass”or“half width”. collected for all stars down to V ∼ 20 mag over the entire There are cases where the values given for the wavelength sky (∼1109 stars), with brighter magnitude limits for and width of the bands are missing or they disagree with spectroscopy and intermediate band photometry. Each the plotted and/or tabulated transmission profiles. In such target star should be measured over a hundred times cases we have computed on the transmission profiles two during the five year mission life-time, in a fashion similar quantities and reported them in the ADPS with the aim to the highly successful Hipparcos operational mode. of clarifying the situation: the WHM (width at half max- The astrophysical guidelines of the GAIA mission are imum: the full wavelength span between the points where discussed by Gilmore et al. (1998, and references therein) the transmission reaches half of the maximum value) and and Perryman (1999). An overview of the GAIA payload λc (central lambda: the wavelength halfway between these and spacecraft is presented by M´erat et al. (1998). half-maximum transmission points). In Paper II we plan to homogenise and standardise the situation regarding the wavelength and width of the bands for all systems 2. The Database with published transmission curves by means of synthetic The 167 systems included in the ADPS are listed in photometry against the same set of observed and syn- Table 1, in order of publication year. The systems are doc- thetic spectra. Finally, for some systems references are umented by individual figures that conform to the com- also provided to papers specifically devoted to the port- mon layout. ing of the system to a different detector (like photo- The reference sources are given in square brackets for graphic plates or CCDs for systems originally designed for all the information provided with a given photometric sys- photo-multipliers). tem and are also listed in Table 2. No information is en- System Analysis. This section deals with assorted in- tered if not present in literature. The information provided formation like the most frequently used colour indices and with the systems surveyed in the ADPS are grouped into their aim (preserving as much as possible the terminol- five main blocks: ogy used by the original authors), reddening-free param- System Code Name. This is formed from the sys- eters, reddening ratios and transformation to other sys- tem name generally used in the literature, the author(s) tems. Transformations are only to chronologically earlier name(s) and the year of publication of the original paper systems in order to avoid duplication. introducing the system. A short sentence describing the Transmission Curves. The last section is devoted to system main usage or aim follows (normally as given by the presentation of the band transmission profiles both in the authors themselves). graphical and tabular form. The transmission curves are General Information. The authors of the system (not not plotted and tabulated if they refer to square bands (es- listed for space missions), the telescope and detector orig- sentially flat 1.0 transmission within the band and 0.0 out- inally adopted, and the main reference article are given side), such as those provided by diaphragms placed on the here. The main reference article is generally the one intro- focal plane of a spectrograph in front of a photo-multiplier ducing the photometric system; however, some of these tube or the square bands synthesised from fluxed digital historical articles contain little information and in such spectra. When the transmission curves have been plotted cases a more recent, informative paper is taken instead. but not tabulated by the authors, we have reconstructed System Description. Basic information like the filters them by measuring the plotted profile. In such a case, used, the wavelength and width of the bands, the zero the reader is warned by a sentence like “As derived from points and the flux calibrations are reported here. The lit- Fig. Y of [XXX]”. erature is heterogeneous regarding these parameters, with values sometimes referring only to the filters, or to the 3. Additional systems filters+detector combination or also including the contri- bution of the telescope optics and atmosphere. So different In this section 34 additional systems are briefly described. quantities as λpeak (peak transmission), λc (unspecified These systems do not appear in the main article body band “centre”), λeff (generally without specification of because – to our own judgment – they (a) lack some the energy distribution of the input source weighting or most of the basic information, and/or (b) have been the transmission profile) or λ0 (again unspecified) are poorly documented, and/or (c) had little or no follow-ups provided by the authors of the photometric systems as the in the literature, and/or (d) have been applied to very wavelength of the bands. The situation is somewhat more few objects, if not to just a single one.