A. Dolcini¹ - F. Farfanelli² - S. Ciprini² - A. Treves¹ - S. Covino³ - G. Tosti² - E. Pian⁴ - B. Sbarufatti¹ - E. Molinari³ - G. Chincarini^3,5 - F. M. Zerbi³ - G. Malaspina³ - P. Conconi³ - L. Nicastro⁶ - E. Palazzi⁶ - V. Testa⁷ - F. Vitali⁷ - L. A. Antonelli⁷ - J. Danziger⁴ - G. Tagliaferri³ - E. Meurs⁸ - S. Vergani⁸ - A. Fernandez-Soto⁹ - E. Distefano¹⁰ - G. Cutispoto¹⁰ - F. D'Alessio⁷

1 - Universit $\rm {\grave{a}}$ degli Studi dell'Insubria, Dipartimento di Fisica e Matematica, via Valleggio 11, 22100 Como, Italy
2 - Dipartimento di Fisica e Osservatorio Astronomico, Universit $\rm {\grave{a}}$ di Perugia, via. A. Pascoli, 06123 Perugia, Italy
3 - INAF - Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy
4 - INAF - Osservatorio Astronomico di Trieste, via G. B. Tiepolo 11, 34143 Trieste, Italy
5 - Universit $\rm {\grave{a}}$ degli Studi di Milano-Bicocca, Dipartimento di Fisica, Piazza delle Scienze, 3, 20126 Milan, Italy
6 - INAF/IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
7 - INAF - Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monteporzio Catone, Italy
8 - Dunsink Observatory, Castleknock, Dublin 15, Ireland
9 - Observatori Astronomic, Universitat de Valencia, Aptdo. Correos 22085, Valencia 46071, Spain
10 - INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy

Key words: galaxies: active - BL Lacertae objects: individual: PKS 2155-30 - errata, addenda

We have found an error in our VRI photometry of PKS 2155-30 due to incorrect transformation of data files. This has unfortunately propagated in various tables and figures.

Table 3: Average intensities for all epochs and all filters. All data are in mJy units.

Table 4: Average intensities and 1-sigma values for all filters for all five nights with more intensive observations in November 2005 (all values are in mJy units).

Table 5: Spectral index values and V values for all spectra plotted in Fig. 11.

$\begin{figure} \includegraphics[width=9cm,clip]{6477efig10.eps}\end{figure}$

Figure 4: Light curves in the H and V filters for five nigths in November 2005, when the observations were more intensive. Dates of observations are reported in each box. The solid line in V band - 4 Nov. box results from a linear regression analysis. The solid line in H band - 8 Nov. box connects the four points of the flare-like structure. In each box it is given a typical error bar. In V band - 4 Nov. box the light curve of one comparison star is also plotted, with a fixed enhancement of 9 mJy.

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$\begin{figure} \includegraphics[width=7cm,clip]{6477efig7.eps}\end{figure}$	Figure 10: 4 November 2005 spectrum - epoch 3. The spectral fit with a single power law yields a spectral index $\alpha$ = 1.32 $\pm$ 0.25. Error bars are comparable with symbols size.
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$\begin{figure} \includegraphics[width=9cm,clip]{6477efig13.eps}\end{figure}$

Figure 11: Different spectra of PKS 2155-304 from observations at other epochs reported in the literature. Symbols correspond to following works: filled circles: this work (13/5/2005 data), filled squares: this work (19/9/2005 data), filled up triangles: this work (4/11/2005 data), open diamonds: Bertone et al. (2000; 24/5/1996 data), open circles: Pesce et al. (1997; 19/5/1994 data, the Hamuy & Maza (1989) calibration is used), open up triangles: Zhang & Xie (1996; 5/7/1994 data), open squares: Bersanelli et al. (1992; 17/1/1987 data), open crosses: Treves et al. (1989; 1/12/1983 data), open stars: Treves et al. (1989; 11/11/1984 data), asterisks: Miller & McAlister (1983; 19/11/1981 data). Spectral index values and V magnitudes for all data sets are reported in Table 5.

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$\begin{figure} \includegraphics[width=9cm,clip]{6477efig8.eps}\end{figure}$	Figure 12: $\alpha$ vs. V plot for data reported in Fig. 11. Symbols are the same as used in Fig. 11.
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$\begin{figure} \includegraphics[width=9cm,clip]{6477efig12.eps}\end{figure}$	Figure 13: SED of PKS 2155-304 in two states, adapted from Chiappetti et al. (1999) (see the paper for details). Data from this work are also plotted. Filled triangles correspond to epoch 1 (13/5/2005 data), while filled hexagons belong to epoch 3 data (20/11/2005). Optical, UV and REM data are dereddened using E(B-V)=0.026 and parameters given by Cardelli et al. (1989).
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REM near-IR and optical multiband observations of PKS2155-304 in 2005