Since then, several new theoretical calculations of atomic parameters have become available for a variety of new ions, which represent great improvements from the previous data. Moreover, the Coronal Diagnostic Spectrometer (CDS - Harrison et al. 1995) and Solar Ultraviolet Measurements of Emitted Radiation (SUMER - Wilhelm et al. 1995) instruments on board of the Solar and Heliospheric Observatory (SOHO) have recorded many spectra between 170 Å and 1600 Å (e.g., Harrison et al. 1997; Brooks et al. 1998, for CDS and Feldman et al. 1997, for SUMER), including emission lines from many ions not accounted for in the 1.0 version of the CHIANTI database. These lines are potentially very useful for plasma diagnostic and chemical composition analysis. The SUMER instrument has also observed strong continuum radiation - a feature not accounted for in CHIANTI 1.0.

In the present paper we present the 2.0 version of the CHIANTI database and we describe the changes and improvements made in order to better reproduce the optically thin spectrum for wavelengths greater than 50 Å. This has greatly increased the number of ions inserted in the database, and the changes are indicated in Tables 1 and 2.

A detailed description of the basic structure of the CHIANTI database is given in Paper I; since no change has been made in the organization of the database, this will not be repeated here, and we refer the reader to Paper I for further details.

In the near future the attention will be focused on the spectral range $\lambda \le$ 50 Å in order to meet the needs of the AXAF and XMM missions, that are scheduled for launch in late-1998 and 1999, respectively. The ions necessary to calculate the spectrum below 50 Å will be inserted in the CHIANTI database in a later version. Moreover, detailed work using the Close Coupling approximation is underway as part of the Iron Project (Hummer et al. 1993) to produce very accurate collisional and radiative data for the iron ions and for other ions as well. One of us (HEM) is a member of the Iron Project consortium and these calculations will be incorporated into CHIANTI as soon as they are available.

The CHIANTI software has been integrated into the CDS science analysis software and several useful IDL routines have been developed (they are described in the CDS software notes available online). CHIANTI has been very useful for the analysis of SOHO data (e.g. Mason et al. 1997; Landi & Landini 1997; Del Zanna & Bromage 1997; Brickhouse & Esser 1997) and for studying the intensity calibration of the CDS spectrometer (Landi et al. 1997). A detailed comparison between CHIANTI and the SERTS spectrum observed in 1989 (Thomas & Neupert 1994) has shown an overall excellent agreement between observed intensities and CHIANTI predictions (Young et al. 1998, Paper II).

**Table 1:** Ions included in the CHIANTI database. $\bullet$ : Ions in the CHIANTI 1.0 version *not* changed in the present update. $\circ$ : Ions in the CHIANTI 1.0 version whose data have been modified/complemented in the present update. $\star$ : New entries for the CHIANTI database
$\begin{tabular} {lcccccccccccccccc} \noalign{\smallskip} \hline \noalign{\smalls... ...ace & $\star$\space \\ Zn & & & & & & & & & & & & & & & & \\ \hline\end{tabular}$

**Table 2:** Ions included in the CHIANTI database. $\bullet$ : Ions in the CHIANTI 1.0 version *not* changed in the present update. $\circ$ : Ions in the CHIANTI 1.0 version whose data have been modified/complemented in the present update. $\star$ : New entries for the CHIANTI database
$\begin{tabular} {lcccccccccccc} \noalign{\smallskip} \hline \noalign{\smallskip}... ...pace & $\star$\space & $\star$\space \\ \noalign{\smallskip} \hline\end{tabular}$

1 Introduction