The archive (tar file) of the
data set presented in the paper can be
The file name includes the
respect to B-band maximum light. Only in case of simultaneous
observations using more than one instrument
is the telescope name included in the file name. Each file includes an
ascii table with three columns: Wavelength
(de-redshifted), Observed Flux, Statistical Error (Based on the optimal
extraction algorithm of the IRAF packages).
Brief summary of the
data reduction steps:
The recession velocity of SN1999ac's host galaxy, NGC
All spectra presented in this paper have been de-redshifted to the rest
this recession velocity.
The data set consists of 14 optical spectra extending from day -15 to
day +42 (in this archive all phases are expressed with respect to
B-band maximum). In most cases, the spectra were acquired using
different instrumental settings for the blue and red parts of the
spectrum to avoid possible second-order contamination. Hence, the 14
fully reduced spectra are the combinations of both blue and red parts.
Spectra were taken with the slit rotated to a position angle close to
the parallactic angle at the mid-point of each exposure.
The data were reduced using standard IRAF routines. The two-dimensional
images were bias-subtracted and flat-fielded. The background sky was
fitted, subtracted, and extracted for systematics checks of the
wavelength calibration. Wavelength and flux calibration were applied to
the one-dimensional extracted spectra using arc and standard star
observations taken with the same instrumental setting and during the
same night as the science observations. The accuracy of the wavelength
calibration was checked against the extracted sky spectra and generally
found to agree to within 2~\AA. Mean smoothed atmospheric extinction
corrections for each observatory, rather than nightly extinction
corrections based on standard stars, were applied. No correction was
yet been made for telluric features or residual fringing. Synthetic
spectrophotometry was computed to check the overall accuracy of the
flux calibration against publicly available photometric data and found
to agree within the quoted statistical uncertainties.
Galactic reddening in the direction of SN 1999ac was estimated
following Schlegel, et al., ApJ 500, 525 (1998). A value
of E(B-V) = 0.046 mag was found. All spectra of SN 1999ac
were corrected for Galactic extinction assuming R_V = 3.1.
No host galaxy reddening correction was applied. (Please refer to the
publication for further detail.)
Any publication that makes use of this data should cite: G.
Garvini, AJ, 130, 2278 (2005). Data made
available by the Supernova Cosmology Project.