SN-1999ac data set

AJ, 130, 2278 (2005), (astro-ph/0507288)

The archive (tar file) of the data set presented in the paper can be downloaded here.

The file name includes the epoch with 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 6063,  is  2848 km/s. All spectra presented in this paper have been de-redshifted to the rest frame using 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.)

Citation Requirement:
Any publication that makes use of this data should cite:  G. Garvini, AJ, 130, 2278 (2005). Data made available by the Supernova Cosmology Project.

For  further information please contact Gabriele Garavini.

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