Status of spectroscopy reduction from low-z working group (April 2001)
The aim of this document is to summarize the reduction status on the spectroscopy data and to give comments about the ongoing work.
All the information and the links you find in this page are also somewhere in the Collaboration Section of this web page.
LOW-z DATA at Stockholm
| TELESCOPE | NUMBER OF NIGHTS | SNe |
| NOT | 6 | sn99z, sn99aa, sn99ab, sn99ac, sn99ae, sn99ai, sn99ak, sn99as,sn99au, sn99aw, sn99bk, sn99bm, sn99bp, sn99bq |
| INT | 2 | sn99aa,sn99bh |
| KPNO4.0 | 2 | sn99ac, sn99as, sn99au, sn99aw, sn99ax, sn99ay, sn99bh, sn99bk, sn99bn, sn99bp |
| Lick3.0 | 4 | sn99aa, sn99ac, sn99ah, sn99ai, sn99as, sn99aw, sn99ax, sn99be, sn99bh, sn99bp |
| ESO3.6 | 6 | sn99ac, sn99af, sn99bq, sn99ao, sn99au, sn99av, sn99aw, sn99ba, sn99bi, sn99bk, sn99bm, sn99bn |
| APO3.5 | 6 | sn99aa, sn99ac, sn99af, sn99ai, sn99av, sn99be, sn99bh, sn99bp |
These data does not include the reference images taken in 2000.
We have builded a table containing useful information about the reduced SNe spectra (type, date of max,
how many spectra we have for each supernova, S/N ratio).
The signal to noise ratios given there are being corrected
for the background contribution to the noise using a home made Iraf
script.The idea of this table is to give a quick impression of what data we have. A more complete set of information will some day be present in the SCP database.
Our spectra reduction method can be seen in our
web page.
It has been modified several times since last
June, thanks also to the careful reading of Alex Conley. The most important update is about the
background subtraction, and the way we consider it in the final error.
A report about the way we compute statistical and systematic errors is
available from our
web page. (In the same
page you can find other documents we wrote)The IDL program that has been written to compute the systematic errors is available from our web page. We will soon add the program used to compute the statistical uncertainties. Contact Serena if you want to know more.
The status of the reduction at Stockholm is the following:- Done all the spectroscopy nights at NOT, KPNO4.0m, Lick3.0m,
ESO3.6m and APO3.5m (22 nights with around 70 spectra of 24 Sne, 17 of
which are type Ia's). Still running the scripts to get statistical
errors right.
- Extracted the INT spectra, but couldn't calibrate them in
wavelength. Only two objects were observed with that telescope.
- Some of the Lick data (red channel) have fringing. We are trying to
figure out how important it is to correct it, and how to do it.
- We still have some final spectra with some cosmic ray lying on the
object. We will have to edit them back on the 2D image. In many other cases,
we could get rid of cosmic rays by combining several images into
one.
Present and future work:- We are developing a tool in IDL to perform measurements on the
spectra. The spectra consist on ASCII tables that list wavelength,
flux, statistical error and systematic error. The script will allow us
to weighed-fit different functions to the profiles and the continua in order
to get line intensities and equivalent widths.