Supernova Spectroscopy with FAST

See also: Spectral extraction and wavelength calibration | Flux calibration

Contents: Applying for telescope time | Requesting SN observations | Collecting the data | Spectral reductions | Data formats and spectrum archiving | SN identification and announcement via IAU circulars | Useful websites

Collecting the data

The day following the observations, you can check the 60'' logs to see how many hours of observing were actually done. or look in /data/fast/Archive/rawdata/

The data are copied over from Arizona to the CfA at around 12:00pm Eastern time.

The main thing when coping the data is to help the COMP file be
the next file after any Science image. for example:
0045.Fiege34.fits
0046.COMP.fits

If the observer takes 3 images, often to center the trace on
the 2-d CCD, just take the last image
for example:
0045.Feige34.fits
0046.Fiege34.fits
0047.Fiege34.fits
0048.COMP.fits

Spectral reductions

First thing is to remove the cosmic rays from the 2-d SN data.
ls *sn*.fits > dolist
for FAST:
.run la_cosmic_16bit.pro
readcol,'dolist',dolist,f='a'
la_cosmic_16bit,dolist,readn=4.40,gain=0.80
exit

The 1D wavelength-calibrated extracted spectra are obtained through standard routines in IRAF. See this page for scripts and examples.

The 1D spectra are then flux calibrated with a set of IDL routines written by Tom Matheson. See this page for scripts and examples.

In most cases you will want to report the velocity of maximum absorption in some line. A quick and simple way to do this is with the IDL vabs.pro routine (get it from /home/sblondin/idl/vabs.tar. Type 'vabs' at the IDL prompt for syntax and options. E.g., to determine the absorption velocity of the Si II 6355 line in sn2008bf-20080330.flm (available at /data/www/projects/supernova/SNfast/reduced/):

IDL> vabs, 'sn2008bf-20080330.flm', 12, 0.024580
 Wavelength of minimum is 6119.88
 Absorption velocity of SiII 6355 is -11296 km/s
 Is this OK? [y/n] :

NOTE on the SN redshift: When using a redshift from NED, you should preferentially choose a redshift measured from optical lines (click on the Vel/z column in the table at the start of the main page for a given galaxy. E.g. for SN 2008bf, host galaxy NGC 4061: this redshift page. If there are several optical redshifts (as is the case for NGC 4061), we usually report that given in the The Updated Zwicky Catalog, reference code 2000UZC...C......0F.

Useful websites

Supernova Follow-up at the CfA
Supernova Identification at the CfA
Telescope Observing Schedules
FLWO 60'' logs
The MMTO Sky Camera
Infrared Supernova Follow Up With PAIRITEL
IAU List of Recent Supernovae
CBAT Unconfirmed Observations Page

Dave Bishop's Bright Supernova webpage
SNfactory Supernova Discoveries
The Katzman Automatic Imaging Telescope
Carnegie Supernova Project

NED Object name search
Ned Wright's Javascript Cosmology Calculator

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Last updated: 20 MAy 2016
peter challis pchallis@cfa.harvard.edu