JS Bach

Keck LRIS Data files:

Date: 21 April 2001
Exposure time:
Data reduced by: Isobel
Weather note:
Reduction notes.
Preliminary reduction: [asc] [fits]

VLT Data files:

Date: 21 April 2001
Exposure time: 3 x 1800s = 5400s
Data reduced by: Chris
Weather note: Cirrus is now thick. Seeing 0.6 - 2.1" over course of night.
SN: [asc] [fits]
Sky: [asc] [fits]
Preliminary reductions: [smoothed ps] [unsmoothed fits]


Chris (preliminary VLT): z=0.765 (Chris & Gaston). Lots of broad bumps in this one. Type Ia at z=0.8?

Isobel (preliminary LRIS): Can't see evidence for z=0.765.

Isobel (preliminary VLT): Now I think there could be OII at z=1.066. SN features look quite good at that z. See Bach_snz.ps.

Chris (final VLT): SN? z?

Rob (preliminary photometry): [Light curve is unusual at z=0.765] Note: I haven't tried to fit it at z=1.066 since the K-corrections from R to whatever blueward of the U-band that the thing K-corrects to (never mind the template lightcurve blueward of the U-band) haven't been done. In any event, I would be surprised if this could really be a SNIa at z>1, given the S/N it was found at in relatievly short exposure R-band images.

Andy (final VLT): I think this is a Ic at z=0.32. It is similar to SN 1991A, which was classified as a Ic, however there is a trace of He in 91A, (which would make 91A a Ib), and there is even some weak H-alpha, which would make 91A a II. In S01-031.91A.ps I compare Bach to the spectrum of 91A at 1-17-91, though it also fits well to the spectrum taken at 1-6-91. Bach is unsmoothed. You can see that Bach doesn't have H-alpha (the feature on the right hand side of the spectrum). Of the double absorption at ~7500 A in 91A, the blue one is probably He I, and the red one is probably Na I D. Note that Bach doesn't appear to have He. The line near 77774 A in Bach is probably from the Earth's atmosphere. Note that 91A was discovered by Pennypacker et al. (!) on January 1, though Gomez and Lopez et al. 1994 say that light was seen on a prediscovery image on December 13 but not on December 6. Assuming that the explosion date was December 10 and the rise time was 2-3 weeks, that puts the Jan 6 observation at 1-2 weeks past maximum light. Note that Bach may still be at maximum in our observation, since we don't have a maximum light spectrum of 91A with which to compare it.

Light curves
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