Re: VLT spectroscopy paper

From: Chris Lidman (clidman@eso.org)
Date: Wed May 19 2004 - 13:37:53 PDT

  • Next message: Tony Spadafora: "Fwd: from M. Sullivan on VLT spectra paper"

    Hi Greg,
      Many thanks for your useful comments and perceptive observations. I've
    modified the text to reflect all the comments you made. The modified
    version of the paper will be ready this evening.

    Cheers, Chris.

    Ok, I finally had a chance to read the VLT spectroscopy paper. I think
    it is ready for submission. I found only a few simple corrections and
    suggestions, and two items that might take a little discussion within
    the SCP:

    Page 1: I suggest thsat "More recently considerable effort ..." be
             changed to "Considerable effort ..." since in the previous
             paragraphs you are referencing work through 2004.

    CLi - Done.

    Table 1: I suggest "Classical with additional wide-field monitoring"
             for the Fall 2002 search, as the other types of search have
             monitoring too. (Indeed, when we used to use CTIO we would obtain
             follow-up with the same instrument, as we did with Subaru, but with
             Subaru we got a significant multiplex advantage.)

    CLi - Done. I also changed the paragraph slightly to emphasize the advantages
    of doing the followup with the a wide field imager.

    Page 2: "searchers, in which ..." should be "searches, in which ..."

    CLi - Done.

    Page 3: "before and the offset ..." should be "before and after the offset ..."
    CLi - Done.

    Page 3: $6150\A$, should be $6150$\A,

    CLi - Done.

    Page 4: "we note down information from the lightcurve ..."
             "we note any relevant information from the lightcurve ..."

    CLi - Done.

    Fig 1: I would prefer solid shading for Type Ia and gray shading for
             Type Ia? Otherwise I have to actually think about which way the
             lines are tilted.

    CLi - Done.

    Are we underselling SN2002lc? Is it as convincing as Riess' z=1.3 ACS
    grism spectrum? Put another way, Riess will play up the fact that three
    8-m class telescopes combined couldn't produce a convincing spectrum of
    a z = 1.3 SN. I think this is my biggest remaining issue.

    CLi - From the VLT spectrum alone, we cannot say too much. If we had
    have integrated for four hours on this one and had better
    conditions (seeing makes such a big difference), I think that we
    would have nailed it. If we add the Subaru and ACS data then
    2002lc is a good match to a SN~Ia at z=1.26. However,
    I think this should be published by our Japanese colleagues, since the
    Subaru spectrum has better S/N than the VLT spectrum

    Fig 2: I would prefer that the labels on %Inc be X rather than log(X).
            The log scaling is fine; I just want it to be obvious that the
            scaling is 10% to 1000%.

    CLi. Done.

    The references need to be updated. There are several references to
    astro-ph articles which are now published (because readers like me have
    been so slow!). These include Hawkins et al, Knop et al, Riess et al,
    Spregel et al and Tonry et al.

    CLi. Done.

    Finally, I noticed that 3 of 4 candidates on finders showing clear
    residual fringing (01gy, C02-016, C02-030, C02-034) lead to untyped
    spectra. Might an alert (or antagonistic) reader infer a causal
    relation (binomial odds are 15%)?

    CLi. Here are some extra information on these SNe. Two are clear SNe

    01gy - Secure Ia

    C02-016, C02-030, C02-034 are all from the CFHT 2002 search.

    The light curves are avaialble from http://supernovae.in2p3.fr/~raux/

    C02-016 (VotezChirax) - Well covered light curve with a a sudden rise
    C02-030 (Troudux) - No light curve available.
    C02-034 (InTheMix) - Bright host. Three lightcurve points

    [I also noticed that for 10 of the 12 cases where the field edge shows
    up in the finder chart, we failed to make a classification. The
    binomial probability for so many failures given our success rate is
    only 12%. However, as the typical CCD was 7 x 14 arcmin and the finders
    show a 3 x 3 arcmin region, I suppose the field edges will show up
    often in the finders.]

    CLi. There might be something in what you say. I found 14 finding charts which
    show the edge of the FOV, and if I exclude T02-047, 9/13 were unclassified
    and 3 of these were within 20" of the edge.

    SN 2001gl - Unclassified with broad SN features.
    SN 2001gr - Ia
    SN 2001gy - Ia
    S02-001 - Unclassified (< 20" from edge)
    S02-025 - Unclassified (< 10" from edge)
    C02-016 - Unclassified but with a solid light curve.
    C02-034 - Unclassified (< 10" from edge)
    SN 2002gi - Ia
    T02-047 - Post SN spectrum. Rob says this has a nice light curve.
    SN 2002kq - Unclassified 30" from the edge
    Suf02-007 - Unclassified 1' from the edge
    SN 2002kn - Ia?
    SuF02-028 - Unclassified 1.4' from the edge
    SuF02-083 - Unclassified 1.4' from the edge



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