From: Greg Aldering (aldering@panisse.lbl.gov)
Date: Fri Jan 30 2004 - 01:23:24 PST
Hi Vitaliy and Serena,
I spoke with John Tonry today concerning 99Q. The photometry he has
consists of the discovery point and those from the HST images. (This is
basically the same as in Vitaliy's thrid fit.) The discovery point has I =
22.3 +/- 0.05 and the fitted date of max is 2451194.4. So, Tonry's date of
max is 3 days earlier than the one used by Adam, and 2.6 days later than
your fit using the discovery point (albeit using a larger value for the
uncertainty).
Tonry said it is possible that Adam might have a "secret stash" of
additional data points (I found this an odd thing for him to say, but
apparently they aren't so good about sharing data within their
collaboration), but this seems unlikely.
So, I think we can safely use 2451194.4, quoting Tonry 2003 & private
communication, for the time of maximum light. Using this modifed date
of max isn't enough to alter the maximum restframe I-band brightness
by more that a few percent. So, it isn't enough to explain why 99Q is
fainter. However, it does mean that we know that stretch as well
as the HZSST does.
Looking more carefully, I see that in the uncorrected Hubble diagram 99Q
is only about 2-sigma too faint using the *inner* error bars. In all
cases 99Q is beter than 1.5-sigma using the outer error bars (i.e.,
including intrinsic error).
All of this suggests to me that we may as well show both the uncorrected
and stretch-corrected results in the I-band paper. It will not be
controversial, but make the paper clearer and more complete. (Right now
one wonders about, or is easily confused by, the use of stretch correction
for the local SNe in the first half of the paper and then skirting of the
stretch correction in the latter half of the paper.)
Cheers,
Greg
On Fri, 23 Jan 2004, Vitaliy Fadeyev wrote:
>
>
> Hi Serena,
>
> these are the results of my fits to SN 1999Q lightcurves:
>
> case m_B dm_R m_B_corr dm_B_corr s ds chisq dof m_R kcorr_R kcorr_I tmax dtmax R-I d(R-I)
> 1 22.82 0.06 23.02 0.16 1.117 0.054 5.29 8 22.06 -0.764 -0.310 2451186.54 1.444 -0.054 0.074
> 2 23.43 0.03 23.59 0.08 1.086 0.031 19.85 9 22.39 -1.042 -0.531 2451197.52 0.000 -0.323 0.029
> 3 23.14 0.02 23.34 0.07 1.119 0.032 9.95 9 22.24 -0.902 -0.419 2451191.83 0.853 -0.188 0.035
>
> The fit "cases" are as follows:
> 1) stand-alone HST data, no constraints. In this case, the day
> of max is shifted to earlier time by 11 days compared to what
> Riess has reported. The Chi^2 is good (too good).
> 2) the maximum is fixed to the Riess's value. The Chi^2 becomes
> "bad".
> 3) Greg pointed out that IAU circular contains the I band discovery
> magnitude. I assumed that that data value has error of 10%
> and that it was measured with similar filter to F814W. Adding
> this point resulted in third case. The day of max is about 6 days
> earlier than reported value, Chi^2 is good.
>
> So, you can take this with appropriately sized grain of salt or
> other substances. Feel free to critisize.
>
> If B band stretch value is all you care about, then it seems that
> proper value would be about 1.1 . However, the time-of-max discrepancy
> is worriesome.
>
> Cheers,
> vitaliy
>
>
>
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