From: Robert A. Knop Jr. (robert.a.knop@vanderbilt.edu)
Date: Tue Apr 30 2002 - 14:45:28 PDT
Below are probably slightly optimistic depth estimates for the CTIO
reference run fields.
The assumptions that went into this: each image gets measured
separately, so that an image of worse seeing doesn't corrupt the
measurement of an image of better seeing. This is thus a better
simulation of what we might get out of lightcurve software than we would
get from image subtraction. This is probably slightly better than we
can really do, and bear in mind that it is defintiely better than what
we'll do with the image subtraction software.
S/N values are straight in the image, *not* in the subtraction. If you
assume a reference no deeper than the image, reduce all S/N values by
sqrt(2). All fields starting with "L" are in the R-band; the two fields
starting with "H" are in the I-band.
Some fiducial supernova values (fodder for thinking about what we might
detect before and after max):
(I think)
rest frame
z t-tmax R I
--------------------------------
0.5 0 22.3 22.2
0.5 10 22.9 22.7
0.5 15 23.4 22.8
0.5 20 24.0 23.0
0.5 30 24.8 23.6
0.8 0 23.9 23.1
0.8 10 24.8 23.6
0.8 20 26.2 24.6
0.8 30 27.0 25.5
1.0 0 25.0 23.7
1.0 10 26.0 24.4
Thus, for instance, a z=1.0 SN at max in the I-band looks like a z=0.5
SN 30 days after max, or a z=0.8 SN 10 days after max. If we find one
of these in a search vs. year-old references, to see the lower z after
max supernovae in the reference run require the reference I-band images
to be good to about magnitude 23 (for 10 rest-days after max at z=0.5 or
at max at z=0.8). (I'm being sloppy with +-2 days here.)
For those examples, we're OK; we'd see 'em. However, a direct new-ref
search *won't* find the z=1 supernovae, since a magnitude 24 limit after
the sqrt(2) reduction takes us down to <4-sigma, and that's a very
optimistic 4-sigma (as the numbers below are almost certainly well
better than we could do with a search subtraction).
I have no conclusion here, this is grist for the mill. I hacked these
numbers together quickly, so it's possible that I did something wrong;
they look a bit optimistc to me.
Raw S/N for object of magnitude...
exp ----------------------------------
field nexp (min) 22.5 23.0 23.5 24.0 24.5 25.0
------------------------------------------------------------------
H2c 13 184. 22.95 14.48 9.14 5.77 3.64 2.30
H3c 16 211. 21.89 13.81 8.71 5.50 3.47 2.19
L341c 6 85. 30.22 19.07 12.03 7.59 4.79 3.02
L350c 2 10. 13.04 8.23 5.19 3.27 2.07 1.30
L344c 2 20. 18.32 11.56 7.29 4.60 2.90 1.83
L340c 2 20. 15.39 9.71 6.13 3.87 2.44 1.54
L022c 2 20. 11.31 7.14 4.50 2.84 1.79 1.13
L221c 2 10. 13.40 8.46 5.34 3.37 2.12 1.34
L222c 2 10. 13.86 8.74 5.52 3.48 2.20 1.39
L210c 2 10. 13.26 8.37 5.28 3.33 2.10 1.33
L211c 2 10. 11.95 7.54 4.76 3.00 1.89 1.20
L212c 2 10. 13.13 8.28 5.23 3.30 2.08 1.31
L260c 2 10. 13.81 8.71 5.50 3.47 2.19 1.38
L261c 3 15. 17.16 10.83 6.83 4.31 2.72 1.72
L262c 2 10. 13.05 8.23 5.19 3.28 2.07 1.30
-Rob
-- --Prof. Robert Knop Department of Physics & Astronomy, Vanderbilt University robert.a.knop@vanderbilt.edu
This archive was generated by hypermail 2.1.4 : Tue Apr 30 2002 - 14:49:33 PDT