From: Saul Perlmutter (saul@lbl.gov)
Date: Mon Dec 09 2002 - 08:30:43 PST
Hi Chris,
I was wondering if you got this message from Naoki in time to avoid
taking R band on those three lower redshift SNe last night (Sunday
night)? If so, I guess the important thing to consider for tonight
and tomorrow would be if we can get sufficient signal-to-noise on 017
without using up too much of the remaining FORS2 time. A possible goal
might be to get another observation with S/N ~ 5, so that the two
telescopes' data together would reach S/N ~ 7 -- based on a rough ETC
estimate, this might take 2 hours of FOR2 exposure time (although if the
seeing is good this may give slightly better S/N than we got with
comparable time but worse seeing on Subaru). Alternatively, we may
want to get a stronger point now (perhaps 3 or 4 hours exposure time),
especially if we have not already used up some FORS2 time on R-band
observations of the lower redshift SNe.
I was also realizing that this field is begining to get more
difficult to observe for many hours in a night. Do you have an estimate
of how many total observable hours are left during the remaining queue
time in December (and maybe the very beginning of January)? If this is
begining make it unlikely that we will get all 24 queue hours on this
field, then we might as well use more of it now.
--Saul
attached mail follows:
Hi Saul,
> 1) Since we are still trying to get sufficient signal-to-noise in the J-band data for 017, we should keep a
> close watch on what Naoki concludes about the i'-band signal-to-noise from the last two nights' Suburu data put
> together. But meanwhile, let's not spend FORS2 time on this yet.
I have checked the Subaru data of last two nights, but the object is very
faint and I do not think signal-to-noise ratio is sufficient.
Current S/N is 4-5.
> 2) There are several lower redshift (z ~ 0.6) SNe for which we have nice SN spectra, and likely good
> i'-band lightcurves, including 001(which was also called 027), 055, and 025. It would be good to get an R-band
> point with S/N ~ 20 for these, since this would provide a useful color to check for extinction. In principle
> these nearer supernovae would not take too much FORS2 exposure time for this purpose: about 25 minutes each
> for 001 and 055, and 12 minutes for 025 (which would give S/N of 15 for the first two and 20 for 025).
> Including overhead, this is probably a good investment of about 75 minutes out of the 24 hours of FORS2 queue
> time we have left.
I have checked the log of SXDS observations and found that
SXDS_2 and SXDS_5 were observed with R-band.
SXDS_2 included -055 and SXDS_5 includes -025 and -001.
The following is the summary of exposures.
SXDS_2 SXDS_5
Nov02 40min(0.72)
Nov03 40min(0.78)
Nov10 32min(0.70) 32min(0.55)
Numbers in parentheses are seeing.
The reference images are not available for these data.
--- Naoki Yasuda @ National Astronomical Observatory of Japan e-mail: naoki.yasuda@nao.ac.jp
This archive was generated by hypermail 2.1.4 : Mon Dec 09 2002 - 08:29:20 PST