December 19, 2000 teleconference: Further Post-Mortem of the last two search runs. These notes are not intended to be complete. Side Note: Peter Nugent pointed out that the first SN from the 7 SNe paper was most likely a type IIL. No spectrum was ever taken. It was partially responsible for the Omega_m = 1 result of that paper. He has prepared a webpage describing this (http://panisse.lbl.gov/~nugent/sn94h.html). The lightcurve matches 1972L, and the colors don't show any UV defecit at maximum, which even 1991T showed. Gerson says that this SN is in his lightcurve paper, and that he is averse to any further delays in getting it out, so he doesn't want to go back and remove it. Greg reports on the fall 1998/Spring 2000 spectroscopic postmortem. He investigate the image quality in both runs, and discussed the issues of Differential Atmospheric Refraction and guding problems. His basic conclusion is that neither of these can explain what happened. He does caution that some of our pivot stars turned out to be galaxies, and that we should avoid this in the future so that we can use our pivot stars to monitor image quality. Reynald starts out by talking about the zero-point issues in the CFHT, comparing the ones calculated from the actual data to the pre-tabulated ones for CCD #9. Saul wants to know if CCD #9 was one of the red-sensitive chips. Apparently there are two kinds of chips in the mosaic, and the red-sensitive ones are about 0.6 mag more sensitive. Anyways, Reynald says that they got the same zero-points in the I band as the pre-tabulated ones, and 0.1 lower than the pre-tabulated ones in the R band. They also calculated slightly different airmass and color dependencies on CCD #9. Somebody has looked it up, and it turns out that CCDs #3,4, and 5 are the high-resistivity, red-sensitive CCDs in the mosaic. Clearly Reynald and company need to check their zero-points on these chips as well. Reynald reports that they haven't changed the magnitude of Ravel by much. For the 1999b run, the depth of the field was 25.2 at a SN of 5 in 3 + 3 hours and 0.9" seeing. For 2000a they got to 25.0 at SN 5 in 2:36 + 2:24 with 1.0" seeing -- both on CCD #9. They have not checked this on the subtractions, and they used the Landolt color to get the V-I color term. There was another field in 1999b that they took data on, but it had worse seeing. Saul wants to know how deep we would get if the seeing were 0.6". Reynald says they looked at what the High-z supernova team got in 1999b, and that they got to 24.9 in 0.65" in 1+1 hours on CCD #0 at a SN of 5. Again, these have not been calculated on the subtraction, but from the sky brightness. The High-z team found most of their high redshift supernova on the red-sensitive chips, not surprisingly. The upshot is that they got about as deep as we did, but found more supernova. Don has some questions about the chip psf. Saul suggests that we may want to take more short exposure and concentrate on the high-resisitivity chips. CFHT claims a median seeing of 0.7", so we got a little unlucky. It would be a good idea to develop some seeing dependant strategies for the upcoming search. Reynald reports that they haven't done the estimates for how many we should have found, nor have they run their search on the high-z team's data to see if they find their supernova. The high-z team found 3 objects in 8 fields, so it's possible that we were just unlucky. On the other hand, this would make Albinoni an amazingly lucky discovery, and would certainly drop the rates by a lot. Peter points out that the High-z team was not complete in their spectroscopic follow up (whereas we were in the Albinoni search) so 3 for 8 fields is a lower limit. Ariel discusses color-selecting galaxies to improve our probability of getting high-redshift candidates. He says that to get z greater than one requires a B magnitude of about 28. We would obviously require subaru or the like to do something like this. Furthermore, this estimate is a somewhat optimistic one. It may be possible to work in other filters at the cost of slightly less certainty. Several people wonder how quickly the certainty falls of with depth. Maybe we'll be able to go a lot shallower but still be able to give ourselves a good chance of selecting the high-redshift galaxies. Saul and Greg tried to pin down the Japanese contingent about what proposals they have put in, since apparently they have in a proposal that doesn't sound like what we planned to do with them. The Japanese still seem very uncertain about the instruments, and expect that they won't be able to do anything for us this year, but maybe next year. They might be able to look in March, but then we may have problems with the SNe interfering with the host galaxy colors, and throwing off the photometric redshift. It might still be useful as a test. The meeting ends with the preliminary scheduling of the next meeting for January 17th at 8:30 am, subject to Reynald's group getting a chance to complete more of their analysis.