Subject: HRI/MRI IP TV4 Flash report Date: Thu, 27 Feb 2003 22:32:24 -0500 From: Dennis Wellnitz Hi all, We started off the day today (Thursday, February 27) at 7:30 am with additional dark current measurements on the HRI and MRI CCD detectors, having followed the dark currents until about 10:30 pm as the CCDs cooled last night. We also discovered that the stimulators for both the HRI and MRI had been on during the cool-down, so that our previous darks were not actually darks, so we took some additional data with the stimulators on and off, to measure how much of the signal was due to the stimulators. After making a correction for the light from the stimulators, we find that the dark currents of the HRI and MRI CCDs are comparable to those of the ITS CCD at similar temperatures, but a factor of about 1.5 to 2 higher. We had selected for the ITS the CCD that had the best cosmetic appearance and the lowest dark current because it is expected to operate at the highest temperature, so this result is quite consistent. Later in the morning we set up the small flat field source, the small (9-inch aperture) integrating sphere, to permit us to make flat field measurements of the MRI near the possible operating temperatures of the ITS. As it slowly cooled past -16 C, we took data on the MRI to determine flat field, exposure time, linearity, and dark current. Once the MRI reached -30 C, at about 5 pm, we took through-focus pinhole data on the MRI through filter number 4 (a 100-nm wide filter centered at 750 nm) to determine best focus at that temperature. We then took data to determine flat field, exposure time, linearity, and dark current at that operating temperature in full frame mode. We also took data to determine exposure time and dark current in all modes at this temperature. Interleaved with these measurements, we also took dark current data on the HRI CCD as it dropped slowly in temperature. As soon as we finished this data taking at 8:20 pm, we asked that the shrouds be flooded with liquid nitrogen to take us to cold operating temperature as quickly as possible. Even so, we expect to spend most of Friday and Saturday cooling the instruments to operating temperature. Because we expect the MRI to cool more rapidly than the HRI, we expect to be able to start some performance and calibration tests on the MRI on Saturday, or perhaps late on Friday. However, most of Friday will be spent in analysis of the data we have taken today, interspersed with dark current measurements on the HRI and MRI CCDs as they cool. Mike A'Hearn arrived at Ball at about 1 pm today, after spending the night in Dallas after his flight from National was delayed an hour and a half due to icing conditions, and was instantly engaged in meetings for most of the afternoon. He was able to spend some time with us late in the day. Jessica Sunshine arrived at Ball shortly before 2:30 pm today, and immediately began settling in and familiarizing herself with the analysis tools available. With this Flash report I have begun using the "Flash reports mailing list", which should greatly reduce the size of the header for this e-mail. Please let me know if you have any questions or comments. Also please let me know if you would prefer not to be included on this Flash report distribution list, or if there is someone else who should be included on this distribution list. Dennis