Subject: HRI/MRI IP TV4 Flash report Date: Tue, 25 Feb 2003 22:55:53 -0500 From: Dennis Wellnitz Hi all, We started off the day today (February 25) with functional tests of the HRI and MRI Instrument Electronics at a temperature of 60 C and a power supply voltage of 35 volts, and saw no problems. We then started cooling the Instrument Electronics for the next functional test, to be done at -30 C and a power supply voltage of 35 volts, the next step in thermal cycling of the Instrument Electronics. Once the Instrument Electronics had cooled adequately and we had taken part in the Science Team telecon, we began looking at the HRI focus and alignment, doing a quick through-focus pinhole test in white light. When we looked at the data, at best focus we saw a line focus at roughly a 45 degree angle, several pixels long. After quickly analyzing this data, and fearing a return of the stray light ghost issue, we ran through quick focused image checks for all filters, and saw nice round images, displaced along a line according to the wavelength of the filter. So, in white light we had seen a spectrum, due to the wedge in the vacuum chamber window! Following this verification of the refractive power of a glass wedge, we took a set of through-focus pinhole data using filter 7, a 100-nm wide filter centered at 750 nm, to determine HRI best focus at this temperature. A quick look at that data set gave very pleasing results. There appears to be no appreciable stray light in the system, verifying our results yesterday with the MRI, and the HRI focus appears to be very close to the predicted hot position. Also in late afternoon, interleaved with the HRI focus work, when the Instrument Electronics had reached -30 C we ran another set of functional tests of the HRI and MRI Instrument Electronics. Overnight we will be heating the Instrument Electronics to +60 C for the next functional tests at a power supply voltage of 28 volts. We expect to do those tests first thing tomorrow morning, so that we can start cooling the Instrument Electronics for additional tests of the HRI and MRI focus and alignment during the day tomorrow. If all continues to go well, the bake-out of the telescope structures, the thermal cycling and functional tests of the Instrument Electronics, and the warm HRI and MRI focus and alignment tests may all be completed Wednesday evening. That would permit us to begin cooling to operating temperatures Thursday morning, monitoring the dark current of the CCDs as we cool, and gathering additional performance and calibration data at appropriate temperatures during the cool-down. 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