Subject: HRI/MRI IP TV4 Flash report Date: Fri, 07 Mar 2003 04:06:07 -0500 From: Dennis Wellnitz Hi all, This is the flash report for Thursday, March 6, 2003. The first item on the agenda for today was removing enough files from each of the ITOC computers so that we could continue working. That was accomplished relatively quickly. Once again we prioritized the work for today and tomorrow and made a schedule for getting it done; the main emphasis today would be IR and visible work with the HRI, in that order, because the remaining visible work is mainly radiometric, for which we desired minimal ambient light. Our first effort was directed towards setting up the optics outside the ZnSe window for long wavelength work. While this was being done we worked first on getting IR spectrometer darks and then on the IR stimulator. Unfortunately, even at the highest approved DAC setting for the IR stimulator we saw no evidence that it was on. Calculations indicated that if it were working as well as in TV1, we should have seen it, in spite of the higher noise levels we are experiencing due to the higher temperature of the IR-FPA. Next on the agenda were spectral lamps through the silica window. This gave impressive results: bright spectral lines from the top to the bottom of the array, many of them saturated. We added an ND1 filter to reduce the intensity by a factor of ten. Analysis of the Argon and Krypton lamp spectra gave a consistent displacement of the spectrum towards the long wavelength end of the array by 4 physical pixels, as compared to the results from TV2. The SIM bench temperature at the time we made the measurements was stable at 139.1 K, and the usual adjustment to nominal operating temperature was made. Although we had hoped for no displacement from TV2, this displacement is small enough not to require any adjustment of the spectrometer before flight. We followed this up with IR spectrometer through-focus knife-edge measurements with simultaneous visible measurements at each focus step. The results from this test were consistent with previous results from TV1 and TV2, and found very acceptable IR focus at the best visible focus. As expected, best visible focus showed a much narrower range than best IR spatial focus. We used the same set up to move the image of the knife edge across each of the IR spectral filter edges, in both upwards and downwards orientations, in about 5 physical pixel steps, to look for edge glints from the edges of the filter. We saw nothing particularly unusual in the quick look at the data, but expect that this data will require further analysis to reveal how much stray light is generated by the filter edges. At this point the optics had been set up outside the ZnSe window, so we looked at the SIRTF black body with and without the M filter through both the east and west sides of the HRI telescope aperture. We saw no evidence of the ghosts, even at high signal levels. We conclude that the baffle is doing its job well. We also took advantage of this setup to look at the SIRTF black body through ND filters, to get additional long-wave flat-field data. We were stymied in our attempt to look at the calibrated tungsten lamp with the sapphire window, which we hope to use as our connection between long-wavelength and shorter-wavelength flat fields, because the power supply blew a fuse. We hope to repair or replace the power supply Friday and make another attempt to get this data. We were also able to see the krypton and argon spectral lamps through the ZnSe window, now that we had found the correct alignment. But the spectra are weak. We hope to look at the data in detail on Friday. By this time sunset was approaching and the skylights were dimming, so we set up for the evening radiometric work. The first task was getting ambient light levels with the lamps off in the large integrating sphere. Then, while the lamp for the integrating sphere was warming up and stabilizing, we took a look at the HRI visible stimulator, followed by taking biases in all modes of the visible detector. The quick look at the HRI visible stimulator showed illumination very similar to that of the MRI, which means that it will be very useful both in on-going pre-flight tests and for in-flight tests. Once the lamp of the large integrating sphere had stabilized, we continued with the radiometric calibration and flat-fields of the remaining HRI filters: 5, 7, 8, and 9. All of this data looked quite good. We should be able to get very good flat fields for all of the filters. To provide cross-correlation between the large and small integrating spheres, we then took MRI flat-fields using the large sphere as the illumination source, through all of the MRI filters. We then looked at the large integrating sphere with the IR spectrometer in mode 4. After covering the aperture with three screens to reduce the intensity to a level that showed no saturation, we took data in all modes of the spectrometer. Noting a slight variation in intensity in the spatial direction, we then took visible images in filters 5 and 9, to compare once we have done careful flat-fielding. To finish up this work, we took IR ambients in all modes, and then IR biases looking at the nitrogen-cooled shroud, each in all modes. These are by far the best flat fields we have obtained for the shorter wavelength end of the IR spectrometer, out to the cut-off of the fused silica window. That ended our data taking for the night. We made two copies of all of the data taken today. In the morning, after checking that everything has been backed up elsewhere, we will delete these files from the ITOCs to make room for Friday's data. On Friday we expect a final marathon performance and calibration testing day to finish up all remaining tests at this temperature. We then expect to cold soak the instruments over Saturday and Sunday, concluding the tests at this temperature with final thermal balance measurements on Sunday night. Overnight on Sunday we expect to raise the temperature of the HRI by about 10 degrees to permit us to make some final measurements at a slightly higher temperature, and then begin warming back up to room temperature. Final measurements in the chamber will be made at ambient temperature and dry composite conditions, before the HRI and MRI are removed from the chamber and returned to the clean room for repair of the Instrument Platform. 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 ---------- HRI filters Number Center Width (nm) 1 650 >700 4 350 100** 2 450 100 3 550 100 9 650 100 7 750 100 8 850 100 5 950 100* 6 600 >700 * 950 filter is longpass ** due to materials constraints, cut-on wavelength is about 340 nm