Subject: HRI/MRI IP TV4 Flash report Date: Tue, 04 Mar 2003 04:01:45 -0500 From: Dennis Wellnitz Hi all, Today (Monday, March 3) we met at 1 pm MST to review and plan the day's activities. We had already arranged for through-focus pinhole measurements on the MRI and HRI in the morning, conducted by Jim Baer, Peter Spuhler and Marty Huisjen. Don Hampton and many of the Science Team representatives worked part of the morning either to support the focus measurements or to continue work on analysis. For many of us it was a very short night. At the meeting there was lively discussion of the IR spectrometer results to date, particularly the blotchiness due to the relatively high temperature of the IR-FPA, which is making it hard to do a reasonable flat-field determination including the effects of the baffle and filter. Both the MRI and the HRI have stabilized in temperature and are no longer cooling significantly, but there are heaters running to simulate the heat inputs from the spacecraft, the SIRU, and the star trackers, for thermal balance. We would like to find some way to get the IR-FPA a few degrees colder to be able to get better data; this may involve reducing the heat inputs as soon as the current thermal balance measurements are complete. We agreed that the major emphases today were to be focus measurements during the morning and early afternoon, and then continuation of the radiometric calibration of the MRI for the rest of the afternoon and evening. If we have finished the MRI and small integrating sphere early enough, we might take a look at the the large integrating sphere with both the MRI and HRI. In the morning re-doing the MRI through-focus pinhole gave essentially the same focus position as was obtained on Saturday, within a few tens of microns, so there appeared to be nothing wrong with the procedure as carried out on Saturday. It now appears that the MRI best focus position is significantly different from the desired cold focus position. This will not cause us any difficulties in performance and calibration testing, but does raise the possibility that we may wish to consider an MRI focus adjustment after warm up. In the late morning, and again in the afternoon, HRI through-focus pinholes were done. We saw general agreement between the two HRI focus measurements, though scatter in the second one was considerably larger than desired. The alignment cube survey and HRI to MRI co-alignment data-taking were deferred to tomorrow (Tuesday), because the afternoon was disappearing and we wanted to get started on continuing the MRI radiometric calibrations. Once the focus measurements were completed, we set up the small integrating sphere to do the narrow-band MRI filters. To get enough light to provide acceptable integration times, we opened the external lamp aperture to full brightness and turned on two additional lamps inside the sphere. We needed sunglasses to look into the integrating sphere, so daytime ambient light inside the tent was not a problem. We started our work with the radiometric calibration of filter number 9, centered at 309 nm with a width of 6.2 nm. We continued with filter 8, centered at 345 nm with a width of 6.8 nm; then filter 7, centered at 387 with a width of 6.2 nm; then filter 2, centered at 514 nm with a width of 11.8 nm, at which point we were able to turn off the two extra lamps and go back to operating with only the external light with variable shutter attenuation. By this point it was 9:40 pm, and we had already had the lights off for a couple of hours, so it was quite dark and ambient illumination was quite small. We then continued with filter 3, centered at 526 nm with a width of 5.6 nm; then filter 4, centered at 750 nm with a width of 100 nm; and then finished up with filter 5, centered at 950 nm with a width of 100 nm. We finished data taking at 1 am and then powered down the systems for the night. These radiometric measurements completed the radiometric calibration data set for the MRI. When we set up the large (24-inch aperture) integrating sphere tomorrow, we plan to take a few measurements of it using the MRI before we start the calibration of the HRI, so that we have a cross-calibration between the integrating spheres. We found nothing particularly surprising in our quick looks at the MRI radiometric calibration data, except for the puzzling behavior of mode 9 for short integration times. However, we did find three dust specks on the telescope side of filter 8, and one dust speck nearly centered on the telescope side of filter 2. Tomorrow we plan to continue the focus and alignment measurements of the HRI, MRI, and the alignment cubes, and then perhaps to start imaging test targets at best focus for each telescope. Later in the day we plan to set up the large integrating sphere, cross-calibrate using the MRI, and then to start the HRI radiometric calibrations, which we expect will continue late into the evening. We plan to have a calibration review and planning meeting at about 1 pm. 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