o SR. Blast Mtg Notes, 29 Dec 51 In the following discussions, on attempt was made to locate stations where such facilities are already present. II. IVY BLAST PROGRAM* Table I is a summary of the discussion. cussed in detail below. A. The measurements are dis- Air Pressure vs Time and Distance at Ground Level (SC) wee Wiancko gauges will be used. The location of these gauges as finally agreed upon is shown in Table I. The question of whether or not to instrument for the higher yleld range was discussed at length. Since placement and recording of another gauge in a station already built constitutes little additional effort, it was agreed that in those locations where recording shelters are provided, gauges to cover the higher range may be included. All gauges will be battery operated, thus requiring no power. Timing signals will be used where available. Where they are not, the gauges will be started wih ablue box and alarm clock, since it is desired to have filaments running about one-half hour before shot time. For the first five stations listed on the table, recording will be done at Bogon, requiring wires from these stations. At all the other stations, data will be recorded directly at the instrument. As noted, some recording shelters exist from Greenhouse. The recorder will be of the NOL type which scratches pressure-time records on a drum. A system to give 1 msec time resolution is desired, and it is planned to have 6 minutes of recording on the tape. This length of time is desired for several reasons: 35 minutes of recording are needed at the far stations, and Sandia also plans to record the close measurements of afterwind on the same recorders. Too, in order to get arrival time with any accuracy, zero time is required on the record. (These gauges still do not get arrival time as accurately as one would like. However, Cox pointed out that this determination also necessitates a measurement of acoustic velocity and any way one can measure time of arrival is probably better than any measurement of acoustic velocity.) — Reference is made to J-9092, Memo fm Ogle to Graves, 23 Nov 51, "Ivy Blast Program” and SC Ltr Sym: 1(181), Landry to Tyler, 3 Dec 51, "Sandia Labo- ratory Participation in Operntion Ivy” for a detailed statement of objectives of the measurements.