From kawabe_k@ligo-wa.caltech.edu Tue Jan 1 16:01:07 2008 Date: Tue, 1 Jan 2008 13:00:35 -0800 From: keita kawabe To: Keith Riles Cc: Xavier Siemens , Brian O'Reilly , "Keita Kawabe@LIGO" Subject: Annoucement 1/2: New data flag for V3 h(t) Happy new year Keith, The calibration review team would like to make two announcements concerning the calibration of h(t) V3 for the upcoming AAS talks, and this is one of them (the other is going to be the error bar). We've been working very hard in the past months to assess the calibration of h(t) frames specifically for the AAS meeting. Through our study, recently we have concluded that there were two short periods in S5, one for H1 and the other for L1, where the h(t) was incorrect. H1: GPS 835045153 to 835503749 (Segments 1657-1693), about 5 days in Jun 2006 L1: GPS 822656471 to 822883666, about 3 days in Jan/Feb 2006 For H1 this is the exact time of the event, and we know exactly what happened and why. For L1 this is a very conservative estimate in that we know that the entire event was inside this window. The nature of the error is a big, frequency dependent systematic that goes as large as 30% for H1 and a factor of 2-ish for L1. Since V3 h(t) is in wide use, regenerating the h(t) frames for V3 would probably cause more confusion than necessary. Instead, we decided to flag the bad segments. Things are going to be fixed in V4. As far as I understand, the parties that might be affected by this regarding the AAS talks are the CW group (Crab F-stat) and the stochastic group. There should be no impact on the burst talk because of the time of the event. The flag is yet to be released, but considering the urgency of the matter, several persons in the search groups (CW: JoeB, MattP, Michael and MAP, Stochastic: Vuk, Burst: ErikK and PeterS) were already notified of this. As for the error bars, we'd like to make a separate announcement within a couple of days. Most probably it's going to be something like "5% on top of h(f) error budget announced by Michael Landry, except close proximities of the 60Hz harmonics, calibration lines and violins within X Hz." Sam Waldman is running his code to look at things near the lines with smaller bandwidth, and we hope that we can release that data which we hope is going to be useful for the error estimate of e.g. Crab F-stat. I can talk about this in the next detchar. Best regards, Keita