@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ @ @ MTA Monitoring Report 3/24/00 - 3/30/00 @ @ @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ ************ CTI trend ************* No prominant changes are observed. All of them are steady. CCD 7 Al Ka may have larger standard deviation. >>>>>>>> Please read the memo from Scott Wolk below <<<<<<<<<<<<<< ************** MTA Problem Tracking. ***************** No new problems are reported this week; only same preoblems are keep coming: EB1DI, EPOVSPR, TSAMYT, TSAPYT, EOESAC2C, EOESAC1C, AOSAILLM, EB2DI, EB3DI, ESAMYI,AOPSAMUL, 1DPDBBON, ES1P5CV, ES2P5CV, ASPEB5DV, AGWS2V, EB2CI, EB1CI,EB3CI, AIOBP5CV, C2SVMONB, CUSOB28V, CIUB5V, CIUB15V, EB3 ******** Trending *********** Although there are no new trend is observed, here are some trends whcih we are seeing for a while. * Acis Thermal: some msids show larger scattering for the last few weeks. * Epin temp/electronics: continue to show strong upwared trend. * HRMA struts/cone/tfte: show mildly strong upward trend. * ACA thermal: many shows upward trend * IRU temp/electronics: AIRU1G1L show sudden drop. * Spacecraft temp/electronics: larger scatter *********** ACIS Focal Temperature ******** Focal palne temperature is shooting upto around 108 C about every 2 days. see http://asc.harvard.edu/mta_days/mta_fp/fp_week_temp.html The peak and width are expected to be larger as seaon progresses. ************* Telemetry *********** Battery Usage: EOEB1DIC showed a big jump from the end of 3/25 to the early part of 3/26. The peak reached 25.63 (from usually 0). One large serge is observed at the end of 3/27 to the first part of 3/28: * Spacecraft OOBAPWR * Spacecraft electronics Side B: ELBI * HRMA temperature related msid (esp. HRMA Cone) *********** Photon Page ************ Although there are about 40 new entries, following are obsid are analyzed this week. OBSID DETECTOR GRATING TARGET ANALYSIS --------------------------------------------------------- 611 ACIS-I NONE W3B OK 872 ACIS-S NONE NGC 6503 OK 539 ACIS-I NONE Z5247 OK 859 ACIS-S LETG NGC 4051 NO SKY 71 HRC-I NONE REJ1236+47 WRONG INSTRUMENT 69 HRC-I NONE REJ1236+47 WRONG INSTRUMENT 47 ACIS-I NONE STAR C,CYG OB2 OK 62 HRC-I LETG HZ43,2 WRONG INSTRUMENT 70 HRC-I NONE REJ1236+47 WRONG INSTRUMENT 614 ACIS-S HETIG FKCOM/HD117555 NO SKY 934 ACIS-S NONE M101 NO SKY 715 ACIS-S HETG GX 249+2 NO DATA POSTED 640 ACIS-S HETG ZET PUP NO SKY ************ Some Comments from Exparts ******** ------------------------------------------------ From Scott Wolk (3/27/00) ----- Comments on CTI ------------------------------------------------ Hi Roger and Harvey, I took an action last week at the CTI telecon essentially to answer the above question. I will be unable to attend that telecon (Travel) and I wanted to give you guys a heads up on the situation. It is not too good because we probably will run into trouble with the focal plane temperature. Here is the status: Our current automated measurements are good to about 3x10^-6 per measurement (i.e 1 line, one node). The limitation is photon statistics, not the algorithm. No human effort can improve the formal error. (We are working on tweaks to the code which impact the absolute value) In the simplest analysis it takes about 9 measurements to determine a change of 1x10^-6. This is 5 orbits or 2 weeks. One could imagine trying to correlate trends in the 24 nodes and 3 lines measured at any given time. We might be able to attain 1x10-6 sensitivity per orbit with such an approach, unless the noise is correlated. The ACIS team will doubtless point out many reasons why monitoring the mean CTI measurement is meaningless, but if they don't We could start to monitor a "mean CTI" within 1 week. complications: Background - the ACIS team demonstrated that high background (measured by dropped exposures) gives the effect of improving CTI by up to 1x10-5 since the noise is filling the traps. We have speced a code to monitor this background and expect it to be in place in a month. But, the relationship between background rate and observed CTI is not well understood. At this point (and for the next 2-3 months) the best plan is to drop measurements where the CTI seems to improve. Focal plane temperature - THIS IS THE CRITICAL ONE Rino and I have been independently putting together data on the temperature spikes. Short result: Due to seasonal effects the spikes will get higher and wider for the next 3 months. Peaking about July 1. Soon,( <1 month ) the focal plane will be warm during the CTI measurements. We won't really be monitoring anything if we make CTI measurements when the FP is say -117. We may have to change to an operating procedure where HRC observations start and end each orbit and CTI measurements are made during science time. The alternative is a good calibration of the effect of temperature on CTI. Wish the news was better, Scott --------------------------------------------------------------------------- From MAxim Markevitch (3/23/00) ----- Frequency of ACIS background flares --------------------------------------------------------------------------- I have just finished looking into some recent ACIS data to estimate the flare frequency. It looks like they are becoming somewhat less frequent compared to August (as some already suggested). Take a look at the figure on the internal cal page: http://icxc.harvard.edu/cal/acisbg/bg_newhist.html username: CXCCal password: ChaXAF93 The figure shows frequency for three periods -- August, September-November and December-January. I think the note being sent to observers should now say "the S3 background is more than twice the quiescent rate about 20% of the time" (was 30%). The probability to have flares above a factor of 1.2 is 30-40% for S3 (this is when the data become useless for most galaxy cluster analysis). This probability for S2 is now 5-15%. Maxim