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RXTE News Archive: 2010 RXTE
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Contents:


RXTE Cycle 15 Accepted Program Now Available

November 28, 2010

The accepted targets from the RXTE Cycle 15 Peer Review of Open-Time targets are now available on the Web. These targets will be scheduled for observation in 2011, along with the previously announced RXTE Cycle 15 Core Program. All observations from both programs will be public immediately. Please note that all accepted targets are contingent on the continuation of the mission and the availability of operating funds in FY2011.


Updated RXTE Tools in Latest HEASOFT Release (6.10)

November 28, 2010

The latest HEASOFT release (HEASOFT 6.10) contains updates or improvements to the following RXTE data analysis tools: axbary, faxbary, hxtback, proc2pcu, saextrct (for 64-bit platforms), and sebitmask (for 64-bit platforms). For details on these changes, see the RXTE section of the HEASOFT 6.10 Release Notes. To get the latest release, follow the directions at the "HEASOFT 6.10" link, above.


RXTE Team Updates ASM Color and Lightcurve Data

November 28, 2010

The RXTE ASM team is pleased to announce a new version of the ASM color and lightcurve datasets. The new version strips away spikes caused by a solar glare problem, and provides mission-long lightcurves for several sources recently added to the ASM monitoring catalog. For details, see the ASM 2010 Update page.


Eclipsing Pulsar Promises Clues to Crushed Matter

August 17, 2010

Astronomers using RXTE have found the first fast X-ray pulsar to be eclipsed by its companion star. Further studies of this unique stellar system will shed light on some of the most compressed matter in the universe and test a key prediction of Einstein's relativity theory.


RXTE Homes in on a Black Hole's Jets

July 1, 2010

For decades, X-ray astronomers have studied the complex behavior of binary systems pairing a normal star with a black hole. In these systems, gas from the normal star streams toward the black hole and forms a disk around it. Friction within the disk heats the gas to millions of degrees -- hot enough to produce X-rays. At the disk's inner edge, near the black hole, strong magnetic fields eject some of the gas into dual, oppositely directed jets that blast outward at about half the speed of light.

Now, astronomers using NASA's Rossi X-ray Timing Explorer (RXTE) satellite, together with optical, infrared and radio data, find that, at times, most of the X-rays come from the jets.


HEXTE Cluster B Update

April 20, 2010

As announced previously, HEXTE Cluster B ceased modulation (i.e., began "staring" instead of "rocking") on December 14, 2009, at approximately 16:10 UT. In January, the RXTE team performed a reboot of cluster B that successfully restored modulation, but only for a brief period before it ceased again. After careful consideration, the RXTE team has decided to permanently leave HEXTE Cluster B in an off-source position, rather than risk it becoming unrecoverable in some other position. The detectors in cluster B are still functioning well and collecting data. The off-source position of data taken by HEXTE Cluster B will thus complement the data taken by HEXTE Cluster A, which, since October 20, 2006, has been "staring" in an on-source position. Software is available to allow HEXTE Cluster A on-source data to be analyzed using HEXTE Cluster B background data (see below).

Important Note about Cluster B Pointing Position

When HEXTE Cluster B first ceased modulation in December, it was in an off-source position, but the telemetry value that indicates cluster position had not yet updated; thus, all data from this earlier staring period has a telemetry value that indicates "Cluster_position" is on-source, when in fact the cluster was pointed off-source. This was also the case after the reboot in January. On March 29 at 18:00 UT, HEXTE Cluster B was commanded to stare off-source, and the telemetry successfully updated at that time to show "Cluster_position" as off-source. The table below shows the exact dates and times of these HEXTE Cluster B events, and the pointing and telemetry values during each period:

Start Time (UT) Stop Time (UT) Actual Pointing Position "Cluster_position" value
in telemetry
2009-12-14 at 16:12 2010-01-22 at 18:16 off-source on-source (incorrect value)
2010-01-22 at ~18:17 2010-01-23 at ~05:44 rocking rocking
2010-01-23 at 05:45 2010-03-29 at 17:42 off-source on-source (incorrect value)
2010-03-29 at 18:00 present off-source off-source

Software to analyze HEXTE data from December 14 to Present

The FTOOL "hextebackest" will make background estimates for HEXTE Cluster A on-source data from HEXTE Cluster B off-source data (see special note below). In some cases a line-like residual at ~63 keV may be evident in spectral fits. Additional smaller line-like residuals may also be seen at lower energies (~53 keV and ~40 keV). The ratio of the peak of the 63 keV residual to the model flux may be as large as 2. Comparisons of power law fits to Cen A data (when Cluster B was still rocking and Cluster A was fixed on-source) with the residualsmodeled as Gaussians show that the best-fit power law index for Cluster A using "hextebackest" may be ~0.1 flatter than for Cluster B.The HEXTE team is working to refine "hextebackest" to reduce the residuals. Note that "hextebackest" has been a part of the FTOOLS distribution for several years, and can be used to analyze HEXTE Cluster A data from 2006 onward, when Cluster A became fixed on-source. (See previous RXTE Latest News items from October 20, 2006 and December 8, 2006.)

The background Cluster B data needed for input to "hextebackest" can be obtained from the FTOOL "hxtback". If you are analyzing data from the 1st or 3rd periods listed in the table above, take careful note: The erroneous cluster position in the HEXTE Cluster B data for this period causes hxtback to create a ".src" file but no ".bkg" file for these periods. The data in the ".src" file is the background data, but it is labled ".src" due to the cluster position telemetry value. You can use this ".src" file as input to hextebackest to generate a background file for Cluster A data during these periods. For more information on any of the FTOOLS mentioned here, see the on-line description of XTE FTOOLS or, if you have FTOOLS installed already, type "fhelp" followed by the name of the tool you are interested in (e.g., "fhelp hextebackest").

Update, September 28, 2010: The latest version of FTOOLS/HEASoft (v6.10) contains a new version of hxtback that properly handles all time periods, including the 1st and 3rd periods listed above. With this hxtback, the output source and background files will always be properly labeled.

If you have further questions or concerns, please write to the RXTE Guest Observer Facility Help Desk.


RXTE Discovers Spin Period of New SGR 1833-0832

March 31, 2010

On March 19, the Swift team announced the detection of a possible new Soft Gamma Repeater (SGR) (GCN Circ. #10526). RXTE performed a rapid turnaround Target of Opportunity observation of the source that same day, discovering the spin period and confirming it as a new SGR. For details, see Astronomers Telegram #2493.


Updated RXTE Software Now Available

March 29, 2010

HEAsoft v6.9 has just been released, and contains updates to four RXTE tools:

    pcarsp - Improves handling of user-supplied dates.
    fgabor - Fixes buffer overflow that caused crashes under certain compilers.
    hextebackest - Will now ignore lack of a QUALITY column in input pha file.
    xenon2fits - Includes TIMEPIXR keyword in output file.
If you have questions about these improvements, please write to the RXTE Guest Observer Facility Help Desk. To install the new software, click on the "HEAsoft v6.9" link, above, and follow the Download instructions.


RXTE Team Resolves Inertial-Hold Situation

January 31, 2010

At 21:21 UT on October 23, 2009, RXTE suspended slewing, similar to two previous anomalies noted in earlier News items. RXTE continued taking data from the calibration source PSR B1509-58 throughout the anomaly. The problem was traced to a faulty telemetry chip that was producing false voltage and current values. RXTE was instructed to ignore these bad telemetry points and slewed to the newly discovered black hole source XTE J1752-223 at 14:53 UT on October 26, 2009. Normal operations with pre-planned slews resumed shortly therafter.

The telemetry that was bypassed provided checks to avoid possible danger to the spacecraft if there was a problem with important spacecraft components, some of which are redundant. Without these checks the spacecraft operations have slightly greater risk of damage if an important component actually fails, since we may not rapidly detect the problem. We believe this is an acceptable risk for RXTE's continued operations.


RXTE HEXTE Cluster B Currently Staring

January 20, 2010

At approximately 16:10 UT on December 14, HEXTE Cluster B stopped rocking. Both HEXTE clusters continue to collect data and are otherwise performing normally. The RXTE team is investigating several courses of action and will keep the community updated as events progress.


If you have a question about RXTE, please send email to one of our help desks.

This page is maintained by the RXTE GOF and was last modified on Thursday, 17-Mar-2011 15:52:19 EDT.