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Chandra Electronic Announcement #73

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1. Possible Early Observation of Cycle 13 Targets
2. AtomDB Announcements

Item 1: Possible Early Observation of Cycle 13 Targets

Similarly to Cycle 12, we are seeking early scheduling of
approved Cycle 13 targets which are unconstrained and at
good pitch for observation in July-Sept.

This is necessary because limitations on the pitch angle of
observations made during the "MUPS Anomaly" in July-Aug 2009 (see for more
information), meant that many Cycle 12 targets at good pitch angles for
observation in July-Sept were observed in 2010. This results in a
lack of such Cycle 12 targets available for observation during the
same period in 2011.  To maintain an efficient observing schedule,
we are therefore planning to observe early those approved Cycle 13 
targets which are unconstrained and at good pitch for July-Sept.  
As a result, we need to ingest any such targets into the ObsCat and contact
PIs to confirm observation parameters quickly so that targets can
be scheduled.

Our planned procedure is as follows:

- Now that the peer review is completed, targets which are at
good pitch and are definitely on the approved target list will be
ingested into the ObsCAT and passed to USINT (Uplink Support INTerface)
for the usual, detailed observation parameter review

- The PIs/Observers for these targets will be contacted by USINT, in
some cases before the final target list has been announced, requesting
a detailed check of all observing parameters

- We ask that PIs/Observers be prepared to respond quickly so that the
target can be approved for scheduling as soon as possible or
unapproved should early observations not be desirable.

We will ONLY contact PIs/Observers with targets fitting fairly
stringent parameters. So the lack of a USINT contact does NOT NECESSARILY
mean your proposal has been rejected.

The final approved target list will be posted by July 15th on the
Chandra X-ray Center website, as usual.

Please let us know (via the helpdesk) if you have any questions or

Belinda Wilkes

Assistant Director
Chandra X-ray Center

Item 2. AtomDB Announcements
* Version 2.0.1 Released

We have discovered, thanks to Michael Loewenstein, a mistake in the
AtomDB v2.0.0 release which has necessitated the release of v2.0.1. The
error was in the iron radiative recombination continuum, which was
overestimated for certain iron ions (specifically Fe XVIII and Fe XXI)
by up to a factor of ~8 due to incorrect data in the database for the
recombination to the ground state. In addition, we have identified other
ions where the ground state recombination was mistakenly omitted. In
both equilibrium and ionizing plasmas, the recombination continua from
iron ions is a minor term relative to the bremsstrahluing continuum, so
this omission did not create any noticeable impact. Nonetheless, it has
been fixed in the new release.

Since the error was limited to recombination to the ground state, there
is no impact to any line emission.

We recommend all users of AtomDB update to the new version immediately,
and not use the Version 2.0.0 files (for example, the files
apec_v2.0_line.fits and apec_v2.0_coco.fits). We apologize for any
confusion or mistakes caused by the error. The new files are available
on the AtomDB site at

Instructions for using these files with XSPEC, Sherpa, and ISIS are
available at

* New version of AtomDB WebGUIDE available

A new version of the AtomDB WebGUIDE tool is now available at :

The new version includes more information about individual transitions.
After specifying a specific transition, or clicking on a specific line
after selecting a line list, the website now lists all the relevant
information about the transition (including the electronic
configuration, the quantum state, oscillator strengths, etc) as well as
the source of the electronic collisional excitation data and any other
relevant data in AtomDB.

Thanks to Eugene Churazov for suggesting these enhancements. Please do
not hesitate to suggest improvements to either the AtomDB database or
web pages!

Last modified: 07/08/11

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