There’s not even room enough to be anywhere. It’s not dark yet, but it’s gettin there. – Bob Dylan
Such is the state of neutron stars. Packed so densely in their cores that we barely know the physics, and cooling so rapidly that the surface emission is often barely detectable, they harbor secrets that can only be revealed through X-ray studies. As Craig Heinke describes in this Newsletter, Chandra observations continue to provide some of the most important probes of neutron star physics.
Chandra observations in recent months have continued to include studies to probe neutron star cooling, along with many other highlights-in-the-making, including observations of GW170817 that reveal the apparent emergence of a new emission component (GCN 29038, 29041, 29055), the completion of a deep survey of the Orion Nebula Cluster, and the completion of a large project on the Type Ia supernova remnant SNR 0509-67.5. At present, Chandra observations from Cycle 22 are well underway, while we are still working to complete observations from Cycle 21 as well. As most users know, there is a significant period of overlap from one Cycle to the next that is associated with the careful dance that Mission Planners choreograph over the course of the year in order to cool various parts of the spacecraft after temperatures have increased due to Sun illumination during each observation.
The last six months have been marked by continued successful operation of the Observatory. As described in Grant Tremblay’s article in this Newsletter, the process of switching to redundant electronics for the HRC detector was completely successful, with a full return to HRC science observations in November. Chandra has had no load interruptions in the past six months other than to support TOO or DDT observations. Roughly half of the weekly schedules included TOO/DDT observations or follow-ups.
By now, Chandra observers are properly catching their breath after another active round of proposal work for Cycle 23. Despite the pandemic, our community has continued to submit proposals at their regular rate. Work is now underway to arrange the Cycle 23 peer review, which will be carried out fully remotely again this year.
Early this year, the Chandra Source Catalog 2.0 team was presented with a NASA Group Achievement Award for development and release of this vast resource. Version 2.0.1 of the catalog was also recently released, incorporating updates on intra-observation and inter-observation variability. Work is proceeding on the next large-scale CSC update, which will follow the ongoing full reprocessing of the Chandra data set. The reprocessing effort is proceeding on schedule.
Catalog results were also featured in a webinar during the January AAS meeting (Chandra Source Catalog: Multiband Counterparts and SDSS-V Spectroscopic Followup). An additional webinar was also presented on A Day in the Life of the Chandra Operation Control Center, telling the gripping tale of what happens during a serious Chandra anomaly response. (I read the news today, oh boy…) We are currently working on plans for the 2021 Summer AAS meeting, and encourage all members of the Chandra community to visit our virtual booth.
Recent months have also seen the release of several novel sonification representations of Chandra observations, including the Bullet Cluster, Crab Nebula, and SN 1987A. The sonifications, made by combining data from Chandra with additional data from Hubble, Spitzer, and ground-based telescopes, represent astronomical information presented as a succession of sounds rather than through the conventional visual representation. View a few and your mind will surely be jumping with new ideas on how to use this technique!
There has been a recent development regarding exclusive-use periods for Chandra data. To date the policy has provided a 12-month exclusive-use period for data obtained through GO/TOO, GTO, and LP proposals. VLP/XVP proposals carry no such exclusive-use periods, and DDT proposals have up to three month periods, at the discretion of the Director. Proposal forms provide for the option of waiving such exclusive-use periods. Following a NASA request for a review of this policy, and incorporating input from the Chandra Users Committee, a recommendation was made by the CXC Director and the Chandra Project Scientist that the current exclusive-use policy be kept in place. After review, NASA HQ directed the CXC to update the policy, effective beginning in fiscal year 2023, such that the default exclusive-use period for GO/TOO, LP, and GTO data will be no more than six months. This will bring the Chandra data policies more in line with other NASA space missions.
Several significant CXC staff changes have occurred in recent months. First, Scott Randall has taken over leadership of the Science Mission Planning Team for the CXC, following my own departure from that position. Scott is already an old hand, having been a member of the Mission Planning team for many years. At the same time, Jan Vrtilek has transitioned off of the team and is concentrating on Flight Director duties.
Another very significant staff development is that Roger Brissenden, the CXC Program Manager (PM), has decided to step down from this position and relocate back to his native Australia. Ed Mattison, who has been the Deputy CXC Program Manager, has moved into the PM role, and Mark Weber has come on board as the Deputy PM. Roger will be continuing to support Chandra activities part time and remotely for the remainder of the year. Roger has been with the Chandra project since 1990, taking on ever-increasing levels of responsibility that, over the years, included Software Scientist, Flight Director, and Program Manager. He also served as Associate Director of CfA’s High Energy Astrophysics Division, Deputy Director of the CfA, and Acting Under Secretary for Science of the Smithsonian Institution – all of these while still managing the CXC first and foremost. That’s more than a job well done, and we wish Roger the best in his new pursuits.