Chandra X-Ray Observatory
	(CXC)

CDA - News Item 001

Search cxc.harvard.edu
Data Analysis Links
CDA Status
  • The archive is fully functional.
Reprocessing Status
    Reprocessing IV has been completed in December 2014.
Current Software Releases
  • ASCDSVER: 10.11.1
  • CALDBVER: 4.10.2
What's New
  • Electrical Outage 11/05/21 - 11/06/21
    2021-11-05
    There will be a planned electrical outage Friday, November 5 2021, 5:30PM - Saturday, November 6 2021, 6:00PM EDT. During this time period ChaSeR and other archive interfaces will be unavailable.
  • Electrical Outage on 07/28/21
    2021-07-26
    There will be a planned electrical outage Wednesday, July 28 2021, 8:00PM - 10:00PM EDT. During this time period ChaSeR and other archive interfaces will be unavailable.
  • Downtime on 6/12/21
    2021-06-10
    Due to electrical work, the public interfaces of the Chandra Data Archive will not be available on Saturday 6/12 from 4 AM to 9 PM.
  • Repro V Begins
    2020-10-26
    The fifth major reprocessing of the archive (Repro V) has started! Details can be found here.
  • Past Notices
News Item 001

Changed Sequence Numbers

In the past, when observations needed to be split (for instance, a partially completed observation had to be continued with different ACIS chips), a new ObsId with a new Sequence Number was created. We have changed that policy and currently a new ObsId with the old Sequence Number is created. In order to facilitate uniform bookkeeping, we are now changing the Sequence Numbers of past observations for these split cases so that the current policy will appear uniformly applied since the beginning of the mission. This way, different pieces of the same observation can always be tied together by their common Sequence Number.

We have posted lists of ObsIds that had their Sequence Number changed, accompanied by their parent ObsIds, separately for GTO and GO observations.

This page maintained by the Chandra Data Archive (arcops@cfa.harvard.edu).

Last modified: 2019-08-26

Smithsonian Institute Smithsonian Institute

The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email:   cxchelp@head.cfa.harvard.edu Smithsonian Institution, Copyright © 1998-2019. All rights reserved.