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• Date: May 11, 2021 at 07:00 PDT = 10:00 EDT = 14:00 UTC = 16:00 CEST = 22:00 CST = 23:00 JST
• Connection: Zoom connection circulated by email
• Attendees: TBD
• Next meeting: TBD

Agenda

• Where the the Clusters WG left off (from the 2018 IACHEC workshop in Italy: Clusters_WG_report_2018.pdf)
  • eROSITA cross-calibration with clusters
    • Cluster not useful for absolute calibration. 
    • Clusters good for cross-calibration whichis not a high priority
    • A1795 and A2029 are in the calibration program

    • GO time may yield nearby clusters (with a single pointing far beyond the virial radius)

    • Any updates on eROSITA cluster observations that might be useful for IACHEC?
  • Multi-Mission Study
    • 2017 plan was (from Clusters_WG_session_2017_final.pdf):
      • TASK 1: Define the extraction radius
        • Statistics requirement and PSF minimisation prefer bigger values
        • bkg and vignetting minimisation prefer smaller values
        • Extraction radius = 6 arcmin
      • TASK 2: Define a suitable cluster
        • Hot enough (minimise 1 keV line emission, better src/to bkg at 7 keV energies
        • Not too distant to yield enough photons
        • Preferably low NH... if high, harder to get enough photons at the lowest energies. But we can cut the low energy band and use the rest. No requirement for NH at the moment
        • kT > 6 keV z < 0.1
      • TASK 3: Define a suitable observation
        • Long enough for statistics.
        • Cluster center – FOV center offaxis minimised
        • Proceed with single on-axis observations. If too constraining (not enough clusters with enough counts) we will discuss about merging several observations.
        • 100000 c in central 6 arcmin (40000 for PSPC)
        • Offaxis < 3 arcmin
      • Following PRELIMINARY! list consists hot nearby clusters from HIFLUGCS sample, following these criteria:
        • kT > 6 keV, except for Perseus
        • Offset btw. the cluster center and pointing FOV center < 3 arcmin
        • Exposure > 10 ks in the available data
          Image Added
      • A/I Task 4: Compile a list of available clusters and obs. ID:s fulfilling our criteria: Larry (Chandra), Eric (Suzaku), Andy B. (Swift), Steven Snowden (ROSAT), Jukka (XMM) Deadline end of April
      • A/I Task 5: Extract and process data with May 2017 calibration information. Deadline end of June
      • A/I Task 6: Jukka will do the stack residuals ratio analysis.
    • 2018 summary used just XMM EPIC pn vs. ROSAT PSPC, just 6 arcmin extraction radius
    • Action items from 2018
      • A/I TASK 1: Check ROSAT PSPC calibration using one of our clusters (Jukka & M. Freyberg)
      • A/I TASK 2: Check one cluster with Konrad's methods. Needs isothermal region for simple and accurate modelling.
      • A/I TASK 3: Swift XRT flux weighting of ARFs
      • A/I TASK 4: Draft ready by next IACHEC
• Where do we go from here?
  • Complete multi-mission study?
    • Jukka has the full details of this and is unlikely to share.
    • Any updates on whether Jukka is actively working on this? It was the subject of an AHEAD award.
  • Simply supply data to the Concordance WG?
  • We need point people for each mission/instrument.
    • XMM EPIC MOS & pn: Ivan?
    • Chandra ACIS: Larry? Gerrit?
    • Suzaku XIS: Eric?
    • Swift XRT: Andy B.?
    • ROSAT PSPC: ?
    • NuSTAR: ?
      
    • eROSITA: ?
    • ASTROSAT: ?
    • NICER: ?
• Next meeting
  • Two more WG meetings before September IACHEC meeting in Virginia
  TBD