Skip to main content
End of INTEGRAL Operations. See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
  1. GRB 211221A: BOOTES-4/MET optical upper limit
  2. GRB 211218A: MITSuME Akeno optical upper limits
  3. GRB 211221A: MeerLICHT optical limits
  4. GRB 211221A: NOT optical limits
  5. GRB 211221A: Enhanced Swift-XRT position
  6. Swift GRB 211221A: Global MASTER-Net observations report
  7. GRB 211221A: Swift detection of a burst
  8. IceCube-211216B: No significant detection in HAWC
  9. IceCube-211216A: No significant detection in HAWC
  10. GRB 211219A: AGILE detection
  11. GRB 211219A: Swift/BAT-GUANO detection outside the coded FOV
  12. Fermi GRB 211219B: Global MASTER-Net observations report
  13. GRB 211219B: Fermi GBM Final Real-time Localization
  14. Fermi GRB 211219A: Global MASTER-Net observations report
  15. GRB 211219A: Fermi GBM Final Real-time Localization
  16. GRB 211211A: MMT/MMIRS Observations Indicate Fading of K-band Source
  17. GRB 211216A: Fermi GBM observation
  18. IceCube-211216B: No neutrino counterpart candidates in ANTARES search
  19. GRB 211218A, MAXI J0909-041: MAXI/GSC detection
  20. MAXI GRB211218.04: Global MASTER-Net observations report
  21. GRB 211106A: XMM-Newton monitoring campaign detections
  22. Fermi-LAT Gamma-ray Observations of IceCube-211216B
  23. Fermi-LAT Gamma-ray Observations of IceCube-211216A
  24. IceCube-211216B: Upper limits from Fermi-GBM Observations
  25. IceCube-211216A: Upper limits from Fermi-GBM Observations
  26. IceCube-211216A: Upper limits from a search for additional neutrino events in IceCube
  27. Fermi trigger No 661417475: Global MASTER-Net observations report
  28. IceCube-211216A: No neutrino counterpart candidates in ANTARES search
  29. GRB 211217A: GECAM detection
  30. GRB 211216A: Swift/BAT-GUANO detection outside the coded FOV
  31. IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event
  32. IceCube Alert 211216.99: Global MASTER-Net observations report
  33. Fermi GRB 211216B: Global MASTER-Net observations report
  34. GRB 211216B: GECAM detection
  35. IceCube Alert 211216.30: Global MASTER-Net observations report
  36. GRB 211216B: Fermi GBM Final Real-time Localization
  37. IceCube-211216A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  38. GRB 211211A: TNG NIR observations
  39. IceCube-211216A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 211216A: GECAM detection
  41. GRB 211216A: BALROG localization (Fermi Trigger 661329957 / GRB 211216282)
  42. Fermi GRB 211216A: Global MASTER-Net observations report
  43. GRB 211216A: Fermi GBM Final Real-time Localization
  44. GRB 211211A: Insight-HXMT/HE detection
  45. GRB 211211A - Gemini K-band detection
  46. GRB 211211A: SAO RAS optical observations
  47. GRB 211211A: AbAO optical observations
  48. GRB 211211A: GMG upper limit
  49. Chandra observation of GW170817 at ~1575 days since merger (all epochs)
  50. GRB 211211A: redshift estimation and SPI-ACS/INTEGRAL detection
  51. GRB 211211A: Very fast decay observed from CAFOS/2.2mCAHA
  52. GRB 211211A: Further observations from CAFOS/2.2m CAHA
  53. GRB 211211A: HCT and GIT optical follow up observations
  54. GRB 211211A: CALET Gamma-Ray Burst Monitor detection
  55. IceCube-211208A: No neutrino counterpart detected with ANTARES
  56. Fermi GRB 211212A: Global MASTER-Net observations report
  57. GRB 211211A: incorrect E_iso value in GCN 31221
  58. GRB 211211A: Swift/UVOT detection
  59. GRB 211211A: NOT optical spectroscopy
  60. GRB 211211B: GECAM detection
  61. Fermi GRB 211212B: Global MASTER-Net observations report
  62. GRB 211211A: Afterglow detection from CAFOS/2.2m CAHA
  63. GRB 211211A: MITSuME Akeno optical observation
  64. Swift GRB 211211A: Global MASTER-Net observations report
  65. GRB 211212B: Fermi GBM Final Real-time Localization
  66. GRB 211211A: LCO Optical Observations
  67. GRB 211211A: Nanshan/NEXT optical observations
  68. GRB 211211A: Swift-XRT refined Analysis
  69. GRB 211212A: Fermi GBM Final Real-time Localization
  70. GRB 211211A: Fermi GBM observation
  71. GRB 211211A: Swift-BAT refined analysis
  72. Fermi GRB 211211B: Global MASTER-Net observations report
  73. GRB 211211B: Fermi GBM Final Real-time Localization
  74. Fermi GRB 211211A: Global MASTER-Net observations report
  75. GRB 211211A: Enhanced Swift-XRT position
  76. GRB 211207A: Swift/UVOT Detection
  77. GRB 211211A: KAIT Optical Afterglow Candidate
  78. GRB 211211A: Swift detection of a bright burst
  79. GRB 211211A: Fermi GBM Final Real-time Localization
  80. Fermi trigger No 660868196: Global MASTER-Net observations report
  81. IceCube-211208A: No significant detection in HAWC
  82. AMON NuEm-211020A: No neutrino counterpart detected with ANTARES
  83. Fermi trigger No 660736561: Global MASTER-Net observations report
  84. GRB 211130A: MeerLICHT identification of possible afterglow candidate
  85. IceCube-211208A: Upper limits from a search for additional neutrino events in IceCube
  86. Fermi-LAT Gamma-ray Observations of IceCube-211208A
  87. IceCube-211208A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  88. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211209A
  89. IceCube-211208A - IceCube observation of a high-energy neutrino candidate track-like event
  90. IceCube Alert 211208.84: Global MASTER-Net observations report
  91. GRB 211207A: Swift-BAT refined analysis
  92. GRB 211207A: VLT/X-shooter redshift
  93. Chandra observation of GW170817 at ~1573 days since merger (Epoch 1 of 4)
  94. GRB 211204C: Fermi GBM detection
  95. GRB 211207A: Swift-XRT refined Analysis
  96. GRB 211207A: Enhanced Swift-XRT position
  97. Swift GRB 211207A: Global MASTER-Net observations report
  98. GRB 211207A: Swift detection of a burst with an optical counterpart
  99. GRB 211206A: Not observable by Fermi-GBM
  100. GRB 211206A: AstroSat CZTI detection

Advanced

Download all Circulars as a .tar.gz archive:
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov