Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. The EP-WXT trigger 01709320726 is likely a flaring star
  2. GRB 260924A: COLIBRÍ optical observations
  3. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  4. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  5. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  6. GRB 260925A: Swift-XRT refined Analysis
  7. EP260924a: EP-FXT follow-up observation
  8. Swift Trigger 1513439 is probably not a GRB
  9. GRB 260925A: Swift/UVOT Upper Limits
  10. Konus-Wind detection of GRB 260924A
  11. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  12. GRB 260923A: Glowbug gamma-ray detection
  13. GRB 260924A: Optical follow-up observations with Kinder
  14. GRB 260922A: Glowbug gamma-ray detection
  15. GRB 260925A: Enhanced Swift-XRT position
  16. GRB 260925A: COLIBRÍ optical upper limits
  17. GRB 260925A: FRAM-Auger optical limit
  18. GRB 260924A: Ondrejov D50 optical afterglow detection
  19. EP260924a: J-band upper limit with WINTER
  20. GRB 260924A: SVOM/GRM observation
  21. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  22. GRB 260925A: Swift detection of a burst
  23. GRB 260923A: Insight-HXMT/HE detection
  24. EP260924a: EP-WXT detection of an X-ray transient
  25. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  26. GRB 260924A: Swift/UVOT Detection
  27. GRB 260924A: GROWTH-India Telescope optical observations
  28. GRB 260924A: Swift-BAT refined analysis
  29. GRB 260924A: NuSTAR detection of prompt emission
  30. GRB 260924A: Swift/UVOT Upper Limits
  31. GRB 260924A: Swift-XRT refined Analysis
  32. Konus-Wind detection of GRB 260922A
  33. GRB 260922A: NuSTAR detection of prompt emission
  34. GRB 260921A: NuSTAR detection of prompt emission
  35. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  36. GRB 260921A: SVOM/GRM observation
  37. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  38. GRB 260924A: Fermi GRB Observation
  39. Konus-Wind detection of GRB 260921A (possible merger-origin)
  40. GRB 260924A: Fermi-LAT detection of a bright burst
  41. GRB 260924A: AstroSat CZTI detection
  42. GRB 260920A: SVOM/GRM observation
  43. GRB 260924A: NOT optical counterpart confirmation
  44. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  45. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  46. GRB 260924A: Enhanced Swift-XRT position
  47. The EP-WXT trigger 01709319842 is likely a flaring star
  48. GRB 260924A: Swift detection of a burst
  49. GRB 260924A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260923A: Global MASTER-Net observations report
  51. GRB 260923A: Fermi GBM Final Real-time Localization
  52. Trigger_21914: Swift ToO observations
  53. EP260806a: e-MERLIN detection at 5 GHz
  54. GRB 260922A: Ondrejov D50 optical limit
  55. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  56. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  57. ATCA observations of GRB 260909A
  58. GRB 260922A: Swift-BAT refined analysis
  59. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  60. GRB 260922A: J-band upper limit with WINTER
  61. GRB 260922A: Swift/UVOT Upper Limits
  62. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  63. GRB 260922A: COLIBRÍ optical upper limits
  64. GRB 260922A: Swift-XRT refined Analysis
  65. GRB 260922A: Enhanced Swift-XRT position
  66. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  67. Konus-Wind detection of GRB 260810A
  68. GRB 260920A: Glowbug gamma-ray detection
  69. GRB 260918A: SVOM/ECLAIRs refined analysis
  70. GRB 260922A: SVOM/C-GFT optical upper limit
  71. GRB 260922A: Swift detection of a burst
  72. GRB 260917C: AstroSat CZTI detection
  73. GRB 260920B/EP260920b: GECAM-B detection of a burst
  74. GRB 260921A: AstroSat CZTI detection
  75. GRB 260921A: Swift-BAT refined analysis
  76. GRB 260921B: Fermi GBM Final Localization
  77. GRB 260921A: Fermi GBM Observation
  78. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  79. EP Alert 260921.58: Global MASTER-Net observations report
  80. GRB 260917B:: SVOM/ECLAIRs refined analysis
  81. The EP-WXT trigger 01709319528 is likely a flaring star
  82. EP260920a: VLT/HAWK-I near-infrared candidate
  83. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  84. Swift GRB 260921A: Global MASTER-Net observations report
  85. GRB 260921A: Swift detection of a burst
  86. EP260920b: VLT/X-shooter spectroscopic redshift z = 3.582
  87. GRB 260921A: Fermi GBM Final Real-time Localization
  88. EP260920b: LCO observations
  89. GRB 260920A: AstroSat CZTI detection
  90. EP260920b: SVOM/VT optical observation
  91. EP260920b: refined analysis of the EP-WXT and EP-FXT observations
  92. EP260920b: COLIBRÍ optical observations
  93. EP260920b: LCO optical counterpart detection
  94. The EP-WXT trigger 01709318601 is likely a flaring star
  95. EP Alert 260921.01: Global MASTER-Net observations report
  96. EP260920b: Global MASTER-Net observations report
  97. EP260920b: Einstein Probe detection of an X-ray transient
  98. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  99. EP Alert 260920.66: Global MASTER-Net observations report
  100. EP-WXT detected a brightening of HMXB LS V +44 17

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
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