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"

6788 results found.

  1. GRB 260223A: Fermi GBM Observation
  2. EP260223a: EP-FXT follow-up observation
  3. EP260221a: Optical upper limit with Kinder observations
  4. EP260221a: Gemini South z-band upper limit
  5. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  6. EP260214b: 1.3m DFOT optical upper limit
  7. EP260214b: Optical upper limit with Kinder observations
  8. EP260214a: Optical upper limits with Kinder observations
  9. EP260214b: EP-FXT follow-up observation
  10. EP260214a: refined analysis of the EP-FXT observation
  11. GRB 260212A: Fermi GBM Observation
  12. EP260213a: Optical upper limits with Kinder observations
  13. EP260213a: NUTTelA-TAO Early Optical Limits
  14. EP260213a: refined analysis of the EP-FXT observation
  15. GRB 260208A: Swift UVOT detection
  16. EP260210a: refined analysis of the EP-FXT observation
  17. GRB 260208A: LCO detection of the optical counterpart
  18. EP260210a: Optical upper limits with Kinder observations
  19. GRB 260208B: refined analysis of the EP-FXT observation
  20. GRB 260204A: Swift-XRT afterglow detection
  21. GRB 260208A: Fermi GBM Observation
  22. GRB 260208B: Swift-XRT observations
  23. GRB 260204A: Swift/UVOT Upper Limits
  24. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  25. GRB 260208A: Swift-XRT observations
  26. GRB 260208B: Fermi GBM Detection
  27. GRB 260208B: Fermi-LAT detection
  28. GRB 260208A: Fermi-LAT detection
  29. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  30. GRB 260206A: Swift-XRT observations
  31. GRB 260204A: Swift-XRT observations
  32. Konus-Wind detection of GRB 260131A/B
  33. GRB 260131A/B: Fermi GBM Observation
  34. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  35. GRB 260130A: Fermi GBM Detection
  36. GRB 260127B: Fermi GBM Detection
  37. GRB 260127B: Swift-XRT observations
  38. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  39. GRB 260127A: Fermi GBM Observation
  40. GRB 260127A: Swift-XRT refined Analysis
  41. GRB 260127A: Prompt enhanced Swift-XRT position
  42. GRB 260125A: Swift-XRT observations
  43. EP260126a: EP-FXT follow-up observation
  44. EP260126a: Optical upper limit with Kinder observations
  45. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  46. EP260119a: Mondy and SAO RAS optical upper limits
  47. GRB 260120B: Swift-XRT refined Analysis
  48. GRB 260120B: Fermi GBM Observation
  49. EP260119a: update of EP-FXT follow-up observation
  50. EP260119a: NOT optical observations
  51. EP260119a: SAO RAS optical observations
  52. GRB 260117A: Swift-XRT afterglow detection
  53. EP260119a: EP-WXT detection of a fast X-ray transient
  54. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  55. GRB 260117A: Swift-XRT observations
  56. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  57. GRB 260114A: Swift-XRT refined Analysis
  58. GRB 260114A: NOT optical observations
  59. GRB 260114A: Fermi GBM observation
  60. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  61. EP260110a: NOT and GTC Optical and Near-Infrared Observations
  62. Konus-Wind detection of GRB 260101A
  63. GRB 260111A: Swift-XRT observations
  64. Swift Trigger 1439093: is probably not GRB 260113A
  65. GRB 260111A: Fermi GBM Observation
  66. IceCube Alert 260111A: Global MASTER-Net observations report
  67. Swift Trigger 1434591: possible GRB 260109C
  68. GRB 260102A: Swift-XRT afterglow detection
  69. GRB 260105B: Fermi GBM Detection
  70. GRB 260104A: Swift-XRT refined Analysis
  71. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  72. GRB 260102A: Swift-XRT observations
  73. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  74. GRB 260101A: Fermi GBM Observation
  75. GRB 260101A: Swift-XRT refined Analysis
  76. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  77. EP251229a: Optical upper limit with Kinder observations
  78. GRB 251230A: Swift-XRT refined Analysis
  79. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  80. GRB 251230A: Early optical counterpart detection by LCO.
  81. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  82. GRB 251222A: NUTTelA-TAO Early Measurements
  83. GRB 251222A/EP251222b: Optical detection with Kinder observations
  84. EP251222a: Optical upper limit with Kinder observations
  85. GRB 251222A: Fermi GBM Observation
  86. Konus-Wind detection of GRB 251222A / EP251222b
  87. GRB 251222A: Swift-XRT afterglow detection
  88. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  89. EP251222a: GSP Optical Counterpart Detection
  90. GRB 251221A: Swift-XRT refined Analysis
  91. GRB 251221A: Fermi GBM Observation
  92. EP251220a: EP-FXT follow-up observation
  93. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  94. GRB 251215A: Swift-XRT afterglow detection
  95. GRB 251215A: Swift/UVOT Upper LImits
  96. GRB 251215A: Fermi GBM Observation
  97. GRB 251215A: Swift-XRT observations
  98. EP251214a: Optical upper limit with Kinder observations
  99. GRB 251214B: Fermi GBM Observation
  100. GRB 251209A: Insight-HXMT/HE detection

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov