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"

23572 results found.

  1. SVOM GRB260603.23: Global MASTER-Net observations report
  2. Fermi GRB 260602B: Global MASTER-Net observations report
  3. Fermi GRB 260602B: Global MASTER-Net observations report
  4. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  5. GRB 260601B/EP260601a: J-band upper limit with WINTER
  6. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  7. EP260530a/AT 2026nwl: KAIT optical observations
  8. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  9. EP260602a: Optical upper limits with Kinder observations
  10. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  11. GRB 260601A: Glowbug gamma-ray detection of a short burst
  12. GRB 260531B: Glowbug gamma-ray detection
  13. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  14. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  15. Fermi GRB 260601A: Global MASTER-Net observations report
  16. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  17. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  18. Fermi trigger No 801900520: Global MASTER-Net observations report
  19. GRB 260531A: MAXI/GSC detection
  20. AT 2026nuz: COLIBRÍ optical observations
  21. IPN triangulation of GRB 260527A / EP260527a
  22. GRB 260527A / EP260527a: VLA radio detection
  23. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  24. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  25. GRB 260529A: GOTO tentative optical afterglow candidate
  26. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  27. Fermi GRB 260529A: Global MASTER-Net observations report
  28. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  29. EP260527a / GRB 260527A: NOT optical observations
  30. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  31. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 260526A: GECAM-B observation
  33. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  34. EP260526a: EP-FXT follow-up observation
  35. EP260527a: COLIBRÍ optical detection
  36. The EP-WXT trigger 01709266172 is likely a flaring star
  37. The EP-WXT trigger 01709266147 is likely a flaring star
  38. Fermi trigger No 801580882: Global MASTER-Net observations report
  39. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  40. GRB 260525A: AstroSat CZTI detection
  41. EP260526.405: COLIBRÍ optical upper limits
  42. GRB 260523B: AstroSat CZTI detection
  43. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  44. GRB 260522A: GOTO optical upper limit
  45. GRB 260519C: SVOM/GRM observation
  46. GRB 260511A: iTelescope T-75 optical detection
  47. GRB 260411B: TERI Gamma-ray detection
  48. GRB 260407A: TERI Gamma-ray detection
  49. GRB 260307A: TERI Gamma-ray detection
  50. GRB 260225D: TERI Gamma-ray detection
  51. GRB 251118A: TERI Gamma-ray detection
  52. GRB 251113A: TERI Gamma-ray detection
  53. GRB 260428A: TERI Gamma-ray detection
  54. Konus-Wind detection of GRB 260519C
  55. GRB 260509A: SVOM/ECLAIRs refined analysis
  56. Konus-Wind detection of GRB 260518A
  57. GRB 260518A: AstroSat CZTI detection of a long burst
  58. GRB 260516D: SVOM/ECLAIRs refined analysis
  59. GRB 260515A: SVOM/ECLAIRs refined analysis
  60. GRB 260421B: radio detection with the VLA
  61. GRB 260516D: GOTO optical counterpart detection
  62. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  64. GRB 260516D: SVOM/VT optical bright candidate
  65. GRB 260515A: CrAO ZTSh BVRI optical observations
  66. GRB 260516D: SVOM possible detection of a burst
  67. Konus-Wind detection of GRB 260515A
  68. GRB 260515A: LCO optical counterpart detection
  69. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  70. EP260514a: TRT optical counterpart candidate
  71. GRB 260515A: SVOM/VT optical observations
  72. GRB 260515A: OHP/T193 optical observations
  73. EP260514a: COLIBRÍ optical upper limits
  74. GRB 260515A: GTC/OSIRIS+ spectroscopic redshift z = 0.764
  75. GRB 260515A: SVOM detection of a burst
  76. GRB 260510C: Glowbug gamma-ray detection
  77. GRB 260511B: NOT optical observations
  78. Konus-Wind detection of GRB 260512A
  79. GRB 260510C: CALET Gamma-Ray Burst Monitor detection
  80. EP260512a: LCO optical upper limits
  81. IPN triangulation of GRB 260512A
  82. GRB 260511B: Mephisto multi-band optical followup
  83. GRB 260512A: AstroSat CZTI detection
  84. EP260512a: EP-FXT follow-up observation
  85. GRB 260509A: SVOM/VT optical observations
  86. Konus-Wind detection of GRB 260511B
  87. The EP-WXT trigger 01709262036 is likely a flaring star
  88. EP260512a: COLIBRÍ optical upper limits
  89. EP260512a: Einstein Probe detection of an X-ray transient
  90. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  91. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  92. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  93. GRB 260511A: Glowbug gamma-ray detection
  94. Konus-Wind detection of GRB 260511A
  95. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  96. GRB 260511B: LCO optical counterpart detection
  97. GRB 260511B: GOTO optical counterpart detection
  98. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  99. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  100. GRB 260511B: OSIRIS+/GTC redshift z=2.006

Advanced

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