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"

20205 results found.

  1. GRB 260818B: TNG NIR observations
  2. GRB 260818B: 6 GHz VLA observations
  3. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  4. GRB 260808B: SAO RAS observations of the optical rebrightening
  5. GRB 260822A: SVOM/ECLAIRs refined analysis
  6. GRB 260809A: SVOM/ECLAIRs refined analysis
  7. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  9. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  10. EP260822a: EP-FXT non-detection and upper limit
  11. GRB 260822A: GOTO optical counterpart detection
  12. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  13. EP260822a: Einstein Probe detection of a fast X-ray transient
  14. GRB 260822A: LCO optical upper limits
  15. GRB 260822A: GROWTH-India Telescope Upper Limits
  16. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  17. GRB 260818B: SVOM/C-GFT optical upper limit
  18. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  19. EP detected a brightening of LMXB 1ES 1735-26.9
  20. GRB 260818A: J-band observations with WINTER
  21. GRB 260818B: SVOM/ECLAIRs refined analysis
  22. GRB 260818A: SVOM/ECLAIRs refined analysis
  23. GRB 260818B: NOT optical upper limits
  24. GRB 260810A: SVOM/GRM observation
  25. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. GRB 260818B: LCO optical upper limits
  27. EP260806a: SAO RAS multicolor optical observations
  28. GRB 260818A: LCO optical upper limits
  29. EP260812a: AbAO optical upper limit
  30. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. EP260806a: SVOM/ECLAIRs detection through targeted search
  32. EP260806a: NUTTELA-TAO optical observations
  33. EP260812a: AZT-22 optical upper limit
  34. EP260806a: WFST optical observations
  35. EP260812b: Optical upper limit with Kinder
  36. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  37. GRB 260808B: Liverpool Telescope further optical observations
  38. EP260812a: NOT and Liverpool Telescope upper limits:
  39. EP260812b: Liverpool Telescope observations
  40. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  41. EP260812a: SVOM/C-GFT optical upper limit
  42. EP260812b: COLIBRÍ optical observations
  43. EP260812b: SVOM/VT optical observation
  44. GRB 260808A: SVOM/GRM observation
  45. EP260812b: Einstein Probe detection of an X-ray transient
  46. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  47. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  48. GRB 260810A: AstroSat CZTI detection of a long burst
  49. EP260812a: Einstein Probe detection of an X-ray transient
  50. GRB 260809A: SAO RAS optical observations
  51. GRB 260808B: SAO RAS optical observations
  52. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  53. GRB 260807A: SVOM/ECLAIRs refined analysis
  54. EP260806a: MAO/AZT-22 optical observations
  55. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  56. GRB260808B: MAO/AZT-22 optical observations
  57. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  58. GRB 260809A: J-band upper limit with WINTER
  59. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  60. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  62. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  63. GRB 260809A: NOT optical observations
  64. GRB260809A: MAO/AZT-22 optical observations
  65. GRB260809A: OHP/T193 optical observations
  66. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  67. EP260809a: J-band upper limit with WINTER
  68. GRB 260808B: J-band upper limit with WINTER
  69. GRB 260808B: SVOM/ECLAIRs refined analysis
  70. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  71. GRB 260809A: SVOM detection of a faint burst
  72. GRB 260808B: Liverpool Telescope optical observations
  73. GRB 260808B: NOT optical observations
  74. GRB 260808B: LCO optical observations
  75. EP260809a: COLIBRÍ optical observations
  76. EP260809a: LCO optical observation
  77. EP260809a: OHP/T193 optical observations
  78. GRB260808B: OHP/T193 optical observations
  79. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  80. EP260809a: Einstein Probe detection of an X-ray transient
  81. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  82. GRB 260808B: SVOM/VT optical candidate from VHF data
  83. GRB 260808B: SVOM detection of a faint burst
  84. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  85. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. EP260806a: COLIBRÍ optical observations
  87. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP260806a: SVOM/VT optical observation
  89. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  90. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  91. EP260806a: LCO likely optical counterpart
  92. EP260806a: Einstein Probe detection of an X-ray transient
  93. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  94. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  95. GRB 260804A: Fermi GBM Final Real-time Localization
  96. GRB 260802A: SVOM/VT optical upper limits from VHF data
  97. GRB 260802A: LCO optical upper limits
  98. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  99. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  100. GRB 260731A: AstroSat CZTI detection of a long burst

Advanced

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