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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"

21759 results found.

  1. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  2. EP260806a: MAO/AZT-22 optical observations
  3. GRB260808B: MAO/AZT-22 optical observations
  4. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  5. GRB 260809A: J-band upper limit with WINTER
  6. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  7. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  8. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  9. GRB 260809A: NOT optical observations
  10. GRB260809A: MAO/AZT-22 optical observations
  11. GRB260809A: OHP/T193 optical observations
  12. EP260809a: J-band upper limit with WINTER
  13. GRB 260808B: J-band upper limit with WINTER
  14. GRB 260808B: SVOM/ECLAIRs refined analysis
  15. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  16. GRB 260809A: SVOM detection of a faint burst
  17. GRB 260808B: Liverpool Telescope optical observations
  18. GRB 260808B: NOT optical observations
  19. GRB 260808B: LCO optical observations
  20. EP260809a: COLIBRÍ optical observations
  21. EP260809a: LCO optical observation
  22. EP260809a: OHP/T193 optical observations
  23. GRB260808B: OHP/T193 optical observations
  24. EP260809a: Einstein Probe detection of an X-ray transient
  25. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  26. GRB 260808B: SVOM/VT optical candidate from VHF data
  27. GRB 260808B: SVOM detection of a faint burst
  28. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. EP260806a: COLIBRÍ optical observations
  30. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260806a: SVOM/VT optical observation
  32. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  33. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260806a: LCO likely optical counterpart
  35. EP260806a: Einstein Probe detection of an X-ray transient
  36. GRB 260715A: cubesat Avion detection
  37. GRB 260709A: cubesat Avion detection
  38. GRB 260708A: cubesat Avion detection
  39. SN 2026stf / GRB 260708A: ATLAS forced photometry
  40. GRB 260802A: SVOM/VT optical upper limits from VHF data
  41. GRB 260802A: LCO optical upper limits
  42. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  43. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  44. GRB 260731A: AstroSat CZTI detection of a long burst
  45. GRB 260730B: AstroSat CZTI detection
  46. EP260731a: COLIBRÍ optical upper limit
  47. EP260731a: NOT optical upper limit
  48. EP260731a: Einstein Probe detection of an X-ray transient
  49. GRB 260727A: SVOM/ECLAIRs refined analysis
  50. GRB 260726A: SVOM/ECLAIRs refined analysis
  51. EP260728a: COLIBRÍ optical upper limit
  52. EP260729a: Einstein Probe detection of an X-ray transient
  53. EP260727a: SAO RAS optical observations
  54. GRB 260727A: AbAO and SAO RAS optical observations
  55. GRB 260726A: EP-FXT follow-up observations
  56. EP260728a: Einstein Probe detection of a fast X-ray transient
  57. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  58. EP260727a: OHP/T193 optical observations
  59. Konus-Wind detection of GRB 260727A
  60. GRB 260726A: Liverpool Telescope optical observations
  61. GRB 260727A: Liverpool Telescope optical upper limits
  62. EP260727a: Liverpool Telescope confirmation of optical counterpart
  63. EP260727a: NUTTELA-TAO Early Optical Limits
  64. EP260727a: Einstein Probe detection of an X-ray transient
  65. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  66. GRB 260726A: J-band upper limit with WINTER
  67. GRB 260727A: J-band upper limit with WINTER
  68. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  69. EP260723a: SVOM/ECLAIRs Upper Limit
  70. GRB 260727A: GOTO early optical upper limit
  71. GRB 260727A: Kilonova-Catcher optical upper limit
  72. GRB 260727A: LCO optical upper limits
  73. GRB 260726A: SVOM detection of a burst
  74. EP260725a: EP-WXT detection of an X-ray transient
  75. GRB 260616A: cubesat Avion detection
  76. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  77. GRB 260602B: cubesat Avion detection
  78. GRB 260601A: cubesat Avion detection
  79. GRB 260718A: SVOM/ECLAIRs refined analysis
  80. EP260723a: SVOM/VT optical observation
  81. EP260723a: COLIBRÍ optical observations
  82. EP260723a: NOT optical conterpart confirmation
  83. EP260723a: Liverpool Telescope likely optical counterpart
  84. EP260723a: EP-WXT detection of a fast X-ray transient
  85. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  86. Konus-Wind detection of GRB 260721A
  87. Konus-Wind detection of GRB 260714B
  88. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  89. GRB 260718A: LCO optical upper limits
  90. GRB 260710A: SVOM/GRM observation
  91. GRB 260718A : GRANDMA and KNC upper limits
  92. GRB 260718A: SVOM/VT optical upper limits
  93. GRB 260718A: SVOM/VT optical upper limits from VHF data
  94. GRB 260718A: SVOM detection of a burst
  95. GRB 260714B: SVOM/GRM observation
  96. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  97. GRB 260714B: COLIBRÍ optical counterpart candidate
  98. sb26071506: SVOM detection of a X-ray transient
  99. EP260703a: SVOM/ECLAIRs Upper Limit
  100. GRB 260714B: AstroSat CZTI detection

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