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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"

2380 results found.

  1. GRB 260822A: EP/FXT follow-up observations
  2. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  3. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  4. GRB 260822A: GOTO optical counterpart detection
  5. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  6. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  7. GRB 260822A: LCO optical upper limits
  8. GRB 260822A: GROWTH-India Telescope Upper Limits
  9. GRB 260822A: GOTO optical upper limit
  10. GRB 260822A: SVOM detection of a short burst
  11. GRB 260818B: SVOM/C-GFT optical upper limit
  12. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  13. GRB 260818B: SVOM/GRM observation
  14. GRB 260818B: Insight-HXMT detection
  15. GRB 260818B: EP-FXT follow-up observation
  16. GRB 260818A: J-band observations with WINTER
  17. GRB 260818B: SVOM/ECLAIRs refined analysis
  18. GRB 260818A: SVOM/ECLAIRs refined analysis
  19. GRB 260818B: NOT optical upper limits
  20. GRB 260810A: SVOM/GRM observation
  21. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB260818A: EP-FXT follow-up observation
  23. GRB 260818B: LCO optical upper limits
  24. GRB 260818B: SVOM detection of a short burst
  25. SVOM trigger sb26081806 is not a GRB
  26. GRB 260818A: LCO optical upper limits
  27. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. GRB 260818A: SVOM possible detection of a long and faint GRB
  29. EP260806a: SVOM/ECLAIRs detection through targeted search
  30. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  31. GRB 260808B: Liverpool Telescope further optical observations
  32. EP260812a: SVOM/C-GFT optical upper limit
  33. EP260812b: COLIBRÍ optical observations
  34. EP260812b: SVOM/VT optical observation
  35. GRB 260808A: SVOM/GRM observation
  36. Fermi GBM Sub-Threshold Detection of GRB 260809A
  37. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  38. GRB 260809A: SAO RAS optical observations
  39. GRB 260808B: SAO RAS optical observations
  40. GRB 260808B: SVOM/VT optical re-brightening at day 3
  41. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  42. GRB 260807A: SVOM/ECLAIRs refined analysis
  43. GRB260808B: MAO/AZT-22 optical observations
  44. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  45. GRB 260809A: J-band upper limit with WINTER
  46. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  47. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  48. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  49. GRB 260809A: NOT optical observations
  50. GRB260809A: MAO/AZT-22 optical observations
  51. GRB 260809A: SVOM/VT optical counterpart
  52. GRB 260808B: J-band upper limit with WINTER
  53. GRB 260808B: SVOM/ECLAIRs refined analysis
  54. GRB 260809A: SVOM detection of a faint burst
  55. GRB 260808B: Liverpool Telescope optical observations
  56. GRB 260808B: NOT optical observations
  57. GRB 260808B: LCO optical observations
  58. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  59. GRB 260808B: SVOM/VT optical afterglow confirmation
  60. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  61. GRB 260808B: SVOM/VT optical candidate from VHF data
  62. GRB 260808B: SVOM detection of a faint burst
  63. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. GRB 260807A: SVOM possible detection of a faint burst
  65. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. EP260806a: SVOM/VT optical observation
  67. GRB 260709A: cubesat Avion detection
  68. GRB 260708A: LCO further optical observations show supernova features
  69. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  70. GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
  71. GRB 260802A: SVOM/VT optical upper limits from VHF data
  72. GRB 260802A: LCO optical upper limits
  73. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  74. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  75. GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
  76. GRB 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
  77. GRB 260731A: AstroSat CZTI detection of a long burst
  78. GRB 260730B: NuSTAR detection of prompt emission
  79. GRB 260727A: SVOM/ECLAIRs refined analysis
  80. GRB 260726A: SVOM/ECLAIRs refined analysis
  81. GRB 260727A: AbAO and SAO RAS optical observations
  82. GRB 260726A: EP-FXT follow-up observations
  83. GRB 260727A: SVOM/GRM observation
  84. GRB 260726A: Fermi GBM Observation
  85. Konus-Wind detection of GRB 260727A
  86. GRB 260727A: Liverpool Telescope optical upper limits
  87. GRB 260727A: EP/FXT follow-up observations
  88. GRB 260727A: Glowbug gamma-ray detection
  89. GRB 260726A: J-band upper limit with WINTER
  90. GRB 260727A: J-band upper limit with WINTER
  91. GRB 260726A: SVOM/VT optical candidate
  92. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  93. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  94. EP260723a: SVOM/ECLAIRs Upper Limit
  95. GRB 260727A: GOTO early optical upper limit
  96. GRB 260727A: AstroSat CZTI detection
  97. GRB 260727A: Kilonova-Catcher optical upper limit
  98. GRB 260727A: LCO optical upper limits
  99. GRB 260727A: SVOM detection of a bright long burst
  100. GRB 260726A: SVOM detection of a burst

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