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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

23685 results found.

  1. EP260213a: Mephisto optical upper limits
  2. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  3. EP260223a: COLIBRÍ optical upper limits
  4. GRB 260223A: COLIBRÍ further optical observations and a brightening
  5. EP260221a: Optical upper limit with Kinder observations
  6. GRB 260223A: COLIBRÍ optical observations
  7. GRB 260223A: DDOTI Optical Candidate
  8. EP260221a: COLIBRÍ optical counterpart candidate
  9. EP260221a: EP-FXT follow-up observation
  10. EP-WXT01709258519: Xinglong optical upper limit
  11. EP260221a: Xinglong optical upper limit
  12. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  13. EP260221a: GOTO optical upper limit
  14. EP260221a: COLIBRÍ optical upper limit
  15. SVOM alert sb26021801: LCO optical upper limit
  16. EP260221a: Einstein Probe detection of an X-ray transient
  17. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  18. GRB 260219A: AstroSat CZTI detection
  19. SVOM alert sb26021801: LAST optical upper limit
  20. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  22. EP-WXT 01709258455: NOT optical upper limits
  23. Konus-Wind detection of GRB 260212A
  24. IPN triangulation of GRB 260212A
  25. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  26. EP260214b: Optical upper limit with Kinder observations
  27. EP260214a: Optical upper limits with Kinder observations
  28. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  29. EP260214b: DDOTI Optical Detection
  30. EP260214a: NOT optical upper limits
  31. EP260214a: COLIBRÍ optical upper limits
  32. EP260214b: OHP/T120 optical observations
  33. EP260214b: LCO optical counterpart detection
  34. EP260214b: COLIBRÍ optical observations
  35. EP260214b: NOT optical counterpart detection
  36. EP260214b: Einstein Probe detection of a fast X-ray transient
  37. GRB 260212A: AstroSat CZTI detection
  38. EP260213a: COLIBRÍ optical upper limits
  39. EP260213a: Optical upper limits with Kinder observations
  40. EP260213a: NUTTelA-TAO Early Optical Limits
  41. EP260213a: SVOM/C-GFT upper limit
  42. GRB 260212A: SVOM/GRM observation of a long burst
  43. GRB 260211A - SVOM/ECLAIRs refined analysis
  44. GRB 260204A: SVOM/ECLAIRs refined analysis
  45. GRB 260211A: EP-FXT follow-up observation
  46. GRB 260211A: SVOM/VT optical observation
  47. GRB 260212A: Glowbug gamma-ray detection
  48. GRB 260211A: GOTO optical upper limit
  49. GRB 260211A: LAST optical upper limit
  50. Konus-Wind detection of GRB 260207B
  51. GRB 260128B: SVOM/ECLAIRs refined analysis
  52. GRB 260211A: LCO optical upper limits
  53. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  54. Konus-Wind detection of GRB 260209B
  55. Konus-Wind detection of GRB 260127B
  56. EP260209a: COLIBRÍ optical upper limit
  57. GRB 260208A: LCO detection of the optical counterpart
  58. EP260210a: Optical upper limits with Kinder observations
  59. IPN triangulation of GRB 260207B (short/hard with EE)
  60. GRB 260210A: Glowbug gamma-ray detection
  61. GRB 260210A: AstroSat CZTI detection
  62. GRB 260208C: AstroSat CZTI detection
  63. EP260210a: COLIBRÍ optical upper limit
  64. GRB 260207B: AstroSat CZTI detection
  65. GRB 260204A: Swift-XRT afterglow detection
  66. GRB 260208B: AstroSat CZTI detection of a bright long burst
  67. GRB 260208A: Glowbug gamma-ray detection
  68. GRB 260208B: COLIBRÍ optical observations
  69. GRB 260208A: COLIBRÍ optical observations
  70. GRB 260208B: Fermi-LAT detection
  71. GRB 260208A: Fermi-LAT detection
  72. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  73. EP260131a: VLA detection
  74. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  75. GRB 260204A: Swift-XRT observations
  76. GRB 260204A: LCO optical afterglow detection
  77. GRB 260204A: SVOM/VT optical candidate
  78. GRB 260204A: GOTO optical upper limit
  79. GRB 260204A: LCO optical upper limits
  80. GRB 260204A: SVOM detection of a burst
  81. GRB 260121A: 239Alferov CubeSat detection
  82. Konus-Wind detection of GRB 260121A
  83. GRB 260131A: KAIT optical observations
  84. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  85. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  86. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  87. GRB 260127A: GECAM-B observation
  88. EP260131a: COLIBRÍ further observations
  89. Konus-Wind detection of GRB 260128A / EP260128a
  90. Konus-Wind detection of GRB 260131A/B
  91. EP260131a: Xinglong optical upper limit
  92. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  93. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  94. EP260131a: COLIBRÍ observations of slow optical fading
  95. GRB 260131B: MAXI/GSC detection
  96. EP260131a: COLIBRÍ optical observations of the counterpart
  97. GRB 260127B: AstroSat CZTI detection
  98. GRB 260130A: Fermi GBM Detection
  99. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  100. Fermi GRB 260130A: Global MASTER-Net observations report

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