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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"

23619 results found.

  1. GRB 260303A: J-band observations with WINTER
  2. GRB 260228A: SVOM/ECLAIRs refined analysis
  3. GRB 260225A: SVOM/ECLAIRs refined analysis
  4. EP260302a: LCO observations
  5. EP260302a: BOOTES-7 optical counterpart detection at early times
  6. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  7. GRB 251130B: TERI Gamma-ray detection
  8. GRB 260208A: TERI Gamma-ray detection
  9. GRB 260228A: CAHA 2.2m telescope optical upper limit
  10. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  11. EP260227a: Mephisto optical detection
  12. GRB 260228A: SVOM/VT optical upper limits
  13. GRB 260228A: SVOM detection of a burst
  14. EP260227a: COLIBRÍ optical observations
  15. EP260227a: NOT optical observations
  16. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  17. Konus-Wind detection of GRB 260226A
  18. GRB 260225A: WINTER J-band upper limit
  19. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  20. GRB 260226A: COLIBRÍ optical upper limits
  21. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  22. GRB 260226A: Glowbug gamma-ray detection
  23. GRB 260226A : GROWTH-India Telescope optical observations
  24. GRB 260226A: LAST optical upper limit
  25. GRB 260226A: AstroSat CZTI detection of bright long burst
  26. EP260214a: VLA 6 GHz detection
  27. GRB260225A: SVOM/ECLAIRs refined position
  28. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  29. GRB 260223A: Fermi GBM Observation
  30. EP260126a: VLA 6 GHz detection
  31. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  32. EP 260225.148: COLIBRÍ Confirmation of flaring star
  33. EP260223a: Xinglong optical upper limit
  34. GRB 260223A: Glowbug gamma-ray detection
  35. EP260213a: Mephisto optical upper limits
  36. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  37. EP260223a: COLIBRÍ optical upper limits
  38. GRB 260223A: COLIBRÍ further optical observations and a brightening
  39. EP260221a: Optical upper limit with Kinder observations
  40. GRB 260223A: COLIBRÍ optical observations
  41. GRB 260223A: DDOTI Optical Candidate
  42. EP260221a: COLIBRÍ optical counterpart candidate
  43. EP260221a: EP-FXT follow-up observation
  44. EP-WXT01709258519: Xinglong optical upper limit
  45. EP260221a: Xinglong optical upper limit
  46. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  47. EP260221a: GOTO optical upper limit
  48. EP260221a: COLIBRÍ optical upper limit
  49. SVOM alert sb26021801: LCO optical upper limit
  50. EP260221a: Einstein Probe detection of an X-ray transient
  51. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  52. GRB 260219A: AstroSat CZTI detection
  53. SVOM alert sb26021801: LAST optical upper limit
  54. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  55. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  56. EP-WXT 01709258455: NOT optical upper limits
  57. Konus-Wind detection of GRB 260212A
  58. IPN triangulation of GRB 260212A
  59. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  60. EP260214b: Optical upper limit with Kinder observations
  61. EP260214a: Optical upper limits with Kinder observations
  62. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  63. EP260214b: DDOTI Optical Detection
  64. EP260214a: NOT optical upper limits
  65. EP260214a: COLIBRÍ optical upper limits
  66. EP260214b: OHP/T120 optical observations
  67. EP260214b: LCO optical counterpart detection
  68. EP260214b: COLIBRÍ optical observations
  69. EP260214b: NOT optical counterpart detection
  70. EP260214b: Einstein Probe detection of a fast X-ray transient
  71. GRB 260212A: AstroSat CZTI detection
  72. EP260213a: COLIBRÍ optical upper limits
  73. EP260213a: Optical upper limits with Kinder observations
  74. EP260213a: NUTTelA-TAO Early Optical Limits
  75. EP260213a: SVOM/C-GFT upper limit
  76. GRB 260212A: SVOM/GRM observation of a long burst
  77. GRB 260211A - SVOM/ECLAIRs refined analysis
  78. GRB 260204A: SVOM/ECLAIRs refined analysis
  79. GRB 260211A: EP-FXT follow-up observation
  80. GRB 260211A: SVOM/VT optical observation
  81. GRB 260212A: Glowbug gamma-ray detection
  82. GRB 260211A: GOTO optical upper limit
  83. GRB 260211A: LAST optical upper limit
  84. Konus-Wind detection of GRB 260207B
  85. GRB 260128B: SVOM/ECLAIRs refined analysis
  86. GRB 260211A: LCO optical upper limits
  87. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  88. Konus-Wind detection of GRB 260209B
  89. Konus-Wind detection of GRB 260127B
  90. EP260209a: COLIBRÍ optical upper limit
  91. GRB 260208A: LCO detection of the optical counterpart
  92. EP260210a: Optical upper limits with Kinder observations
  93. IPN triangulation of GRB 260207B (short/hard with EE)
  94. GRB 260210A: Glowbug gamma-ray detection
  95. GRB 260210A: AstroSat CZTI detection
  96. GRB 260208C: AstroSat CZTI detection
  97. EP260210a: COLIBRÍ optical upper limit
  98. GRB 260207B: AstroSat CZTI detection
  99. GRB 260204A: Swift-XRT afterglow detection
  100. GRB 260208B: AstroSat CZTI detection of a bright long burst

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