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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"

2408 results found.

  1. EP260314a: COLIBRÍ optical upper limit
  2. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP260314a: BOOTES-6/DPR optical upper limits at early times
  4. EP260314a: SVOM/VT optical candidate
  5. GRB 260308A: Insight-HXMT/HE detection
  6. GRB 260308A: SVOM/GRM observation of a short GRB
  7. GRB 260307B: SVOM/ECLAIRs refined analysis
  8. GRB 260208A: radio detection with the VLA
  9. Fermi GBM Sub-Threshold Detection of GRB 260307B
  10. GRB 260307B: Mephisto optical upper limits
  11. GRB 260307B: possible NOT optical counterpart
  12. GRB 260307B: SVOM/VT upper limit with X band data analysis
  13. GRB260307B: GROWTH-India Telescope optical upper limit
  14. GRB 260307B: SVOM/VT optical candidate
  15. GRB 260307B: SVOM/C-GFT upper limit
  16. GRB 260307B: SVOM detection of a burst
  17. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  18. EP260302a: SVOM/VT optical observation
  19. EP260306a: SVOM/VT optical observation
  20. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  21. GRB 260303A: 1.3m DFOT optical upper limit
  22. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  23. GRB 260303A: SVOM/ECLAIRs refined analysis
  24. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  25. GRB 260303A: SVOM/VT optical observations
  26. GRB 260228A: SVOM/ECLAIRs refined analysis
  27. GRB 260225A: SVOM/ECLAIRs refined analysis
  28. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  29. GRB 260303A: SVOM detection of a burst
  30. GRB 260228A: EP-FXT follow-up observation
  31. GRB 260228A: CAHA 2.2m telescope optical upper limit
  32. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRID detection of GRB 260225D
  34. EP260227a: SVOM/VT optical observation
  35. GRB 260228A: SVOM/VT optical upper limits
  36. GRB 260225D: SVOM/GRM observation
  37. GRB 260225B: SVOM/GRM observation
  38. GRB 260228A: SVOM detection of a burst
  39. GRB 260225A: SVOM/VT optical continued observations and upper limit
  40. GRID detection of GRB 260223A
  41. GRB 260225A: WINTER J-band upper limit
  42. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  43. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  44. GRB260225A: SVOM/ECLAIRs refined position
  45. GRB 260225A: EP-FXT follow-up observation
  46. GRB 260225A: SVOM/VT optical observation
  47. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  48. GRB 260223A: Fermi GBM Observation
  49. GRB 260225A: SVOM/VT optical upper limits
  50. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  51. GRB 260225A: SVOM detection of a burst
  52. GRB 260223A: Glowbug gamma-ray detection
  53. sb26021801: SVOM/VT optical upper limits
  54. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  55. sb26021801: SVOM/C-GFT upper limit
  56. GRB 260223A: SVOM/VT optical observation
  57. GRB 260223A: SVOM/GRM observation
  58. SVOM alert sb26021801: LCO optical upper limit
  59. SVOM alert sb26021801: LAST optical upper limit
  60. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  62. sb26021801: SVOM detection of a long faint X-ray transient
  63. Konus-Wind detection of GRB 260212A
  64. IPN triangulation of GRB 260212A
  65. EP260214b: SVOM/VT optical observation
  66. EP260214a: COLIBRÍ optical upper limits
  67. EP260214a: refined analysis of the EP-FXT observation
  68. GRB 260211A: SVOM/VT optical counterpart
  69. EP260214a: SVOM/VT optical upper limits
  70. GRB 260212A: Fermi GBM Observation
  71. GRB 260212A: GECAM-B observation
  72. EP260213a: SVOM/VT optical upper limit
  73. EP260213a: SVOM/C-GFT upper limit
  74. GRB 260212A: SVOM/GRM observation of a long burst
  75. GRB 260211A - SVOM/ECLAIRs refined analysis
  76. GRB 260204A: SVOM/ECLAIRs refined analysis
  77. GRB 260211A: EP-FXT follow-up observation
  78. GRB 260211A: SVOM/VT optical observation
  79. GRB 260211A: GOTO optical upper limit
  80. GRB 260211A: LAST optical upper limit
  81. GRB 260210A: SVOM/GRM observation
  82. Fermi GBM Sub-Threshold Detection of GRB 260211A
  83. GRB 260128B: SVOM/ECLAIRs refined analysis
  84. GRB 260211A: LCO optical upper limits
  85. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  86. GRB 260211A: SVOM detection of a burst
  87. GRB 260210A: Glowbug gamma-ray detection
  88. EP260210a: SVOM/VT optical upper limit
  89. GRB 260210A: AstroSat CZTI detection
  90. GRB 260208C: AstroSat CZTI detection
  91. EP260210a: SVOM/C-GFT upper limit
  92. GRB 260208C: SVOM/GRM observation
  93. GRB 260204A: Swift-XRT afterglow detection
  94. GRB 260208B: AstroSat CZTI detection of a bright long burst
  95. GRB 260204A: Swift/UVOT Upper Limits
  96. GRB 260208B: COLIBRÍ optical observations
  97. GRB 260208B: EP-FXT observation
  98. GRB 260208B: SVOM/VT optical candidate
  99. GRB 260208A: SVOM/VT optical observation
  100. GRB 260208B: SVOM/GRM observation of a bright burst

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