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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"

2409 results found.

  1. GRB 260316B: AstroSat CZTI detection
  2. EP260314a: COLIBRÍ optical upper limit
  3. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  4. EP260314a: BOOTES-6/DPR optical upper limits at early times
  5. EP260314a: SVOM/VT optical candidate
  6. GRB 260308A: Insight-HXMT/HE detection
  7. GRB 260308A: SVOM/GRM observation of a short GRB
  8. GRB 260307B: SVOM/ECLAIRs refined analysis
  9. GRB 260208A: radio detection with the VLA
  10. Fermi GBM Sub-Threshold Detection of GRB 260307B
  11. GRB 260307B: Mephisto optical upper limits
  12. GRB 260307B: possible NOT optical counterpart
  13. GRB 260307B: SVOM/VT upper limit with X band data analysis
  14. GRB260307B: GROWTH-India Telescope optical upper limit
  15. GRB 260307B: SVOM/VT optical candidate
  16. GRB 260307B: SVOM/C-GFT upper limit
  17. GRB 260307B: SVOM detection of a burst
  18. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  19. EP260302a: SVOM/VT optical observation
  20. EP260306a: SVOM/VT optical observation
  21. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  22. GRB 260303A: 1.3m DFOT optical upper limit
  23. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  24. GRB 260303A: SVOM/ECLAIRs refined analysis
  25. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  26. GRB 260303A: SVOM/VT optical observations
  27. GRB 260228A: SVOM/ECLAIRs refined analysis
  28. GRB 260225A: SVOM/ECLAIRs refined analysis
  29. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  30. GRB 260303A: SVOM detection of a burst
  31. GRB 260228A: EP-FXT follow-up observation
  32. GRB 260228A: CAHA 2.2m telescope optical upper limit
  33. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. GRID detection of GRB 260225D
  35. EP260227a: SVOM/VT optical observation
  36. GRB 260228A: SVOM/VT optical upper limits
  37. GRB 260225D: SVOM/GRM observation
  38. GRB 260225B: SVOM/GRM observation
  39. GRB 260228A: SVOM detection of a burst
  40. GRB 260225A: SVOM/VT optical continued observations and upper limit
  41. GRID detection of GRB 260223A
  42. GRB 260225A: WINTER J-band upper limit
  43. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  44. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  45. GRB260225A: SVOM/ECLAIRs refined position
  46. GRB 260225A: EP-FXT follow-up observation
  47. GRB 260225A: SVOM/VT optical observation
  48. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  49. GRB 260223A: Fermi GBM Observation
  50. GRB 260225A: SVOM/VT optical upper limits
  51. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  52. GRB 260225A: SVOM detection of a burst
  53. GRB 260223A: Glowbug gamma-ray detection
  54. sb26021801: SVOM/VT optical upper limits
  55. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  56. sb26021801: SVOM/C-GFT upper limit
  57. GRB 260223A: SVOM/VT optical observation
  58. GRB 260223A: SVOM/GRM observation
  59. SVOM alert sb26021801: LCO optical upper limit
  60. SVOM alert sb26021801: LAST optical upper limit
  61. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  63. sb26021801: SVOM detection of a long faint X-ray transient
  64. Konus-Wind detection of GRB 260212A
  65. IPN triangulation of GRB 260212A
  66. EP260214b: SVOM/VT optical observation
  67. EP260214a: COLIBRÍ optical upper limits
  68. EP260214a: refined analysis of the EP-FXT observation
  69. GRB 260211A: SVOM/VT optical counterpart
  70. EP260214a: SVOM/VT optical upper limits
  71. GRB 260212A: Fermi GBM Observation
  72. GRB 260212A: GECAM-B observation
  73. EP260213a: SVOM/VT optical upper limit
  74. EP260213a: SVOM/C-GFT upper limit
  75. GRB 260212A: SVOM/GRM observation of a long burst
  76. GRB 260211A - SVOM/ECLAIRs refined analysis
  77. GRB 260204A: SVOM/ECLAIRs refined analysis
  78. GRB 260211A: EP-FXT follow-up observation
  79. GRB 260211A: SVOM/VT optical observation
  80. GRB 260211A: GOTO optical upper limit
  81. GRB 260211A: LAST optical upper limit
  82. GRB 260210A: SVOM/GRM observation
  83. Fermi GBM Sub-Threshold Detection of GRB 260211A
  84. GRB 260128B: SVOM/ECLAIRs refined analysis
  85. GRB 260211A: LCO optical upper limits
  86. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  87. GRB 260211A: SVOM detection of a burst
  88. GRB 260210A: Glowbug gamma-ray detection
  89. EP260210a: SVOM/VT optical upper limit
  90. GRB 260210A: AstroSat CZTI detection
  91. GRB 260208C: AstroSat CZTI detection
  92. EP260210a: SVOM/C-GFT upper limit
  93. GRB 260208C: SVOM/GRM observation
  94. GRB 260204A: Swift-XRT afterglow detection
  95. GRB 260208B: AstroSat CZTI detection of a bright long burst
  96. GRB 260204A: Swift/UVOT Upper Limits
  97. GRB 260208B: COLIBRÍ optical observations
  98. GRB 260208B: EP-FXT observation
  99. GRB 260208B: SVOM/VT optical candidate
  100. GRB 260208A: SVOM/VT optical observation

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