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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"

39259 results found.

  1. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  2. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  3. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  4. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  5. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  6. GRB260310A / AT2026fgk: P200 Spectroscopy
  7. GRB 260312B: Glowbug gamma-ray detection
  8. GRB 260310A: Fermi GBM Observation
  9. GRB 260310A: potential optical counterpart
  10. Fermi GRB 260312B: Global MASTER-Net observations report
  11. Fermi GRB 260311B: Global MASTER-Net observations report
  12. Swift BAT trigger 1500148: A solar flare
  13. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  14. GRB 260312B: Fermi GBM Final Real-time Localization
  15. GRB 260310B: GECAM-B observation of a burst
  16. Retraction of GCN 43965: GRB is actually solar flare
  17. GRB 260312A: Swift detection of a burst
  18. GRB 260311B: Fermi GBM Final Real-time Localization
  19. GRB 260131A/B: radio detection with the VLA
  20. GRB260307A: GECAM-B observation of a burst
  21. GRB 260308A: SVOM/GRM observation of a short GRB
  22. EP260306a: Mondy optical upper limit
  23. GRB 260310A: AstroSat CZTI detection of a long burst
  24. GRB 260311A: Fermi GBM Final Real-time Localization
  25. Fermi GRB 260310B: Global MASTER-Net observations report
  26. GRB 260310B: Fermi GBM Final Real-time Localization
  27. Fermi GRB 260310A: Global MASTER-Net observations report
  28. GRB 260307B: SVOM/ECLAIRs refined analysis
  29. GRB 260208A: radio detection with the VLA
  30. GRB 260310A: Fermi GBM Final Real-time Localization
  31. GRB 260307A: Glowbug gamma-ray detection
  32. GRB 260308A: Fermi GBM Final Real-time Localization
  33. Fermi GBM Sub-Threshold Detection of GRB 260307B
  34. GRB 260307B: Mephisto optical upper limits
  35. GRB 260307B: possible NOT optical counterpart
  36. GRB 260307B: SVOM/VT upper limit with X band data analysis
  37. Fermi GRB 260307A: Global MASTER-Net observations report
  38. GRB260307B: GROWTH-India Telescope optical upper limit
  39. GRB 260307B: SVOM/VT optical candidate
  40. GRB 260307B: SVOM/C-GFT upper limit
  41. GRB 260307B: SVOM detection of a burst
  42. GRB 260307A: Fermi GBM Final Localization
  43. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  44. GRB 260207A: TESS Detection and Possible VLA Counterpart
  45. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  46. EP260302a: Optical afterglow rebrightening
  47. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  48. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  49. GRB 260303A: 1.3m DFOT optical upper limit
  50. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  51. GRB 260303A: SVOM/ECLAIRs refined analysis
  52. Fermi GRB 260305A: Global MASTER-Net observations report
  53. GRB 260305A: Fermi GBM Final Real-time Localization
  54. GRB 260303B: AstroSat CZTI detection
  55. GRB 260304A: AstroSat CZTI detection of a long burst
  56. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  57. GRB 260303A: SVOM/VT optical observations
  58. GRB 260303A: J-band observations with WINTER
  59. GRB 260303B: NuSTAR detection of prompt emission
  60. EP260302a: Global MASTER-Net observations report
  61. Fermi GRB 260303B: Global MASTER-Net observations report
  62. GRB 260228A: SVOM/ECLAIRs refined analysis
  63. GRB 260225A: SVOM/ECLAIRs refined analysis
  64. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  65. GRB 260303B: Fermi GBM Final Real-time Localization
  66. EP260302a: LCO observations
  67. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  68. GRB 260303A: SVOM detection of a burst
  69. GRB 260228A: EP-FXT follow-up observation
  70. GRB 251130B: TERI Gamma-ray detection
  71. GRB 260208A: TERI Gamma-ray detection
  72. GRB 260302A: Fermi GBM Final Real-time Localization
  73. EP260227a: Mondy optical observations
  74. GRB 260228A: CAHA 2.2m telescope optical upper limit
  75. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. EP260227a: Mephisto optical detection
  77. GRID detection of GRB 260225D
  78. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  79. EP260227a: further LCO observations
  80. GRB 260228A: SVOM/VT optical upper limits
  81. GRB 260225D: SVOM/GRM observation
  82. EP260227A: 3.6m DOT optical afterglow detection
  83. GRB 260225B: SVOM/GRM observation
  84. GRB 260228A: SVOM detection of a burst
  85. GRB 260226A: Asiago r-band upper limit
  86. EP260227a: COLIBRÍ optical observations
  87. GRB 260225A: SVOM/VT optical continued observations and upper limit
  88. GRID detection of GRB 260223A
  89. EP260227a: Global MASTER-Net observations report
  90. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  91. Konus-Wind detection of GRB 260226A
  92. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  93. GRB 260225A: WINTER J-band upper limit
  94. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  95. GRB 260226A: COLIBRÍ optical upper limits
  96. GRB 260226A: LCOGT Optical Upper Limit
  97. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  98. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  99. GRB 260226A: Glowbug gamma-ray detection
  100. GRB 260226A: NuSTAR detection of bright prompt emission

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