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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"

39287 results found.

  1. EP260227a: Mondy optical observations
  2. GRB 260228A: CAHA 2.2m telescope optical upper limit
  3. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  4. EP260227a: Mephisto optical detection
  5. GRID detection of GRB 260225D
  6. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  7. EP260227a: further LCO observations
  8. GRB 260228A: SVOM/VT optical upper limits
  9. GRB 260225D: SVOM/GRM observation
  10. EP260227A: 3.6m DOT optical afterglow detection
  11. GRB 260225B: SVOM/GRM observation
  12. GRB 260228A: SVOM detection of a burst
  13. GRB 260226A: Asiago r-band upper limit
  14. EP260227a: COLIBRÍ optical observations
  15. GRB 260225A: SVOM/VT optical continued observations and upper limit
  16. GRID detection of GRB 260223A
  17. EP260227a: Global MASTER-Net observations report
  18. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  19. Konus-Wind detection of GRB 260226A
  20. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  21. GRB 260225A: WINTER J-band upper limit
  22. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  23. GRB 260226A: COLIBRÍ optical upper limits
  24. GRB 260226A: LCOGT Optical Upper Limit
  25. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  26. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  27. GRB 260226A: Glowbug gamma-ray detection
  28. GRB 260226A: NuSTAR detection of bright prompt emission
  29. GRB 260226A : GROWTH-India Telescope optical observations
  30. GRB 260226A: LAST optical upper limit
  31. GRB 260226A: Fermi GBM observation
  32. GRB 260226A: Fermi-LAT refined analysis
  33. LAT GRB260226.44: Global MASTER-Net observations report
  34. Fermi GRB 260226A: Global MASTER-Net observations report
  35. GRB 260226A: AstroSat CZTI detection of bright long burst
  36. GRB 260226A: Fermi-LAT detection of a bright burst
  37. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  38. EP260224a: LCO optical upper limits
  39. GRB260225A: SVOM/ECLAIRs refined position
  40. GRB 260226A: Fermi GBM Final Real-time Localization
  41. GRB 260225A: EP-FXT follow-up observation
  42. GRB 260225A: SVOM/VT optical observation
  43. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  44. GRB 260225C: Fermi GBM Final Real-time Localization
  45. GRB 260223A: Fermi GBM Observation
  46. GRB 260225A: SVOM/VT optical upper limits
  47. GRB 260225B: Fermi GBM Final Real-time Localization
  48. EP260126a: VLA 6 GHz detection
  49. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  50. GRB 260225A: SVOM detection of a burst
  51. EP 260225.148: COLIBRÍ Confirmation of flaring star
  52. GRB 260223A: Glowbug gamma-ray detection
  53. EP260213a: Mephisto optical upper limits
  54. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  55. sb26021801: SVOM/C-GFT upper limit
  56. EP260223a: COLIBRÍ optical upper limits
  57. GRB 260223A: SVOM/VT optical observation
  58. GRB 260223A: SVOM/GRM observation
  59. GRB 260223A: COLIBRÍ further optical observations and a brightening
  60. GRB 260223A: COLIBRÍ optical observations
  61. GRB 260223A: DDOTI Optical Candidate
  62. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  63. Fermi GRB 260223A: Global MASTER-Net observations report
  64. GRB 260223A: Fermi GBM Final Real-time Localization
  65. EP260221a: COLIBRÍ optical counterpart candidate
  66. GRB 260222A: Fermi GBM Final Real-time Localization
  67. EP260221a: Global MASTER-Net observations report
  68. Fermi GRB 260221B: Global MASTER-Net observations report
  69. GRB 260221B: Fermi GBM Final Real-time Localization
  70. Fermi GRB 260221A: Global MASTER-Net observations report
  71. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  72. GRB 260221A: Fermi GBM Final Real-time Localization
  73. EP260221a: COLIBRÍ optical upper limit
  74. GRB 260219A: AstroSat CZTI detection
  75. GRB 260219A: GECAM-B observation of a long burst
  76. Fermi GRB 260219A: Global MASTER-Net observations report
  77. GRB 260219A: Fermi GBM Final Real-time Localization
  78. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. IceCube Alert 260217A: Global MASTER-Net observations report
  80. GRB 260217A: Fermi GBM Final Localization
  81. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  82. sb26021801: SVOM detection of a long faint X-ray transient
  83. EP260214b: Mondy optical observations
  84. EP260214b: 1.3m DFOT optical upper limit
  85. EP260210a: Mondy optical upper limits
  86. Konus-Wind detection of GRB 260212A
  87. GRB 260208A: AbAO and Terskol optical upper limits
  88. GRB 260208A: continued Mondy optical observations
  89. IPN triangulation of GRB 260212A
  90. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  91. GRB 260213A: GECAM-B observation of a short burst
  92. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  93. GRB 260216A: Fermi GBM Final Real-time Localization
  94. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  95. EP260214a: Optical upper limits with Kinder observations
  96. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  97. EP260214b: GROWTH-India Telescope optical upper limit
  98. EP260214a: COLIBRÍ optical upper limits
  99. EP260214b: LCO optical counterpart detection
  100. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208

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