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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"

2433 results found.

  1. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  2. GRB 260226A: Glowbug gamma-ray detection
  3. GRB 260226A: NuSTAR detection of bright prompt emission
  4. GRB 260226A : GROWTH-India Telescope optical observations
  5. GRB 260226A: LAST optical upper limit
  6. GRB 260226A: Fermi GBM observation
  7. GRB 260226A: Fermi-LAT refined analysis
  8. The EP-WXT trigger 01709258652 is likely a flaring star
  9. LAT GRB260226.44: Global MASTER-Net observations report
  10. Fermi GRB 260226A: Global MASTER-Net observations report
  11. GRB 260226A: AstroSat CZTI detection of bright long burst
  12. EP260214a: VLA 6 GHz detection
  13. GRB 260226A: Fermi-LAT detection of a bright burst
  14. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  15. EP260224a: LCO optical upper limits
  16. GRB 260226A: Fermi GBM Final Real-time Localization
  17. GRB 260225A: EP-FXT follow-up observation
  18. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  19. GRB 260225C: Fermi GBM Final Real-time Localization
  20. GRB 260223A: Fermi GBM Observation
  21. GRB 260225A: SVOM/VT optical upper limits
  22. GRB 260225B: Fermi GBM Final Real-time Localization
  23. EP260126a: VLA 6 GHz detection
  24. EP260223a: Liverpool Telescope upper limits
  25. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  26. GRB 260225A: SVOM detection of a burst
  27. EP260224a: Einstein Probe detection of an X-ray transient
  28. EP 260225.148: COLIBRÍ Confirmation of flaring star
  29. EP260223a: Xinglong optical upper limit
  30. The EP-WXT trigger 01709258631 is likely a flaring star
  31. GRB 260223A: Glowbug gamma-ray detection
  32. EP260213a: Mephisto optical upper limits
  33. EP260223a: EP-FXT follow-up observation
  34. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  35. sb26021801: SVOM/C-GFT upper limit
  36. EP260223a: COLIBRÍ optical upper limits
  37. EP260223a: Einstein Probe detection of an X-ray transient
  38. GRB 260223A: SVOM/VT optical observation
  39. GRB 260223A: SVOM/GRM observation
  40. GRB 260223A: COLIBRÍ further optical observations and a brightening
  41. EP260221a: Optical upper limit with Kinder observations
  42. GRB 260223A: COLIBRÍ optical observations
  43. GRB 260223A: DDOTI Optical Candidate
  44. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  45. Fermi GRB 260223A: Global MASTER-Net observations report
  46. GRB 260223A: Fermi GBM Final Real-time Localization
  47. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  48. EP260221a: COLIBRÍ optical counterpart candidate
  49. EP260221a: Gemini South z-band upper limit
  50. GRB 260222A: Fermi GBM Final Real-time Localization
  51. EP260221a: Global MASTER-Net observations report
  52. EP260221a: EP-FXT follow-up observation
  53. Fermi GRB 260221B: Global MASTER-Net observations report
  54. GRB 260221B: Fermi GBM Final Real-time Localization
  55. EP-WXT01709258519: Xinglong optical upper limit
  56. EP260221a: Xinglong optical upper limit
  57. Fermi GRB 260221A: Global MASTER-Net observations report
  58. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  59. GRB 260221A: Fermi GBM Final Real-time Localization
  60. EP260221a: GOTO optical upper limit
  61. EP260221a: COLIBRÍ optical upper limit
  62. SVOM alert sb26021801: LCO optical upper limit
  63. EP260221a: Einstein Probe detection of an X-ray transient
  64. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  65. GRB 260219A: AstroSat CZTI detection
  66. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  67. GRB 260219A: GECAM-B observation of a long burst
  68. Fermi GRB 260219A: Global MASTER-Net observations report
  69. GRB 260219A: Fermi GBM Final Real-time Localization
  70. SVOM alert sb26021801: LAST optical upper limit
  71. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. IceCube Alert 260217A: Global MASTER-Net observations report
  73. GRB 260217A: Fermi GBM Final Localization
  74. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  75. sb26021801: SVOM detection of a long faint X-ray transient
  76. The EP-WXT trigger 01709258455 is likely a flaring star
  77. EP-WXT 01709258455: NOT optical upper limits
  78. EP260214b: Mondy optical observations
  79. EP260214b: 1.3m DFOT optical upper limit
  80. EP260210a: Mondy optical upper limits
  81. GRB 260208A: AbAO and Terskol optical upper limits
  82. GRB 260208A: continued Mondy optical observations
  83. GRB 260213A: GECAM-B observation of a short burst
  84. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  85. GRB 260216A: Fermi GBM Final Real-time Localization
  86. EP260214b: Liverpool Telescope optical observations
  87. EP260214b: Optical upper limit with Kinder observations
  88. EP260214a: Optical upper limits with Kinder observations
  89. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  90. EP260214b: DDOTI Optical Detection
  91. EP260214b: GROWTH-India Telescope optical upper limit
  92. EP260214b: SVOM/VT optical observation
  93. EP260214a: NOT optical upper limits
  94. EP260214a: COLIBRÍ optical upper limits
  95. EP260214b: OHP/T120 optical observations
  96. EP260214a: refined analysis of the EP-FXT observation
  97. EP260214b: LCO optical counterpart detection
  98. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  99. GRB 260211A: SVOM/VT optical counterpart
  100. EP260214b: COLIBRÍ optical observations

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