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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"

42920 results found.

  1. EP260227a: LCOGT Optical Observations
  2. GRB 260226A: Asiago r-band upper limit
  3. EP260227a: Thai National Telescope observations
  4. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  5. EP260227a: Liverpool Telescope observations
  6. EP260227a: COLIBRÍ optical observations
  7. EP260227a: NOT optical observations
  8. GRB 260225A: SVOM/VT optical continued observations and upper limit
  9. GRID detection of GRB 260223A
  10. EP260227a: Global MASTER-Net observations report
  11. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  12. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  13. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  14. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  15. Konus-Wind detection of GRB 260226A
  16. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  17. EP260214a: VLT/FORS2 optical observations
  18. GRB 260225A: WINTER J-band upper limit
  19. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  20. GRB 260226A: COLIBRÍ optical upper limits
  21. GRB 260226A: LCOGT Optical Upper Limit
  22. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  23. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  24. GRB 260226A: Glowbug gamma-ray detection
  25. GRB 260226A: NuSTAR detection of bright prompt emission
  26. GRB 260226A : GROWTH-India Telescope optical observations
  27. GRB 260226A: LAST optical upper limit
  28. GRB 260226A: Fermi GBM observation
  29. GRB 260226A: Fermi-LAT refined analysis
  30. The EP-WXT trigger 01709258652 is likely a flaring star
  31. LAT GRB260226.44: Global MASTER-Net observations report
  32. Fermi GRB 260226A: Global MASTER-Net observations report
  33. GRB 260226A: AstroSat CZTI detection of bright long burst
  34. EP260214a: VLA 6 GHz detection
  35. GRB 260226A: Fermi-LAT detection of a bright burst
  36. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  37. EP260224a: LCO optical upper limits
  38. GRB260225A: SVOM/ECLAIRs refined position
  39. GRB 260226A: Fermi GBM Final Real-time Localization
  40. GRB 260225A: EP-FXT follow-up observation
  41. GRB 260225A: SVOM/VT optical observation
  42. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  43. GRB 260225C: Fermi GBM Final Real-time Localization
  44. GRB 260223A: Fermi GBM Observation
  45. GRB 260225A: SVOM/VT optical upper limits
  46. GRB 260225B: Fermi GBM Final Real-time Localization
  47. EP260126a: VLA 6 GHz detection
  48. EP260223a: Liverpool Telescope upper limits
  49. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  50. GRB 260225A: SVOM detection of a burst
  51. EP260224a: Einstein Probe detection of an X-ray transient
  52. EP 260225.148: COLIBRÍ Confirmation of flaring star
  53. EP260223a: Xinglong optical upper limit
  54. The EP-WXT trigger 01709258631 is likely a flaring star
  55. GRB 260223A: Glowbug gamma-ray detection
  56. EP260213a: Mephisto optical upper limits
  57. EP260223a: EP-FXT follow-up observation
  58. sb26021801: SVOM/VT optical upper limits
  59. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  60. sb26021801: SVOM/C-GFT upper limit
  61. EP260223a: COLIBRÍ optical upper limits
  62. EP260223a: Einstein Probe detection of an X-ray transient
  63. GRB 260223A: SVOM/VT optical observation
  64. GRB 260223A: SVOM/GRM observation
  65. GRB 260223A: COLIBRÍ further optical observations and a brightening
  66. EP260221a: Optical upper limit with Kinder observations
  67. GRB 260223A: COLIBRÍ optical observations
  68. GRB 260223A: DDOTI Optical Candidate
  69. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  70. Fermi GRB 260223A: Global MASTER-Net observations report
  71. GRB 260223A: Fermi GBM Final Real-time Localization
  72. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  73. EP260221a: COLIBRÍ optical counterpart candidate
  74. EP260221a: Gemini South z-band upper limit
  75. GRB 260222A: Fermi GBM Final Real-time Localization
  76. EP260221a: Global MASTER-Net observations report
  77. EP260221a: EP-FXT follow-up observation
  78. Fermi GRB 260221B: Global MASTER-Net observations report
  79. GRB 260221B: Fermi GBM Final Real-time Localization
  80. EP260221a: Xinglong optical upper limit
  81. Fermi GRB 260221A: Global MASTER-Net observations report
  82. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  83. GRB 260221A: Fermi GBM Final Real-time Localization
  84. EP260221a: GOTO optical upper limit
  85. EP260221a: COLIBRÍ optical upper limit
  86. SVOM alert sb26021801: LCO optical upper limit
  87. EP260221a: Einstein Probe detection of an X-ray transient
  88. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  89. GRB 260219A: AstroSat CZTI detection
  90. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  91. GRB 260219A: GECAM-B observation of a long burst
  92. Fermi GRB 260219A: Global MASTER-Net observations report
  93. GRB 260219A: Fermi GBM Final Real-time Localization
  94. SVOM alert sb26021801: LAST optical upper limit
  95. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. IceCube Alert 260217A: Global MASTER-Net observations report
  97. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  98. GRB 260217A: Fermi GBM Final Localization
  99. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  100. sb26021801: SVOM detection of a long faint X-ray transient

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