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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"

28234 results found.

  1. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  2. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  3. GRB 260312B: AstroSat CZTI detection
  4. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  5. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  6. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  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. GRB 260312B: BALROG localization (Fermi Trigger 795001611 / GRB 260312407)
  13. GRB 260131A/B: radio detection with the VLA
  14. EP260302a: MeerKAT radio counterpart
  15. GRB 260308A: SVOM/GRM observation of a short GRB
  16. EP260306a: Mondy optical upper limit
  17. Fermi GRB 260310B: Global MASTER-Net observations report
  18. Fermi GRB 260310A: Global MASTER-Net observations report
  19. GRB 260208A: radio detection with the VLA
  20. GRB 260307A: Glowbug gamma-ray detection
  21. Fermi GBM Sub-Threshold Detection of GRB 260307B
  22. GRB 260307B: Mephisto optical upper limits
  23. GRB 260307B: possible NOT optical counterpart
  24. GRB 260307B: SVOM/VT upper limit with X band data analysis
  25. Fermi GRB 260307A: Global MASTER-Net observations report
  26. GRB260307B: GROWTH-India Telescope optical upper limit
  27. GRB 260307B: SVOM/VT optical candidate
  28. GRB 260307B: SVOM/C-GFT upper limit
  29. GRB 260307B: SVOM detection of a burst
  30. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  31. GRB 260207A: TESS Detection and Possible VLA Counterpart
  32. EP260302a: SVOM/VT optical observation
  33. EP260306a: Gemini-North redshift z = 4.773
  34. EP260306a: SVOM/VT optical observation
  35. EP260302a: Gemini-South redshift z = 1.535
  36. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  37. EP260306a: Einstein Probe detection of an X-ray transient
  38. EP260302a: Optical afterglow rebrightening
  39. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  40. GRB 260303A: 1.3m DFOT optical upper limit
  41. Fermi GRB 260305A: Global MASTER-Net observations report
  42. GRB 260303B: AstroSat CZTI detection
  43. GRB 260303A: SVOM/VT optical observations
  44. GRB 260303A: J-band observations with WINTER
  45. GRB 260303B: NuSTAR detection of prompt emission
  46. EP260302a: Global MASTER-Net observations report
  47. Fermi GRB 260303B: Global MASTER-Net observations report
  48. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  49. EP260302a: analysis of the follow-up EP-FXT observation
  50. EP260302a: LCO observations
  51. EP260302a: BOOTES-7 optical counterpart detection at early times
  52. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  53. GRB 260303A: SVOM detection of a burst
  54. GRB 260228A: EP-FXT follow-up observation
  55. EP260302a: Einstein Probe detection of an X-ray transient
  56. The EP-WXT trigger 01709258736: Las Cumbres discovery of the optical counterpart
  57. GRB 251130B: TERI Gamma-ray detection
  58. GRB 260208A: TERI Gamma-ray detection
  59. EP260227a: Mondy optical observations
  60. GRB 260228A: CAHA 2.2m telescope optical upper limit
  61. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. EP260227a: Mephisto optical detection
  63. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  64. EP260227a: SVOM/VT optical observation
  65. GRB 260228A: SVOM/VT optical upper limits
  66. GRB 260225D: SVOM/GRM observation
  67. EP260227A: 3.6m DOT optical afterglow detection
  68. GRB 260225B: SVOM/GRM observation
  69. EP260227a: Liverpool Telescope optical observations
  70. EP260227a: LCOGT Optical Observations
  71. GRB 260226A: Asiago r-band upper limit
  72. EP260227a: Liverpool Telescope observations
  73. EP260227a: COLIBRÍ optical observations
  74. EP260227a: NOT optical observations
  75. EP260227a: Global MASTER-Net observations report
  76. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  77. The EP-WXT trigger 01709258681 (EP260227a?): Las Cumbres follow-up observation of the optical counterpart
  78. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  79. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  80. EP260214a: VLT/FORS2 optical observations
  81. GRB 260225A: WINTER J-band upper limit
  82. GRB 260226A: COLIBRÍ optical upper limits
  83. GRB 260226A: LCOGT Optical Upper Limit
  84. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  85. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  86. GRB 260226A: Glowbug gamma-ray detection
  87. GRB 260226A: NuSTAR detection of bright prompt emission
  88. GRB 260226A : GROWTH-India Telescope optical observations
  89. GRB 260226A: LAST optical upper limit
  90. GRB 260226A: Fermi GBM observation
  91. LAT GRB260226.44: Global MASTER-Net observations report
  92. Fermi GRB 260226A: Global MASTER-Net observations report
  93. GRB 260226A: AstroSat CZTI detection of bright long burst
  94. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  95. EP260224a: LCO optical upper limits
  96. GRB 260225A: EP-FXT follow-up observation
  97. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  98. GRB 260223A: Fermi GBM Observation
  99. GRB 260225A: SVOM/VT optical upper limits
  100. EP260223a: Liverpool Telescope upper limits

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