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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"

32685 results found.

  1. GRB 260604C: LAST detection of optical counterpart candidate
  2. Fermi GRB 260604C: Global MASTER-Net observations report
  3. Fermi GRB 260604C: Global MASTER-Net observations report
  4. GRB 260604C: SVOM detection of a long burst
  5. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  6. GRB 260603A: NOT optical observations
  7. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  8. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  9. EP260602a: EP-FXT follow-up observation
  10. EP260603a: Global MASTER-Net observations report
  11. EP260602d: Optical Upper limits with kinder observations
  12. EP260602b: Liverpool Telescope observations
  13. EP260602a: Liverpool Telescope optical upper limits
  14. EP260602b: Liverpool Telescope and LCO observations
  15. EP260602a: GTC and Liverpool Telescope optical observations
  16. Konus-Wind detection of GRB 260601B/EP260601a
  17. GRB 260603A: EP-FXT follow-up observation
  18. EP260601a/GRB 260601B: EP-FXT follow-up observation
  19. GRB 260601B / EP260601a: Mondy optical upper limit
  20. EP260602b: EP-FXT follow-up observation
  21. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  22. GRB 260603A: Kilonova-Catcher optical upper limit
  23. GRB 260603A: SVOM/VT optical observations
  24. EP260602a: NOT NIR J-band observations
  25. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  26. EP260602d: Einstein Probe detection of a fast X-ray transient
  27. EP260602a: SVOM/VT optical magnitudes correction
  28. GRB 260601A: SVOM/GRM observation of a short burst
  29. EP260602c: Einstein Probe detection of a fast X-ray transient
  30. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  31. EP260602a: COLIBRÍ optical observations
  32. GRB260601B/EP260601a: NOT near-infrared observations
  33. EP260602b: Einstein Probe detection of a fast X-ray transient
  34. GRB 260601B/EP260601a: Insight-HXMT detection
  35. Fermi GRB 260602B: Global MASTER-Net observations report
  36. Fermi GRB 260602B: Global MASTER-Net observations report
  37. EP260602a: SVOM/VT optical candidate
  38. GRB 260601A: GECAM-B observation of a short burst
  39. GRB 260601B/EP260601a: J-band upper limit with WINTER
  40. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  41. EP260530a/AT 2026nwl: KAIT optical observations
  42. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  43. EP260602a: Optical upper limits with Kinder observations
  44. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  45. GRB 260601B/EP260601a: SVOM/VT optical observations
  46. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  47. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  48. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  49. GRB 260601A: Glowbug gamma-ray detection of a short burst
  50. GRB 260531B: Glowbug gamma-ray detection
  51. GRB 260516D: VLA radio detection
  52. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  53. Fermi GRB 260601A: Global MASTER-Net observations report
  54. GRB 260531B: GECAM-B observation
  55. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  56. AT 2026nuz: COLIBRÍ optical observations
  57. IPN triangulation of GRB 260527A / EP260527a
  58. EP260527a/GRB 260527A: further FTW optical and NIR observations
  59. GRB 260527A / EP260527a: VLA radio detection
  60. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  61. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  62. GRB 260529A: GOTO tentative optical afterglow candidate
  63. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  64. GRB 260527A/EP260527a: Insight-HXMT detection
  65. Fermi GRB 260529A: Global MASTER-Net observations report
  66. EP260526a: SVOM/VT optical upper limits
  67. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  68. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  69. EP260527a / GRB 260527A: NOT optical observations
  70. GRB 260527A/EP260527a: FTW optical and NIR observations
  71. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  72. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  73. EP260527a/GRB 260527A: EP-FXT follow-up observation
  74. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  75. GRB 260526A: GECAM-B observation
  76. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  77. EP260526a: EP-FXT follow-up observation
  78. EP260527a: SVOM/VT optical observation
  79. EP260527a: COLIBRÍ optical detection
  80. EP260526a: LCO optical upper limits
  81. EP260526a: Einstein Probe detection of a fast X-ray transient
  82. GRB 260525A: AstroSat CZTI detection
  83. The EP-WXT trigger 01709266106 is not a real source
  84. Fermi GRB 260526A: Global MASTER-Net observations report
  85. Fermi GRB 260525A: Global MASTER-Net observations report
  86. GRB 260523B: AstroSat CZTI detection
  87. GRB 260523B: GECAM-B observation
  88. Fermi GRB 260523A: Global MASTER-Net observations report
  89. GRB 260522A: Fermi GBM Observation
  90. GRB 260522B: NuSTAR detection of prompt emission
  91. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  92. GRB 260522A: GOTO optical upper limit
  93. Fermi GRB 260522A: Global MASTER-Net observations report
  94. GRB 260522A: Fermi-LAT detection
  95. GRB 260519C: SVOM/GRM observation
  96. GRB 260511A: iTelescope T-75 optical detection
  97. GRB 260520B: SVOM/GRM observation
  98. GRB 260411B: TERI Gamma-ray detection
  99. GRB 260407A: TERI Gamma-ray detection
  100. GRB 260307A: TERI Gamma-ray detection

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