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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"

38571 results found.

  1. EP260601a/GRB 260601B: EP-FXT follow-up observation
  2. GRB 260601B / EP260601a: Mondy optical upper limit
  3. EP260602b: EP-FXT follow-up observation
  4. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  5. GRB 260603A: Kilonova-Catcher optical upper limit
  6. GRB 260603A: SVOM/VT optical observations
  7. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  8. EP260602d: Einstein Probe detection of a fast X-ray transient
  9. EP260602a: SVOM/VT optical magnitudes correction
  10. GRB 260601A: SVOM/GRM observation of a short burst
  11. EP260602c: Einstein Probe detection of a fast X-ray transient
  12. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  13. EP260602a: COLIBRÍ optical observations
  14. SVOM GRB260603.23: Global MASTER-Net observations report
  15. GRB 260603A: SVOM detection of a burst
  16. EP260602b: Einstein Probe detection of a fast X-ray transient
  17. GRB 260601B/EP260601a: Insight-HXMT detection
  18. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  19. EP260602a: SVOM/VT optical candidate
  20. GRB 260602B: Fermi GBM Final Localization
  21. GRB 260601A: GECAM-B observation of a short burst
  22. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  23. EP260530a/AT 2026nwl: KAIT optical observations
  24. GRB 260602A: Fermi GBM Final Real-time Localization
  25. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  26. EP260602a: Optical upper limits with Kinder observations
  27. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  28. EP260602a: Einstein Probe detection of a fast X-ray transient
  29. GRB 260601B/EP260601a: SVOM/VT optical observations
  30. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  31. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  32. EP260601a: Einstein Probe detection of an X-ray transient
  33. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  34. GRB 260601A: Glowbug gamma-ray detection of a short burst
  35. GRB 260531B: Glowbug gamma-ray detection
  36. GRB 260516D: VLA radio detection
  37. GRB 260601A: Fermi GBM Observation
  38. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  39. GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
  40. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  41. GRB 260601A: Fermi GBM Final Real-time Localization
  42. GRB 260531B: GECAM-B observation
  43. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  44. The EP-WXT trigger 01709266272 is likely a flaring star
  45. GRB 260531C: Fermi GBM Final Localization Correction
  46. Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
  47. GRB 260531B: Fermi GBM Final Real-time Localization
  48. GRB 260531A: MAXI/GSC detection
  49. AT 2026nuz: COLIBRÍ optical observations
  50. IPN triangulation of GRB 260527A / EP260527a
  51. GRB 260530B: SVOM/GRM detection of a possible bright short GRB
  52. GRB 260530A: Fermi GBM Final Real-time Localization
  53. GRB 260527A / EP260527a: VLA radio detection
  54. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  55. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  56. GRB 260529A: GOTO tentative optical afterglow candidate
  57. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  58. GRB 260527A/EP260527a: Insight-HXMT detection
  59. GRB 260529A: Fermi GBM Final Real-time Localization
  60. EP260526a: SVOM/VT optical upper limits
  61. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  62. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  63. EP260527a / GRB 260527A: NOT optical observations
  64. GRB 260527A/EP260527a: FTW optical and NIR observations
  65. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  66. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  67. EP260527a/GRB 260527A: EP-FXT follow-up observation
  68. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  69. GRB 260526A: GECAM-B observation
  70. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  71. EP260526a: EP-FXT follow-up observation
  72. EP260527a: SVOM/VT optical observation
  73. EP260527a: COLIBRÍ optical detection
  74. EP260527a: Einstein Probe detection of a fast X-ray transient
  75. The EP-WXT trigger 01709266172 is likely a flaring star
  76. The EP-WXT trigger 01709266147 is likely a flaring star
  77. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  78. EP260526a: LCO optical upper limits
  79. EP260526a: Einstein Probe detection of a fast X-ray transient
  80. GRB 260525A: AstroSat CZTI detection
  81. EP260526.405: COLIBRÍ optical upper limits
  82. The EP-WXT trigger 01709266106 is not a real source
  83. GRB 260526A: Fermi GBM Final Real-time Localization
  84. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  85. EP-WXT 01709266106: NOT optical upper limits
  86. GRB 260525A: Fermi GBM Final Real-time Localization
  87. GRB 260523B: AstroSat CZTI detection
  88. GRB 260523B: GECAM-B observation
  89. GRB 260523B: Fermi GBM Final Real-time Localization
  90. GRB 260523A: Fermi GBM Final Real-time Localization
  91. GRB 260522A: Fermi GBM Observation
  92. GRB 260522B: NuSTAR detection of prompt emission
  93. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  94. GRB 260522B: Fermi GBM Final Real-time Localization
  95. GRB 260522A: GOTO optical upper limit
  96. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  97. GRB 260522A: Fermi-LAT detection
  98. GRB 260519C: SVOM/GRM observation
  99. GRB 260522A: Fermi GBM Final Real-time Localization
  100. GRB 260511A: iTelescope T-75 optical detection

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