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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

32492 results found.

  1. GRB 260604C: Correction to GCN 44828
  2. GRB 260604C: Kilonova-Catcher optical afterglow detection
  3. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  4. GRB 260604C: Jinshan optical observations
  5. GRB 260604C: Fermi GBM Observation
  6. EP260602d: J-band upper limit with WINTER
  7. EP260602b: J-band upper limit with WINTER
  8. GRB 260604C: LAST detection of optical counterpart candidate
  9. Fermi GRB 260604C: Global MASTER-Net observations report
  10. Fermi GRB 260604C: Global MASTER-Net observations report
  11. GRB 260604C: SVOM detection of a long burst
  12. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  13. GRB 260603A: NOT optical observations
  14. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  15. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  16. EP260602a: EP-FXT follow-up observation
  17. EP260603a: Global MASTER-Net observations report
  18. EP260602d: Optical Upper limits with kinder observations
  19. EP260602b: Liverpool Telescope observations
  20. EP260602a: Liverpool Telescope optical upper limits
  21. EP260602b: Liverpool Telescope and LCO observations
  22. EP260602a: GTC and Liverpool Telescope optical observations
  23. Konus-Wind detection of GRB 260601B/EP260601a
  24. GRB 260603A: EP-FXT follow-up observation
  25. EP260601a/GRB 260601B: EP-FXT follow-up observation
  26. GRB 260601B / EP260601a: Mondy optical upper limit
  27. EP260602b: EP-FXT follow-up observation
  28. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  29. GRB 260603A: Kilonova-Catcher optical upper limit
  30. GRB 260603A: SVOM/VT optical observations
  31. EP260602a: NOT NIR J-band observations
  32. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  33. EP260602d: Einstein Probe detection of a fast X-ray transient
  34. EP260602a: SVOM/VT optical magnitudes correction
  35. GRB 260601A: SVOM/GRM observation of a short burst
  36. EP260602c: Einstein Probe detection of a fast X-ray transient
  37. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  38. EP260602a: COLIBRÍ optical observations
  39. GRB260601B/EP260601a: NOT near-infrared observations
  40. EP260602b: Einstein Probe detection of a fast X-ray transient
  41. GRB 260601B/EP260601a: Insight-HXMT detection
  42. Fermi GRB 260602B: Global MASTER-Net observations report
  43. Fermi GRB 260602B: Global MASTER-Net observations report
  44. EP260602a: SVOM/VT optical candidate
  45. GRB 260601A: GECAM-B observation of a short burst
  46. GRB 260601B/EP260601a: J-band upper limit with WINTER
  47. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  48. EP260530a/AT 2026nwl: KAIT optical observations
  49. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  50. EP260602a: Optical upper limits with Kinder observations
  51. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  52. GRB 260601B/EP260601a: SVOM/VT optical observations
  53. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  54. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  55. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  56. GRB 260601A: Glowbug gamma-ray detection of a short burst
  57. GRB 260531B: Glowbug gamma-ray detection
  58. GRB 260516D: VLA radio detection
  59. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  60. Fermi GRB 260601A: Global MASTER-Net observations report
  61. GRB 260531B: GECAM-B observation
  62. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  63. AT 2026nuz: COLIBRÍ optical observations
  64. IPN triangulation of GRB 260527A / EP260527a
  65. EP260527a/GRB 260527A: further FTW optical and NIR observations
  66. GRB 260527A / EP260527a: VLA radio detection
  67. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  68. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  69. GRB 260529A: GOTO tentative optical afterglow candidate
  70. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  71. GRB 260527A/EP260527a: Insight-HXMT detection
  72. Fermi GRB 260529A: Global MASTER-Net observations report
  73. EP260526a: SVOM/VT optical upper limits
  74. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  75. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  76. EP260527a / GRB 260527A: NOT optical observations
  77. GRB 260527A/EP260527a: FTW optical and NIR observations
  78. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  79. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  80. EP260527a/GRB 260527A: EP-FXT follow-up observation
  81. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  82. GRB 260526A: GECAM-B observation
  83. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  84. EP260526a: EP-FXT follow-up observation
  85. EP260527a: SVOM/VT optical observation
  86. EP260527a: COLIBRÍ optical detection
  87. EP260526a: LCO optical upper limits
  88. EP260526a: Einstein Probe detection of a fast X-ray transient
  89. GRB 260525A: AstroSat CZTI detection
  90. The EP-WXT trigger 01709266106 is not a real source
  91. Fermi GRB 260526A: Global MASTER-Net observations report
  92. Fermi GRB 260525A: Global MASTER-Net observations report
  93. GRB 260523B: AstroSat CZTI detection
  94. GRB 260523B: GECAM-B observation
  95. Fermi GRB 260523A: Global MASTER-Net observations report
  96. GRB 260522A: Fermi GBM Observation
  97. GRB 260522B: NuSTAR detection of prompt emission
  98. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  99. GRB 260522A: GOTO optical upper limit
  100. Fermi GRB 260522A: Global MASTER-Net observations report

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