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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"
  1. GRB 240627A: NuSTAR Detection of the long GRB
  2. GRB 240615A: SAI CMO J- band observations
  3. GRB 240627A: AstroSat CZTI detection
  4. Fermi trigger No 741211696: Global MASTER-Net observations report
  5. EP240626a: Montarrenti Observatory optical upper limit
  6. EP240626a: KAIT optical upper limit
  7. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  8. EP240625a: GRANDMA Optical Upper Limits
  9. EP240626a: EP-FXT detection of the X-ray emission
  10. GRB 240624A: Swift-BAT refined analysis
  11. Konus-Wind detection of GRB 240619A
  12. EP240626a: BOOTES-7 optical upper limit
  13. EP240626a: EP-WXT detection of a fast X-ray transient
  14. Fermi GRB 240625B: Global MASTER-Net observations report
  15. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  16. GRB 240625B: Fermi GBM Final Real-time Localization
  17. GRB 240625A: Fermi GBM Observation
  18. EP240625a: NOT optical counterpart candidate
  19. EP240625a: EP-FXT detection of the X-ray emission
  20. GRB 240624B: GRBAlpha detection
  21. GRB 240625A: Fermi GBM Final Real-time Localization
  22. EP240625a: EP-WXT detection of a fast X-ray transient
  23. GRB240624A: Fermi GBM Observation
  24. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  27. Swift GRB 240624A: Global MASTER-Net observations report
  28. GRB240615A: Gemini-North observations of the BAT and XRT positions
  29. Fermi GRB 240624A: Global MASTER-Net observations report
  30. GRB 240624B: Fermi GBM Final Real-time Localization
  31. Fermi trigger No 740949590: Global MASTER-Net observations report
  32. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate
  33. GRB240615A: Gemini-North observations of the BAT and XRT positions
  34. GRB 240624A: Fermi GBM Final Real-time Localization
  35. GRB 240619A: detection of a radio counterpart with AMI-LA
  36. GRB 240624A: Swift detection of a burst
  37. LIGO/Virgo/KAGRA S240623dg: Retraction of GW compact binary merger candidate
  38. EP240618a: NOT further optical observations
  39. GRB 240619A: J-band detection with WINTER (duplicate submission of GCN 36739)
  40. GRB 240619A: J-band detection with WINTER
  41. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  42. Fermi trigger No 740744838: Global MASTER-Net observations report
  43. EP240618a: NOT optical counterpart candidate
  44. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  45. GRB 240529A: JinShan optical observations
  46. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  47. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  48. EP240618a: GSP optical upper limit
  49. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  53. IPN triangulation of GRB 240615A (short)
  54. X-ray transient EP240618a: Fermi/GBM non-detection
  55. GRB 240619A: GRBAlpha detection
  56. EP240618a: Swift/XRT upper limit
  57. EP240617a: tentative Swift/XRT detection of the afterglow
  58. GRB 240619A: Swift-XRT probable afterglow detection
  59. GRB 240619A: Swift ToO observations
  60. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  61. GRB 240619C: NuSTAR automated detection of the GRB
  62. GRB 240619A: Fermi GBM Observation
  63. Fermi GBM Sub-Threshold Detection of GRB 240619C
  64. GRB 240619A: GOTO candidate optical afterglow
  65. EP240618a: Abastumani optical observationsEP240618a
  66. GRB 240615A: NOT optical observations
  67. EP240618a: GRANDMA Optical Upper Limits
  68. GRB 240619C: AstroSat CZTI detection
  69. EP240618a: TRT optical upper limit
  70. Fermi trigger No 740474239: Global MASTER-Net observations report
  71. Fermi GRB 240619A: Global MASTER-Net observations report
  72. EP240617a: STEP/T80S optical limits
  73. GRB 240615A: possible transient detection from Wendelstein observations
  74. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  75. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  76. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  77. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  78. EP240618a: BOOTES-6/DPRT optical upper limit
  79. Fermi Gamma-ray Burst Monitor trigger 740474239/240619304 is not a GRB
  80. GRB 240619B: Fermi GBM Final Real-time Localization
  81. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  82. Fermi trigger No 740430582: Global MASTER-Net observations report
  83. GRB240615A: 1.3m DFOT optical upper limit
  84. GRB 240619A: BALROG localization (Fermi Trigger 740461416 / GRB 240619155)
  85. GRB 240619A: Fermi GBM Final Real-time Localization
  86. EP240617a: BOOTES-6/DPRT optical upper limit
  87. EP240617a is likely a GRB event
  88. EP240617a: EP-WXT detection of a fast X-ray transient
  89. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  90. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  92. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  93. GRB 240615A: J-band upper limits from WINTER
  94. GRB 240615A: Fermi GBM Observation
  95. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  96. GRB 240615A: Swift-XRT observations
  97. GRB 240615A: GECAM detection
  98. X-ray transient EP240414a: Chandra late time observation
  99. GRB 240615A: FLWO-1.2m optical upper limits
  100. Fermi trigger No 740221779: Global MASTER-Net observations report

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