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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"

32501 results found.

  1. EP240625a: NOT optical counterpart candidate
  2. EP240625a: EP-FXT detection of the X-ray emission
  3. GRB 240624B: GRBAlpha detection
  4. GRB240624A: Fermi GBM Observation
  5. Swift GRB 240624A: Global MASTER-Net observations report
  6. GRB240615A: Gemini-North observations of the BAT and XRT positions
  7. Fermi GRB 240624A: Global MASTER-Net observations report
  8. GRB240615A: Gemini-North observations of the BAT and XRT positions
  9. GRB 240619A: detection of a radio counterpart with AMI-LA
  10. EP240618a: NOT further optical observations
  11. GRB 240619A: J-band detection with WINTER (duplicate submission of GCN 36739)
  12. GRB 240619A: J-band detection with WINTER
  13. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  14. EP240618a: NOT optical counterpart candidate
  15. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  16. GRB 240529A: JinShan optical observations
  17. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  18. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  19. EP240618a: GSP optical upper limit
  20. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  24. IPN triangulation of GRB 240615A (short)
  25. X-ray transient EP240618a: Fermi/GBM non-detection
  26. GRB 240619A: GRBAlpha detection
  27. EP240618a: Swift/XRT upper limit
  28. EP240617a: tentative Swift/XRT detection of the afterglow
  29. GRB 240619A: Swift-XRT probable afterglow detection
  30. GRB 240619A: Swift ToO observations
  31. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  32. GRB 240619C: NuSTAR automated detection of the GRB
  33. GRB 240619A: Fermi GBM Observation
  34. Fermi GBM Sub-Threshold Detection of GRB 240619C
  35. GRB 240619A: GOTO candidate optical afterglow
  36. EP240618a: Abastumani optical observationsEP240618a
  37. GRB 240615A: NOT optical observations
  38. EP240618a: GRANDMA Optical Upper Limits
  39. EP240618a: TRT optical upper limit
  40. Fermi GRB 240619A: Global MASTER-Net observations report
  41. EP240617a: STEP/T80S optical limits
  42. GRB 240615A: possible transient detection from Wendelstein observations
  43. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  44. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  45. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  46. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  47. GRB240615A: 1.3m DFOT optical upper limit
  48. EP240617a is likely a GRB event
  49. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  50. GRB 240615A: J-band upper limits from WINTER
  51. GRB 240615A: Fermi GBM Observation
  52. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  53. GRB 240615A: GECAM detection
  54. X-ray transient EP240414a: Chandra late time observation
  55. GRB 240615A: FLWO-1.2m optical upper limits
  56. Fermi GRB 240616A: Global MASTER-Net observations report
  57. Konus-Wind detection of GRB 240615A (short/hard)
  58. GRB 240615A: GOTO optical upper limits
  59. GRB 240615A: Swift ToO observations
  60. GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
  61. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  63. GRB 240603A: VZLUSAT-2 detection
  64. GRB 240612A: GRBAlpha detection
  65. Fermi GRB 240612B: Global MASTER-Net observations report
  66. Fermi GRB 240612A: Global MASTER-Net observations report
  67. GRB 240607A: GECAM detection of a bright long burst
  68. Fermi GRB 240611A: Global MASTER-Net observations report
  69. Konus-Wind detection of GRB 240607A
  70. EXO 0748-676: Swift-BAT refined analysis
  71. GRB 240529A: LBT optical detection and late temporal decay
  72. GRB 240529A : MITSuME Akeno optical afterglow detection
  73. Fermi GRB 240610A: Global MASTER-Net observations report
  74. IPN triangulation of GRB 240607A
  75. Fermi GRB 240608A: Global MASTER-Net observations report
  76. Konus-Wind detection of GRB 240606B
  77. Fermi GRB 240607A: Global MASTER-Net observations report
  78. GRB 240529A: NOEMA detection
  79. GRB 240607A: Fermi GBM Observation
  80. GRB 240606B: Fermi GBM Observation
  81. Swift Trigger 1235109: consistent with noise and not astrophysical
  82. GRB 240607A: AstroSat CZTI detection of bright long burst
  83. GRB 240607A: Fermi GBM detection of a very bright burst
  84. GRB 240529A: radio detection with AMI-LA
  85. GRB 240606B: GECAM-B detection a long burst
  86. GRB 240606B: Swift ToO observations
  87. GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
  88. Konus-Wind detection of GRB 240603A
  89. Fermi GRB 240604A: Global MASTER-Net observations report
  90. IPN triangulation of GRB 240531A (short)
  91. Fermi GRB 240605A: Global MASTER-Net observations report
  92. Fermi GRB 240605C: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  94. IPN triangulation of GRB 240603A
  95. GRB 240529A: SAO RAS optical observations
  96. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  97. Fermi GRB 240603C: Global MASTER-Net observations report
  98. Swift Trigger 1232465: consistent with noise
  99. GRB 240529A: MASTER prompt OT detection
  100. GRB 240529A: continued SAO RAS optical observations

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