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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"

3724 results found.

  1. GRB 240720A: Swift-BAT refined analysis
  2. Fermi trigger No 743219692: Global MASTER-Net observations report
  3. GRB 240721A: Fermi GBM Final Real-time Localization
  4. Fermi GRB 240720A: Global MASTER-Net observations report
  5. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  6. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  7. Fermi trigger No 742405878: Global MASTER-Net observations report
  8. Fermi trigger No 742317942: Global MASTER-Net observations report
  9. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  10. Fermi trigger No 741448122: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  12. Fermi trigger No 741356809: Global MASTER-Net observations report
  13. GRB 240624A: Swift-BAT refined analysis
  14. Fermi trigger No 740949590: Global MASTER-Net observations report
  15. EP240617a: tentative Swift/XRT detection of the afterglow
  16. EP240618a: GRANDMA Optical Upper Limits
  17. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  18. Fermi trigger No 740430582: Global MASTER-Net observations report
  19. Fermi trigger No 740221779: Global MASTER-Net observations report
  20. Fermi GRB 240616A: Global MASTER-Net observations report
  21. Fermi trigger No 740166710: Global MASTER-Net observations report
  22. Fermi trigger No 739506569: Global MASTER-Net observations report
  23. Fermi GRB 240607A: Global MASTER-Net observations report
  24. GRB 240607A: AstroSat CZTI detection of bright long burst
  25. Fermi GRB 240604A: Global MASTER-Net observations report
  26. GRB 240603B: Swift detection of a possible burst
  27. Fermi GRB 240602A: Global MASTER-Net observations report
  28. GRB 240529A: AKO Optical Afterglow Detection
  29. Fermi trigger No 738348224: Global MASTER-Net observations report
  30. Fermi trigger No 738330463: Global MASTER-Net observations report
  31. Fermi trigger No 737996942: Global MASTER-Net observations report
  32. Fermi trigger No 737788024: Global MASTER-Net observations report
  33. GRB 240514E: A possible candidate BD-21 1074
  34. Fermi trigger No 737559855: Global MASTER-Net observations report
  35. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  36. Fermi trigger No 737523389: Global MASTER-Net observations report
  37. MAXI GRB240514.78: Global MASTER-Net observations report
  38. GRB 240514E: MAXI/GSC detection of a probable afterglow
  39. LAT GRB240513.31: Global MASTER-Net observations report
  40. Fermi trigger No 737277727: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  42. Fermi trigger No 737258655: Global MASTER-Net observations report
  43. Fermi trigger No 737247400: Global MASTER-Net observations report
  44. Fermi trigger No 737196587: Global MASTER-Net observations report
  45. Fermi trigger No 737152719: Global MASTER-Net observations report
  46. Fermi trigger No 736967879: Global MASTER-Net observations report
  47. Fermi trigger No 736564880: Global MASTER-Net observations report
  48. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  49. GRB 240502C: GOTO possible optical counterpart candidates
  50. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  51. Fermi GRB 240501A: Global MASTER-Net observations report
  52. Fermi trigger No 736197684: Global MASTER-Net observations report
  53. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  54. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  55. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  56. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  57. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  58. GRB 240421B: Swift-BAT refined analysis
  59. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  60. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  61. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  62. IceCube Alert 240424.08: Global MASTER-Net observations report
  63. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  64. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  65. GRB 240419A: Swift-BAT refined analysis
  66. GRB 240421B: ATCA radio observations
  67. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  68. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  69. Fermi trigger No 735470374: Global MASTER-Net observations report
  70. Fermi trigger No 735280430: Global MASTER-Net observations report
  71. IceCube Alert 240419.98: Global MASTER-Net observations report
  72. GRB 240411A: GOTO early optical upper limits
  73. Fermi GRB 240417A: Global MASTER-Net observations report
  74. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  75. EP240416A: Khureltogoot optical upper limit
  76. Improved IPN triangulation of GRB 240411A
  77. EP240416A: MASTER optical observations
  78. GRB 240414A: Swift-BAT refined analysis
  79. Fermi GRB 240415A: Global MASTER-Net observations report
  80. GRB 240415A: Fermi GBM Final Real-time Localization
  81. Fermi trigger No 734754044: Global MASTER-Net observations report
  82. GRB 240414A : OHP/T193 redshift determination
  83. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  84. IceCube Alert 240412.23: Global MASTER-Net observations report
  85. EP240408a: Swift follow-up observation
  86. Fermi GRB 240405B: Global MASTER-Net observations report
  87. GRB 240403B: Glowbug gamma-ray detection
  88. GRB 240403A: Glowbug gamma-ray detection
  89. Konus-Wind detection of LXT 240402A/GRB 240402B
  90. GRB 240403A: Fermi GBM Detection
  91. GRB 240403A: BALROG localization (Fermi Trigger 733838255 / GRB 240403498)
  92. Fermi GRB 240402A: Global MASTER-Net observations report
  93. Fermi trigger No 733097506: Global MASTER-Net observations report
  94. Fermi GRB 240320A: Global MASTER-Net observations report
  95. Fermi GRB 240317B: Global MASTER-Net observations report
  96. Fermi trigger No 732299243: Global MASTER-Net observations report
  97. Fermi GRB 240314A: Global MASTER-Net observations report
  98. Fermi GRB 240310A: Global MASTER-Net observations report
  99. GRB 240309A: MAXI/GSC detection
  100. Fermi GRB 240306A: Global MASTER-Net observations report

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