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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"

3612 results found.

  1. GRB 240624A: Swift-BAT refined analysis
  2. Fermi trigger No 740949590: Global MASTER-Net observations report
  3. EP240617a: tentative Swift/XRT detection of the afterglow
  4. EP240618a: GRANDMA Optical Upper Limits
  5. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  6. Fermi trigger No 740430582: Global MASTER-Net observations report
  7. Fermi trigger No 740221779: Global MASTER-Net observations report
  8. Fermi GRB 240616A: Global MASTER-Net observations report
  9. Fermi trigger No 740166710: Global MASTER-Net observations report
  10. Fermi trigger No 739506569: Global MASTER-Net observations report
  11. Fermi GRB 240607A: Global MASTER-Net observations report
  12. GRB 240607A: AstroSat CZTI detection of bright long burst
  13. Fermi GRB 240604A: Global MASTER-Net observations report
  14. GRB 240603B: Swift detection of a possible burst
  15. Fermi GRB 240602A: Global MASTER-Net observations report
  16. GRB 240529A: AKO Optical Afterglow Detection
  17. Fermi trigger No 738348224: Global MASTER-Net observations report
  18. Fermi trigger No 738330463: Global MASTER-Net observations report
  19. Fermi trigger No 737996942: Global MASTER-Net observations report
  20. Fermi trigger No 737788024: Global MASTER-Net observations report
  21. GRB 240514E: A possible candidate BD-21 1074
  22. Fermi trigger No 737559855: Global MASTER-Net observations report
  23. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  24. Fermi trigger No 737523389: Global MASTER-Net observations report
  25. MAXI GRB240514.78: Global MASTER-Net observations report
  26. GRB 240514E: MAXI/GSC detection of a probable afterglow
  27. LAT GRB240513.31: Global MASTER-Net observations report
  28. Fermi trigger No 737277727: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  30. Fermi trigger No 737258655: Global MASTER-Net observations report
  31. Fermi trigger No 737247400: Global MASTER-Net observations report
  32. Fermi trigger No 737196587: Global MASTER-Net observations report
  33. Fermi trigger No 737152719: Global MASTER-Net observations report
  34. Fermi trigger No 736967879: Global MASTER-Net observations report
  35. Fermi trigger No 736564880: Global MASTER-Net observations report
  36. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  37. GRB 240502C: GOTO possible optical counterpart candidates
  38. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  39. Fermi GRB 240501A: Global MASTER-Net observations report
  40. Fermi trigger No 736197684: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  42. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  43. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  44. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  45. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  46. GRB 240421B: Swift-BAT refined analysis
  47. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  48. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  49. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  50. IceCube Alert 240424.08: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  52. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  53. GRB 240419A: Swift-BAT refined analysis
  54. GRB 240421B: ATCA radio observations
  55. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  56. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  57. Fermi trigger No 735470374: Global MASTER-Net observations report
  58. Fermi trigger No 735280430: Global MASTER-Net observations report
  59. IceCube Alert 240419.98: Global MASTER-Net observations report
  60. GRB 240411A: GOTO early optical upper limits
  61. Fermi GRB 240417A: Global MASTER-Net observations report
  62. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  63. EP240416A: Khureltogoot optical upper limit
  64. Improved IPN triangulation of GRB 240411A
  65. EP240416A: MASTER optical observations
  66. GRB 240414A: Swift-BAT refined analysis
  67. Fermi GRB 240415A: Global MASTER-Net observations report
  68. GRB 240415A: Fermi GBM Final Real-time Localization
  69. Fermi trigger No 734754044: Global MASTER-Net observations report
  70. GRB 240414A : OHP/T193 redshift determination
  71. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  72. IceCube Alert 240412.23: Global MASTER-Net observations report
  73. EP240408a: Swift follow-up observation
  74. Fermi GRB 240405B: Global MASTER-Net observations report
  75. GRB 240403B: Glowbug gamma-ray detection
  76. GRB 240403A: Glowbug gamma-ray detection
  77. Konus-Wind detection of LXT 240402A/GRB 240402B
  78. GRB 240403A: Fermi GBM Detection
  79. GRB 240403A: BALROG localization (Fermi Trigger 733838255 / GRB 240403498)
  80. Fermi GRB 240402A: Global MASTER-Net observations report
  81. Fermi trigger No 733097506: Global MASTER-Net observations report
  82. Fermi GRB 240320A: Global MASTER-Net observations report
  83. Fermi GRB 240317B: Global MASTER-Net observations report
  84. Fermi trigger No 732299243: Global MASTER-Net observations report
  85. Fermi GRB 240314A: Global MASTER-Net observations report
  86. Fermi GRB 240310A: Global MASTER-Net observations report
  87. GRB 240309A: MAXI/GSC detection
  88. Fermi GRB 240306A: Global MASTER-Net observations report
  89. Fermi GRB 240305A: Global MASTER-Net observations report
  90. Swift J151857.0-572147: Swift-BAT refined analysis
  91. GRB 240225B: Swift-XRT afterglow detection
  92. GRB 240225B: Glowbug gamma-ray detection
  93. Fermi GRB 240229A: Global MASTER-Net observations report
  94. IceCube Alert 240229.66: Global MASTER-Net observations report
  95. GRB 240225B: Swift ToO observations
  96. Konus-Wind detection of GRB 240225B (long)
  97. GRB 240225B: VLT/X-shooter redshift
  98. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  99. GRB 240225B: 3.6m DOT observation
  100. GRB 240225B: NOT optical observations

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