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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"

3400 results found.

  1. Fermi GRB 240604A: Global MASTER-Net observations report
  2. GRB 240603B: Swift detection of a possible burst
  3. Fermi GRB 240602A: Global MASTER-Net observations report
  4. GRB 240529A: AKO Optical Afterglow Detection
  5. Fermi trigger No 738348224: Global MASTER-Net observations report
  6. Fermi trigger No 738330463: Global MASTER-Net observations report
  7. Fermi trigger No 737996942: Global MASTER-Net observations report
  8. Fermi trigger No 737788024: Global MASTER-Net observations report
  9. GRB 240514E: A possible candidate BD-21 1074
  10. Fermi trigger No 737559855: Global MASTER-Net observations report
  11. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  12. Fermi trigger No 737523389: Global MASTER-Net observations report
  13. MAXI GRB240514.78: Global MASTER-Net observations report
  14. GRB 240514E: MAXI/GSC detection of a probable afterglow
  15. LAT GRB240513.31: Global MASTER-Net observations report
  16. Fermi trigger No 737277727: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  18. Fermi trigger No 737258655: Global MASTER-Net observations report
  19. Fermi trigger No 737247400: Global MASTER-Net observations report
  20. Fermi trigger No 737196587: Global MASTER-Net observations report
  21. Fermi trigger No 737152719: Global MASTER-Net observations report
  22. Fermi trigger No 736967879: Global MASTER-Net observations report
  23. Fermi trigger No 736564880: Global MASTER-Net observations report
  24. IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
  25. GRB 240502C: GOTO possible optical counterpart candidates
  26. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  27. Fermi GRB 240501A: Global MASTER-Net observations report
  28. Fermi trigger No 736197684: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S240422ed: EP-FXT Detection of the Potential Opitcal Electromagnetic Counterpart AT 2024hfq Reported by DECam
  30. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  31. IceCube-240424A: Upper limits from a search for additional neutrino events in IceCube
  32. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  33. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  34. GRB 240421B: Swift-BAT refined analysis
  35. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  36. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  37. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  38. IceCube Alert 240424.08: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  40. LIGO/Virgo/KAGRA S240422ed: Potential Candidates from Magellan galaxy-based search
  41. GRB 240419A: Swift-BAT refined analysis
  42. GRB 240421B: ATCA radio observations
  43. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  44. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  45. Fermi trigger No 735470374: Global MASTER-Net observations report
  46. Fermi trigger No 735280430: Global MASTER-Net observations report
  47. IceCube Alert 240419.98: Global MASTER-Net observations report
  48. GRB 240411A: GOTO early optical upper limits
  49. Fermi GRB 240417A: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  51. EP240416A: Khureltogoot optical upper limit
  52. Improved IPN triangulation of GRB 240411A
  53. EP240416A: MASTER optical observations
  54. GRB 240414A: Swift-BAT refined analysis
  55. Fermi GRB 240415A: Global MASTER-Net observations report
  56. GRB 240415A: Fermi GBM Final Real-time Localization
  57. Fermi trigger No 734754044: Global MASTER-Net observations report
  58. GRB 240414A : OHP/T193 redshift determination
  59. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  60. IceCube Alert 240412.23: Global MASTER-Net observations report
  61. EP240408a: Swift follow-up observation
  62. Fermi GRB 240405B: Global MASTER-Net observations report
  63. GRB 240403B: Glowbug gamma-ray detection
  64. GRB 240403A: Glowbug gamma-ray detection
  65. Konus-Wind detection of LXT 240402A/GRB 240402B
  66. GRB 240403A: Fermi GBM Detection
  67. GRB 240403A: BALROG localization (Fermi Trigger 733838255 / GRB 240403498)
  68. Fermi GRB 240402A: Global MASTER-Net observations report
  69. Fermi trigger No 733097506: Global MASTER-Net observations report
  70. Fermi GRB 240320A: Global MASTER-Net observations report
  71. Fermi GRB 240317B: Global MASTER-Net observations report
  72. Fermi trigger No 732299243: Global MASTER-Net observations report
  73. Fermi GRB 240314A: Global MASTER-Net observations report
  74. Fermi GRB 240310A: Global MASTER-Net observations report
  75. GRB 240309A: MAXI/GSC detection
  76. Fermi GRB 240306A: Global MASTER-Net observations report
  77. Fermi GRB 240305A: Global MASTER-Net observations report
  78. Swift J151857.0-572147: Swift-BAT refined analysis
  79. GRB 240225B: Swift-XRT afterglow detection
  80. GRB 240225B: Glowbug gamma-ray detection
  81. Fermi GRB 240229A: Global MASTER-Net observations report
  82. IceCube Alert 240229.66: Global MASTER-Net observations report
  83. GRB 240225B: Swift ToO observations
  84. Konus-Wind detection of GRB 240225B (long)
  85. GRB 240225B: VLT/X-shooter redshift
  86. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  87. GRB 240225B: 3.6m DOT observation
  88. GRB 240225B: NOT optical observations
  89. GRB 240225B: Nanshan/HMT optical afterglow detection
  90. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  91. GRB 240225B: Swift-XRT observations
  92. GRB 240225B: GOTO detection of a candidate optical afterglow
  93. Fermi trigger No 730618809: Global MASTER-Net observations report
  94. GRB 240225B: AstroSat CZTI detection
  95. GRB 240225B: Tiled Swift observations
  96. GRB 240225B: MAXI/GSC detection
  97. GRB 240216A: Glowbug gamma-ray detection
  98. GRB 240218A: Swift-BAT refined analysis
  99. GRB 240215A: Fermi GBM Observation
  100. GRB 240216A: GRBAlpha detection

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