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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"

4047 results found.

  1. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  2. GRB 240629A: Fermi GBM Final Real-time Localization
  3. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  4. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  5. Konus-Wind detection of GRB 240619A
  6. Fermi trigger No 740949590: Global MASTER-Net observations report
  7. GRB 240529A: JinShan optical observations
  8. Fermi trigger No 740474239: Global MASTER-Net observations report
  9. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  10. Fermi trigger No 740430582: Global MASTER-Net observations report
  11. Fermi GRB 240616A: Global MASTER-Net observations report
  12. Fermi trigger No 740166710: Global MASTER-Net observations report
  13. GRB 240612A: GRBAlpha detection
  14. Fermi GRB 240611A: Global MASTER-Net observations report
  15. GRB 240529A : MITSuME Akeno optical afterglow detection
  16. Fermi GRB 240604A: Global MASTER-Net observations report
  17. Fermi GRB 240605A: Global MASTER-Net observations report
  18. GRB 240529A: MASTER prompt OT detection
  19. Fermi GRB 240602A: Global MASTER-Net observations report
  20. The EP-WXT source triggered on June 1st is likely a flaring star
  21. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  22. GRB 240529A: optical photometry from Konkoly
  23. GRB 240529A: GROWTH-India optical follow-up
  24. GRB 240529A: AKO Optical Afterglow Detection
  25. GRB 240529A: J-band detections with WINTER
  26. GRB 240529A: Skynet Optical Observations
  27. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  28. GRB240529A: BOOTES-6/DPRT optical detection
  29. GRB 240529A: NOT optical observations
  30. GRB 240529A: AstroSat CZTI detection
  31. Swift GRB240529.12: Global MASTER-Net observations report
  32. Fermi GRB 240527A: Global MASTER-Net observations report
  33. LAT GRB240527.59: Global MASTER-Net observations report
  34. Fermi trigger No 738348224: Global MASTER-Net observations report
  35. Fermi trigger No 738330463: Global MASTER-Net observations report
  36. Fermi trigger No 737996942: Global MASTER-Net observations report
  37. GRB 240516B: AstroSat CZTI detection
  38. GRB 240516A: Swift-BAT refined analysis
  39. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  40. GRB 240516A: GOTO optical upper limit
  41. GRB 240516A: Swift detection of a burst
  42. Fermi GRB 240514B: Global MASTER-Net observations report
  43. LAT GRB240513.31: Global MASTER-Net observations report
  44. Fermi GRB 240513B: Global MASTER-Net observations report
  45. Fermi trigger No 737277727: Global MASTER-Net observations report
  46. Fermi trigger No 737247400: Global MASTER-Net observations report
  47. Fermi trigger No 737168073: Global MASTER-Net observations report
  48. Fermi trigger No 737173236: Global MASTER-Net observations report
  49. Fermi trigger No 737105243: Global MASTER-Net observations report
  50. Fermi trigger No 737152719: Global MASTER-Net observations report
  51. Fermi trigger No 737111207: Global MASTER-Net observations report
  52. EP240506a: CrAO ZTSH optical upper limit
  53. EP240506a: Optical upper limit with Kinder observations
  54. IPN triangulation of GRB 240504A
  55. GRB 240502A: 1.3m DFOT Optical upper limit
  56. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  57. GRB 240415A 1.3m DFOT Optical upper limit
  58. Fermi GRB 240502B: Global MASTER-Net observations report
  59. Fermi GRB 240502A: Global MASTER-Net observations report
  60. Fermi trigger No 736197684: Global MASTER-Net observations report
  61. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  62. GRB 240429A: Fermi GBM Final Real-time Localization
  63. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  65. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  66. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  67. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  68. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  69. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  70. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  71. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  72. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  73. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  74. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  75. Fermi trigger No 735470374: Global MASTER-Net observations report
  76. Fermi GRB 240421B: Global MASTER-Net observations report
  77. GRB 240421B: Fermi GBM Observation
  78. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  79. Fermi trigger No 735280430: Global MASTER-Net observations report
  80. GRB 240411A: GOTO early optical upper limits
  81. Fermi GRB 240417A: Global MASTER-Net observations report
  82. Fermi GRB 240415A: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  84. IPN triangulation of GRB 240410A
  85. IPN triangulation of GRB 240411A
  86. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  87. Fermi GRB 240407A: Global MASTER-Net observations report
  88. GRB 240402C: Glowbug gamma-ray detection
  89. GRB 240402C: GRBAlpha detection
  90. Fermi GRB 240402A: Global MASTER-Net observations report
  91. GRB 240329A: Glowbug gamma-ray detection
  92. GRB 240329A: AstroSat CZTI detection
  93. GRB 240329A: GRBAlpha detection
  94. Fermi trigger No 733366352: Global MASTER-Net observations report
  95. Fermi GRB 240329A: Global MASTER-Net observations report
  96. GRB 240329A: BALROG localization (Fermi Trigger 733441392 / GRB 240329905)
  97. GRB 240329A: Fermi GBM Final Real-time Localization
  98. Fermi GRB 240328B: Global MASTER-Net observations report
  99. Fermi GRB 240328A: Global MASTER-Net observations report
  100. GRB 240320A: Glowbug gamma-ray detection

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