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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"

4252 results found.

  1. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  2. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  3. Fermi trigger No 741356809: Global MASTER-Net observations report
  4. Fermi GRB 240629A: Global MASTER-Net observations report
  5. Fermi Gamma-ray Burst Monitor trigger 741362867/240629589 is not a GRB
  6. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  7. GRB 240629A: Fermi GBM Final Real-time Localization
  8. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  9. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  10. Konus-Wind detection of GRB 240619A
  11. Fermi trigger No 740949590: Global MASTER-Net observations report
  12. GRB 240529A: JinShan optical observations
  13. Fermi trigger No 740474239: Global MASTER-Net observations report
  14. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  15. Fermi trigger No 740430582: Global MASTER-Net observations report
  16. Fermi GRB 240616A: Global MASTER-Net observations report
  17. Fermi trigger No 740166710: Global MASTER-Net observations report
  18. GRB 240612A: GRBAlpha detection
  19. Fermi GRB 240611A: Global MASTER-Net observations report
  20. GRB 240529A : MITSuME Akeno optical afterglow detection
  21. Fermi GRB 240604A: Global MASTER-Net observations report
  22. Fermi GRB 240605A: Global MASTER-Net observations report
  23. GRB 240529A: MASTER prompt OT detection
  24. Fermi GRB 240602A: Global MASTER-Net observations report
  25. The EP-WXT source triggered on June 1st is likely a flaring star
  26. GRB 240529A: AKO Optical Afterglow Follow-Up Observations
  27. GRB 240529A: optical photometry from Konkoly
  28. GRB 240529A: GROWTH-India optical follow-up
  29. GRB 240529A: AKO Optical Afterglow Detection
  30. GRB 240529A: J-band detections with WINTER
  31. GRB 240529A: Skynet Optical Observations
  32. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  33. GRB240529A: BOOTES-6/DPRT optical detection
  34. GRB 240529A: NOT optical observations
  35. GRB 240529A: AstroSat CZTI detection
  36. Swift GRB240529.12: Global MASTER-Net observations report
  37. Fermi GRB 240527A: Global MASTER-Net observations report
  38. LAT GRB240527.59: Global MASTER-Net observations report
  39. Fermi trigger No 738348224: Global MASTER-Net observations report
  40. Fermi trigger No 738330463: Global MASTER-Net observations report
  41. Fermi trigger No 737996942: Global MASTER-Net observations report
  42. GRB 240516B: AstroSat CZTI detection
  43. GRB 240516A: Swift-BAT refined analysis
  44. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  45. GRB 240516A: GOTO optical upper limit
  46. GRB 240516A: Swift detection of a burst
  47. Fermi GRB 240514B: Global MASTER-Net observations report
  48. LAT GRB240513.31: Global MASTER-Net observations report
  49. Fermi GRB 240513B: Global MASTER-Net observations report
  50. Fermi trigger No 737277727: Global MASTER-Net observations report
  51. Fermi trigger No 737247400: Global MASTER-Net observations report
  52. Fermi trigger No 737168073: Global MASTER-Net observations report
  53. Fermi trigger No 737173236: Global MASTER-Net observations report
  54. Fermi trigger No 737105243: Global MASTER-Net observations report
  55. Fermi trigger No 737152719: Global MASTER-Net observations report
  56. Fermi trigger No 737111207: Global MASTER-Net observations report
  57. EP240506a: CrAO ZTSH optical upper limit
  58. EP240506a: Optical upper limit with Kinder observations
  59. IPN triangulation of GRB 240504A
  60. GRB 240502A: 1.3m DFOT Optical upper limit
  61. GRB 240502C: Zeiss-1000 at Koshka observatory observations of GOTO optical counterpart candidates
  62. GRB 240415A 1.3m DFOT Optical upper limit
  63. Fermi GRB 240502B: Global MASTER-Net observations report
  64. Fermi GRB 240502A: Global MASTER-Net observations report
  65. Fermi trigger No 736197684: Global MASTER-Net observations report
  66. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  67. GRB 240429A: Fermi GBM Final Real-time Localization
  68. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  70. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  71. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  72. LIGO/Virgo/KAGRA S240422ed: EP-FXT detection of a candidate counterpart EP240426a
  73. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  74. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  75. LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
  76. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  77. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  78. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  79. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  80. Fermi trigger No 735470374: Global MASTER-Net observations report
  81. Fermi GRB 240421B: Global MASTER-Net observations report
  82. GRB 240421B: Fermi GBM Observation
  83. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  84. Fermi trigger No 735280430: Global MASTER-Net observations report
  85. GRB 240411A: GOTO early optical upper limits
  86. Fermi GRB 240417A: Global MASTER-Net observations report
  87. Fermi GRB 240415A: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  89. IPN triangulation of GRB 240410A
  90. IPN triangulation of GRB 240411A
  91. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  92. Fermi GRB 240407A: Global MASTER-Net observations report
  93. GRB 240402C: Glowbug gamma-ray detection
  94. GRB 240402C: GRBAlpha detection
  95. Fermi GRB 240402A: Global MASTER-Net observations report
  96. GRB 240329A: Glowbug gamma-ray detection
  97. GRB 240329A: AstroSat CZTI detection
  98. GRB 240329A: GRBAlpha detection
  99. Fermi trigger No 733366352: Global MASTER-Net observations report
  100. Fermi GRB 240329A: Global MASTER-Net observations report

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