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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28247 results found.

  1. GRB 250509A: Swift-XRT refined Analysis
  2. GRB 250510A: SVOM possible detection of a burst
  3. GRB 250507A: J-band observations with WINTER
  4. GRB 250509A: Enhanced Swift-XRT position
  5. GRB 250509A: Swift detection of a burst
  6. GRB 250506A: NOT optical upper limits
  7. EP250508a: Liverpool Telescope optical upper limits
  8. EP250508a: KAIT optical upper limit
  9. GRB 250507A: KAIT optical upper limit
  10. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  11. GRB 250505B: SVOM/GRM observation of a short burst
  12. GRB 250502A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  13. EP250508a: REM optical/NIR observations
  14. GRB 250506A: Swift-XRT afterglow detection
  15. EP250508a: COLIBRÍ Optical Limit
  16. EP250508a: Einstein Probe detection of an X-ray transient
  17. GRB 250507A: Swift-XRT refined Analysis
  18. IceCube-250506A: Upper limits from a search for additional neutrino events in IceCube
  19. GRB 250506A: Swift/UVOT Upper Limits
  20. GRB 250507A: follow-up observation with EP-FXT
  21. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  22. GRB 250507A: REM optical/NIR observations
  23. GRB 250507A: SVOM/VT optical upper limit
  24. GRB 250506A: Swift-XRT observations
  25. Fermi-LAT Gamma-ray Observations of IceCube-250506A
  26. GRB 250507A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  27. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  28. GRB 250507A: SVOM detection of a long burst
  29. GRB 250506A: Mephisto optical upper limits
  30. GRB 250504A: EIRSAT-1 GMOD Detection
  31. GRB 250502A: Bassano Bresciano Observatory upper limit
  32. GRB 250506A: Xinglong 2.16m optical upper limit
  33. SVOM/sb25050601: EP-FXT observations
  34. GRB 250506A: SVOM improved position and MXT detection of a fading X-ray afterglow
  35. GRB 250506A: REM optical/NIR upper limits
  36. GRB 250506A: Fermi GBM Observation
  37. GRB 250506A: Swift XRT observations and possible counterpart detection
  38. GRB 250506A: TRT optical observations
  39. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  40. GRB 250506A: SVOM detection of a burst
  41. GRB 250504A: Swift-BAT refined analysis
  42. GRB 250430A: Swift-BAT refined analysis
  43. GRB 250504A: Swift-XRT refined Analysis
  44. GRB 250504A: VLT/X-shooter upper limits
  45. GRB 250504A: REM optical/NIR observations
  46. GRB 250502A: REM optical/NIR observations
  47. GRB 250504A: MeerLICHT optical afterglow detection
  48. GRB 250504A: Fermi GBM Observation
  49. GRB 250504A: Enhanced Swift-XRT position
  50. Fermi GRB 250504A: Global MASTER-Net observations report
  51. GRB 250504A: Swift detection of a burst
  52. GRB 250502A: Swift/UVOT Follow up
  53. GRB 250502A: Mondy and Tien-Shan Optical Observations
  54. GRB 250502A: KAIT optical observations
  55. GRB 250502A: Montarrenti Observatory optical detection
  56. GRB 250502A: Swift-XRT afterglow detection
  57. GRB 250502A: NOT optical observations
  58. GRB 250502B: AstroSat CZTI detection
  59. GRB 250502A: AKO Optical Afterglow Detection
  60. GRB 250502A: LCO optical counterpart detection
  61. GRB 250502A: Redshift from OSIRIS+/GTC z = 2.163
  62. GRB 250407A: VZLUSAT-2 detection
  63. Fermi-LAT Gamma-ray Observations of IceCube-250429A
  64. GRB 250502B: DDOTI Optical Observations
  65. GRB 250430A: Swift-XRT refined Analysis
  66. GRB 250502A: Early optical counterpart detection by LCO.
  67. GRB 250430A: Swift/UVOT Detection
  68. GRB 250502A: TRT optical afterglow confirmation
  69. GRB 250430A: Enhanced Swift-XRT position
  70. GRB 250502A: SVOM/COLIBRÍ (FM-GFT) Detection of a Bright Optical Counterpart Candidate
  71. GRB 250502A: SVOM detection of a burst
  72. GRB 250430A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  73. GRB 250430A: KAIT optical observations
  74. GRB 250430A / EP250430a: J-band upper limits with WINTER
  75. GRB 250430A: NUTTelA-TAO Early Measurements
  76. GRB 250430A: DDOTI Optical Observations
  77. GRB 250430A: Leavitt Observatory optical upper limit
  78. GRB 250430A: Bassano Bresciano Observatory upper limit
  79. GRB 250430A : MITSuME Akeno optical upper limits
  80. SVOM/sb25043004: EP-FXT observations
  81. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  82. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  83. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  84. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  85. GRB 250430A: AKO Optical Afterglow Detection
  86. GRB 250430A: Kanata optical upper limit
  87. EP 250427A: Optical counterpart detection by LCO.
  88. GRB 250430A: Swift detection of a burst with optical counterpart
  89. EP250427a/GRB250427A: HCT optical follow-up
  90. SVOM/sb25043004: SVOM detection of a X-ray transient
  91. EP250428b: GROWTH-India telescope optical upper limit
  92. EP250428b: SAO RAS optical upper limit
  93. EP250428b: LAST optical upper limit
  94. GRB 250427A: Swift/UVOT Detection
  95. EP250428b: Global MASTER-Net observations report
  96. EP250428b: Einstein Probe detection of a fast X-ray transient
  97. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  98. EP250427a: Lesedi optical counterpart detection
  99. EP250427A: COLIBRÍ Continuing Optical Observations
  100. GRB250427A/EP250427a GIT optical afterglow detection:

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