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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"

45507 results found.

  1. GRB 250625A: OHP/T193 optical detection
  2. GRB 250625A: COLIBRÍ optical observations
  3. GRB 250625A: Fermi-LAT detection
  4. GRB 250625A: Swift-XRT refined Analysis
  5. GRB 250625A: JinShan optical observations
  6. GRB250625A: Fermi GBM Observation
  7. Swift GRB 250625A: Global MASTER-Net observations report
  8. GRB 250625A: NOT z-band upper limit
  9. GRB 250625A: SVOM/VT optical confirmation
  10. GRB 250620B: Fermi GBM Observation
  11. GRB 250625A: SAO RAS possible optical afterglow
  12. GRB 250625A: Enhanced Swift-XRT position
  13. Fermi GRB 250625A: Global MASTER-Net observations report
  14. GRB 250625A: Swift detection of a burst
  15. GRB 250625A: Fermi GBM Final Real-time Localization
  16. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  17. GRB 250620A: AstroSat CZTI detection
  18. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  19. GRB 241018A: Maidanak optical observations
  20. GRB 250620C: AstroSat CZTI detection
  21. Fermi GRB 250624A: Global MASTER-Net observations report
  22. GRB 250624A: Fermi GBM Final Real-time Localization
  23. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  24. Fermi GRB 250623A: Global MASTER-Net observations report
  25. GRB 250623A: Fermi GBM Final Real-time Localization
  26. GRB 250521A: VZLUSAT-2 detection
  27. GRB 250617B: Swift-BAT refined analysis
  28. Fermi trigger No 772190032: Global MASTER-Net observations report
  29. Konus-Wind detection of GRB 250620C
  30. IPN triangulation of GRB 250620C (long/bright)
  31. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  32. GRB 250620C: SVOM/GRM observation
  33. GRB 250620A: SVOM/GRM observation of a short burst
  34. GRB250620A: Fermi GBM Observation
  35. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  36. Fermi GRB 250621A: Global MASTER-Net observations report
  37. GRB 250619B: Fermi GBM Observation
  38. GRB 250621A: Fermi GBM Final Real-time Localization
  39. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  40. GRB250620C: Fermi GBM Observation
  41. GRB 250506A - SVOM/ECLAIRs Refined analysis
  42. The EP-WXT trigger 01709179071 is likely a flaring star
  43. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  44. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  45. GRB 250620C: Fermi GBM Final Real-time Localization
  46. Fermi trigger No 772128434: Global MASTER-Net observations report
  47. GRB 250620B: Fermi GBM Final Real-time Localization
  48. GRB 250620A: Fermi GBM Final Real-time Localization
  49. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  50. GRB 250617B: Nickel telescope optical observations
  51. GRB 250619B: Fermi GBM Final Real-time Localization
  52. Fermi trigger No 772058337: Global MASTER-Net observations report
  53. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  54. GRB 250615A: Kilonova-Catcher optical upper limits
  55. GRB 250619A: Fermi GBM Final Real-time Localization
  56. GRB 250617B: Assy AZT-20 Optical Observations
  57. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  58. Fermi GRB 250617A: Global MASTER-Net observations report
  59. GRB 250615A/EP250615a: FTW optical and NIR observations
  60. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  61. GRB 250617B: Swift/UVOT Detection
  62. GRB 250617B: Kilonova-Catcher optical afterglow detection
  63. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  64. GRB 250617B: COLIBRÍ optical observations
  65. GRB 250617B: NOT NIR observations of the afterglow
  66. GRB 250617B: Swift-XRT refined Analysis
  67. GRB 250617B: SVOM/VT optical observation
  68. GRB 250617B: NUTTelA-TAO early time optical observations
  69. Fermi trigger No 771886893: Global MASTER-Net observations report
  70. Swift GRB 250617B: Global MASTER-Net observations report
  71. GRB 250617B: GOTO optical upper limit
  72. GRB 250617B: Enhanced Swift-XRT position
  73. GRB 250617B: Fermi GBM Observation
  74. GRB 250615A: Swift-BAT refined analysis
  75. The EP-WXT trigger 01709178990 is likely a flaring star
  76. GRB 250617B: Fermi GBM Final Localization
  77. GRB 250617B: Ondrejov D50 optical afterglow detection
  78. GRB 250617B: SAO RAS optical observations
  79. GRB 250617B: Swift detection of a burst with an optical counterpart
  80. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  81. GRB 250617A: Fermi GBM Final Real-time Localization
  82. IPN triangulation of GRB 250612C (short/hard)
  83. EP#01709178975: Swift-XRT counterpart detection
  84. EP-WXT trigger 01709178975: GOTO optical upper limit
  85. The EP-WXT trigger 01709178975 is likely a flaring star
  86. Konus-Wind detection of GRB 250615A / EP250615a
  87. GRB 250615A / EP250615a: AstroSat CZTI detection
  88. Fermi Gamma-ray Burst Monitor trigger 771803204/250616907 is not a GRB
  89. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  90. GRB 250615A: COLIBRÍ optical upper limit
  91. GRB 250615A: DDOTI Optical Upper Limit
  92. GRB 250615A: Swift/UVOT Upper Limits
  93. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  94. GRB 250615A: Swift-XRT refined Analysis
  95. sb25061207/SVOM: T120 OHP optical upper limit
  96. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  97. Fermi trigger No 771752663: Global MASTER-Net observations report
  98. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  99. The EP-WXT trigger 01709178875 is likely a flaring star
  100. GRB 250615A: Enhanced Swift-XRT position

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