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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"

42538 results found.

  1. GRB250625A: Fermi GBM Observation
  2. Swift GRB 250625A: Global MASTER-Net observations report
  3. GRB 250625A: NOT z-band upper limit
  4. GRB 250625A: SVOM/VT optical confirmation
  5. GRB 250620B: Fermi GBM Observation
  6. GRB 250625A: SAO RAS possible optical afterglow
  7. GRB 250625A: Enhanced Swift-XRT position
  8. Fermi GRB 250625A: Global MASTER-Net observations report
  9. GRB 250625A: Swift detection of a burst
  10. GRB 250625A: Fermi GBM Final Real-time Localization
  11. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  12. GRB 250620A: AstroSat CZTI detection
  13. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  14. GRB 241018A: Maidanak optical observations
  15. GRB 250620C: AstroSat CZTI detection
  16. Fermi GRB 250624A: Global MASTER-Net observations report
  17. GRB 250624A: Fermi GBM Final Real-time Localization
  18. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  19. Fermi GRB 250623A: Global MASTER-Net observations report
  20. GRB 250623A: Fermi GBM Final Real-time Localization
  21. GRB 250617B: Swift-BAT refined analysis
  22. Fermi trigger No 772190032: Global MASTER-Net observations report
  23. Konus-Wind detection of GRB 250620C
  24. IPN triangulation of GRB 250620C (long/bright)
  25. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  26. GRB 250620C: SVOM/GRM observation
  27. GRB 250620A: SVOM/GRM observation of a short burst
  28. GRB250620A: Fermi GBM Observation
  29. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  30. Fermi GRB 250621A: Global MASTER-Net observations report
  31. GRB 250619B: Fermi GBM Observation
  32. GRB 250621A: Fermi GBM Final Real-time Localization
  33. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  34. GRB250620C: Fermi GBM Observation
  35. GRB 250506A - SVOM/ECLAIRs Refined analysis
  36. The EP-WXT trigger 01709179071 is likely a flaring star
  37. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  38. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 250620C: Fermi GBM Final Real-time Localization
  40. Fermi trigger No 772128434: Global MASTER-Net observations report
  41. GRB 250620B: Fermi GBM Final Real-time Localization
  42. GRB 250620A: Fermi GBM Final Real-time Localization
  43. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  44. GRB 250617B: Nickel telescope optical observations
  45. GRB 250619B: Fermi GBM Final Real-time Localization
  46. Fermi trigger No 772058337: Global MASTER-Net observations report
  47. GRB 250615A: Kilonova-Catcher optical upper limits
  48. GRB 250619A: Fermi GBM Final Real-time Localization
  49. GRB 250617B: Assy AZT-20 Optical Observations
  50. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  51. Fermi GRB 250617A: Global MASTER-Net observations report
  52. GRB 250615A/EP250615a: FTW optical and NIR observations
  53. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  54. GRB 250617B: Swift/UVOT Detection
  55. GRB 250617B: Kilonova-Catcher optical afterglow detection
  56. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  57. GRB 250617B: COLIBRÍ optical observations
  58. GRB 250617B: NOT NIR observations of the afterglow
  59. GRB 250617B: Swift-XRT refined Analysis
  60. GRB 250617B: SVOM/VT optical observation
  61. GRB 250617B: NUTTelA-TAO early time optical observations
  62. Fermi trigger No 771886893: Global MASTER-Net observations report
  63. Swift GRB 250617B: Global MASTER-Net observations report
  64. GRB 250617B: GOTO optical upper limit
  65. GRB 250617B: Enhanced Swift-XRT position
  66. GRB 250617B: Fermi GBM Observation
  67. GRB 250615A: Swift-BAT refined analysis
  68. The EP-WXT trigger 01709178990 is likely a flaring star
  69. GRB 250617B: Fermi GBM Final Localization
  70. GRB 250617B: Ondrejov D50 optical afterglow detection
  71. GRB 250617B: SAO RAS optical observations
  72. GRB 250617B: Swift detection of a burst with an optical counterpart
  73. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  74. GRB 250617A: Fermi GBM Final Real-time Localization
  75. IPN triangulation of GRB 250612C (short/hard)
  76. EP#01709178975: Swift-XRT counterpart detection
  77. EP-WXT trigger 01709178975: GOTO optical upper limit
  78. The EP-WXT trigger 01709178975 is likely a flaring star
  79. Konus-Wind detection of GRB 250615A / EP250615a
  80. GRB 250615A / EP250615a: AstroSat CZTI detection
  81. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  82. GRB 250615A: COLIBRÍ optical upper limit
  83. GRB 250615A: DDOTI Optical Upper Limit
  84. GRB 250615A: Swift/UVOT Upper Limits
  85. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  86. GRB 250615A: Swift-XRT refined Analysis
  87. sb25061207/SVOM: T120 OHP optical upper limit
  88. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  89. Fermi trigger No 771752663: Global MASTER-Net observations report
  90. The EP-WXT trigger 01709178875 is likely a flaring star
  91. GRB 250615A: Enhanced Swift-XRT position
  92. GRB 250615A: Prompt enhanced Swift-XRT position
  93. GRB 250615A: Swift detection of a burst
  94. Swift GRB 250615A: Global MASTER-Net observations report
  95. Fermi trigger No 771718064: Global MASTER-Net observations report
  96. GRID detection of GRB 250612C
  97. sb25061207: Mephisto optical upper limits
  98. IceCube alert 141029_8144692 retraction
  99. GRB 250614A: Fermi GBM Final Real-time Localization
  100. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate

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