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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"

42537 results found.

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

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