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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"

2037 results found.

  1. GRB 250711A: SVOM/GRM observation
  2. GRB 250704A: GRANDMA observations
  3. GRB 250704A: SVOM/ECLAIRs refined analysis
  4. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  5. GRB 250706B/C: Insight-HXMT detection
  6. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  7. EP250704a/GRB250704B : HCT optical and NIR upper limits
  8. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  9. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  10. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  11. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  12. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  13. GRB 250706B/C: Fermi-LAT detection
  14. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  15. GRB 250706B: Swift/UVOT Detection
  16. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  17. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  18. GRB 250706B: refined SVOM/MXT data analysis
  19. GRB 250706B: REM optical observations
  20. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  21. GRB250706B: Swift-XRT counterpart detection
  22. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  23. GRB 250706B: SVOM/VT optical observation
  24. GRB 250706B: TRT bright optical counterpart detection
  25. GRB 250706B: SVOM detection of a long burst
  26. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  27. GRB 250704B: Swift/UVOT Upper Limits
  28. GRB 250704A: Swift/UVOT Detection
  29. GRB 250704B: Insight-HXMT detection
  30. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  31. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  32. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  33. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  34. EP250704a / GRB 250704B: JinShan optical observations
  35. GRB 250704A: SVOM/VT optical observation
  36. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  37. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  38. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  39. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  40. EP250704a / GRB250704B: Swift-XRT counterpart detection
  41. GRB 250704A: Swift-XRT afterglow detection
  42. GRB 250704B: SVOM/GRM observation of a short burst
  43. GRB 250704A: REM detection of the optical afterglow
  44. GRB 250702F: SVOM/VT optical observation
  45. GRB 250704A: SVOM detection of a burst
  46. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  47. Konus-Wind detection of GRB 250627A
  48. IPN triangulation of GRB 250627A (short)
  49. GRB 250628B: Swift-XRT observations
  50. GRB 250628B: SVOM/VT optical upper limit
  51. GRB 250628B: EP-FXT counterpart detection
  52. GRB 250627A: Insight-HXMT detection
  53. GRB 250627A: SVOM/GRM detection of a short burst
  54. GRB 250628B: SVOM detection of a long burst
  55. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  56. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  57. GRB 250625A: SVOM/C-GFT upper limit in early phase
  58. GRB 250625A: Fermi-LAT detection
  59. GRB 250625A: JinShan optical observations
  60. GRB250625A: Fermi GBM Observation
  61. GRB 250625A: SVOM/VT optical confirmation
  62. GRB 250620A: AstroSat CZTI detection
  63. GRB 241018A: Maidanak optical observations
  64. GRB 250620C: AstroSat CZTI detection
  65. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  66. Konus-Wind detection of GRB 250620C
  67. IPN triangulation of GRB 250620C (long/bright)
  68. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  69. GRB 250620C: SVOM/GRM observation
  70. GRB 250620A: SVOM/GRM observation of a short burst
  71. GRB 250506A - SVOM/ECLAIRs Refined analysis
  72. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  73. GRB 250617B: Kilonova-Catcher optical afterglow detection
  74. GRB 250617B: SVOM/VT optical observation
  75. IPN triangulation of GRB 250612C (short/hard)
  76. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  77. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  78. sb25061207/SVOM: T120 OHP optical upper limit
  79. GRID detection of GRB 250612C
  80. sb25061207: Mephisto optical upper limits
  81. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  82. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. sb25061218: Swift-XRT observations
  84. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  85. sb25061207: EP-FXT follow-up observation and afterglow candidate
  86. EP250612a: SVOM/VT optical candidate
  87. GRB 250612C: Fermi GBM Observation
  88. sb25061218: SVOM detection of a X-ray transient
  89. sb25061207: Swift-XRT observations
  90. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  91. sb25061207: SVOM/VT optical counterpart
  92. GRB 250610B: Swift-XRT refined Analysis
  93. GRB 250610B: Liverpool Telescope continued monitoring
  94. sb25061207: SVOM detection of a X-ray transient
  95. GRB 250610B - SVOM/ECLAIRs refined analysis
  96. Fermi GBM Sub-Threshold Detection of GRB 250610B
  97. GRB 250610B: Swift/UVOT Detection
  98. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  99. GRB 250610B: REM optical/NIR observations
  100. GRB 250610B: SVOM/VT optical shallow decay

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