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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"

2410 results found.

  1. GRB 250704A: Swift/UVOT Detection
  2. GRB 250704B: Insight-HXMT detection
  3. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  4. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  5. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  6. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  7. EP250704a / GRB 250704B: JinShan optical observations
  8. GRB 250704A: SVOM/VT optical observation
  9. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  10. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  11. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  12. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  13. EP250704a / GRB250704B: Swift-XRT counterpart detection
  14. GRB 250704A: Swift-XRT afterglow detection
  15. GRB 250704B: SVOM/GRM observation of a short burst
  16. GRB 250704A: REM detection of the optical afterglow
  17. GRB 250702F: SVOM/VT optical observation
  18. GRB 250704A: SVOM detection of a burst
  19. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  20. Konus-Wind detection of GRB 250627A
  21. IPN triangulation of GRB 250627A (short)
  22. GRB 250628B: Swift-XRT observations
  23. GRB 250628B: SVOM/VT optical upper limit
  24. GRB 250628B: EP-FXT counterpart detection
  25. GRB 250627A: Insight-HXMT detection
  26. GRB 250627A: SVOM/GRM detection of a short burst
  27. GRB 250628B: SVOM detection of a long burst
  28. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  29. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  30. GRB 250625A: SVOM/C-GFT upper limit in early phase
  31. GRB 250625A: Fermi-LAT detection
  32. GRB 250625A: JinShan optical observations
  33. GRB250625A: Fermi GBM Observation
  34. GRB 250625A: SVOM/VT optical confirmation
  35. GRB 250620A: AstroSat CZTI detection
  36. GRB 241018A: Maidanak optical observations
  37. GRB 250620C: AstroSat CZTI detection
  38. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  39. Konus-Wind detection of GRB 250620C
  40. IPN triangulation of GRB 250620C (long/bright)
  41. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  42. GRB 250620C: SVOM/GRM observation
  43. GRB 250620A: SVOM/GRM observation of a short burst
  44. GRB 250506A - SVOM/ECLAIRs Refined analysis
  45. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  46. GRB 250617B: Kilonova-Catcher optical afterglow detection
  47. GRB 250617B: SVOM/VT optical observation
  48. IPN triangulation of GRB 250612C (short/hard)
  49. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  50. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  51. sb25061207/SVOM: T120 OHP optical upper limit
  52. GRID detection of GRB 250612C
  53. sb25061207: Mephisto optical upper limits
  54. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  55. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  56. sb25061218: Swift-XRT observations
  57. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  58. sb25061207: EP-FXT follow-up observation and afterglow candidate
  59. EP250612a: SVOM/VT optical candidate
  60. GRB 250612C: Fermi GBM Observation
  61. sb25061218: SVOM detection of a X-ray transient
  62. sb25061207: Swift-XRT observations
  63. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  64. sb25061207: SVOM/VT optical counterpart
  65. GRB 250610B: Swift-XRT refined Analysis
  66. GRB 250610B: Liverpool Telescope continued monitoring
  67. sb25061207: SVOM detection of a X-ray transient
  68. GRB 250610B - SVOM/ECLAIRs refined analysis
  69. Fermi GBM Sub-Threshold Detection of GRB 250610B
  70. GRB 250610B: Swift/UVOT Detection
  71. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. GRB 250610B: REM optical/NIR observations
  73. GRB 250610B: SVOM/VT optical shallow decay
  74. GRB 250610B: SVOM/GRM analysis
  75. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  76. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  77. GRB 250610B: Swift-XRT counterpart detection
  78. GRB 250610B: SVOM/VT optical counterpart
  79. GRB 250610B: LT detection of the optical counterpart
  80. GRB 250610B: GOTO optical upper limit
  81. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  82. GRB 250610B: SVOM detection of a long burst
  83. EP250610a: SVOM/VT optical upper limit
  84. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  85. GRB 250607A: SVOM/GRM observation of a long burst
  86. GRB 250605A: SVOM/VT optical upper limit
  87. GRB 250530A: SVOM/GRM analysis
  88. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  89. EP#01709177494: SVOM/VT optical observations
  90. GRB 250530A: TNG detection of a NIR source inside the Swift/XRT error circle
  91. GRB 250530A: EP-FXT counterpart detection
  92. GRB 250530A: SVOM/VT optical upper limit
  93. GRB 250530A: Swift-XRT counterpart detection
  94. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate retraction and detection limit
  95. GRB 250530A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  96. GRB 250530A: SVOM detection of a burst
  97. EP250526a: SVOM/VT optical upper limit
  98. GRB 250521D: SVOM/GRM analysis suggests a possible “long” duration type I burst
  99. GRB 250314A: CIDER NB1008 upper limit
  100. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation

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