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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"

11836 results found.

  1. GRB250706B: Swift-XRT counterpart detection
  2. GRB 250706B: iTelescope optical observations
  3. GRB 250706B: SVOM detection of a long burst
  4. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  5. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  6. Konus-Wind detection of GRB 250703A
  7. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  8. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  9. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  10. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  11. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  12. EP250704a / GRB250704B: Swift-XRT counterpart detection
  13. GRB 250704A: Swift-XRT afterglow detection
  14. Konus-Wind detection of GRB 250702F
  15. EP250704a: COLIBRÍ optical counterpart candidate
  16. EP250704a: Einstein Probe detection of an X-ray transient
  17. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  18. GRB 250704A: SVOM detection of a burst
  19. Fermi GRB 250703A: Global MASTER-Net observations report
  20. GRB 250702F: Swift-XRT refined Analysis
  21. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  22. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  23. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  24. EP250702a: Global MASTER-Net observations report
  25. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  26. Fermi GRB 250702C: Global MASTER-Net observations report
  27. Konus-Wind detection of GRB 250627A
  28. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  29. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  30. GRB 250628B: Swift-XRT observations
  31. GRB 250628A: REM optical/NIR upper limits
  32. GRB 250628B: SVOM detection of a long burst
  33. GRB 250628A: Swift-XRT refined Analysis
  34. Fermi GRB 250626A: Global MASTER-Net observations report
  35. GRB 250628A: Swift detection of a burst
  36. GRB 250625A: Leavitt Observatory afterglow detection
  37. GRB 250625A: ABObservatory afterglow detection
  38. GRB 250625A: OHP/T193 optical detection
  39. GRB 250625A: Fermi-LAT detection
  40. GRB 250625A: Swift-XRT refined Analysis
  41. Swift GRB 250625A: Global MASTER-Net observations report
  42. GRB 250620B: Fermi GBM Observation
  43. GRB 250625A: SAO RAS possible optical afterglow
  44. Fermi GRB 250625A: Global MASTER-Net observations report
  45. GRB 250625A: Swift detection of a burst
  46. GRB 250620A: AstroSat CZTI detection
  47. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  48. GRB 241018A: Maidanak optical observations
  49. GRB 250620C: AstroSat CZTI detection
  50. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  51. Fermi GRB 250623A: Global MASTER-Net observations report
  52. Fermi trigger No 772190032: Global MASTER-Net observations report
  53. Konus-Wind detection of GRB 250620C
  54. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  55. GRB250620A: Fermi GBM Observation
  56. Fermi GRB 250621A: Global MASTER-Net observations report
  57. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  58. GRB250620C: Fermi GBM Observation
  59. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  60. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  61. GRB 250620C: Fermi GBM Final Real-time Localization
  62. Fermi trigger No 772128434: Global MASTER-Net observations report
  63. GRB 250620B: Fermi GBM Final Real-time Localization
  64. GRB 250620A: Fermi GBM Final Real-time Localization
  65. Fermi trigger No 772058337: Global MASTER-Net observations report
  66. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  67. GRB 250617B: Assy AZT-20 Optical Observations
  68. GRB 250615A/EP250615a: FTW optical and NIR observations
  69. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  70. GRB 250617B: COLIBRÍ optical observations
  71. GRB 250617B: Swift-XRT refined Analysis
  72. GRB 250617B: Swift detection of a burst with an optical counterpart
  73. EP#01709178975: Swift-XRT counterpart detection
  74. Konus-Wind detection of GRB 250615A / EP250615a
  75. GRB 250615A / EP250615a: AstroSat CZTI detection
  76. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  77. Fermi trigger No 771752663: Global MASTER-Net observations report
  78. sb25061218: Swift-XRT observations
  79. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  80. EP250612a: SVOM/VT optical candidate
  81. sb25061207: Swift-XRT observations
  82. GRB 250610B: Swift-XRT refined Analysis
  83. EP250612a: Einstein Probe detection of an X-ray transient
  84. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  85. sb25061207: SVOM detection of a X-ray transient
  86. Swift GRB250612.04: Global MASTER-Net observations report
  87. GRB 250610B: Swift-XRT counterpart detection
  88. GRB 250610B: SVOM/VT optical counterpart
  89. GRB 250610B: OHP/T120 optical counterpart candidate
  90. GRB 250610B: GOTO optical upper limit
  91. EP250610a: Global MASTER-Net observations report
  92. GRB 250610B: SVOM detection of a long burst
  93. EP250610a: Swift-XRT counterpart detection
  94. EP250610a: Einstein Probe detection of an X-ray transient
  95. Fermi trigger No 771072240: Global MASTER-Net observations report
  96. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  97. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  98. GRB 250605A: Swift-XRT refined Analysis
  99. Fermi GRB 250606A: Global MASTER-Net observations report
  100. Fermi trigger No 770867684: Global MASTER-Net observations report

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