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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"

43899 results found.

  1. IceCube-250416A: DDOTI Optical Upper Limit
  2. IceCube-250706A: COLIBRÍ optical upper limits
  3. Swift GRB 250706A: Global MASTER-Net observations report
  4. GRB 250706A: JinShan optical upper limits
  5. GRB 250706A: SAO RAS optical observations
  6. EP250704A: NOWT Detection
  7. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  8. The EP-WXT trigger 01709181580 is likely a flaring star
  9. GRB250706B: Swift-XRT counterpart detection
  10. GRB 250706B: iTelescope optical observations
  11. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  12. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  13. GRB 250706B: SVOM/VT optical observation
  14. GRB 250706B: TRT bright optical counterpart detection
  15. GRB 250706A: GROWTH-India Telescope optical upper limit
  16. GRB 250706B: SVOM detection of a long burst
  17. GRB 250706A: Swift detection of a burst
  18. GRB 250704B: Swift-XRT refined Analysis
  19. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  20. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  21. GRB 250703A: EIRSAT-1 GMOD Detection
  22. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  23. GRB 250704A: Swift/UVOT Detection
  24. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  25. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  26. GRB 250704B: Insight-HXMT detection
  27. Konus-Wind detection of GRB 250703A
  28. IPN triangulation of GRB 250703A
  29. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  30. EP250704a/GRB 250704B: FTW optical and NIR observations of the 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/HAWK-I NIR afterglow detection
  34. GRB 250702F: Kilonova-Catcher optical afterglow detection
  35. GRB 250702F: Monte Agliale Observatory optical observations
  36. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  37. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  38. EP250704a / GRB 250704B: JinShan optical observations
  39. GRB 250704A: SVOM/VT optical observation
  40. EP250704a / GRB 250704B: SAO RAS optical observations
  41. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  42. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  43. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  44. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  45. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  46. EP 250704a: BOOTES-5 optical detection
  47. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  48. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  49. GRB 250702A: Insight-HXMT detection
  50. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  51. EP250704a / GRB250704B: Swift-XRT counterpart detection
  52. GRB 250704A: Swift-XRT afterglow detection
  53. GRB 250702B / EP2050702a: FTW optical and NIR observations
  54. Konus-Wind detection of GRB 250702F
  55. EP250704a / GRB 250704B - REM observations
  56. GRB 250702F: GROWTH-India Telescope optical observations
  57. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  58. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  59. EP250702a: WFST optical observations
  60. EP250704a: COLIBRÍ optical counterpart candidate
  61. EP250704a: Einstein Probe detection of an X-ray transient
  62. GRB 250704B: SVOM/GRM observation of a short burst
  63. GRB 250702F: optical photometry from Konkoly
  64. GRB 250704A: REM detection of the optical afterglow
  65. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  66. GRB 250702F: SVOM/VT optical observation
  67. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  68. GRB 250704A: SVOM detection of a burst
  69. GRB 250702F: Swift/UVOT Detection
  70. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  71. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  72. Fermi GRB 250703A: Global MASTER-Net observations report
  73. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  74. GRB 250702F: Swift-XRT refined Analysis
  75. GRB 250702F: Fermi GBM Observation
  76. GRB 250702F: Leavitt Observatory optical observations
  77. GRB 250702F: AKO Optical Afterglow Detection
  78. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  79. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  80. GRB 250702A: GECAM-B detection
  81. GRB 250702F: Skynet Optical Observations
  82. GRB 250424A: VIRT Optical Upper Limit
  83. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  84. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  85. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  86. GRB 250702F: TRT Optical Observation
  87. GRB 250703A: DDOTI Optical Upper Limit
  88. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  89. GRB 250702F: REM optical afterglow detection
  90. EP250702a: Global MASTER-Net observations report
  91. GRB 250702F: DDOTI Optical Observation
  92. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  93. GRB 250703A: Fermi GBM Final Real-time Localization
  94. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  95. GRB 250702F: COLIBRÍ Observations of the Afterglow
  96. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  97. Fermi GRB 250702E: Global MASTER-Net observations report
  98. Fermi GRB 250702B: Global MASTER-Net observations report
  99. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  100. GRB 250702F: Enhanced Swift-XRT position

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