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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"

17477 results found.

  1. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  2. GRB 250713A: Mephisto optical upper limits
  3. GRB 250713A: SVOM/VT optical upper limit
  4. GRB 250713A: NOT optical upper limits
  5. GRB 250713A: OHP/T193 upper limit
  6. GRB 250713A: SVOM/C-GFT upper limit
  7. GRB 250706B/C: 7DT Follow-up Observations
  8. EP250711a: COLIBRÍ continuous optical observations
  9. GRB 250713A: JinShan optical upper limits
  10. GRB 250713A: SVOM detection of a long burst
  11. GRB 250711A: DDOTI Optical Upper Limit
  12. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  13. GRB 250711A: SVOM/GRM observation
  14. EP250711a: NOT optical counterpart candidate
  15. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  16. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  17. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  18. GRB 250704A: GRANDMA observations
  19. GRB 250704A: SVOM/ECLAIRs refined analysis
  20. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  21. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  22. IceCube-250708A: No Candidates from WINTER
  23. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  24. EP250704a/GRB 250704B: 10 GHz VLA detection
  25. IceCube-250706A: No Candidates from WINTER
  26. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  27. GRB 250704B / EP250704a: VLA radio detection
  28. EP250704a/GRB250704B : HCT optical and NIR upper limits
  29. GRB 250708A: Fermi GBM Final Real-time Localization
  30. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  31. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  32. GRB 250702F: radio detection with the VLA
  33. IceCube-250706A: EP-FXT follow-up observations
  34. GRB 250706B/C: Fermi-LAT detection
  35. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  36. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  37. GRB 250706B: Swift/UVOT Detection
  38. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 250702F: GRANDMA observations
  40. GRB 250706A: Swift/UVOT Upper Limits
  41. GRB 250706B: REM optical observations
  42. GRB 250706A: REM optical/NIR observations
  43. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  44. IceCube-250416A: DDOTI Optical Upper Limit
  45. IceCube-250706A: COLIBRÍ optical upper limits
  46. GRB 250706A: JinShan optical upper limits
  47. GRB 250706A: SAO RAS optical observations
  48. EP250704A: NOWT Detection
  49. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  50. GRB 250706B: iTelescope optical observations
  51. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  52. GRB 250706B: SVOM/VT optical observation
  53. GRB 250706B: TRT bright optical counterpart detection
  54. GRB 250706A: GROWTH-India Telescope optical upper limit
  55. GRB 250706B: SVOM detection of a long burst
  56. GRB 250706A: Swift detection of a burst
  57. GRB 250704B: Swift-XRT refined Analysis
  58. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  59. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  60. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  61. GRB 250704B: Swift/UVOT Upper Limits
  62. GRB 250704A: Swift/UVOT Detection
  63. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  64. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  65. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  66. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  67. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  68. GRB 250702F: Kilonova-Catcher optical afterglow detection
  69. GRB 250702F: Monte Agliale Observatory optical observations
  70. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  71. EP250704a / GRB 250704B: JinShan optical observations
  72. EP250704a / GRB 250704B: SAO RAS optical observations
  73. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  74. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  75. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  76. GRB 250704A: Swift-XRT afterglow detection
  77. EP250704a / GRB 250704B - REM observations
  78. GRB 250702F: GROWTH-India Telescope optical observations
  79. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  80. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  81. EP250702a: WFST optical observations
  82. EP250704a: COLIBRÍ optical counterpart candidate
  83. EP250704a: Einstein Probe detection of an X-ray transient
  84. GRB 250704A: REM detection of the optical afterglow
  85. GRB 250704A: SVOM detection of a burst
  86. GRB 250702F: Swift/UVOT Detection
  87. GRB 250702F: Leavitt Observatory optical observations
  88. GRB 250702F: AKO Optical Afterglow Detection
  89. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  90. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  91. GRB 250702F: Skynet Optical Observations
  92. GRB 250424A: VIRT Optical Upper Limit
  93. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  94. GRB 250702F: TRT Optical Observation
  95. GRB 250703A: DDOTI Optical Upper Limit
  96. GRB 250702F: REM optical afterglow detection
  97. GRB 250702F: DDOTI Optical Observation
  98. GRB 250702F: COLIBRÍ Observations of the Afterglow
  99. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  100. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient

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