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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"

20502 results found.

  1. GRB 250713A: NOT optical upper limits
  2. GRB 250713A: OHP/T193 upper limit
  3. GRB 250713A: SVOM/C-GFT upper limit
  4. GRB 250706B/C: 7DT Follow-up Observations
  5. GRB 250713A: EP-FXT counterpart detection
  6. EP250711a: COLIBRÍ continuous optical observations
  7. GRB 250713A: JinShan optical upper limits
  8. GRB 250713A: SVOM detection of a long burst
  9. GRB 250711A: DDOTI Optical Upper Limit
  10. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  11. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  12. GRB 250711A: SVOM/GRM observation
  13. EP250711a: NOT optical counterpart candidate
  14. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  15. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  16. GRB 250704A: GRANDMA observations
  17. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  20. IceCube-250708A: No Candidates from WINTER
  21. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  22. EP250704a/GRB 250704B: 10 GHz VLA detection
  23. IceCube-250706A: No Candidates from WINTER
  24. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  25. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  26. EP250704a/GRB250704B : HCT optical and NIR upper limits
  27. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  28. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  29. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  30. GRB 250702F: radio detection with the VLA
  31. IceCube-250706A: EP-FXT follow-up observations
  32. GRB 250706B/C: Fermi-LAT detection
  33. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  35. GRB 250706B: Swift/UVOT Detection
  36. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  37. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  38. GRB 250702F: GRANDMA observations
  39. GRB 250706A: Swift-XRT refined Analysis
  40. GRB 250706B: refined SVOM/MXT data analysis
  41. GRB 250706A: Swift/UVOT Upper Limits
  42. GRB 250706B: REM optical observations
  43. GRB 250706A: REM optical/NIR observations
  44. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  45. IceCube-250416A: DDOTI Optical Upper Limit
  46. IceCube-250706A: COLIBRÍ optical upper limits
  47. GRB 250706A: JinShan optical upper limits
  48. GRB 250706A: SAO RAS optical observations
  49. EP250704A: NOWT Detection
  50. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  51. GRB 250706B: iTelescope optical observations
  52. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  53. GRB 250706B: SVOM/VT optical observation
  54. GRB 250706B: TRT bright optical counterpart detection
  55. GRB 250706A: GROWTH-India Telescope optical upper limit
  56. GRB 250706B: SVOM detection of a long burst
  57. GRB 250706A: Swift detection of a burst
  58. GRB 250704B: Swift-XRT refined Analysis
  59. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  60. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  61. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  62. GRB 250704B: Swift/UVOT Upper Limits
  63. GRB 250704A: Swift/UVOT Detection
  64. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  65. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  66. Konus-Wind detection of GRB 250703A
  67. IPN triangulation of GRB 250703A
  68. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  69. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  70. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  71. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  72. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  73. GRB 250702F: Kilonova-Catcher optical afterglow detection
  74. GRB 250702F: Monte Agliale Observatory optical observations
  75. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  76. EP250704a / GRB 250704B: JinShan optical observations
  77. EP250704a / GRB 250704B: SAO RAS optical observations
  78. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  79. EP 250704a: BOOTES-5 optical detection
  80. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  81. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  82. GRB 250704A: Swift-XRT afterglow detection
  83. Konus-Wind detection of GRB 250702F
  84. EP250704a / GRB 250704B - REM observations
  85. GRB 250702F: GROWTH-India Telescope optical observations
  86. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  87. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  88. EP250702a: WFST optical observations
  89. EP250704a: COLIBRÍ optical counterpart candidate
  90. EP250704a: Einstein Probe detection of an X-ray transient
  91. GRB 250702F: optical photometry from Konkoly
  92. GRB 250704A: REM detection of the optical afterglow
  93. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  94. GRB 250704A: SVOM detection of a burst
  95. GRB 250702F: Swift/UVOT Detection
  96. GRB 250702F: Leavitt Observatory optical observations
  97. GRB 250702F: AKO Optical Afterglow Detection
  98. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  99. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  100. GRB 250702F: Skynet Optical Observations

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