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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"

20597 results found.

  1. EP250711a: COLIBRÍ continuous optical observations
  2. GRB 250713A: JinShan optical upper limits
  3. GRB 250713A: SVOM detection of a long burst
  4. GRB 250711A: DDOTI Optical Upper Limit
  5. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  6. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  7. GRB 250711A: SVOM/GRM observation
  8. EP250711a: NOT optical counterpart candidate
  9. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  10. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  11. GRB 250704A: GRANDMA observations
  12. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  13. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  14. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  15. IceCube-250708A: No Candidates from WINTER
  16. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  17. EP250704a/GRB 250704B: 10 GHz VLA detection
  18. IceCube-250706A: No Candidates from WINTER
  19. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  20. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  21. EP250704a/GRB250704B : HCT optical and NIR upper limits
  22. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  23. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  24. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  25. GRB 250702F: radio detection with the VLA
  26. IceCube-250706A: EP-FXT follow-up observations
  27. GRB 250706B/C: Fermi-LAT detection
  28. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  29. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  30. GRB 250706B: Swift/UVOT Detection
  31. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  32. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  33. GRB 250702F: GRANDMA observations
  34. GRB 250706A: Swift-XRT refined Analysis
  35. GRB 250706B: refined SVOM/MXT data analysis
  36. GRB 250706A: Swift/UVOT Upper Limits
  37. GRB 250706B: REM optical observations
  38. GRB 250706A: REM optical/NIR observations
  39. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  40. IceCube-250416A: DDOTI Optical Upper Limit
  41. IceCube-250706A: COLIBRÍ optical upper limits
  42. GRB 250706A: JinShan optical upper limits
  43. GRB 250706A: SAO RAS optical observations
  44. EP250704A: NOWT Detection
  45. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  46. GRB 250706B: iTelescope optical observations
  47. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  48. GRB 250706B: SVOM/VT optical observation
  49. GRB 250706B: TRT bright optical counterpart detection
  50. GRB 250706A: GROWTH-India Telescope optical upper limit
  51. GRB 250706B: SVOM detection of a long burst
  52. GRB 250706A: Swift detection of a burst
  53. GRB 250704B: Swift-XRT refined Analysis
  54. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  55. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  56. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  57. GRB 250704B: Swift/UVOT Upper Limits
  58. GRB 250704A: Swift/UVOT Detection
  59. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  60. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  61. Konus-Wind detection of GRB 250703A
  62. IPN triangulation of GRB 250703A
  63. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  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. EP 250704a: BOOTES-5 optical detection
  75. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  76. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  77. GRB 250704A: Swift-XRT afterglow detection
  78. Konus-Wind detection of GRB 250702F
  79. EP250704a / GRB 250704B - REM observations
  80. GRB 250702F: GROWTH-India Telescope optical observations
  81. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  82. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  83. EP250702a: WFST optical observations
  84. EP250704a: COLIBRÍ optical counterpart candidate
  85. EP250704a: Einstein Probe detection of an X-ray transient
  86. GRB 250702F: optical photometry from Konkoly
  87. GRB 250704A: REM detection of the optical afterglow
  88. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  89. GRB 250704A: SVOM detection of a burst
  90. GRB 250702F: Swift/UVOT Detection
  91. GRB 250702F: Leavitt Observatory optical observations
  92. GRB 250702F: AKO Optical Afterglow Detection
  93. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  94. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  95. GRB 250702F: Skynet Optical Observations
  96. GRB 250424A: VIRT Optical Upper Limit
  97. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  98. GRB 250702F: TRT Optical Observation
  99. GRB 250703A: DDOTI Optical Upper Limit
  100. GRB 250702F: REM optical afterglow detection

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