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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"

21207 results found.

  1. GRB 250716A: GOTO tentative optical counterpart candidate
  2. GRB 250714A: SVOM/GRM observation
  3. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  4. GRB 250713A: Mephisto optical upper limits
  5. GRB 250713A: SVOM/VT optical upper limit
  6. GRB 250713A: NOT optical upper limits
  7. GRB 250713A: OHP/T193 upper limit
  8. GRB 250713A: SVOM/C-GFT upper limit
  9. GRB 250706B/C: 7DT Follow-up Observations
  10. GRB 250713A: EP-FXT counterpart detection
  11. EP250711a: COLIBRÍ continuous optical observations
  12. GRB 250713A: JinShan optical upper limits
  13. GRB 250713A: SVOM detection of a long burst
  14. GRB 250711A: DDOTI Optical Upper Limit
  15. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  16. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  17. GRB 250711A: SVOM/GRM observation
  18. EP250711a: NOT optical counterpart candidate
  19. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  20. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  21. GRB 250704A: GRANDMA observations
  22. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  24. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  25. IceCube-250708A: No Candidates from WINTER
  26. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  27. EP250704a/GRB 250704B: 10 GHz VLA detection
  28. IceCube-250706A: No Candidates from WINTER
  29. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  30. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  31. EP250704a/GRB250704B : HCT optical and NIR upper limits
  32. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  33. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  34. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  35. GRB 250702F: radio detection with the VLA
  36. IceCube-250706A: EP-FXT follow-up observations
  37. GRB 250706B/C: Fermi-LAT detection
  38. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  39. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  40. GRB 250706B: Swift/UVOT Detection
  41. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  42. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 250702F: GRANDMA observations
  44. GRB 250706A: Swift-XRT refined Analysis
  45. GRB 250706B: refined SVOM/MXT data analysis
  46. GRB 250706A: Swift/UVOT Upper Limits
  47. GRB 250706B: REM optical observations
  48. GRB 250706A: REM optical/NIR observations
  49. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  50. IceCube-250416A: DDOTI Optical Upper Limit
  51. IceCube-250706A: COLIBRÍ optical upper limits
  52. GRB 250706A: JinShan optical upper limits
  53. GRB 250706A: SAO RAS optical observations
  54. EP250704A: NOWT Detection
  55. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  56. GRB 250706B: iTelescope optical observations
  57. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  58. GRB 250706B: SVOM/VT optical observation
  59. GRB 250706B: TRT bright optical counterpart detection
  60. GRB 250706A: GROWTH-India Telescope optical upper limit
  61. GRB 250706B: SVOM detection of a long burst
  62. GRB 250706A: Swift detection of a burst
  63. GRB 250704B: Swift-XRT refined Analysis
  64. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  65. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  66. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  67. GRB 250704B: Swift/UVOT Upper Limits
  68. GRB 250704A: Swift/UVOT Detection
  69. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  70. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  71. Konus-Wind detection of GRB 250703A
  72. IPN triangulation of GRB 250703A
  73. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  74. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  75. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  76. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  77. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  78. GRB 250702F: Kilonova-Catcher optical afterglow detection
  79. GRB 250702F: Monte Agliale Observatory optical observations
  80. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  81. EP250704a / GRB 250704B: JinShan optical observations
  82. EP250704a / GRB 250704B: SAO RAS optical observations
  83. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  84. EP 250704a: BOOTES-5 optical detection
  85. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  86. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  87. GRB 250704A: Swift-XRT afterglow detection
  88. Konus-Wind detection of GRB 250702F
  89. EP250704a / GRB 250704B - REM observations
  90. GRB 250702F: GROWTH-India Telescope optical observations
  91. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  92. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  93. EP250702a: WFST optical observations
  94. EP250704a: COLIBRÍ optical counterpart candidate
  95. EP250704a: Einstein Probe detection of an X-ray transient
  96. GRB 250702F: optical photometry from Konkoly
  97. GRB 250704A: REM detection of the optical afterglow
  98. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  99. GRB 250704A: SVOM detection of a burst
  100. GRB 250702F: Swift/UVOT Detection

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