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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"

25025 results found.

  1. GRB 250713A: SVOM/C-GFT upper limit
  2. GRB 250706B/C: 7DT Follow-up Observations
  3. GRB 250713A: Swift-XRT observations
  4. GRB 250713A: EP-FXT counterpart detection
  5. EP250711a: COLIBRÍ continuous optical observations
  6. GRB 250706A: Swift-BAT refined analysis
  7. GRB 250702F: Swift-BAT refined analysis
  8. GRB 250628A: Swift-BAT refined analysis
  9. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  10. GRB 250713A: JinShan optical upper limits
  11. GRB 250713A: SVOM detection of a short burst
  12. EP250711a: Global MASTER-Net observations report
  13. GRB 250711A: DDOTI Optical Upper Limit
  14. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  15. EP250711a: COLIBRÍ refined photometry and optical confirmation of the 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. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  23. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  25. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  26. IceCube-250708A: No Candidates from WINTER
  27. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  28. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  29. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  30. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  31. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  32. EP250704a/GRB 250704B: 10 GHz VLA detection
  33. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  34. IceCube-250706A: No Candidates from WINTER
  35. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  36. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  37. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  38. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  39. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  40. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  41. EP250704a/GRB250704B : HCT optical and NIR upper limits
  42. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  43. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  44. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  45. GRB 250702F: radio detection with the VLA
  46. IceCube-250706A: EP-FXT follow-up observations
  47. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  48. GRB 250706B/C: Fermi-LAT detection
  49. IceCube-250706A: Global MASTER-Net observations report
  50. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  51. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  52. GRB 250706B: Swift/UVOT Detection
  53. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  54. GRB 250702F: GRANDMA observations
  55. GRB 250706A: Swift-XRT refined Analysis
  56. GRB 250706B: refined SVOM/MXT data analysis
  57. GRB 250706A: Swift/UVOT Upper Limits
  58. GRB 250706B: REM optical observations
  59. GRB 250706A: REM optical/NIR observations
  60. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  61. IceCube-250416A: DDOTI Optical Upper Limit
  62. IceCube-250706A: COLIBRÍ optical upper limits
  63. GRB 250706A: JinShan optical upper limits
  64. GRB 250706A: SAO RAS optical observations
  65. EP250704A: NOWT Detection
  66. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  67. GRB250706B: Swift-XRT counterpart detection
  68. GRB 250706B: iTelescope optical observations
  69. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  70. GRB 250706B: SVOM/VT optical observation
  71. GRB 250706B: TRT bright optical counterpart detection
  72. GRB 250706A: GROWTH-India Telescope optical upper limit
  73. GRB 250706B: SVOM detection of a long burst
  74. GRB 250706A: Swift detection of a burst
  75. GRB 250704B: Swift-XRT refined Analysis
  76. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  77. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  78. GRB 250703A: EIRSAT-1 GMOD Detection
  79. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  80. GRB 250704B: Swift/UVOT Upper Limits
  81. GRB 250704A: Swift/UVOT Detection
  82. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  83. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  84. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  85. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  86. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  87. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  88. GRB 250702F: Kilonova-Catcher optical afterglow detection
  89. GRB 250702F: Monte Agliale Observatory optical observations
  90. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  91. EP250704a / GRB 250704B: JinShan optical observations
  92. EP250704a / GRB 250704B: SAO RAS optical observations
  93. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  94. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  95. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  96. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  97. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  98. EP250704a / GRB250704B: Swift-XRT counterpart detection
  99. GRB 250704A: Swift-XRT afterglow detection
  100. EP250704a / GRB 250704B - REM observations

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