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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"

26328 results found.

  1. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray 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. GRB 250713A: Swift-XRT observations
  9. GRB 250713A: EP-FXT counterpart detection
  10. EP250711a: COLIBRÍ continuous optical observations
  11. GRB 250706A: Swift-BAT refined analysis
  12. GRB 250702F: Swift-BAT refined analysis
  13. GRB 250628A: Swift-BAT refined analysis
  14. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  15. GRB 250713A: JinShan optical upper limits
  16. GRB 250713A: SVOM detection of a long burst
  17. EP250711a: Global MASTER-Net observations report
  18. GRB 250711A: DDOTI Optical Upper Limit
  19. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  20. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  21. GRB 250711A: SVOM/GRM observation
  22. EP250711a: NOT optical counterpart candidate
  23. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  24. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  25. GRB 250704A: GRANDMA observations
  26. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  27. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  29. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  30. IceCube-250708A: No Candidates from WINTER
  31. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  32. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  33. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  34. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  35. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  36. EP250704a/GRB 250704B: 10 GHz VLA detection
  37. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  38. IceCube-250706A: No Candidates from WINTER
  39. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  40. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  41. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  42. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  43. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  44. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  45. EP250704a/GRB250704B : HCT optical and NIR upper limits
  46. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  47. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  48. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  49. GRB 250702F: radio detection with the VLA
  50. IceCube-250706A: EP-FXT follow-up observations
  51. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  52. GRB 250706B/C: Fermi-LAT detection
  53. IceCube-250706A: Global MASTER-Net observations report
  54. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  55. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  56. GRB 250706B: Swift/UVOT Detection
  57. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250702F: GRANDMA observations
  59. GRB 250706A: Swift-XRT refined Analysis
  60. GRB 250706B: refined SVOM/MXT data analysis
  61. GRB 250706A: Swift/UVOT Upper Limits
  62. GRB 250706B: REM optical observations
  63. GRB 250706A: REM optical/NIR observations
  64. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  65. IceCube-250416A: DDOTI Optical Upper Limit
  66. IceCube-250706A: COLIBRÍ optical upper limits
  67. GRB 250706A: JinShan optical upper limits
  68. GRB 250706A: SAO RAS optical observations
  69. EP250704A: NOWT Detection
  70. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  71. GRB250706B: Swift-XRT counterpart detection
  72. GRB 250706B: iTelescope optical observations
  73. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  74. GRB 250706B: SVOM/VT optical observation
  75. GRB 250706B: TRT bright optical counterpart detection
  76. GRB 250706A: GROWTH-India Telescope optical upper limit
  77. GRB 250706B: SVOM detection of a long burst
  78. GRB 250706A: Swift detection of a burst
  79. GRB 250704B: Swift-XRT refined Analysis
  80. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  81. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  82. GRB 250703A: EIRSAT-1 GMOD Detection
  83. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  84. GRB 250704B: Swift/UVOT Upper Limits
  85. GRB 250704A: Swift/UVOT Detection
  86. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  87. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  88. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  89. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  90. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  91. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  92. GRB 250702F: Kilonova-Catcher optical afterglow detection
  93. GRB 250702F: Monte Agliale Observatory optical observations
  94. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  95. EP250704a / GRB 250704B: JinShan optical observations
  96. EP250704a / GRB 250704B: SAO RAS optical observations
  97. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  98. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  99. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  100. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations

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