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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"

25027 results found.

  1. GRB 250713A: SVOM/VT optical upper limit
  2. GRB 250713A: NOT optical upper limits
  3. GRB 250713A: OHP/T193 upper limit
  4. GRB 250713A: SVOM/C-GFT upper limit
  5. GRB 250706B/C: 7DT Follow-up Observations
  6. GRB 250713A: Swift-XRT observations
  7. GRB 250713A: EP-FXT counterpart detection
  8. EP250711a: COLIBRÍ continuous optical observations
  9. GRB 250706A: Swift-BAT refined analysis
  10. GRB 250702F: Swift-BAT refined analysis
  11. GRB 250628A: Swift-BAT refined analysis
  12. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  13. GRB 250713A: JinShan optical upper limits
  14. GRB 250713A: SVOM detection of a short burst
  15. EP250711a: Global MASTER-Net observations report
  16. GRB 250711A: DDOTI Optical Upper Limit
  17. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  18. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  19. GRB 250711A: SVOM/GRM observation
  20. EP250711a: NOT optical counterpart candidate
  21. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  22. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  23. GRB 250704A: GRANDMA observations
  24. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  25. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  28. IceCube-250708A: No Candidates from WINTER
  29. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  30. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  31. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  32. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  33. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  34. EP250704a/GRB 250704B: 10 GHz VLA detection
  35. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  36. IceCube-250706A: No Candidates from WINTER
  37. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  38. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  39. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  40. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  41. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  42. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  43. EP250704a/GRB250704B : HCT optical and NIR upper limits
  44. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  45. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  46. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  47. GRB 250702F: radio detection with the VLA
  48. IceCube-250706A: EP-FXT follow-up observations
  49. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  50. GRB 250706B/C: Fermi-LAT detection
  51. IceCube-250706A: Global MASTER-Net observations report
  52. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. EP250702a/GRB250702 B,D,E: GRANDMA Upper Limit
  54. GRB 250706B: Swift/UVOT Detection
  55. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 250702F: GRANDMA observations
  57. GRB 250706A: Swift-XRT refined Analysis
  58. GRB 250706B: refined SVOM/MXT data analysis
  59. GRB 250706A: Swift/UVOT Upper Limits
  60. GRB 250706B: REM optical observations
  61. GRB 250706A: REM optical/NIR observations
  62. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  63. IceCube-250416A: DDOTI Optical Upper Limit
  64. IceCube-250706A: COLIBRÍ optical upper limits
  65. GRB 250706A: JinShan optical upper limits
  66. GRB 250706A: SAO RAS optical observations
  67. EP250704A: NOWT Detection
  68. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  69. GRB250706B: Swift-XRT counterpart detection
  70. GRB 250706B: iTelescope optical observations
  71. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  72. GRB 250706B: SVOM/VT optical observation
  73. GRB 250706B: TRT bright optical counterpart detection
  74. GRB 250706A: GROWTH-India Telescope optical upper limit
  75. GRB 250706B: SVOM detection of a long burst
  76. GRB 250706A: Swift detection of a burst
  77. GRB 250704B: Swift-XRT refined Analysis
  78. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  79. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  80. GRB 250703A: EIRSAT-1 GMOD Detection
  81. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  82. GRB 250704B: Swift/UVOT Upper Limits
  83. GRB 250704A: Swift/UVOT Detection
  84. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  85. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  86. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  87. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  88. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  89. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  90. GRB 250702F: Kilonova-Catcher optical afterglow detection
  91. GRB 250702F: Monte Agliale Observatory optical observations
  92. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  93. EP250704a / GRB 250704B: JinShan optical observations
  94. EP250704a / GRB 250704B: SAO RAS optical observations
  95. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  96. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  97. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  98. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  99. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  100. EP250704a / GRB250704B: Swift-XRT counterpart detection

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