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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"

11102 results found.

  1. GRB 250711A: SVOM/GRM observation
  2. Fermi GRB 250711A: Global MASTER-Net observations report
  3. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  4. GRB 250711A: Fermi GBM Final Real-time Localization
  5. GRB 250702B,D,E / EP250702a: ALMA detection
  6. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  7. GRB 250709A: Fermi GBM Final Localization
  8. GRB 250706B/C: Insight-HXMT detection
  9. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  10. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  11. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  12. Fermi GRB 250708A: Global MASTER-Net observations report
  13. GRB 250708A: Fermi GBM Final Real-time Localization
  14. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  15. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  16. GRB 250702F: radio detection with the VLA
  17. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  18. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  19. GRB 250706B/C: Fermi-LAT detection
  20. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  21. GRB 250702F: GRANDMA observations
  22. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  24. GRB 250703A: EIRSAT-1 GMOD Detection
  25. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  26. Konus-Wind detection of GRB 250703A
  27. IPN triangulation of GRB 250703A
  28. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  29. GRB 250702F: Kilonova-Catcher optical afterglow detection
  30. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  31. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  32. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  33. GRB 250702A: Insight-HXMT detection
  34. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  35. GRB 250702B / EP2050702a: FTW optical and NIR observations
  36. Konus-Wind detection of GRB 250702F
  37. GRB 250702F: GROWTH-India Telescope optical observations
  38. EP250702a: WFST optical observations
  39. GRB 250702F: optical photometry from Konkoly
  40. GRB 250702F: SVOM/VT optical observation
  41. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  42. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  43. Fermi GRB 250703A: Global MASTER-Net observations report
  44. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  45. GRB 250702F: Fermi GBM Observation
  46. GRB 250702F: Leavitt Observatory optical observations
  47. GRB 250702F: AKO Optical Afterglow Detection
  48. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  49. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  50. GRB 250702A: GECAM-B detection
  51. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  52. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  53. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  54. GRB 250702F: TRT Optical Observation
  55. GRB 250703A: DDOTI Optical Upper Limit
  56. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  57. GRB 250702F: REM optical afterglow detection
  58. GRB 250702F: DDOTI Optical Observation
  59. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  60. GRB 250703A: Fermi GBM Final Real-time Localization
  61. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  62. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  63. Fermi GRB 250702E: Global MASTER-Net observations report
  64. Fermi GRB 250702B: Global MASTER-Net observations report
  65. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  66. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  67. GRB 250702F: NOT observations of the optical afterglow
  68. GRB 250702F: MASTER optical afterglow observation
  69. Fermi GRB 250702F: Global MASTER-Net observations report
  70. Fermi GRB 250702C: Global MASTER-Net observations report
  71. GRB 250702F: GOTO optical counterpart detection
  72. GRB 250702F: Ondrejov D50 optical afterglow detection
  73. GRB 250702F: Swift detection of a burst with an optical counterpart
  74. GRB 250702F: Fermi GBM Final Real-time Localization
  75. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  76. GRB 250702E: Fermi GBM Final Real-time Localization
  77. GRB 250702A: Fermi GBM Detection
  78. GRB 250702D: Fermi GBM Final Localization Correction
  79. GRB 250702C: Fermi GBM Final Real-time Localization
  80. GRB 250702B: Fermi GBM Final Real-time Localization
  81. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  82. GRB 250702A: Fermi GBM Final Real-time Localization
  83. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  84. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  85. GRB 250628C: Fermi GBM Final Real-time Localization
  86. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  87. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  88. Fermi GRB 250626A: Global MASTER-Net observations report
  89. GRB 250625A: Leavitt Observatory afterglow detection
  90. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  91. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  92. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  93. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  94. GRB 250626A: Fermi GBM Final Real-time Localization
  95. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  96. GRB 250625A: SVOM/C-GFT upper limit in early phase
  97. GRB 250625A: GECAM-B detection
  98. GRB 250625A: ABObservatory afterglow detection
  99. GRB 250625A: OHP/T193 optical detection
  100. GRB 250625A: COLIBRÍ optical observations

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