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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"

11528 results found.

  1. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  2. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  3. GRB 250717B: COLIBRÍ optical upper limit
  4. GRB 250717B: Swift-XRT observations
  5. GRB 250718B: Fermi GBM Final Localization Correction
  6. GRB 250718B: Fermi GBM Final Real-time Localization
  7. GRB 250717B: Swift ToO observations
  8. GRB 250717B: Fermi GBM Observation
  9. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  10. Konus-Wind detection of GRB 250716A
  11. GRB 250716A: Swift-XRT afterglow detection
  12. GRB 250717B: Fermi GBM Final Real-time Localization
  13. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  14. GRB 250717A: Fermi GBM Final Real-time Localization
  15. GRB 250716A: Swift ToO observations
  16. GRB 250716A: GOTO tentative optical counterpart candidate
  17. GRB 250716A: Fermi GBM Observation
  18. GRB 250714A: SVOM/GRM observation
  19. Fermi GRB 250716A: Global MASTER-Net observations report
  20. GRB 250716A: Fermi GBM Final Real-time Localization
  21. Fermi GRB 250715A: Global MASTER-Net observations report
  22. GRB 250715A: Fermi GBM Final Real-time Localization
  23. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  24. Fermi GRB 250714A: Global MASTER-Net observations report
  25. GRB 250714A: Fermi GBM Final Real-time Localization
  26. GRB 250711A: DDOTI Optical Upper Limit
  27. GRB 250711A: SVOM/GRM observation
  28. Fermi GRB 250711A: Global MASTER-Net observations report
  29. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  30. GRB 250711A: Fermi GBM Final Real-time Localization
  31. GRB 250702B,D,E / EP250702a: ALMA detection
  32. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  33. GRB 250709A: Fermi GBM Final Localization
  34. GRB 250706B/C: Insight-HXMT detection
  35. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  36. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  37. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  38. Fermi GRB 250708A: Global MASTER-Net observations report
  39. GRB 250708A: Fermi GBM Final Real-time Localization
  40. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  41. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  42. GRB 250702F: radio detection with the VLA
  43. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  44. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  45. GRB 250706B/C: Fermi-LAT detection
  46. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250702F: GRANDMA observations
  48. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  49. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  50. GRB 250703A: EIRSAT-1 GMOD Detection
  51. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  52. Konus-Wind detection of GRB 250703A
  53. IPN triangulation of GRB 250703A
  54. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  55. GRB 250702F: Kilonova-Catcher optical afterglow detection
  56. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  57. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  58. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  59. GRB 250702A: Insight-HXMT detection
  60. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  61. GRB 250702B / EP2050702a: FTW optical and NIR observations
  62. Konus-Wind detection of GRB 250702F
  63. GRB 250702F: GROWTH-India Telescope optical observations
  64. EP250702a: WFST optical observations
  65. GRB 250702F: optical photometry from Konkoly
  66. GRB 250702F: SVOM/VT optical observation
  67. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  68. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  69. Fermi GRB 250703A: Global MASTER-Net observations report
  70. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  71. GRB 250702F: Fermi GBM Observation
  72. GRB 250702F: Leavitt Observatory optical observations
  73. GRB 250702F: AKO Optical Afterglow Detection
  74. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  75. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  76. GRB 250702A: GECAM-B detection
  77. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  78. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  79. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  80. GRB 250702F: TRT Optical Observation
  81. GRB 250703A: DDOTI Optical Upper Limit
  82. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  83. GRB 250702F: REM optical afterglow detection
  84. GRB 250702F: DDOTI Optical Observation
  85. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  86. GRB 250703A: Fermi GBM Final Real-time Localization
  87. EP250702a/GRB 250702B,C,D,E: GOTO optical upper limits
  88. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  89. Fermi GRB 250702E: Global MASTER-Net observations report
  90. Fermi GRB 250702B: Global MASTER-Net observations report
  91. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  92. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  93. GRB 250702F: NOT observations of the optical afterglow
  94. GRB 250702F: MASTER optical afterglow observation
  95. Fermi GRB 250702F: Global MASTER-Net observations report
  96. Fermi GRB 250702C: Global MASTER-Net observations report
  97. GRB 250702F: GOTO optical counterpart detection
  98. GRB 250702F: Ondrejov D50 optical afterglow detection
  99. GRB 250702F: Swift detection of a burst with an optical counterpart
  100. GRB 250702F: Fermi GBM Final Real-time Localization

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