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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"

11556 results found.

  1. GRB 250725A: SVOM/GRM observation
  2. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  3. GRB 250725A: Fermi-LAT detection
  4. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  5. GRB 250725A: SVOM/VT optical candidate
  6. GRB 250725A: Fermi GBM Final Real-time Localization
  7. Fermi GRB 250725A: Global MASTER-Net observations report
  8. GRB 250723B: Fermi GBM Final Real-time Localization
  9. GRB 250721A: Fermi GBM Observation
  10. GRB 250723A: Fermi GBM Final Real-time Localization
  11. GRB 250722A: Fermi GBM Final Real-time Localization
  12. GRB 250717B: SVOM/GRM observation
  13. GRB 250721A: MAXI/GSC detection
  14. GRB 250721A: Fermi GBM Final Localization
  15. GRB 250720B: Fermi GBM Final Localization Correction
  16. GRB 250720A: Fermi GBM Final Localization
  17. Fermi trigger No 774730635: Global MASTER-Net observations report
  18. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  19. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  20. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  21. GRB 250717B: COLIBRÍ optical upper limit
  22. GRB 250717B: Swift-XRT observations
  23. GRB 250718B: Fermi GBM Final Localization Correction
  24. GRB 250718B: Fermi GBM Final Real-time Localization
  25. GRB 250717B: Swift ToO observations
  26. GRB 250717B: Fermi GBM Observation
  27. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  28. Konus-Wind detection of GRB 250716A
  29. GRB 250716A: Swift-XRT afterglow detection
  30. GRB 250717B: Fermi GBM Final Real-time Localization
  31. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  32. GRB 250717A: Fermi GBM Final Real-time Localization
  33. GRB 250716A: Swift ToO observations
  34. GRB 250716A: GOTO tentative optical counterpart candidate
  35. GRB 250716A: Fermi GBM Observation
  36. GRB 250714A: SVOM/GRM observation
  37. Fermi GRB 250716A: Global MASTER-Net observations report
  38. GRB 250716A: Fermi GBM Final Real-time Localization
  39. Fermi GRB 250715A: Global MASTER-Net observations report
  40. GRB 250715A: Fermi GBM Final Real-time Localization
  41. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  42. Fermi GRB 250714A: Global MASTER-Net observations report
  43. GRB 250714A: Fermi GBM Final Real-time Localization
  44. GRB 250711A: DDOTI Optical Upper Limit
  45. GRB 250711A: SVOM/GRM observation
  46. Fermi GRB 250711A: Global MASTER-Net observations report
  47. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  48. GRB 250711A: Fermi GBM Final Real-time Localization
  49. GRB 250702B,D,E / EP250702a: ALMA detection
  50. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  51. GRB 250709A: Fermi GBM Final Localization
  52. GRB 250706B/C: Insight-HXMT detection
  53. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  54. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  55. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  56. Fermi GRB 250708A: Global MASTER-Net observations report
  57. GRB 250708A: Fermi GBM Final Real-time Localization
  58. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  59. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  60. GRB 250702F: radio detection with the VLA
  61. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  62. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  63. GRB 250706B/C: Fermi-LAT detection
  64. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  65. GRB 250702F: GRANDMA observations
  66. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  68. GRB 250703A: EIRSAT-1 GMOD Detection
  69. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  70. Konus-Wind detection of GRB 250703A
  71. IPN triangulation of GRB 250703A
  72. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  73. GRB 250702F: Kilonova-Catcher optical afterglow detection
  74. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  75. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  76. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  77. GRB 250702A: Insight-HXMT detection
  78. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  79. GRB 250702B / EP2050702a: FTW optical and NIR observations
  80. Konus-Wind detection of GRB 250702F
  81. GRB 250702F: GROWTH-India Telescope optical observations
  82. EP250702a: WFST optical observations
  83. GRB 250702F: optical photometry from Konkoly
  84. GRB 250702F: SVOM/VT optical observation
  85. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  86. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  87. Fermi GRB 250703A: Global MASTER-Net observations report
  88. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  89. GRB 250702F: Fermi GBM Observation
  90. GRB 250702F: Leavitt Observatory optical observations
  91. GRB 250702F: AKO Optical Afterglow Detection
  92. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  93. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  94. GRB 250702A: GECAM-B detection
  95. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  96. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  97. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  98. GRB 250702F: TRT Optical Observation
  99. GRB 250703A: DDOTI Optical Upper Limit
  100. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity

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