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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"

24365 results found.

  1. GRB 250713A: EP-FXT counterpart detection
  2. GRB 250706A: Swift-BAT refined analysis
  3. GRB 250702F: Swift-BAT refined analysis
  4. GRB 250628A: Swift-BAT refined analysis
  5. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  6. GRB 250713A: SVOM detection of a long burst
  7. EP250711a: Global MASTER-Net observations report
  8. LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
  9. GRB 250711A: SVOM/GRM observation
  10. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  11. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  12. Fermi GRB 250711A: Global MASTER-Net observations report
  13. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  14. GRB 250711A: Fermi GBM Final Real-time Localization
  15. GRB 250704A: SVOM/ECLAIRs refined analysis
  16. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  17. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  18. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  19. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  20. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  21. IceCube-250708A: No Candidates from WINTER
  22. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  23. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  24. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 250709A: Fermi GBM Final Localization
  26. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  27. EP/WXT 01709181970: GOTO observations confirm stellar variability
  28. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  29. EP250704a/GRB 250704B: 10 GHz VLA detection
  30. The EP-WXT trigger 01709181970 is likely a flaring star
  31. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  32. IceCube-250706A: No Candidates from WINTER
  33. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  34. IceCube-250706A: No Candidates from the Zwicky Transient Facility
  35. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 250704B / EP250704a: VLA radio detection
  37. Fermi GRB 250708A: Global MASTER-Net observations report
  38. IceCube-250708A: Global MASTER-Net observations report
  39. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  40. LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
  41. LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
  42. LIGO/Virgo/KAGRA S250702n: Updated Sky localization
  43. LIGO/Virgo/KAGRA S250701bq: Updated Sky localization
  44. EP250704a/GRB250704B : HCT optical and NIR upper limits
  45. LIGO/Virgo/KAGRA S250701bp: Updated Sky localization
  46. GRB 250708A: Fermi GBM Final Real-time Localization
  47. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  48. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  49. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  50. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  51. IceCube-250706A: EP-FXT follow-up observations
  52. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  53. GRB 250706B/C: Fermi-LAT detection
  54. IceCube-250706A: Global MASTER-Net observations report
  55. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  56. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  57. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250706B: refined SVOM/MXT data analysis
  59. GRB 250706B: REM optical observations
  60. GRB 250706A: REM optical/NIR observations
  61. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  62. Swift GRB 250706A: Global MASTER-Net observations report
  63. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  64. The EP-WXT trigger 01709181580 is likely a flaring star
  65. GRB 250706B: iTelescope optical observations
  66. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 250706B: SVOM/VT optical observation
  68. GRB 250706A: GROWTH-India Telescope optical upper limit
  69. GRB 250706B: SVOM detection of a long burst
  70. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  71. GRB 250703A: EIRSAT-1 GMOD Detection
  72. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  73. Konus-Wind detection of GRB 250703A
  74. IPN triangulation of GRB 250703A
  75. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  76. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  77. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  78. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  79. EP250704a / GRB 250704B: JinShan optical observations
  80. GRB 250704A: SVOM/VT optical observation
  81. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  82. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  83. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  84. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  85. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  86. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  87. GRB 250702B / EP2050702a: FTW optical and NIR observations
  88. Konus-Wind detection of GRB 250702F
  89. EP250704a / GRB 250704B - REM observations
  90. GRB 250702F: GROWTH-India Telescope optical observations
  91. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  92. GRB 250704B: SVOM/GRM observation of a short burst
  93. GRB 250704A: REM detection of the optical afterglow
  94. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  95. GRB 250702F: SVOM/VT optical observation
  96. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  97. GRB 250704A: SVOM detection of a burst
  98. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  99. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  100. Fermi GRB 250703A: Global MASTER-Net observations report

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