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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

32711 results found.

  1. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  2. GRB 250117A: GECAM observation of a short burst
  3. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  4. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  7. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  8. EP250108a / AT2025kg: GMG Optical Observations
  9. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  10. EP250108a / AT2025kg: VLA radio upper limit
  11. Konus-Wind detection of GRB 250116A
  12. GRB 250116A: GECAM-B detection of a long burst
  13. GRB 241217A / EP241217B: radio detection with the VLA
  14. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  15. GRB 250116A: Fermi-LAT detection
  16. GRB 250114B: Swift-XRT afterglow detection
  17. GRB 250114B: SVOM/VT upper limit
  18. EP250108a: MeerKAT radio upper limit
  19. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  20. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  21. Konus-Wind detection of GRB 250113A
  22. IPN triangulation of GRB 250113A
  23. GRB 250114B: Liverpool Telescope optical upper limit
  24. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  25. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  26. GRB 250114A: LCO optical counterpart detection.
  27. GRB 250114B: OHP/T193 optical upper limit
  28. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  29. GRB 250114A: LCOGT optical afterglow i-band detection
  30. GRB 250114B : GIT optical upper limit
  31. GRB 250114B: Swift ToO observations
  32. EP250111a: SAO RAS optical upper limit
  33. EP250108a: correction to GCN 38908
  34. GRB 250113A: INTEGRAL/SPI-ACS detection
  35. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  36. GRB 250114A: REM detection of the optical and NIR counterpart
  37. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  38. GRB 250114A: LCO optical observations
  39. GRB 250114A: TRT optical observations
  40. Swift GRB 250114A: Global MASTER-Net observations report
  41. GRB 250101A: Terskol Zeiss-2000 optical observations
  42. EP250108a / AT 2025kg: SAO RAS optical observations
  43. EP241021a: SMA radio observation
  44. GRB 250107A: VZLUSAT-2 detection
  45. GRB 250109A / EP250109a: GRBAlpha detection
  46. GRB 250107D: GRBAlpha detection
  47. EP250111a: KAIT optical observations
  48. GRB 250109A / EP250109a: Mephisto optical upper limits
  49. EP250108a: Mephisto detection
  50. EP250111a: Mondy optical observation
  51. EP250108a / AT 2025kg: LCO optical observations
  52. EP250111a: Global MASTER-Net observations report
  53. EP250111a: Swift/XRT detection and fading
  54. EP250108a / AT 2025kg: Swift UVOT detections
  55. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  56. EP250108a: optical follow-up observations with the Liverpool Telescope
  57. EP250111a: NOT likely optical counterpart
  58. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  59. GRB 250101B: Fermi GBM Observation
  60. EP250108a: further NOT optical observations
  61. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  62. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  63. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  64. GRB 250108A: Swift/XRT afterglow fading
  65. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  66. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  67. Konus-Wind detection of GRB 250107C
  68. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  69. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  70. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  71. GRB 250101A: CMO RC-500 optical observations
  72. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  73. EP250108a: EP-FXT follow-up observation
  74. GRB 250109A: Fermi GBM Observation
  75. EP250108a: NOT optical observations
  76. GRB 250109a: GMG Optical Upper Limit
  77. EP250109a: Swift/UVOT non-detection
  78. Konus-Wind detection of GRB 250107D (short/hard)
  79. IPN triangulation of GRB 250107D (short/hard)
  80. IPN triangulation of GRB 250107C
  81. EP250108a: Liverpool Telescope likely optical counterpart
  82. GRB 250108B: Gemini-North likely redshift z = 2.197
  83. GRB 250108B: Swift-BAT refined analysis
  84. GRB 250108B: 1.3m DFOT upper limit
  85. GRB 250108B: REM optical/NIR upper limits
  86. GRB 250109A /EP250109a: Fermi GBM Final Localization
  87. EP250109a: SVOM/VT optical candidate
  88. EP250109a: Global MASTER-Net observations report
  89. GRB 250101A: Terskol K-800 optical observations
  90. EP250109a: GOTO optical upper limits
  91. EP250109a: Swift/XRT non-detection
  92. GRB 250108A: Swift/UVOT Upper Limits
  93. EP250108a: Global MASTER-Net observations report
  94. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  95. GRB 250108A: NOT optical upper limit
  96. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  97. Swift GRB 250108B: Global MASTER-Net observations report
  98. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  99. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  100. GRB 250103A: 1.6m Mephisto optical observations

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