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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"

32505 results found.

  1. EP250108a / AT2025kg: GMG Optical Observations
  2. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  3. EP250108a / AT2025kg: VLA radio upper limit
  4. Konus-Wind detection of GRB 250116A
  5. GRB 250116A: GECAM-B detection of a long burst
  6. GRB 241217A / EP241217B: radio detection with the VLA
  7. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  8. GRB 250116A: Fermi-LAT detection
  9. GRB 250114B: Swift-XRT afterglow detection
  10. GRB 250114B: SVOM/VT upper limit
  11. EP250108a: MeerKAT radio upper limit
  12. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  13. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  14. Konus-Wind detection of GRB 250113A
  15. IPN triangulation of GRB 250113A
  16. GRB 250114B: Liverpool Telescope optical upper limit
  17. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  18. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  19. GRB 250114A: LCO optical counterpart detection.
  20. GRB 250114B: OHP/T193 optical upper limit
  21. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  22. GRB 250114A: LCOGT optical afterglow i-band detection
  23. GRB 250114B : GIT optical upper limit
  24. GRB 250114B: Swift ToO observations
  25. EP250111a: SAO RAS optical upper limit
  26. EP250108a: correction to GCN 38908
  27. GRB 250113A: INTEGRAL/SPI-ACS detection
  28. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  29. GRB 250114A: REM detection of the optical and NIR counterpart
  30. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  31. GRB 250114A: LCO optical observations
  32. GRB 250114A: TRT optical observations
  33. Swift GRB 250114A: Global MASTER-Net observations report
  34. GRB 250101A: Terskol Zeiss-2000 optical observations
  35. EP250108a / AT 2025kg: SAO RAS optical observations
  36. EP241021a: SMA radio observation
  37. GRB 250107A: VZLUSAT-2 detection
  38. GRB 250109A / EP250109a: GRBAlpha detection
  39. GRB 250107D: GRBAlpha detection
  40. EP250111a: KAIT optical observations
  41. GRB 250109A / EP250109a: Mephisto optical upper limits
  42. EP250108a: Mephisto detection
  43. EP250111a: Mondy optical observation
  44. EP250108a / AT 2025kg: LCO optical observations
  45. EP250111a: Global MASTER-Net observations report
  46. EP250111a: Swift/XRT detection and fading
  47. EP250108a / AT 2025kg: Swift UVOT detections
  48. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  49. EP250108a: optical follow-up observations with the Liverpool Telescope
  50. EP250111a: NOT likely optical counterpart
  51. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  52. GRB 250101B: Fermi GBM Observation
  53. EP250108a: further NOT optical observations
  54. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  55. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  57. GRB 250108A: Swift/XRT afterglow fading
  58. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  59. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  60. Konus-Wind detection of GRB 250107C
  61. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  62. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  63. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  64. GRB 250101A: CMO RC-500 optical observations
  65. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  66. EP250108a: EP-FXT follow-up observation
  67. GRB 250109A: Fermi GBM Observation
  68. EP250108a: NOT optical observations
  69. GRB 250109a: GMG Optical Upper Limit
  70. EP250109a: Swift/UVOT non-detection
  71. Konus-Wind detection of GRB 250107D (short/hard)
  72. IPN triangulation of GRB 250107D (short/hard)
  73. IPN triangulation of GRB 250107C
  74. EP250108a: Liverpool Telescope likely optical counterpart
  75. GRB 250108B: Gemini-North likely redshift z = 2.197
  76. GRB 250108B: Swift-BAT refined analysis
  77. GRB 250108B: 1.3m DFOT upper limit
  78. GRB 250108B: REM optical/NIR upper limits
  79. GRB 250109A /EP250109a: Fermi GBM Final Localization
  80. EP250109a: SVOM/VT optical candidate
  81. EP250109a: Global MASTER-Net observations report
  82. GRB 250101A: Terskol K-800 optical observations
  83. EP250109a: GOTO optical upper limits
  84. EP250109a: Swift/XRT non-detection
  85. GRB 250108A: Swift/UVOT Upper Limits
  86. EP250108a: Global MASTER-Net observations report
  87. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  88. GRB 250108A: NOT optical upper limit
  89. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  90. Swift GRB 250108B: Global MASTER-Net observations report
  91. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  92. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  93. GRB 250103A: 1.6m Mephisto optical observations
  94. GRB 250108A:SVOM/VT optical candidate
  95. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  96. GRB 250108B: Swift/UVOT Upper Limits
  97. GRB 250108A: Swift ToO observations
  98. GRB 250107A: Fermi GBM Observation
  99. GRB 241228B: Fermi-LAT detection
  100. Fermi GRB 250107B: Global MASTER-Net observations report

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