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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"
  1. EP250108a / SN 2025kg: Refined Analysis of EP-WXT Detection
  2. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  3. GRB 250126A: Fermi GBM Final Real-time Localization
  4. GECAM-A detection of a bright burst from SGR 1E1841-045
  5. GRB 250118A: Fermi GBM Observation
  6. EP250125a: Optical upper limit with Kinder observations
  7. EP250125a: REM optical counterpart detection
  8. GRB 250119C: Fermi GBM Observation
  9. EP250125a: Swift/XRT detection of a fading counterpart
  10. EP250125a: a new X-ray transient detected by Einstein Probe
  11. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  12. The EP-WXT trigger 01709130758 is a false trigger
  13. The EP-WXT trigger 01709130758 is a false trigger
  14. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  15. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  16. IPN triangulation of a bright burst from SGR 1E1841-045
  17. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  18. EP250108a: AbAO, CMO and Terskol optical upper limits
  19. Konus-Wind detection of GRB 250118B
  20. GRB 250121A: Fermi GBM Observation
  21. IPN triangulation of GRB 250118B
  22. Konus-Wind detection of GRB 250119B
  23. IPN triangulation of GRB 250119B
  24. GRB 250122A: Fermi GBM Final Real-time Localization
  25. Improved IPN triangulation of GRB 250107C
  26. GRB 250114A: Swift-BAT refined analysis
  27. GRB 250121A: INTEGRAL/SPI-ACS detection
  28. GRB 250121A: Fermi-LAT detection
  29. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  30. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  31. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  32. GRB 250121A: Fermi GBM Final Real-time Localization
  33. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  34. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  35. GRB 250119B: Fermi GBM Observation
  36. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  37. Konus-Wind detection of GRB 250117A
  38. IPN triangulation of GRB 250117A (short)
  39. ATCA detection of possible radio counterpart to GRB 250114A
  40. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  41. GRB 250119B: INTEGRAL/SPI-ACS detection
  42. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  43. EP 250108A: Late-time optical observation by LCO
  44. GRB 250117A: SVOM/GRM observation of a short burst
  45. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  46. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  47. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  48. GRB 250119C: Fermi GBM Final Real-time Localization
  49. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  50. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  51. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  52. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  54. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  55. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  56. GRB 250117A: GECAM observation of a short burst
  57. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  58. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  59. GRB 250119B: Fermi GBM Final Real-time Localization
  60. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  61. GRB 250119A: Fermi GBM Final Real-time Localization
  62. GRB 250118A: Fermi GBM Final Real-time Localization
  63. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  65. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  66. EP250108a / AT2025kg: GMG Optical Observations
  67. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  68. EP250108a / AT2025kg: VLA radio upper limit
  69. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  70. Konus-Wind detection of GRB 250116A
  71. GRB 250116A: GECAM-B detection of a long burst
  72. GRB 241217A / EP241217B: radio detection with the VLA
  73. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  74. Swift Trigger 1282245 is not a GRB
  75. GRB 250116A: Fermi-LAT detection
  76. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  77. GRB 250114B: Swift-XRT afterglow detection
  78. GRB 250114B: SVOM/VT upper limit
  79. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  80. EP250108a: MeerKAT radio upper limit
  81. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  82. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  83. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  84. Konus-Wind detection of GRB 250113A
  85. IPN triangulation of GRB 250113A
  86. GRB 250114B: Liverpool Telescope optical upper limit
  87. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  88. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  89. GRB 250114B: Swift-XRT observations
  90. GRB 250114A: LCO optical counterpart detection.
  91. GRB 250114B: OHP/T193 optical upper limit
  92. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  93. GRB 250114A: Swift-XRT refined Analysis
  94. Integral GRB250114.55: Global MASTER-Net observations report
  95. GRB 250114A: LCOGT optical afterglow i-band detection
  96. GRB 250114B : GIT optical upper limit
  97. GRB 250114B: Swift ToO observations
  98. EP250111a: SAO RAS optical upper limit
  99. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  100. GRB 250114B: a short GRB detected with INTEGRAL

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