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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"

43896 results found.

  1. GRB 250912A: SVOM detection of a burst
  2. GRB 250912A: Fermi GBM Final Real-time Localization
  3. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  4. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  5. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  6. EP250911a: Upper limit from Fermi-GBM Observations
  7. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  8. GRB 250911A: GECAM-B detection
  9. GRB 250911A: Swift-BAT refined analysis
  10. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  11. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  12. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  13. GRB 250910B: SVOM/GRM observation
  14. EP250911a: SVOM/VT optical observation
  15. GRB 250911A: MASTER optical counterpart observations
  16. EP250911a: SAO RAS optical observations
  17. GRB 250911A: Swift-XRT refined Analysis
  18. GRB 250910C: Fermi GBM Final Localization Correction
  19. EP250911a: Swift-XRT observations
  20. EP250911a: Optical detection with Kinder observations
  21. GRB 250911A: Swift/UVOT Detection
  22. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  23. GRB 250909B: Insight-HXMT detection
  24. GRB 250909B: SVOM/GRM observation
  25. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  26. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  27. EP250911a: COLIBRÍ optical observations
  28. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  29. Fermi GRB 250910B: Global MASTER-Net observations report
  30. EP250911a: LCO optical counterpart discovery
  31. EP250910a: Global MASTER-Net observations report
  32. EP250911a: Einstein Probe detection of an X-ray transient
  33. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  34. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  35. GRB 250903A: SVOM/ECLAIRs refined analysis
  36. GRB 250911A: Enhanced Swift-XRT position
  37. GRB 250911A: Swift-XRT observations
  38. GRB 250911A: COLIBRÍ optical counterpart candidate
  39. GRB 250911A: Swift detection of a burst
  40. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  41. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  42. GRB 250910B: Fermi GBM Final Real-time Localization
  43. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  44. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  45. GRB 250909B: AstroSat CZTI detection of a long burst
  46. GRB 250910A: SVOM/VT optical upper limit
  47. GRB 250910A: LCO optical upper limit
  48. GRB 250909A: AstroSat CZTI detection
  49. GRB 250910A: SVOM/MXT possible afterglow detection
  50. GRB 250910A: SVOM detection of a faint burst
  51. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  52. GRB 250702B: Late time Chandra observations
  53. EP#01709240653: Swift-XRT observations
  54. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  55. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  56. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  57. EP250908c: SVOM/VT optical observation
  58. EP250908c: VLT/FORS2 optical counterpart identification
  59. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  60. EP250908b: SVOM/VT optical candidate
  61. The EP-WXT trigger EP250908a/01709240652 is not a real source
  62. EP250908c: Global MASTER-Net observations report
  63. Fermi GRB 250909A: Global MASTER-Net observations report
  64. EP250908c: Einstein Probe detection of an X-ray transient
  65. GRB 250909A: Fermi GBM Final Real-time Localization
  66. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  67. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  68. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  69. GRB 250907A: GECAM-B detection
  70. GRB 250905A: Swift-BAT refined analysis
  71. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  72. GRB 250903A: Swift-XRT afterglow detection
  73. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  74. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  75. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  76. EP250905a: Liverpool Telescope i-band upper limits
  77. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  78. EP250905b: EP-FXT follow-up observation
  79. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  80. EP250905a: Liverpool Telescope observations
  81. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  82. EP250905b: Global MASTER-Net observations report
  83. EP250905b: EP-WXT detection of a fast X-ray transient
  84. EP250905a: FTW one optical and multiple NIR counterpart candidates
  85. GRB 250905A: Swift-XRT refined Analysis
  86. EP250905a: JinShan likely optical counterpart detection
  87. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 250904A: Swift-BAT refined analysis
  89. IceCube Alert 250905.84: Global MASTER-Net observations report
  90. EP250905a: Global MASTER-Net observations report
  91. GRB 250901A - SVOM/ECLAIRs refined analysis
  92. EP250905a: Einstein Probe detection of an X-ray transient
  93. GRB 250905B: Fermi GBM Final Localization
  94. GRB250904A: Liverpool Telescope upper limits
  95. GRB 250905A: Enhanced Swift-XRT position
  96. GRB 250904A: Swift/UVOT Detection
  97. GRB 250903A: Swift/UVOT detection
  98. GRB 250904A: Swift-XRT refined Analysis
  99. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  100. LIGO/Virgo/KAGRA S250904br: Updated Sky localization

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