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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"

43012 results found.

  1. GRB 250912A: VLT observations
  2. GRB 250912A: Fermi GBM Observation
  3. GRB 250911A: Insight-HXMT detection
  4. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  5. GRB 250912A:SVOM/VT optical upper limit
  6. GRB 250912A: LCO optical upper limit
  7. The EP-WXT trigger 01709240768 is likely a flaring star
  8. Fermi GRB 250912A: Global MASTER-Net observations report
  9. EP250911a: Global MASTER-Net observations report
  10. GRB 250912A: SVOM detection of a burst
  11. GRB 250912A: Fermi GBM Final Real-time Localization
  12. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  13. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  14. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  15. EP250911a: Upper limit from Fermi-GBM Observations
  16. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  17. GRB 250911A: GECAM-B detection
  18. GRB 250911A: Swift-BAT refined analysis
  19. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  20. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  21. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  22. GRB 250910B: SVOM/GRM observation
  23. EP250911a: SVOM/VT optical observation
  24. GRB 250911A: MASTER optical counterpart observations
  25. EP250911a: SAO RAS optical observations
  26. GRB 250911A: Swift-XRT refined Analysis
  27. GRB 250910C: Fermi GBM Final Localization Correction
  28. EP250911a: Swift-XRT observations
  29. EP250911a: Optical detection with Kinder observations
  30. GRB 250911A: Swift/UVOT Detection
  31. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  32. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  33. GRB 250909B: Insight-HXMT detection
  34. GRB 250909B: SVOM/GRM observation
  35. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  36. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  37. EP250911a: COLIBRÍ optical observations
  38. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  39. Fermi GRB 250910B: Global MASTER-Net observations report
  40. EP250911a: LCO optical counterpart discovery
  41. EP250910a: Global MASTER-Net observations report
  42. EP250911a: Einstein Probe detection of an X-ray transient
  43. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  44. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  45. GRB 250903A: SVOM/ECLAIRs refined analysis
  46. GRB 250911A: Enhanced Swift-XRT position
  47. GRB 250911A: Swift-XRT observations
  48. GRB 250911A: COLIBRÍ optical counterpart candidate
  49. GRB 250911A: Swift detection of a burst
  50. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  51. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  52. GRB 250910B: Fermi GBM Final Real-time Localization
  53. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  54. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  55. GRB 250909B: AstroSat CZTI detection of a long burst
  56. GRB 250910A: SVOM/VT optical upper limit
  57. EP250908C: GROND observation of the fading optical counterpart
  58. GRB 250910A: LCO optical upper limit
  59. GRB 250909A: AstroSat CZTI detection
  60. GRB 250910A: SVOM/MXT possible afterglow detection
  61. GRB 250910A: SVOM detection of a faint burst
  62. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  63. GRB 250702B: Late time Chandra observations
  64. EP250908b/EP#01709240653: Swift/UVOT Detection
  65. EP#01709240653: Swift-XRT observations
  66. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  67. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  69. EP250908c: SVOM/VT optical observation
  70. EP250908c: VLT/FORS2 optical counterpart identification
  71. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  72. EP250908b: SVOM/VT optical candidate
  73. EP250908c: Global MASTER-Net observations report
  74. Fermi GRB 250909A: Global MASTER-Net observations report
  75. EP250908c: Einstein Probe detection of an X-ray transient
  76. GRB 250909A: Fermi GBM Final Real-time Localization
  77. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  78. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  79. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  80. GRB 250907A: GECAM-B detection
  81. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  82. GRB 250903A: Swift-XRT afterglow detection
  83. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  84. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  85. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  86. EP250905a: Liverpool Telescope i-band upper limits
  87. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  88. EP250905b: EP-FXT follow-up observation
  89. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  90. EP250905a: Liverpool Telescope observations
  91. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  92. EP250905b: Global MASTER-Net observations report
  93. EP250905b: EP-WXT detection of a fast X-ray transient
  94. EP250905a: FTW one optical and multiple NIR counterpart candidates
  95. GRB 250905A: Swift-XRT refined Analysis
  96. EP250905a: JinShan likely optical counterpart detection
  97. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  98. IceCube Alert 250905.84: Global MASTER-Net observations report
  99. GRB 250905A: Swift/UVOT Upper Limits
  100. EP250905a: Global MASTER-Net observations report

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