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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"

42482 results found.

  1. EP250827b: VLA Observations
  2. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  3. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  4. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  5. SVOM/sb25091517: SVOM detection of an X-ray transient
  6. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  7. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  8. GRB 250912A: Swift-XRT observations
  9. GRB250912A: VLT/HAWK-I follow-up observations
  10. GRB 250912A: VLT observations
  11. GRB 250912A: Fermi GBM Observation
  12. GRB 250911A: Insight-HXMT detection
  13. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  14. GRB 250912A:SVOM/VT optical upper limit
  15. GRB 250912A: LCO optical upper limit
  16. The EP-WXT trigger 01709240768 is likely a flaring star
  17. Fermi GRB 250912A: Global MASTER-Net observations report
  18. EP250911a: Global MASTER-Net observations report
  19. GRB 250912A: SVOM detection of a burst
  20. GRB 250912A: Fermi GBM Final Real-time Localization
  21. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  22. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  23. EP250908c: tentative VLT/FORS2 redshift z = 2.87
  24. EP250911a: Upper limit from Fermi-GBM Observations
  25. GRB 250911A: GECAM-B detection
  26. GRB 250911A: Swift-BAT refined analysis
  27. EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
  28. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  29. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 250910B: SVOM/GRM observation
  31. EP250911a: SVOM/VT optical observation
  32. GRB 250911A: MASTER optical counterpart observations
  33. EP250911a: SAO RAS optical observations
  34. GRB 250911A: Swift-XRT refined Analysis
  35. GRB 250910C: Fermi GBM Final Localization Correction
  36. EP250911a: Swift-XRT observations
  37. EP250911a: Optical detection with Kinder observations
  38. GRB 250911A: Swift/UVOT Detection
  39. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  40. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  41. GRB 250909B: Insight-HXMT detection
  42. GRB 250909B: SVOM/GRM observation
  43. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  44. EP250911a: COLIBRÍ optical observations
  45. Fermi GRB 250910B: Global MASTER-Net observations report
  46. EP250911a: LCO optical counterpart discovery
  47. EP250910a: Global MASTER-Net observations report
  48. EP250911a: Einstein Probe detection of an X-ray transient
  49. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  50. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  51. GRB 250903A: SVOM/ECLAIRs refined analysis
  52. GRB 250911A: Enhanced Swift-XRT position
  53. GRB 250911A: Swift-XRT observations
  54. GRB 250911A: COLIBRÍ optical counterpart candidate
  55. GRB 250911A: Swift detection of a burst
  56. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  57. GRB 250910B: Fermi GBM Final Real-time Localization
  58. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  59. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  60. GRB 250909B: AstroSat CZTI detection of a long burst
  61. GRB 250910A: SVOM/VT optical upper limit
  62. EP250908C: GROND observation of the fading optical counterpart
  63. GRB 250910A: LCO optical upper limit
  64. GRB 250909A: AstroSat CZTI detection
  65. GRB 250910A: SVOM/MXT possible afterglow detection
  66. GRB 250910A: SVOM detection of a faint burst
  67. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  68. GRB 250702B: Late time Chandra observations
  69. EP#01709240653: Swift-XRT observations
  70. The EP-WXT trigger 01709240674 is triggered by the known source SS Cyg
  71. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  72. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  73. EP250908c: SVOM/VT optical observation
  74. EP250908c: VLT/FORS2 optical counterpart identification
  75. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  76. EP250908b: SVOM/VT optical candidate
  77. EP250908c: Global MASTER-Net observations report
  78. Fermi GRB 250909A: Global MASTER-Net observations report
  79. EP250908c: Einstein Probe detection of an X-ray transient
  80. GRB 250909A: Fermi GBM Final Real-time Localization
  81. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  82. EP#01709240652 (possibly EP250908a): FTW optical and NIR observations
  83. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  84. GRB 250907A: GECAM-B detection
  85. GRB 250905A: Swift-BAT refined analysis
  86. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  87. GRB 250903A: Swift-XRT afterglow detection
  88. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  89. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  90. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  91. EP250905a: Liverpool Telescope i-band upper limits
  92. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  93. EP250905b: EP-FXT follow-up observation
  94. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  95. EP250905a: Liverpool Telescope observations
  96. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP250905b: Global MASTER-Net observations report
  98. EP250905b: EP-WXT detection of a fast X-ray transient
  99. EP250905a: FTW one optical and multiple NIR counterpart candidates
  100. GRB 250905A: Swift-XRT refined Analysis

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