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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"

32769 results found.

  1. EP250908c: SVOM/VT optical observation
  2. EP250908c: VLT/FORS2 optical counterpart identification
  3. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  4. EP250908b: SVOM/VT optical candidate
  5. EP250908c: Global MASTER-Net observations report
  6. Fermi GRB 250909A: Global MASTER-Net observations report
  7. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  8. GRB 250905A: Swift-BAT refined analysis
  9. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  10. GRB 250903A: Swift-XRT afterglow detection
  11. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  12. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  13. EP250905a: Liverpool Telescope i-band upper limits
  14. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  15. EP250905b: EP-FXT follow-up observation
  16. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  17. EP250905a: Liverpool Telescope observations
  18. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  19. EP250905b: Global MASTER-Net observations report
  20. EP250905a: FTW one optical and multiple NIR counterpart candidates
  21. EP250905a: JinShan likely optical counterpart detection
  22. GRB 250904A: Swift-BAT refined analysis
  23. GRB 250905A: Swift/UVOT Upper Limits
  24. EP250905a: Global MASTER-Net observations report
  25. GRB 250901A - SVOM/ECLAIRs refined analysis
  26. GRB250904A: Liverpool Telescope upper limits
  27. GRB 250904A: Swift/UVOT Detection
  28. GRB 250903A: Swift/UVOT detection
  29. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  30. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  31. GRB 250905A: KAIT optical upper limit
  32. Swift GRB 250904A: Global MASTER-Net observations report
  33. GRB 250904A: TRT optical counterpart detection
  34. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  35. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  36. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  37. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  38. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  39. GRB 250902A: VZLUSAT-2 detection
  40. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  41. GRB 250903A: Swift-XRT observations
  42. EP250903a: Swift-XRT observations
  43. EP#01709201209: Swift-XRT observations
  44. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  45. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  46. GRB 250830C: VZLUSAT-2 detection
  47. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  48. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  49. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  50. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  51. GRB 250903A: EP-FXT counterpart detection
  52. GRB 250902A: GECAM-B detection
  53. GRB 250903A: LCO optical observation
  54. GRB 250903A: LCO optical afterglow detection
  55. GRB 250903A: SVOM/VT optical confirmation with VHF data
  56. EP250903a: SVOM/VT optical confirmation
  57. EP250901a: Mondy, Assy and SAO RAS optical limits
  58. Subject GRB 250903A: SVOM/MXT afterglow detection
  59. EP250903a: LCO candidate counterpart discovery
  60. GRB 250903A: TRT optical counterpart detection
  61. GRB 250902B: AstroSat CZTI detection
  62. EP250903a: Global MASTER-Net observations report
  63. EP250903a: TRT optical observations
  64. EP250903a: Einstein Probe detection of an X-ray transient
  65. EP 250827B: Detection of supernova counterpart by LCO.
  66. EP250827b / AT 2025wkm: TRT optical observations
  67. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  68. EP250827b: continued Liverpool Telescope observations
  69. GRB 250902B: SVOM/GRM observation
  70. EP250827b: SVOM/VT observation of AT 2025wkm
  71. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  72. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  73. Fermi GRB 250902B: Global MASTER-Net observations report
  74. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  75. GRB 250902A: Fermi GBM Detection
  76. GRB 250901A: Swift/UVOT Upper Limit
  77. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  78. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  79. EP250827b: Liverpool Telescope observations
  80. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  81. GRB 250902A: SVOM/GRM observation
  82. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  83. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  84. GRB 250901A: EP-FXT follow-up observation
  85. GRB 250901A: NOT optical observations
  86. GRB 250901A: SVOM/VT optical afterglow with VHF data
  87. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  88. GRB 250901A: LCO optical upper limit
  89. EP250827b: Swift observations of AT 2025wkm
  90. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  91. EP250827b: Gemini Spectroscopy of AT 2025wkm
  92. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  93. EP250831a: NOT optical observations and tentative afterglow candidate
  94. EP250827b: FTW Observations of AT 2025wkm
  95. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  96. GRB 250830C: Insight-HXMT detection
  97. EP250901a: Mephisto optical upper limits
  98. EP250901a: Global MASTER-Net observations report
  99. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  100. EP250831a: EP-FXT follow-up observation

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