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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 250901A - SVOM/ECLAIRs refined analysis
  2. EP250905a: Einstein Probe detection of an X-ray transient
  3. GRB 250905B: Fermi GBM Final Localization
  4. GRB250904A: Liverpool Telescope upper limits
  5. GRB 250905A: Enhanced Swift-XRT position
  6. GRB 250904A: Swift/UVOT Detection
  7. GRB 250903A: Swift/UVOT detection
  8. GRB 250904A: Swift-XRT refined Analysis
  9. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  10. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  11. EP detected a brightening of LMXB 1ES 1735-26.9
  12. GRB 250905A: KAIT optical upper limit
  13. GRB 250905A: Swift detection of a burst
  14. Swift GRB250905.09: Global MASTER-Net observations report
  15. Swift GRB 250904A: Global MASTER-Net observations report
  16. GRB 250904A: Enhanced Swift-XRT position
  17. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  18. GRB 250904A: TRT optical counterpart detection
  19. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  20. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  21. GRB 250904A: Prompt enhanced Swift-XRT position
  22. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  23. GRB 250904A: Swift detection of a burst
  24. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  25. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  26. GRB 250902A: VZLUSAT-2 detection
  27. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  28. GRB 250903A: Swift-XRT observations
  29. EP250903a: Swift-XRT observations
  30. EP#01709201209: Swift-XRT observations
  31. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  32. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  33. GRB 250830C: VZLUSAT-2 detection
  34. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  35. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  36. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  37. The EP-WXT trigger 01709201209 is likely a flaring star
  38. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  39. GRB 250903A: EP-FXT counterpart detection
  40. GRB 250902A: GECAM-B detection
  41. GRB 250903A: LCO optical observation
  42. GRB 250903A: LCO optical afterglow detection
  43. GRB 250903A: SVOM/VT optical confirmation with VHF data
  44. EP250903a: SVOM/VT optical confirmation
  45. EP250901a: Mondy, Assy and SAO RAS optical limits
  46. Subject GRB 250903A: SVOM/MXT afterglow detection
  47. EP250903a: LCO candidate counterpart discovery
  48. GRB 250903A: TRT optical counterpart detection
  49. GRB 250902B: AstroSat CZTI detection
  50. GRB 250903A: SVOM detection of a burst
  51. EP250903a: Global MASTER-Net observations report
  52. EP250903a: TRT optical observations
  53. EP250903a: Einstein Probe detection of an X-ray transient
  54. EP 250827B: Detection of supernova counterpart by LCO.
  55. EP/WXT01709201159: GOTO optical follow-up
  56. EP250827b / AT 2025wkm: TRT optical observations
  57. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  58. EP250827b: continued Liverpool Telescope observations
  59. GRB 250902B: SVOM/GRM observation
  60. EP250827b: SVOM/VT observation of AT 2025wkm
  61. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  62. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  63. Fermi GRB 250902B: Global MASTER-Net observations report
  64. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  65. GRB 250902A: Fermi GBM Detection
  66. GRB 250901A: Swift/UVOT Upper Limit
  67. GRB 250902B: Fermi GBM Final Real-time Localization
  68. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  69. GRB 250830B: Swift-XRT afterglow detection
  70. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  71. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  72. EP250827b: Liverpool Telescope observations
  73. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  74. GRB 250902A: SVOM/GRM observation
  75. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  76. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  77. GRB 250901A: EP-FXT follow-up observation
  78. GRB 250901A: NOT optical observations
  79. GRB 250902A: Fermi GBM Final Real-time Localization
  80. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 250901A: SVOM/VT optical afterglow with VHF data
  82. GRB 250901A: Swift-XRT afterglow detection
  83. EP250901a: Swift-XRT observations
  84. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  85. GRB 250901A: LCO optical upper limit
  86. EP250827b: Swift observations of AT 2025wkm
  87. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  88. EP250827b: Gemini Spectroscopy of AT 2025wkm
  89. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  90. EP250831a: NOT optical observations and tentative afterglow candidate
  91. EP250827b: FTW Observations of AT 2025wkm
  92. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  93. GRB 250901A: SVOM detection of a burst
  94. GRB 250831B: SVOM/GRM observation
  95. GRB 250830C: Insight-HXMT detection
  96. EP250901a: Mephisto optical upper limits
  97. GRB 250830C: GECAM-B detection
  98. EP250901a: Global MASTER-Net observations report
  99. GRB 250830C: AstroSat CZTI detection of a long burst
  100. EP250901a: Einstein Probe detection of an X-ray transient

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