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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"

32751 results found.

  1. EP250905b: Global MASTER-Net observations report
  2. EP250905a: FTW one optical and multiple NIR counterpart candidates
  3. EP250905a: JinShan likely optical counterpart detection
  4. GRB 250904A: Swift-BAT refined analysis
  5. GRB 250905A: Swift/UVOT Upper Limits
  6. EP250905a: Global MASTER-Net observations report
  7. GRB 250901A - SVOM/ECLAIRs refined analysis
  8. GRB250904A: Liverpool Telescope upper limits
  9. GRB 250904A: Swift/UVOT Detection
  10. GRB 250903A: Swift/UVOT detection
  11. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  12. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  13. GRB 250905A: KAIT optical upper limit
  14. Swift GRB 250904A: Global MASTER-Net observations report
  15. GRB 250904A: TRT optical counterpart detection
  16. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  17. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  18. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  19. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  20. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  21. GRB 250902A: VZLUSAT-2 detection
  22. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  23. GRB 250903A: Swift-XRT observations
  24. EP250903a: Swift-XRT observations
  25. EP#01709201209: Swift-XRT observations
  26. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  27. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  28. GRB 250830C: VZLUSAT-2 detection
  29. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  30. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  31. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  32. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  33. GRB 250903A: EP-FXT counterpart detection
  34. GRB 250902A: GECAM-B detection
  35. GRB 250903A: LCO optical observation
  36. GRB 250903A: LCO optical afterglow detection
  37. GRB 250903A: SVOM/VT optical confirmation with VHF data
  38. EP250903a: SVOM/VT optical confirmation
  39. EP250901a: Mondy, Assy and SAO RAS optical limits
  40. Subject GRB 250903A: SVOM/MXT afterglow detection
  41. EP250903a: LCO candidate counterpart discovery
  42. GRB 250903A: TRT optical counterpart detection
  43. GRB 250902B: AstroSat CZTI detection
  44. EP250903a: Global MASTER-Net observations report
  45. EP250903a: TRT optical observations
  46. EP250903a: Einstein Probe detection of an X-ray transient
  47. EP 250827B: Detection of supernova counterpart by LCO.
  48. EP250827b / AT 2025wkm: TRT optical observations
  49. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  50. EP250827b: continued Liverpool Telescope observations
  51. GRB 250902B: SVOM/GRM observation
  52. EP250827b: SVOM/VT observation of AT 2025wkm
  53. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  54. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  55. Fermi GRB 250902B: Global MASTER-Net observations report
  56. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  57. GRB 250902A: Fermi GBM Detection
  58. GRB 250901A: Swift/UVOT Upper Limit
  59. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  60. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  61. EP250827b: Liverpool Telescope observations
  62. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  63. GRB 250902A: SVOM/GRM observation
  64. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  65. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 250901A: EP-FXT follow-up observation
  67. GRB 250901A: NOT optical observations
  68. GRB 250901A: SVOM/VT optical afterglow with VHF data
  69. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  70. GRB 250901A: LCO optical upper limit
  71. EP250827b: Swift observations of AT 2025wkm
  72. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  73. EP250827b: Gemini Spectroscopy of AT 2025wkm
  74. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  75. EP250831a: NOT optical observations and tentative afterglow candidate
  76. EP250827b: FTW Observations of AT 2025wkm
  77. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  78. GRB 250830C: Insight-HXMT detection
  79. EP250901a: Mephisto optical upper limits
  80. EP250901a: Global MASTER-Net observations report
  81. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  82. EP250831a: EP-FXT follow-up observation
  83. EP250831a: Swift-XRT observations
  84. EP250831a: Global MASTER-Net observations report
  85. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  86. GRB 250831A: Swift-XRT counterpart detection
  87. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB 250831A: SVOM/VT upper limit with VHF data
  89. EP250830a: Global MASTER-Net observations report
  90. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  91. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  92. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  93. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  94. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  95. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  96. GRB 250830B: Swift ToO observations
  97. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  98. GRB 250828B: Swift-BAT refined analysis
  99. EP250821a: SOAR observations
  100. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger

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