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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"

26672 results found.

  1. GRB 250905A: Swift-XRT refined Analysis
  2. EP250905a: JinShan likely optical counterpart detection
  3. GRB 250905A: Swift/UVOT Upper Limits
  4. GRB 250901A - SVOM/ECLAIRs refined analysis
  5. EP250905a: Einstein Probe detection of an X-ray transient
  6. GRB250904A: Liverpool Telescope upper limits
  7. GRB 250905A: Enhanced Swift-XRT position
  8. GRB 250904A: Swift/UVOT Detection
  9. GRB 250903A: Swift/UVOT detection
  10. GRB 250904A: Swift-XRT refined Analysis
  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. GRB 250904A: Enhanced Swift-XRT position
  15. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  16. GRB 250904A: TRT optical counterpart detection
  17. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  18. GRB 250904A: Swift detection of a burst
  19. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  20. GRB 250902A: VZLUSAT-2 detection
  21. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  22. GRB 250903A: Swift-XRT observations
  23. EP250903a: Swift-XRT observations
  24. EP#01709201209: Swift-XRT observations
  25. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  26. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  27. GRB 250830C: VZLUSAT-2 detection
  28. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  29. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  30. The EP-WXT trigger 01709201209 is likely a flaring star
  31. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  32. GRB 250902A: GECAM-B detection
  33. GRB 250903A: LCO optical observation
  34. GRB 250903A: LCO optical afterglow detection
  35. GRB 250903A: SVOM/VT optical confirmation with VHF data
  36. EP250901a: Mondy, Assy and SAO RAS optical limits
  37. GRB 250903A: TRT optical counterpart detection
  38. GRB 250902B: AstroSat CZTI detection
  39. GRB 250903A: SVOM detection of a burst
  40. EP250903a: TRT optical observations
  41. EP250903a: Einstein Probe detection of an X-ray transient
  42. EP 250827B: Detection of supernova counterpart by LCO.
  43. GRB 250902B: SVOM/GRM observation
  44. EP250827b: SVOM/VT observation of AT 2025wkm
  45. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  46. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  47. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  48. GRB 250902A: Fermi GBM Detection
  49. GRB 250901A: Swift/UVOT Upper Limit
  50. GRB 250902B: Fermi GBM Final Real-time Localization
  51. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 250830B: Swift-XRT afterglow detection
  53. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  54. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  55. GRB 250902A: SVOM/GRM observation
  56. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  57. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  58. GRB 250901A: EP-FXT follow-up observation
  59. GRB 250902A: Fermi GBM Final Real-time Localization
  60. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 250901A: SVOM/VT optical afterglow with VHF data
  62. GRB 250901A: Swift-XRT afterglow detection
  63. EP250901a: Swift-XRT observations
  64. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  65. GRB 250901A: LCO optical upper limit
  66. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  67. EP250831a: NOT optical observations and tentative afterglow candidate
  68. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  69. GRB 250901A: SVOM detection of a burst
  70. EP250901a: Mephisto optical upper limits
  71. GRB 250830C: GECAM-B detection
  72. EP250901a: Einstein Probe detection of an X-ray transient
  73. EP250831a: EP-FXT follow-up observation
  74. EP250831a: Swift-XRT observations
  75. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  76. EP250831a: EP-WXT detection of a fast X-ray transient
  77. GRB 250831A: Swift-XRT counterpart detection
  78. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  79. GRB 250831A: SVOM/VT upper limit with VHF data
  80. GRB 250831A: SVOM detection of a soft burst
  81. GRB 250830B: Swift-XRT observations
  82. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  83. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  84. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  85. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  86. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  87. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  88. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  89. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  90. The EP-WXT trigger 01709200994 is likely a flaring star
  91. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  92. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  93. GRB 250808B: SVOM detection of a burst through offline search
  94. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  95. EP250828a: Optical counterpart detection with Kinder observations
  96. EP250828a: Liverpool Telescope upper limits
  97. EP-WXT trigger 01709200800 : KAIT optical observations
  98. EP250828a: KAIT optical upper limit
  99. EP250827a: Swift/UVOT Detection
  100. EP250828a: NOT optical counterpart confirmation

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