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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"

27222 results found.

  1. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  2. GRB 250210A: SVOM/GRM observation of a long burst
  3. EP250207b: Global MASTER-Net observations report
  4. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  5. GRB 250207A: Skynet optical afterglow observations
  6. EP250207b: Gemini GMOS-N z-band observations
  7. EP250207A: Upper limits from Fermi-GBM Observations
  8. EP250207b: a new X-ray transient detected by Einstein Probe
  9. Fermi GRB 250210A: Global MASTER-Net observations report
  10. GRB 250210A: Fermi GBM Final Real-time Localization
  11. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  12. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  13. IceCube Alert 250207.09: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  15. GRB 250207A: 1.3m DFOT Optical observations
  16. GRB 250129A: GRANDMA Continued Afterglow Detection
  17. GRB 250207A: Swift-BAT refined analysis
  18. GRB 250205A: 1.3m DFOT optical upper limit
  19. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  20. GRB 250206A: Fermi-LAT detection
  21. LIGO/Virgo/KAGRA S250206dm: Candidates from the Zwicky Transient Facility
  22. GRB 250208A: Fermi GBM Final Real-time Localization
  23. EP250207a: EP-WXT detection and XRT follow-up observation
  24. LIGO/Virgo/KAGRA S250206dm: MMT galaxy targeted observations
  25. GRB 250207A: Swift-XRT refined Analysis
  26. EP-WXT trigger 01709131361: correction to GCN 39214
  27. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  28. LIGO/Virgo/KAGRA S250206dm: GOTO counterpart search update - AT2025bar
  29. EP-WXT trigger 01709131361 / LIGO/Virgo/KAGRA S250206dm: FTW optical and NIR observations
  30. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  31. GRB 250207A: REM IR afterglow detection
  32. GRB 250207A: FRAM-Auger optical detection
  33. GRB 250207A: REM optical afterglow detection
  34. GRB 250207A: Swift/UVOT Detection
  35. LIGO/Virgo/KAGRA S250206dm: GOTO observations of optical candidates AT 2025azn and AT 2025azm
  36. LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
  37. GRB 250129A: Continued AbAO and Mondy optical observations
  38. The EP-WXT trigger 01709131347 is likely a flaring star
  39. The EP-WXT trigger 01709131332 is likely a flaring star
  40. The EP-WXT trigger 01709131290 is likely a flaring star
  41. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  42. GRB 250207A: Swift detection of a burst with optical counterpart
  43. GRB 250207A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
  45. LIGO/Virgo/KAGRA S250206dm: Two counterpart neutrino candidates from IceCube neutrino searches
  46. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  47. GRB 250206A: Fermi GBM Final Real-time Localization
  48. GRB 250205A: Fermi GBM Observation
  49. GRB 250205A: REM NIR upper limit
  50. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  51. GRB 250205A: Swift/UVOT Upper Limits
  52. EP250205a/GRB 250205A: Einstein Probe observation
  53. GRB 250127C: SVOM/GRM observation of a burst
  54. GRB 250204B: SVOM/GRM observation of a likely short burst
  55. GRB 250205A: Swift/XRT detection
  56. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  57. GRB250205A: SVOM/VT optical afterglow detection
  58. GRB 250205A: GOTO optical upper limits
  59. GRB 250205A: OHP/T193 optical counterpart candidate
  60. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  61. GRB 250205A: SVOM detection of a burst
  62. GRB 250129A: Swift-BAT refined analysis
  63. EP 250108A: Upper limits from Fermi-GBM Observations
  64. IPN triangulation of GRB 250204B (short/hard)
  65. IPN triangulation of GRB 250202B
  66. GRB 250204B: Fermi GBM Final Localization
  67. GRB 250129A: LCO late afterglow detection
  68. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  69. GRB 250204A: Fermi GBM Final Real-time Localization
  70. GRB 250202B: NuSTAR detection of the prompt emission
  71. GRB 250202B: Fermi GBM Detection
  72. GRB 250129a: Liverpool Telescope optical follow-up
  73. The EP-WXT trigger 01709131196 is likely a flaring star
  74. GRB 250202C: Fermi GBM Final Real-time Localization
  75. GRB 250129A: SVOM/C-GFT optical observations
  76. The EP-WXT trigger 01709131153 is not a real source
  77. LIGO/Virgo/KAGRA S250202ad: Retraction of GW compact binary merger candidate
  78. GRB 250202B: Fermi GBM Final Real-time Localization
  79. Swift GRB250129A: MASTER 4 days observations report
  80. GRB 250202A: Fermi GBM Final Real-time Localization
  81. GRB 250129A: 1.3m DFOT Optical observations
  82. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  83. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  84. GRB 250201A: Fermi GBM Final Real-time Localization
  85. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  86. GRB 250129A: Skynet Continued Optical Observations
  87. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  88. EP250108A / SN 2025kg: Upper limits from a neutrino search with IceCube
  89. GRB 250129A: optical photometry from Konkoly
  90. GRB 250129A: iTelescope optical observation
  91. GRB 250129A: NOT optical observations of continuining activity
  92. GRB 250129a: Liverpool Telescope optical follow-up
  93. GRB 250129A: AKO Optical Afterglow Detection
  94. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  95. GRB 250128B: VLA radio upper limit
  96. Ep250125A: 1.3m DFOT optical upper limit
  97. GRB 250129A: Skynet optical observations
  98. GRB 250129A: Swift-XRT refined Analysis
  99. GRB 250128B: Gemini-North optical extended source detection
  100. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare

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