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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"

23558 results found.

  1. GRB 250328A: 1.6m Mephisto optical observations
  2. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  3. GRB 250330A: VLT/FORS2 Optical Observations
  4. GRB 250329B: Swift-XRT afterglow detection
  5. GRB 250330A: Swift detection of a burst
  6. GRB 250329B: SVOM/C-GFT optical upper limit
  7. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  8. GRB 250329B: SVOM/VT optical upper limit
  9. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  10. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  11. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  12. GRB250329A: REM optical afterglow detection
  13. GRB 250329B: GWAC-F50A optical upper limit
  14. GRB 250329A: Swift-XRT afterglow detection
  15. GRB 250328A: SVOM/VT optical observation
  16. GRB 250329A: Fading optical counterpart detection by LCO.
  17. GRB 250328A: SVOM/C-GFT optical upper limit
  18. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  19. GRB 250329A: SVOM/VT optical counterpart confirmation
  20. GRB 250329A: SVOM detection of a burst
  21. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  22. GRB 250327B: J-band observations with WINTER
  23. GRB 250327B: LCO optical counterpart detection
  24. GRB 250328A: GWAC-F50A optical upper limit
  25. FRB 20250316A: FTW optical observations
  26. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  27. GRB 250327B: CrAO and SAO RAS Optical Observations
  28. EP250315a: Pan-STARRS r and i-band imaging and photometry
  29. GRB 250327b: Liverpool Telescope optical observations
  30. GRB 250322A: GRANDMA/TNOT optical upper limits
  31. GRB 250327A: SVOM/VT upper limits on the XRT position
  32. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  33. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  34. GRB 250327B: Las Cumbres optical counterpart detection
  35. GRB 250327B: 1.6m Mephisto optical observations
  36. GRB 250327B: SVOM/VT optically bright counterpart
  37. GRB 250327B: SAO RAS optical candidate
  38. GRB 250327B: SVOM detection of a burst
  39. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  40. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  41. GRB 250327A: J-band observations with WINTER
  42. GRB 250327A: SVOM/VT optical candidate
  43. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  44. GRB 250327A: DDOTI Optical Observations
  45. GRB 250327A: COLIBRÍ optical upper limit
  46. GRB 250327A: Swift detection of a burst
  47. Fermi trigger No 764700395: Global MASTER-Net observations report
  48. Konus-Wind detection of GRB 250322A (short)
  49. IPN triangulation of GRB 250322B
  50. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  51. EP250321a: Mondy AZT-33IK Continued Optical Observations
  52. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  53. GRB 250322A: third epoch of NOT optical observations
  54. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  55. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  56. GRB 250322A: further NOT optical observations
  57. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  58. GRB 250322A: Swift/UVOT Upper Limits
  59. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  60. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  61. GRB 250321B: Swift-XRT observations
  62. EP250321a: TNOT Observation of Optical Counterpart
  63. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  64. GRB 250322B: AstroSat CZTI detection of a bright long burst
  65. GRB250322A: STEP/T80S optical limits
  66. GRB 250322A: Gemini-South optical observations
  67. GRB 250322A: VLT optical observations
  68. GRB 250322A: VLT near-infrared observations
  69. FRB 250316A: DDOTI Continued Optical Observations
  70. GRB 250322A: NOT optical upper limits
  71. GRB 250322A: Enhanced Swift-XRT position
  72. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  73. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  74. EP250321a: Liverpool Telescope optical follow-up
  75. EP250321a: Mondy AZT-33IK Optical Observations
  76. GRB 250322A: Swift detection of a short burst
  77. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  78. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  79. EP250321A: COLIBRÍ Continuing Optical Observations
  80. EP250321a: WFST optical observations
  81. EP250321a: Xinglong 216 decaying optical observations
  82. GRB 250321A: Swift-XRT refined Analysis
  83. EP 250321A: Optical counterpart detection by LCO.
  84. EP250321a: Kinder optical follow-up observations
  85. GRB 250321A: Swift/UVOT Upper Limits
  86. GRB 250320B: SVOM/GRM observation of a long burst
  87. EP250321a: LCO optical counterpart detection
  88. EP250321A: COLIBRÍ Optical Observations
  89. GRB 250320B: AstroSat CZTI detection
  90. EP250321a: REM optical/NIR afterglow detection
  91. EP250321a: TRT optical counterpart detection
  92. EP250321a: Einstein Probe detection of an X-ray transient
  93. GRB 250321A: GOTO optical upper limits
  94. GRB 250314A: Keck/NIRC2 J-band upper limit
  95. EP250226a/GRB 250226A: KAIT optical observations
  96. GRB 250321A: Swift detection of a burst
  97. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  98. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  99. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  100. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations

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