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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

23577 results found.

  1. GRB 250322B possible detection by the AstroSat Satellite
  2. GRB 250330B: SVOM/GRM observation of a short burst
  3. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  4. GRB 250331C: Enhanced Swift-XRT position
  5. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  6. GRB 250331B: Enhanced Swift-XRT position
  7. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  8. GRB 250330A: VLT/FORS2 Afterglow Detection
  9. GRB20250327B: 45th Parallel Observatory upper limit
  10. GRB 250328A: Swift/UVOT Detection
  11. GRB 250328A: Swift-XRT refined Analysis
  12. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  13. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  14. GRB 250331C: Swift detection of a burst
  15. GRB 250331B: Swift detection of a burst
  16. GRB 250330A: SVOM/VT optical upper limit
  17. LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
  18. GRB 250330A: Swift/UVOT Upper Limits
  19. GRB 250330A: Swift-XRT afterglow detection
  20. GRB 250328A: 1.6m Mephisto optical observations
  21. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  22. GRB 250330A: VLT/FORS2 Optical Observations
  23. GRB 250329B: Swift-XRT afterglow detection
  24. GRB 250330A: Swift detection of a burst
  25. GRB 250329B: SVOM/C-GFT optical upper limit
  26. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  27. GRB 250329B: SVOM/VT optical upper limit
  28. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  29. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  30. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  31. GRB250329A: REM optical afterglow detection
  32. GRB 250329B: GWAC-F50A optical upper limit
  33. GRB 250329A: Swift-XRT afterglow detection
  34. GRB 250328A: SVOM/VT optical observation
  35. GRB 250329A: Fading optical counterpart detection by LCO.
  36. GRB 250328A: SVOM/C-GFT optical upper limit
  37. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  38. GRB 250329A: SVOM/VT optical counterpart confirmation
  39. GRB 250329A: SVOM detection of a burst
  40. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  41. GRB 250327B: J-band observations with WINTER
  42. GRB 250327B: LCO optical counterpart detection
  43. GRB 250328A: GWAC-F50A optical upper limit
  44. FRB 20250316A: FTW optical observations
  45. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  46. GRB 250327B: CrAO and SAO RAS Optical Observations
  47. EP250315a: Pan-STARRS r and i-band imaging and photometry
  48. GRB 250327b: Liverpool Telescope optical observations
  49. GRB 250322A: GRANDMA/TNOT optical upper limits
  50. GRB 250327A: SVOM/VT upper limits on the XRT position
  51. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  52. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  53. GRB 250327B: Las Cumbres optical counterpart detection
  54. GRB 250327B: 1.6m Mephisto optical observations
  55. GRB 250327B: SVOM/VT optically bright counterpart
  56. GRB 250327B: SAO RAS optical candidate
  57. GRB 250327B: SVOM detection of a burst
  58. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  59. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  60. GRB 250327A: J-band observations with WINTER
  61. GRB 250327A: SVOM/VT optical candidate
  62. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  63. GRB 250327A: DDOTI Optical Observations
  64. GRB 250327A: COLIBRÍ optical upper limit
  65. GRB 250327A: Swift detection of a burst
  66. Fermi trigger No 764700395: Global MASTER-Net observations report
  67. Konus-Wind detection of GRB 250322A (short)
  68. IPN triangulation of GRB 250322B
  69. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  70. EP250321a: Mondy AZT-33IK Continued Optical Observations
  71. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  72. GRB 250322A: third epoch of NOT optical observations
  73. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  74. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  75. GRB 250322A: further NOT optical observations
  76. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  77. GRB 250322A: Swift/UVOT Upper Limits
  78. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  79. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  80. GRB 250321B: Swift-XRT observations
  81. EP250321a: TNOT Observation of Optical Counterpart
  82. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  83. GRB 250322B: AstroSat CZTI detection of a bright long burst
  84. GRB250322A: STEP/T80S optical limits
  85. GRB 250322A: Gemini-South optical observations
  86. GRB 250322A: VLT optical observations
  87. GRB 250322A: VLT near-infrared observations
  88. FRB 250316A: DDOTI Continued Optical Observations
  89. GRB 250322A: NOT optical upper limits
  90. GRB 250322A: Enhanced Swift-XRT position
  91. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  92. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  93. EP250321a: Liverpool Telescope optical follow-up
  94. EP250321a: Mondy AZT-33IK Optical Observations
  95. GRB 250322A: Swift detection of a short burst
  96. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  97. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  98. EP250321A: COLIBRÍ Continuing Optical Observations
  99. EP250321a: WFST optical observations
  100. EP250321a: Xinglong 216 decaying optical observations

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