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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"

16110 results found.

  1. GRB 250327B: VLA detection
  2. GRB 250329B: SVOM/VT optical upper limit
  3. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  4. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  5. GRB250329A: REM optical afterglow detection
  6. GRB 250329B: GWAC-F50A optical upper limit
  7. GRB 250329A: Swift-XRT afterglow detection
  8. GRB 250328A: SVOM/VT optical observation
  9. GRB 250329A: Fading optical counterpart detection by LCO.
  10. GRB 250328A: SVOM/C-GFT optical upper limit
  11. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  12. GRB 250329A: VLT/X-shooter redshift z = 2.921
  13. GRB 250329A: SVOM/VT optical counterpart confirmation
  14. GRB 250329A: SVOM detection of a burst
  15. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  16. GRB 250327B: J-band observations with WINTER
  17. GRB 250327B: MASTER detection of OT rebrightening
  18. GRB 250327B: LCO optical counterpart detection
  19. GRB 250328A: GWAC-F50A optical upper limit
  20. FRB 20250316A: FTW optical observations
  21. GRB 250327B: CrAO and SAO RAS Optical Observations
  22. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  23. GRB 250327B: further optical observations by LCOGT
  24. EP250315a: Pan-STARRS r and i-band imaging and photometry
  25. GRB 250327b: Liverpool Telescope optical observations
  26. GRB 250322A: GRANDMA/TNOT optical upper limits
  27. GRB 250327B: Las Cumbres optical counterpart detection
  28. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  29. GRB 250327B: 1.6m Mephisto optical observations
  30. GRB 250327B: NOT spectroscopic redshift z = 3.035
  31. GRB 250327B: GOTO optical counterpart detection
  32. GRB 250327B: SVOM/VT optically bright counterpart
  33. GRB 250327B: SAO RAS optical candidate
  34. GRB 250327B: SVOM detection of a burst
  35. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  36. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  37. GRB 250327A: SVOM/VT optical candidate
  38. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  39. GRB 250327A: DDOTI Optical Observations
  40. GRB 250327A: COLIBRÍ optical upper limit
  41. EP250321a: Mondy AZT-33IK Continued Optical Observations
  42. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  43. GRB 250322A: third epoch of NOT optical observations
  44. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  45. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  46. GRB 250322A: further NOT optical observations
  47. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  48. GRB 250322A: Swift/UVOT Upper Limits
  49. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  50. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  51. EP250321a: TNOT Observation of Optical Counterpart
  52. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  53. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  54. GRB250322A: STEP/T80S optical limits
  55. GRB 250322A: Gemini-South optical observations
  56. GRB 250322A: VLT optical observations
  57. FRB 250316A: DDOTI Continued Optical Observations
  58. GRB 250322A: NOT optical upper limits
  59. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  60. GRB 250322A: MASTER optical observation
  61. EP250321a: Liverpool Telescope optical follow-up
  62. EP250321a: Mondy AZT-33IK Optical Observations
  63. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  64. EP250321a: KAIT optical observations
  65. EP250321A: COLIBRÍ Continuing Optical Observations
  66. EP250321a: WFST optical observations
  67. EP250321a: Xinglong 216 decaying optical observations
  68. EP250321a: SVOM/VT optical observation
  69. EP 250321A: Optical counterpart detection by LCO.
  70. EP250321a: Kinder optical follow-up observations
  71. GRB 250321A: Swift/UVOT Upper Limits
  72. GRB 250320B: SVOM/GRM observation of a long burst
  73. EP250321a: LCO optical counterpart detection
  74. EP250321a: Swift-XRT detection of an X-ray source
  75. EP250321A: COLIBRÍ Optical Observations
  76. EP250321a: VLT/X-shooter redshift z = 4.368
  77. EP250321a: REM optical/NIR afterglow detection
  78. EP250321a: BOOTES-5/JGT optical afterglow detection
  79. EP250321a: TRT optical counterpart detection
  80. GRB 250321A: GOTO optical upper limits
  81. EP250226a/GRB 250226A: KAIT optical observations
  82. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  83. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  84. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  85. GRB 250314A: ATCA radio upper limits
  86. EP250302a: VLA observations
  87. GRB 250317B: OHP/T193 continued follow-up
  88. GRB 250317C: SVOM/GRM observation of a long burst
  89. GRB 250317B: Leavitt Observatory optical upper limit
  90. GRB 250309B/AT2025dws: further ATCA observations
  91. GRB 250317B: Mondy AZT-33IK Optical Observations
  92. GRB 250317B: NOT optical observations suggest an optical plateau phase
  93. GRB 250317B: OHP/T193 optical observations
  94. GRB250312A: Swift/UVOT Upper Limits
  95. GRB 250317B: REM optical/NIR observations
  96. GRB 250317B: Swift-XRT observations
  97. GRB 250316A: Swift/UVOT Upper Limits
  98. GRB 250314A: REM optical/NIR upper limits
  99. GRB 250316A: AbAO AS-32 Optical Upper Limit
  100. EP 250317B: Fading optical counterpart detection by LCO

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