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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"

28110 results found.

  1. GRB 250327B: CrAO and SAO RAS Optical Observations
  2. GRB 250327b: Liverpool Telescope optical observations
  3. GRB 250322A: GRANDMA/TNOT optical upper limits
  4. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  5. GRB 250327A: SVOM/VT upper limits on the XRT position
  6. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  7. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  8. GRB 250327B: Las Cumbres optical counterpart detection
  9. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  10. GRB 250327B: 1.6m Mephisto optical observations
  11. GRB 250327A: Swift-XRT refined Analysis
  12. GRB 250327B: SVOM/VT optically bright counterpart
  13. GRB 250327B: SAO RAS optical candidate
  14. GRB 250327B: SVOM detection of a burst
  15. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  16. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  17. GRB 250327A: J-band observations with WINTER
  18. GRB 250327A: SVOM/VT optical candidate
  19. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  20. GRB 250327A: DDOTI Optical Observations
  21. GRB 250327A: COLIBRÍ optical upper limit
  22. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  23. IPN triangulation of GRB 250322B
  24. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  25. EP250321a: Mondy AZT-33IK Continued Optical Observations
  26. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  27. GRB 250322A: third epoch of NOT optical observations
  28. GRB 250322A: Swift-BAT refined analysis
  29. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  30. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  31. GRB 250322A: further NOT optical observations
  32. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  33. GRB 250322A: Swift/UVOT Upper Limits
  34. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  35. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  36. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  37. GRB 250321B: Swift-XRT observations
  38. GRB 250322A: Swift-XRT refined Analysis
  39. EP250321a: TNOT Observation of Optical Counterpart
  40. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  41. SVOM/sb25032302: SVOM detection of a long X-ray transient
  42. GRB 250322B: AstroSat CZTI detection of a bright long burst
  43. GRB 250322A: VLT optical observations
  44. GRB 250322A: VLT near-infrared observations
  45. FRB 250316A: DDOTI Continued Optical Observations
  46. GRB 250322A: NOT optical upper limits
  47. GRB 250322A: Enhanced Swift-XRT position
  48. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  49. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  50. EP250321a: Liverpool Telescope optical follow-up
  51. EP250321a: Mondy AZT-33IK Optical Observations
  52. GRB 250322A: Swift detection of a short burst
  53. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  54. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP250321A: COLIBRÍ Continuing Optical Observations
  56. EP250321a: WFST optical observations
  57. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  58. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  59. GRB 250320B: Fermi GBM Observation
  60. EP250321a: Xinglong 216 decaying optical observations
  61. GRB 250321A: Swift-BAT refined analysis
  62. GRB 250321A: Swift-XRT refined Analysis
  63. EP 250321A: Optical counterpart detection by LCO.
  64. EP250321a: Kinder optical follow-up observations
  65. GRB 250321A: Swift/UVOT Upper Limits
  66. GRB 250320B: SVOM/GRM observation of a long burst
  67. EP250321a: LCO optical counterpart detection
  68. EP250321a: Swift-XRT detection of an X-ray source
  69. EP250321A: COLIBRÍ Optical Observations
  70. GRB 250320B: AstroSat CZTI detection
  71. EP250321a: REM optical/NIR afterglow detection
  72. EP250321a: TRT optical counterpart detection
  73. Swift GRB 250321A: Global MASTER-Net observations report
  74. EP250321a: Einstein Probe detection of an X-ray transient
  75. GRB 250321A: GOTO optical upper limits
  76. GRB 250314A: Keck/NIRC2 J-band upper limit
  77. EP250226a/GRB 250226A: KAIT optical observations
  78. GRB 250321A: Fermi GBM Observation
  79. GRB 250321A: Swift detection of a burst
  80. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  81. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  82. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  83. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  84. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  85. GRB 250317D: EIRSAT-1 GMOD Detection
  86. LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
  87. GRB 250314A: ATCA radio upper limits
  88. GRB 250317B: OHP/T193 continued follow-up
  89. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  90. GRB 250317C: SVOM/GRM observation of a long burst
  91. GRB 250317B: Leavitt Observatory optical upper limit
  92. GRB 250317B: Mondy AZT-33IK Optical Observations
  93. GRB 250317B: NOT optical observations suggest an optical plateau phase
  94. GRB 250317C: GECAM-B detection
  95. GRB 250317B: OHP/T193 optical observations
  96. GRB250312A: Swift/UVOT Upper Limits
  97. GRB 250317B: REM optical/NIR observations
  98. GRB 250317B: Swift-XRT observations
  99. GRB 250316A: Swift/UVOT Upper Limits
  100. GRB 250314A: REM optical/NIR upper limits

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