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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"

28125 results found.

  1. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  2. GRB250329A: REM optical afterglow detection
  3. GRB 250329A: Swift-XRT afterglow detection
  4. GRB 250328A: SVOM/VT optical observation
  5. GRB 250329A: Fading optical counterpart detection by LCO.
  6. GRB 250328A: SVOM/C-GFT optical upper limit
  7. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  8. GRB 250329A: SVOM/VT optical counterpart confirmation
  9. GRB 250329A: SVOM detection of a burst
  10. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  11. GRB 250327B: J-band observations with WINTER
  12. GRB 250327B: LCO optical counterpart detection
  13. GRB 250328A: SVOM detection of a burst
  14. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  15. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  16. GRB 250327B: CrAO and SAO RAS Optical Observations
  17. GRB 250327b: Liverpool Telescope optical observations
  18. GRB 250322A: GRANDMA/TNOT optical upper limits
  19. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  20. GRB 250327A: SVOM/VT upper limits on the XRT position
  21. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  22. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  23. GRB 250327B: Las Cumbres optical counterpart detection
  24. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  25. GRB 250327B: 1.6m Mephisto optical observations
  26. GRB 250327A: Swift-XRT refined Analysis
  27. GRB 250327B: SVOM/VT optically bright counterpart
  28. GRB 250327B: SAO RAS optical candidate
  29. GRB 250327B: SVOM detection of a burst
  30. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  31. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  32. GRB 250327A: J-band observations with WINTER
  33. GRB 250327A: SVOM/VT optical candidate
  34. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  35. GRB 250327A: DDOTI Optical Observations
  36. GRB 250327A: COLIBRÍ optical upper limit
  37. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  38. IPN triangulation of GRB 250322B
  39. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  40. EP250321a: Mondy AZT-33IK Continued Optical Observations
  41. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  42. GRB 250322A: third epoch of NOT optical observations
  43. GRB 250322A: Swift-BAT refined analysis
  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. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  52. GRB 250321B: Swift-XRT observations
  53. GRB 250322A: Swift-XRT refined Analysis
  54. EP250321a: TNOT Observation of Optical Counterpart
  55. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  56. SVOM/sb25032302: SVOM detection of a long X-ray transient
  57. GRB 250322B: AstroSat CZTI detection of a bright long burst
  58. GRB 250322A: VLT optical observations
  59. GRB 250322A: VLT near-infrared observations
  60. FRB 250316A: DDOTI Continued Optical Observations
  61. GRB 250322A: NOT optical upper limits
  62. GRB 250322A: Enhanced Swift-XRT position
  63. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  64. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  65. EP250321a: Liverpool Telescope optical follow-up
  66. EP250321a: Mondy AZT-33IK Optical Observations
  67. GRB 250322A: Swift detection of a short burst
  68. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  69. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  70. EP250321A: COLIBRÍ Continuing Optical Observations
  71. EP250321a: WFST optical observations
  72. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  73. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  74. GRB 250320B: Fermi GBM Observation
  75. EP250321a: Xinglong 216 decaying optical observations
  76. GRB 250321A: Swift-BAT refined analysis
  77. GRB 250321A: Swift-XRT refined Analysis
  78. EP 250321A: Optical counterpart detection by LCO.
  79. EP250321a: Kinder optical follow-up observations
  80. GRB 250321A: Swift/UVOT Upper Limits
  81. GRB 250320B: SVOM/GRM observation of a long burst
  82. EP250321a: LCO optical counterpart detection
  83. EP250321a: Swift-XRT detection of an X-ray source
  84. EP250321A: COLIBRÍ Optical Observations
  85. GRB 250320B: AstroSat CZTI detection
  86. EP250321a: REM optical/NIR afterglow detection
  87. EP250321a: TRT optical counterpart detection
  88. Swift GRB 250321A: Global MASTER-Net observations report
  89. EP250321a: Einstein Probe detection of an X-ray transient
  90. GRB 250321A: GOTO optical upper limits
  91. GRB 250314A: Keck/NIRC2 J-band upper limit
  92. EP250226a/GRB 250226A: KAIT optical observations
  93. GRB 250321A: Fermi GBM Observation
  94. GRB 250321A: Swift detection of a burst
  95. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  96. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  97. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  98. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  99. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  100. GRB 250317D: EIRSAT-1 GMOD Detection

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