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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

23162 results found.

  1. GRB 250327B: J-band observations with WINTER
  2. GRB 250327B: LCO optical counterpart detection
  3. GRB 250328A: GWAC-F50A optical upper limit
  4. GRB 250328A: SVOM detection of a burst
  5. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  6. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  7. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  8. GRB 250327B: further optical observations by LCOGT
  9. EP250315a: Pan-STARRS r and i-band imaging and photometry
  10. GRB 250322A: GRANDMA/TNOT optical upper limits
  11. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  12. GRB 250327B: Las Cumbres optical counterpart detection
  13. GRB 250327B: 1.6m Mephisto optical observations
  14. GRB 250327A: Swift-XRT refined Analysis
  15. GRB 250327B: GOTO optical counterpart detection
  16. GRB 250327B: SAO RAS optical candidate
  17. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  18. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  19. GRB 250327A: J-band observations with WINTER
  20. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  21. Swift GRB 250327A: Global MASTER-Net observations report
  22. GRB 250327A: DDOTI Optical Observations
  23. GRB 250327A: Swift detection of a burst
  24. Konus-Wind detection of GRB 250322A (short)
  25. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  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. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  30. GRB 250322A: further NOT optical observations
  31. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  32. GRB 250321B: Swift-XRT observations
  33. GRB 250322A: Swift-XRT refined Analysis
  34. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  35. GRB 250322A: AstroSat CZTI detection of a short burst
  36. GRB 250322B: AstroSat CZTI detection of a bright long burst
  37. GRB250322A: STEP/T80S optical limits
  38. FRB 250316A: DDOTI Continued Optical Observations
  39. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  40. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  41. GRB 250322A: Swift detection of a short burst
  42. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  43. EP250321a: KAIT optical observations
  44. EP250321A: COLIBRÍ Continuing Optical Observations
  45. GRB 250225B: GECAM-A detection
  46. EP250321a: Xinglong 216 decaying optical observations
  47. GRB 250321A: Swift-BAT refined analysis
  48. GRB 250321A: Swift-XRT refined Analysis
  49. GRB 250320B: Fermi-LAT detection
  50. GRB 250321B: SVOM detection of a sub-threshold transient event
  51. EP 250321A: Optical counterpart detection by LCO.
  52. EP250321a: Kinder optical follow-up observations
  53. EP250321a: LCO optical counterpart detection
  54. EP250321A: COLIBRÍ Optical Observations
  55. EP250321a: REM optical/NIR afterglow detection
  56. EP250321a: BOOTES-5/JGT optical afterglow detection
  57. EP250321a: TRT optical counterpart detection
  58. Fermi GRB 250321A: Global MASTER-Net observations report
  59. GRB 250321A: GOTO optical upper limits
  60. GRB 250314A: Keck/NIRC2 J-band upper limit
  61. EP250226a/GRB 250226A: KAIT optical observations
  62. GRB 250321A: Fermi GBM Observation
  63. GRB 250321A: Swift detection of a burst
  64. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  65. GRB 250313A: GRBAlpha detection
  66. GRB 250317D: EIRSAT-1 GMOD Detection
  67. GRB 250317B: OHP/T193 continued follow-up
  68. GRB 250317C: AstroSat CZTI detection
  69. GRB 250317B: OHP/T193 optical observations
  70. GRB250312A: Swift/UVOT Upper Limits
  71. GRB 250317B: REM optical/NIR observations
  72. GRB 250316A: Swift/UVOT Upper Limits
  73. GRB 250314A: REM optical/NIR upper limits
  74. EP 250317B: Fading optical counterpart detection by LCO
  75. GRB 250316A: Swift-XRT afterglow detection
  76. GRB 250317B: LCO detection of the fading optical afterglow
  77. GRB 250317B: refined SVOM/MXT analysis
  78. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  79. GRB 250316A: Swift-XRT observations
  80. The EP-WXT trigger 01709132801 is likely a flaring star
  81. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  82. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250314A: Swift/UVOT Upper Limits
  84. GRB 250312B: GRBAlpha detection
  85. EP250315a: optical counterpart candidate detected by Gemini North
  86. EP250315a: Einstein Probe detection of an X-ray transient
  87. SVOM/MXT upper limit on GRB 250314A
  88. GRB 250313A: Fermi GBM Detection
  89. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  90. GRB 250313A: Swift-XRT observations
  91. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  92. Konus-Wind detection of GRB 250313A
  93. Konus-Wind detection of GRB 250308A
  94. GRB 250314A: SVOM detection of a burst
  95. GRB 250313A: AstroSat CZTI detection of a bright long burst
  96. GRB 250313A: Fermi-LAT detection
  97. EP250304a: Pan-STARRS r and i-band imaging and photometry
  98. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  99. GRB 250312A: Swift-XRT refined Analysis
  100. GRB 250302A: Fermi GBM Observation

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