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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"

45673 results found.

  1. GRB 250327B: further optical observations by LCOGT
  2. EP250315a: Pan-STARRS r and i-band imaging and photometry
  3. GRB 250327b: Liverpool Telescope optical observations
  4. GRB 250322A: GRANDMA/TNOT optical upper limits
  5. LIGO/Virgo/KAGRA S250328ae: Updated Sky localization
  6. GRB 250327A: SVOM/VT upper limits on the XRT position
  7. LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
  8. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  9. GRB 250327B: Las Cumbres optical counterpart detection
  10. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  11. GRB 250327B: 1.6m Mephisto optical observations
  12. GRB 250327B: NOT spectroscopic redshift z = 3.035
  13. GRB 250327A: Swift-XRT refined Analysis
  14. GRB 250327B: GOTO optical counterpart detection
  15. GRB 250327B: SVOM/VT optically bright counterpart
  16. GRB 250327B: SAO RAS optical candidate
  17. GRB 250327B: SVOM detection of a burst
  18. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  19. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  20. GRB 250327A: J-band observations with WINTER
  21. GRB 250327A: SVOM/VT optical candidate
  22. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  23. GRB 250327A: Fermi GBM observation
  24. Fermi GRB 250327A: Global MASTER-Net observations report
  25. Swift GRB 250327A: Global MASTER-Net observations report
  26. GRB 250327A: DDOTI Optical Observations
  27. GRB 250327A: COLIBRÍ optical upper limit
  28. GRB 250327A: Swift detection of a burst
  29. GRB 250327A: Fermi GBM Final Real-time Localization
  30. Fermi trigger No 764700395: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  32. Konus-Wind detection of GRB 250322A (short)
  33. IPN triangulation of GRB 250322B
  34. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  35. EP250321a: Mondy AZT-33IK Continued Optical Observations
  36. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  37. GRB 250322A: third epoch of NOT optical observations
  38. GRB 250322A: Swift-BAT refined analysis
  39. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  40. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  41. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  42. GRB 250322A: further NOT optical observations
  43. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  44. GRB 250322A: Swift/UVOT Upper Limits
  45. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  46. GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
  47. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  48. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  49. GRB 250321B: Swift-XRT observations
  50. GRB 250322A: Swift-XRT refined Analysis
  51. EP250321a: TNOT Observation of Optical Counterpart
  52. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  53. GRB 250322A: Gemini-North redshift of candidate host galaxy
  54. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  55. SVOM/sb25032302: SVOM detection of a long X-ray transient
  56. GRB 250322A: AstroSat CZTI detection of a short burst
  57. GRB 250322B: AstroSat CZTI detection of a bright long burst
  58. GRB250322A: STEP/T80S optical limits
  59. GRB 250322A: Gemini-South optical observations
  60. GRB 250322A: VLT optical observations
  61. GRB 250322A: VLT near-infrared observations
  62. FRB 250316A: DDOTI Continued Optical Observations
  63. GRB 250322A: NOT optical upper limits
  64. GRB 250322A: Enhanced Swift-XRT position
  65. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  66. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  67. GRB 250322A: MASTER optical observation
  68. EP250321a: Liverpool Telescope optical follow-up
  69. EP250321a: Mondy AZT-33IK Optical Observations
  70. GRB 250322A: Swift detection of a short burst
  71. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  72. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  73. EP250321a: KAIT optical observations
  74. EP250321A: COLIBRÍ Continuing Optical Observations
  75. GRB 250225B: GECAM-A detection
  76. GRB 250312A: GECAM-A detection
  77. GRB 250321B: Swift ToO observations
  78. EP250321a: WFST optical observations
  79. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  80. GRB 250321C: Fermi GBM Final Real-time Localization
  81. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  82. GRB 250320B: Fermi GBM Observation
  83. EP250321a: Xinglong 216 decaying optical observations
  84. GRB 250321A: Swift-BAT refined analysis
  85. GRB 250321A: Swift-XRT refined Analysis
  86. GRB 250320B: Fermi-LAT detection
  87. GRB 250321B: SVOM detection of a sub-threshold transient event
  88. EP250321a: SVOM/VT optical observation
  89. EP 250321A: Optical counterpart detection by LCO.
  90. EP250321a: Kinder optical follow-up observations
  91. GRB 250321A: Swift/UVOT Upper Limits
  92. GRB 250320B: SVOM/GRM observation of a long burst
  93. EP250321a: LCO optical counterpart detection
  94. EP250321a: Swift-XRT detection of an X-ray source
  95. EP250321A: COLIBRÍ Optical Observations
  96. EP250321a: VLT/X-shooter redshift z = 4.368
  97. GRB 250320B: AstroSat CZTI detection
  98. EP250321a: REM optical/NIR afterglow detection
  99. Fermi GRB 250320B: Global MASTER-Net observations report
  100. EP250321a: BOOTES-5/JGT optical afterglow detection

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